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Plant secondary metabolites are having the great application in human health and nutritional aspect. Plant cell and organ culture systems are feasible option for the production of secondary metabolites that are of commercial importance in pharmaceuticals, food additives, flavors, and other industrial materials. The stress, including various elicitors or signal molecules, often induces the secondary metabolite production in the plant tissue culture system. The recent developments in elicitation of plant tissue culture have opened a new avenue for the production of secondary metabolite compounds. Secondary metabolite synthesis and accumulation in cell and organ cultures can be triggered by the application of elicitors to the culture medium. Elicitors are the chemical compounds from abiotic and biotic sources that can stimulate stress responses in plants, leading to the enhanced synthesis and accumulation of secondary metabolites or the induction of novel secondary metabolites. Elicitor type, dose, and treatment schedule are major factors determining the effects on the secondary metabolite production. The number of parameters, such as elicitor concentrations, duration of exposure, cell line, nutrient composition, and age or stage of the culture, is also important factors influencing the successful production of biomass and secondary metabolite accumulation. This chapter reviews the various abiotic and biotic elicitors applied to cultural system and their stimulating effects on the accumulation of secondary metabolites.
Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, Al–Hassa, Saudi Arabia
Jameel M. Al–Khayri*
Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, Al–Hassa, Saudi Arabia
*Address all correspondence to: jmkhayri@yahoo.com; jkhayri@kfu.edu.sa
1. Introduction
The total mankind is dependent on plants as a source of carbohydrates, proteins, vitamins, food, and shelter. Plants are studied for their important constituents and the nutritional factors for over decades. Along with the essential primary metabolites, higher plants are also capable to produce a number of low molecular weight compounds. A diverse group of organic compounds that are produced by plants to facilitate interaction with the biotic environment and the establishment of a defense mechanism are called as plant secondary metabolites [1–3]. The production of these metabolites is very low (less than 1% dry weight) and depends greatly on the physiological and developmental stage of the plant [4,5]. Plant natural products have been an important part of medicine throughout human history. In recent years, the use of herbal medicines has steadily increased worldwide [6]. With this increasing demand comes growing concerns about the safety and efficacy of herbal medicines. Although the potential for medicinal plants seems almost limitless, there are a few major obstacles that hinder large-scale utilization by the western medical system. Among them is the lack of reproducibility common in testing many plant extracts (up to 40%), which has limited the enthusiasm for developing plant-based pharmaceuticals [7]. Unlike standardized single-entity pharmaceutical drugs, herbal medicines consist of complex mixtures with multiple compounds responsible for therapeutic activity, making standardization difficult [8]. Further complicating the issue is the fact that plants, unlike synthetic medicines, are living organisms, with inherent biological variation [9]. Just because plant material originates from the same species, it does not necessarily mean that the chemical content will be identical. This lack of reproducibility may be due to two main factors, genetic variability and differences in growing conditions.
In addition, plants are a valuable source of a wide range of secondary metabolites, which are used as pharmaceuticals, agrochemicals, flavors, fragrances, colors, biopesticides, and food additives. Plants are producing new compounds and in future new chemical models are drawing for new drugs because the most of the plants chemistry is yet to be explored [10]. The characterization of molecular structures and chemical analysis helped us to pinpoint the activities of plants under controlled conditions. Although all these advancements, we still depend on the secondary metabolites of biological sources including pharmaceuticals [11].
Due to various agro alimentary, perfumes, flavors, colors, and pharmacological effects, the secondary metabolites are having extensive demand and various commercial preparations are available in the market. Besides, the appeal of using natural products for medicinal purposes is increasing, and metabolic engineering can alter the production of pharmaceuticals and help to design new therapies. The evolving commercial importance of secondary metabolites has in recent years resulted in a greater interest in secondary metabolism, particularly in the possibility of altering the production of bioactive plant metabolites [12]. Secondary metabolites are separated into nitrogen compounds (alkaloids, nonprotein amino acids, amines, alcamides, cyanogenic glycosides, and glucosinolates) and nonnitrogen compounds (monoterpenes, diterpenes, triterpenes, tetraterpenes, sesquiterpenes, saponins, flavonoids, steroids, and coumarins).
The plant tissue culture plays an important role in the rapid clonal propagation, regeneration of genetically manipulated superior clones, conservation of germplasm, production of secondary metabolites, and ex vitro conservation of valuable phytodiversity [13,14]. The plant, cell, tissue and organ culture techniques have come up with an escapable tool with the possibilities of acclaiming and supplementing the conventional method in plant breeding, plant improvement, and biosynthetic pathways. This technique has several potential applications in crop improvement, and efficient regeneration is a prerequisite in such improvement programs. The biotechnological production of secondary metabolites in plant cell and organ cultures is an attractive alternative to the extraction of the whole plant material [15]. In particular, plant–specific important compounds are obtained by using the plant cell and organ cultures [2]. The faster proliferation rates and shorter biosynthetic cycle of cell and organ cultures leads to have a higher rate of metabolism when compared to field grown plants [16]. Further, plant cell/organ cultures are under controlled conditions proliferates at their optimum growth rates when compared to the cultivated plants, which are facing environmental, ecological, and climatic variations. In recent years, various strategies have been developed for use in biomass accumulation and the synthesis of secondary compounds, such as strain improvement, optimization of medium, and culture environments, elicitation, precursor feeding, metabolic engineering, permeabilization, immobilization, and biotransformation methods, bioreactor cultures, and micropropagation [17]. The focus of the present chapter is the influence of abiotic and biotic elicitors on the secondary metabolite production in the in vitro cultured medicinal plants.
2. Classification of elicitors and secondary metabolite production via in vitro culture of medicinal plants
Stress is an important factor in determining the chemical composition and therapeutic activity of medicinal plants. Actively stimulating, or eliciting, the plant stress response to induce the desired chemical response is called elicitation, harnessing the connection between plant stress and phytochemistry. “Elicitor may be defined as a substance for stress factors which, when applied in small quantity to a living system, it induces or improves the biosynthesis of specific compound which do have an important role in the adaptations of plants to a stressful conditions” [18]. Elicitation is the induced or enhanced biosynthesis of metabolites due to addition of trace amounts of elicitors [18]. Several biotechnological strategies have been hypothesized and applied for the productivity enhancement, and elicitation is recognized as the most practically feasible strategy for increasing the production of desirable secondary compounds from cell, organ, and plant systems [19–21].
On the basis of nature, elicitors can be divided into two types abiotic and biotic (Figure 1). Abiotic elicitors comprise of substances that are of nonbiological origin and are grouped in physical, chemical, and hormonal factors. Biotic elicitors are the substances of biological origin that include polysaccharides originated from plant cell walls (e.g. chitin, pectin, and cellulose) and micro–organisms.
As mentioned above, the abiotic elicitors are categorized into physical, chemical, and hormonal elicitors. Abiotic elicitors have wide range of effects on the plants and in the production of secondary metabolites (Table 1).
Effect of Different Abiotic Elicitors on the Production of Various Secondary Metabolites in Plants
3.1. Physical elicitors
Physical elicitors include light, osmotic stress, salinity, drought, and thermal stress.
3.1.1. Light
The light is a physical factor that can affect the metabolite production. Light can stimulate such secondary metabolites include gingerol and zingiberene production in Zingiber officinale callus culture [22]. The effect of light irradiation on anthocyanin production in cell suspension cultures of Perilla frutescens was reported [23]. The effect of light and hormones on the digitoxin accumulation in Digitalis purpurea L. was reported by Hagimori et al. [24]. Moreover, in hairy root cultures of Artemisiaannua, the effect of light irradiation influenced the artemisinin biosynthesis [25]. The effect of white light on taxol and baccatin III accumulation in cell cultures of Taxuscuspidate was reported by Fett–Neto et al. [26]. Ultraviolet (UV) radiation stimulates secondary metabolite production. Increasing UV–B exposure in field–grown plants not only increased the total essential oil and phenolic content but also decreased the amount of the possibly toxic beta–asarone [27]. These findings are to be expected as phenolics are known UV protectants [28]. Catharanthus roseus plants, exposed to UV–B light, show significant increases in the production of vinblastine and vincristine, which have proven effective in the treatment of leukemia and lymphoma [29]. UV–C irradiation promotes the phenylpropanoid pathway and stimulates flavonoid synthesis [30]. UV–C irradiation is an effective method to enhance stilbene production in Vitis vinifera berries [31], V. vinifera leaves [32], and V. vinifera callus of different genotypes [33]. UV–C together with methyl jasmonate (MeJA) or salicylic acid (SA) also used to enhance stilbene production in V. vinifera cell cultures [34].
3.1.2. Osmotic stress
Osmotic stress (water stress) is an abiotic physical elicitor [35] and is one of the important environmental stresses that can alter the physiological and biochemical properties of plants and increase the concentration of secondary metabolites in plant tissues [36]. Proline acts as an osmolyte, as protective agent for cytoplasmic enzymes, as a reservoir of nitrogen and carbon sources for post–stress growth, or even as a stabilizer of the machinery for protein synthesis, regulation of cytosolic acidity and scavenging of free radicals [37]. However, the various roles of proline have been proposed, but the main role could be the osmotic adjustment in osmotically stressed plant tissues and the protection of plasma membrane integrity [38]. Polyethylene glycol (PEG) is an osmotic agent (nonpenetrating osmoticum) that has been used for induction of water stress in many plants [39]. The proline and PEG enhanced the production of steviol glycosides content in both callus as well as suspension culture of Stevia rebaudiana [40]. PEG elicited the pharmacologically active compounds, such as hypericin and pseudohypericin, in Hypericum adenotrichum [41]. Sucrose is a typical osmotic stress agent used for the induction of water stress in plants that also serves as a vital carbon and energy source [42]. It has been shown that water and osmotic imbalance can strongly influence the synthesis of hypericin and hyperforin in Hypericumperforatum plants [43]. In addition, it has been reported that both hypericin and pseudohypericin concentrations decreased, while hyperforin concentration increased significantly in the plants grown under water stress conditions [36].
3.1.3. Salinity
Salinity reduces plant growth and development and alters a wide array of physiological and metabolic processes [44,45]. Plants have developed complex mechanisms for adaptation to the osmotic, ionic, and oxidative stresses that are induced by the salt stress. Exposure to salinity is known to induce or stimulate the production of secondary plant products, such as phenols, terpenes, and alkaloids [46–48]. C. roseus grown under salt stress showed increased levels of the alkaloid vincristine [49]. In Grevillea, a significant increase in anthocyanin concentration was reported under salinity exposure in both the salt–tolerant Grevillea ilicifolia and the salt–sensitive Grevillea arenaria [50]. In contrast to this, salt stress decreased the anthocyanin level in the salt–sensitive species [51]. In Datura innoxia, salt treatment increased the total alkaloid content in young leaves, and the results indicated that at the organ level, tropane alkaloid accumulation was related to plant growth [52]. Glycine betaine was increased under salinity in numerous species including Triticum aestivum [53] and Trifolium repens [54]. Salinity also increased the diamine and polyamine content in Oryza sativa [53]. An improved synthesis of vinblastine and vincristine was observed in C. roseus embryogenic tissue culture by using NaCl as an elicitor [55].
3.1.4. Drought stress
One of the most important abiotic stress is drought, which affect plant growth and their developmental process [56]. The available water in the soil is reduced to such critical levels, and atmospheric conditions add to the continuous loss of water; the situation is called drought stress. The high temperature in the environment and solar radiations add up the water deficit in the soil, which leads to drought stress. Drought stress tolerance is observed in all types of plants, but its extent varies from species to species [56]. Drought stress, which can also greatly reduce plant growth, can increase secondary metabolite content. Mild water stress significantly increased the content of the anti–inflammatory saikosaponins in Bupleurum chinense [57]. Moderate water stress increased the content of salvianolic acid in roots of Salvia miltiorrhiza, although the content of other bioactives, including tanshinone, was lowered [58]. Moderate drought stress also increased the production of rosmarinic, ursolic, and oleanolic acid in Prunella vulgaris [59]. A weak water deficit greatly increased the glycyrrhizic acid content in roots of Glycyrrhiza uralensis [60]. In Hypericum brasiliense, the amounts of various phenols and betulinic acid were drastically increased under drought stress [61].
3.1.5. Thermal stress
Although thermal stress can greatly reduce plant growth and induce senescence, elevated temperatures (heat stress) or low temperatures (cold stress) have also been shown to increase secondary metabolite production. Temperature strongly influences metabolic activity and plant ontology, and high temperatures can induce premature leaf senescence [62]. Elevated temperatures increase leaf senescence and root secondary metabolite concentrations in the herb Panax quinquefolius [63]. A 5°C increase in temperature significantly increased the ginsenoside content in roots of P. quinquefolius [63]. A temperature variation has multiple effects on the metabolic regulation, permeability, and rate of intracellular reactions in plant cell cultures [62]. Temperature range of 17–25°C is normally used for the induction of callus tissues and growth of cultured cells [16]. The temperature and light quality influences on the production of ginsenoside in hairy root culture of Panax ginseng [64]. The Melastoma malabathricum cell cultures incubated at a lower temperature range (20 ± 2°C) grew better and had higher anthocyanin production than those grown at 26 ± 2°C and 29 ± 2°C [65]. Fifteen days at 35°C significantly increased the hypericin and hyperforin content in shoots of Hypericum perforatum [66].
Heavy metals have become one of the main abiotic stress agents for living organisms because of their increasing use in the developing fields of industry and agrotechnics and high bioaccumulation and toxicity [67]. Although a lot of information is available concerning the effects of heavy metals on plant growth and physiology, much less is known regarding their effects on the production of secondary metabolites. Heavy metal–induced changes in metabolic activity of plants can affect the production of photosynthetic pigments, sugars, proteins, and nonprotein thiols. These effects can result from the inhibition of enzymes involved in the production of these natural products, likely through impaired substrate utilization [68]. Metals may alter the production of bioactive compounds by changing aspects of secondary metabolism [2]. Metals including Ni, Ag, Fe, and Co have been shown to elicit the production of secondary metabolites in a variety of plants [69].
An increased oil content up to 35% in Brassicajuncea was seen due to the effective accumulation of metals (Cr, Fe, Zn, and Mn) [70]. The highest accumulations of secondary metabolites such as shikonin [71] and also the production of digitalin [72] were observed by treating Cu2+ and Cd2+. The production of betalains in Beta vulgaris also stimulated by Cu2+ [73]. Co2+ and Cu2+ have a stimulatory effect on the production of secondary metabolites in Beta vulgaris [73]. The betalaines production was enhanced by exposing the hairy root culture to metal ions [74]. The stimulatory effects of Cu2+ on the accumulation of betacyanins in callus cultures of Amaranthus caudatus were reported by Obrenovic [75]. The addition of Zn2+ (900 μM) improved the yield of lepidine in cultures of Lepidium sativum [76]. However, Cu proved more effective than Zn in enhancing the yield product [76]. In hairy root cultures of Brugmansia candida, silver nitrate (AgNO3) or cadmium chloride (CdCl2) elicited the overproduction of two tropane alkaloids, scopolamine, and hyoscyamine [20]. The production of taxol in cell culture of Taxus sp. was enhanced by the rare–earth metal (lanthanum) [77]. AgNO3 stimulated the production of tanshinone in the root culture of Perovskia abrotanoides [78]. The treatment of root cultures of Datura stramonium with cadmium salts at external concentrations of approximately l mM has been found to induce the rapid accumulation of high levels of sesquiterpenoid–defensive compounds, notably lubimin and 3–hydroxylubimin, but not alkaloid [79].
Various plant hormones have been extensively used in elicitation studies. The most studied, because of their key roles in the plant defense response, are jasmonic acid (JA) and SA and its derivatives.
5.1. Jasmonates
Jasmonates, including JA and MeJA, are a family of cyclopentanone compounds that modulate a wide range of plant responses [80,81] and act as effective elicitors to enhance secondary metabolites in in vitro cultures. They constitute an important class of elicitors for many plant secondary metabolic pathways, which are typically manifested by the elicitation of secondary metabolite biosynthesis when plants face particular environmental stresses [82]. JA is an important signal molecule of plant in response to wound and pathogen attack [83]. JA and its more active derivative MeJA can induce the production of a wide range of plant secondary metabolites such as rosmarinic acid, terpenoid indole alkaloid, and plumbagin in various cell cultures [84–86]. JA elicitation are reported to induce the production of rosmarinic acid in Mentha piperita [84], anthocyanin in V. vinifera [87], and plumbagin in hairy roots of Plumbago indica [88]. JA and MeJA have been used as elicitors for stilbene biosynthesis in V. vinifera foliar cuttings [89], V. vinifera cell cultures [90,91], and Vitis rotundifolia hairy root cultures [92]. The addition of MeJA to V. vinifera cell cultures also promoted anthocyanin accumulation [93]. MeJA with transgenic technology highly enhanced the production of tanshinones in Salvia miltiorrhiza hairy roots [94]. In the hairy root culture of Withania somnifera, MeJA elicited the production of withanolide A, withanone, and withaferin A [95]. The MeJA enhanced the production of bacoside A, a valuable triterpenoid saponin having nootropic therapeutic activity in in vitro shoot cultures of Bacopa monnieri [96]. In Andrographis paniculata cell culture, the MeJA induced the production of andrographolide content [97]. In Glycyrrhiza glabra, methyl jasmonate induced the production of the saponin soyasaponin [98]. It enhanced the production of paclitaxel in Tacus canadensis and T. cuspidate [99], and in Rubus idaeus, it stimulated the production of the raspberry ketone benzalacetone [100].
5.2. Salicylic acid
Salicylic acid, well known for the systemic acquired resistance it induces in the plant response to many pathogens, can also elicit the production of secondary metabolites in plants [101,102]. SA with transgenic technology highly enhanced the production of tanshinones in S. miltiorrhiza hairy roots [94]. The higher production of withanolide A, withanone, and withaferin A was reported in the elicited–hairy roots of W. somnifera [95]. SA induced the stilbene production in the cell suspension of V. vinifera [34]. It stimulated the production of alkaloids such as vincristine and vinblastine in periwinkle [103], the tropane alkaloid scopolamine in hairy root cultures of Brugmansia candida [77], and pilocarpine in jaborandi leaves [104]. Anthraquinone production was greatly increased in Rubia cordifolia after a SA treatment [105]. SA also affects terpenoid secondary metabolism in plants. It induced accumulation of the triterpenoids ginsenosides in ginseng and glycyrrhizin in licorice [106,107]. Recent evidence demonstrated that suitable concentrations of SA can also promote monoterpene production [108].
5.3. Gibberellic acid
Gibberellin (GA), a phytohormone, is also well known as an effective elicitor for the production of secondary metabolites [109].
Effect of Different Biotic Elicitors on the Production of Various Secondary Metabolites in Plants
6.1. Polysaccharide
The biotic elicitors have been utilized to increase secondary metabolite production in medicinal plants. In a Panaxginseng cell suspension, the cell wall–derived elicitor oligogalacturonic acid significantly increased the ginseng saponin content [110]. The treatment of cultured cells of Lithospermum erythrorhizon with the polysaccharide agropectin induced the production of the naphthoquinone shikonin [111]. The chitosan treatment of cultures of Plumbago rosea increased the plumbagin content [112]. The application of chitin or chitosan induced the production of coumarins and fluoroquinolone alkaloids in shoot cultures of Ruta graveolens [113]. Chitosan enhanced the production of trans–resveratrol and viniferins in the cell system of V. vinifera [91]. Chitin induced the phenylpropanoid and naphtodianthrone production in cell suspension cultures of H. perforatum [114].
6.2. Yeast origin
For decades, scientists are using yeast extract as one of the biotic elicitors. Yeast extracts stimulated ethylene biosynthesis in tomato [115] and bacterial resistance in bean (Phaseolus vulgaris) [116]. Yeast extract elicited the production of tanshinone in the root culture of Perovskia abrotanoides [78].
6.3. Fungal origin
Biotic elicitors produced by pathogens have mainly been used to induce the plant defense response. In the past, biological mixtures were prepared from pathogens without identification of the active compounds. The use of pathogenic and nonpathogenic fungal preparations as elicitors has become one of the most effective strategies to induce phenylpropanoid/flavonoid biosynthetic pathways in plant cells [117,118]. Necrotrophic pathogens such as Botrytis sp. usually kill the host cells often through secretion of toxins before deriving nutrients from them [119]. On the other hand, biotrophic pathogens Fusarium sp. or Phoma sp. try to avoid killing the host cells, and derive their nutritional benefits from extensive contact with them and by altering the host metabolism and secretion systems [120,121]. An early defense reaction of the plant cell attacked by fungal pathogen includes the rapid and transient production of reactive oxygen species (ROS). Plant cells are usually protected against the detrimental effects of ROS by a complex of nonenzymatic and enzymatic antioxidant systems [122]. It has been demonstrated that the phenylalanine ammonia lyase (PAL) enzyme that catalyses the entry of L–phenylalanine into the phenylpropanoid pathway has reputedly a crucial role in the synthesis of antioxidant/defense–related compounds [117]. The mycelia extracts from the above mentioned fungi induced partitioning of the phenylpropanoid pathway and a rapid stimulation of the monolignol pathway in Linum usitatissimum cultured cells [123]. Cultures of Phytophthora elicited microbial resistance in soybean [124] and potato [125]. Extracts from microbial–enriched composts stimulated systemic resistance to Phytophthora in pepper (Capsicum annuum) [126]. As the plant defense response and the production of secondary metabolites are closely related, it is not surprising that a number of elicitors have also been shown to increase the production of secondary metabolites in medicinal plant cell culture. Similar to plant defense, initial work on secondary metabolite elicitation was performed using biological mixtures. Fungal cell wall fragments increased the production of the indole alkaloids ajmalicine, serpentine, and catharanthine by up to five times in cell suspensions of C. roseus [69,127] and the 12–oxo–phytodienoic acid, raucaffrincine, in Rauwolfia canescens [128]. Fungal mycelia increased the diosgenin content in Dioscorea deltoidea cells by 72% [129]. In Papaver somniferum, fungal spores increased the content of codeine, morphine, and sanguinarine by over eightfold [130,131]. A mixture of fungal polysaccharides increased the amount of the antimicrobial alkaloid acridone epoxide up to 100–fold in cultures of R. graveolens [132]. Taxus chinensis cells treated with an endophytic fungus found in the bark of the T. chinensis tree produced three times as much taxol as nonelicited cells [133].
The content of thiarubrine A was enhanced 3–fold in Ambrosia artemisiifolia hairy root cultures through the utilization of autoclaved cell wall filtrates from the fungus Protomyces gravidus, a pathogen of Ambrosia artemisiifolia [134]. The fungal challenged root cultures of Taverniera cuneifolia, increased the glycyrrhizic acid content [135]. Moreover, maximum increase in glycyrrhizic acid was noticed in Mucor hiemalis treated cultures. In case of Fusarium moniliforme and Aspergillus niger, threefold increase in glycyrrhizic acid was observed as compared to control unchallenged root culture. However, marginal increase in glycyrrhizic acid content was noticed, in Penicillium fellutanum and Aspergillus tenuis challenged cultures [135]. Similarly, biotic elicitors from Claviceps purpurea were included in Azadirachta indica hairy root cultures, leading to a 5–fold increase in the production of azadirachtin [136]. The transformed cell suspension cultures of W. somnifera when treated with the dual elicitation of copper sulfate (100 μM) and the cell extract of Verticilium dahaliae (5% v/v) showed highest production of withaferin A content when compared with the individual elicitors [137].
6.4. Bacterial origin
The bacterial elicitors stimulated the biosynthesis of scopolamine in adventitious hairy root cultures of Scopolia parviflora via the inhibition of H6H (hyoscyamine 6β–hydoxylase) expression [138]. In bacterial elicitation, the maximum glycyrrhizic acid increase was observed in Rhizobium leguminosarum challenged culture as compared to unchallenged control roots of Taverniera cuneifolia [135]. Furthermore, in Bacillus aminovorans, Agrobacterium rhizogenes, and Bacillus cereus challenged cultures, significant increase in glycyrrhizic acid content was observed. However, root culture challenged by Agrobacterium tumefaciens did not show any significant increase in glycyrrhizic acid content [135]. The gradual increase in hypericin and pseudohypericin was observed in seedlings of H. perforatum after challenging with Rhizobacterium [139]. Coronatine, phytotoxin produced by the Pseudomonas syringae species significantly induced taxane synthesis in taxane media cell cultures [140], also induced the viniferins production in the cell culture of V. vinifera [91].
Elicitation has been widely used to increase the production or to induce de novo synthesis of secondary metabolites in in vitro plant cell cultures [141]. This opened up a new area of research that could have important economic benefits for pharmaceutical industry. Several parameters such as elicitor concentration and selectivity, duration of elicitor exposure, age of culture, cell line, growth regulation, nutrient composition, and quality of cell wall materials are also important factors influencing the successful production of secondary metabolite [142]. Some of these parameters were highlighted on elicitation of some medicinal plants for the production of secondary metabolites.
7.1. Elicitor concentration
Elicitor concentration plays a very important role in elicitation process. High dosage of elicitor has been reported to induce hypersensitive response leading to cell death, whereas an optimum level was required for induction [143–145]. At 0.1% (w/v) sodium chloride, ginseng saponin content and productivity were increased to approximately 1.15 and 1.13 times control values, respectively [146]. In the cell culture of S. miltiorrhiza, the effects of different concentrations of SA were affected the accumulation of salvianolic acid B and of caffeic acid. The increased accumulation of salvianolic acid B and of caffeic acid was observed in the applications of 3.125–25.0 mg/L of SA at 8 and 96 h when compared to the 32.0–50.0 mg/L of SA. After 96 h treatments with 3.125–25.0 mg/L of SA, the concentration of the phenolic acids decreased drastically compared to the amount 8 h after the treatments but still accumulated the higher concentrations of compound than that of the control [147]. The various concentrations (50, 100, 150, 200, and 250 μM) of MeJA and SA were used in the cell suspension cultures of Gymnema sylvestre. The MeJA at 150 μM and SA at 200 μM enhanced the accumulation of gymnemic acid content [148]. In the hairy root culture of W. somnifera, the MeJA (15 μM) and SA (150 μM) enhanced the production of withanolide A, withanone, and withaferin A content [95]. In the cell suspension culture of V. vinifera, the cobalt at all three used concentrations (5.0, 25, and 50 μM), Ag, and Cd at low concentration (5.0 μM) were most effective to stimulate the phenolic acid production, increasing the 3–O–glucosyl–resveratrol up to 1.6–fold of the control level (250.5 versus 152.4 μmol/g), 4 h after the treatments [67]. In the A. paniculata cell culture, MeJA at 5 μM showed 5.25 higher accumulation of andrographolide content compared with control [97]. The root cultures of Taverniera cuneifolia treated with increasing concentrations of MeJA (1.0, 2.5, 5, 10, 100, and 1000 μM) [135]. The glycyrrhizic acid content increased gradually with increase in MeJA (1–100 μM) concentration. Approximately 2.5–fold increase in glycyrrhizic acid production was noticed in MeJA (100 μM) treated roots, as compare to the unchallenged root culture. However, further increase in MeJA (1000 μM) concentration resulted in decrease in glycyrrhizic acid production [135].
7.2. Duration of elicitor exposure
The cell suspension culture of G. sylvestre was treated with MeJA and SA for 24 h, 48 h, and 72 h. With the MeJA treatment, the maximum gymnemic acid production was recorded 72 h after treatment with 150 μM (135.41 ± 0.43 mg/g DCW). The gymnemic acid content was 15.4–fold higher than the control cultures that were free of the elicitor. When the MeJA concentration exceeded 150 μM, there was a drastic fall (36.3%) in the gymnemic acid accumulation [148]. A high concentration of 200 μM SA was required to induce substantial quantities of gymnemic aid (43.27 ± 0.80 mg/g DCW) in the suspensions that reached a maximum after 48 h treatment. The SA–induced response toward gymnemic acid accumulation resulted in a 4.9–fold increase in comparison to the control cultures [148]. The different biotic elicitors (A. rhizogenes, Bacillus subtilis, Escherichia coli, Aspergillus niger, and Saccharomyces cerevisiae) required different duration of time (24, 48, 48, 72, and 72 h, respectively) to elicit the gymnimic acid in the cell suspension culture of G. sylvestre [149]. The MeJA and SA for 4 h exposure time enhanced the production of withanolide A, withanone and withaferin A content in the hairy root culture of W. somnifera [95]. The yields of atropine content in the Datura metel hairy roots were increased by nanosilver as an elicitor after 12, 24, and 48 h, but atropine accumulation in D. metel hairy roots was reduced by AgNO3, Bacillus cereus, and Staphylococcus after 12, 24, and 48 h [150]. In the cell culture of Andrographis paniculata, the MeJA induced the highest accumulation of andrographolide at 24 h compared with 48 and 72 h of treatments [97]. In the cell system of V. vinifera, a rapid accumulation of trans–resveratrol was recorded with MeJA treatment, starting from 2 h and reaching its maximum value at 96 h and the highest levels of viniferins recorded in cell cultures elicited with chitin (chitosan) for 144 h [91]. The MeJA produced the highest amount of bacoside A, 1.5–fold higher than the control shoots in the B. monnieri shoot culture after 48 h [96]. MeJA elicitation can cause an initial rapid increase in amount of various secondary metabolites from 24 to 72 h compared to controls after which a subsequent decrease can be found [151].
7.3. Age of culture
Age of culture plays is an important parameter in the production of bioactive compounds by elicitation. The treatment with MeJA and SA in the hairy root culture of W. somnifera showed highest accumulation of withanolide A, withanone, and withaferin A content after 40 days of culture [95]. In a study, 20–day–old cell cultures of C. roseus showed higher yields of ajmalicine on elicitation. The optimum level of ajmalicine (166 μg/g DW) was observed in 20–day–old cells elicited with extracts of Trichoderma viride followed by 90 and 88 μg/g DW ajmalicine in cells elicited with A. niger and F. moniliforme, respectively [127,152]. A similar type of observation was noticed from various workers Rijhwani and Shanks [153] and Ganapathi and Kargi [142]. The selenium addition at inoculum time did not significantly affect ginseng saponin accumulation. However, the addition of 0.5 mM selenium as an elicitor, after 21 days of culture, ginseng saponin content and productivity increased to about 1.31 and 1.33 times control levels, respectively [146]. The MeJA, at a concentration of 10 μM and 100 μM when introduced to cell suspension of C. roseus on day 6 of cell growth increased ajmalicine and serpentine production, respectively, re–elicitation showed a negative effect on both growth and alkaloid synthesis [154].
7.4. Nutrient composition
The composition of the medium or selection of medium also played a vital role in elicitation process. In the callus culture of Erythroxylum coca, the amounts of cocaine, cinnamoylcocaine, chlorogenic acid (CGA), and 4–coumaroyl quinate (CQA) were significantly affected by the culture medium [155]. Cocaine production was nearly an order of magnitude greater on Anderson rhododendron medium (ARM) [156], Gamborg B5 (GB5) [157], and Murashige–Tucker medium (MMT) [158], but the amounts produced on MMT and GB5 were not significantly different from each other. Cinnamoylcocaine was affected in the same way. The major factor controlling tropane alkaloid (TA) accumulation was medium composition, with cocaine levels on ARM being nearly an order of magnitude greater than on the other media. Many nutrients, including cobalt, copper, molybdenum, calcium, magnesium, iron, boron, iodine, manganese, zinc, and myo–inositol, and the growth regulators and the ammonium:nitrate ratio are at equivalent levels in ARM as in one of the other media, and can therefore be excluded as factors promoting TA accumulation. However, a number of factors differed between ARM and the other media, and might be responsible for the elevated TA content. Total ion concentration is lower in ARM, and could be an important factor given the importance of salt content in controlling secondary metabolism [155]. Nitrate concentration was also lower in ARM, and there are numerous reports in the literature of an inverse relationship between nitrate availability and accumulation of secondary metabolites in many plant species, including Arabidopsis thaliana [159], Hordeum vulgare [160], and Nicotiana tabacum [161]. Similarly, the reduction of nitrate concentration in the culture medium of Atropa belladonna hairy roots increases alkaloid content [162]. In regards to CGA, the media were all significantly different from each other with the lowest production on ARM and highest on MMT. Less CQA was produced on ARM than on either of the other two media, which did not differ from each other [155]. Apart from these characteristics, the efficiency of elicitation also depends on elicitor specificity, cell line or clones of microbial elicitor used the presence of growth regulators, nutrient composition of the medium, and the environmental conditions.
The development of plant tissue cultures for the production of secondary metabolites has been underway for more than three decades. Although there are well–established plant tissue culture techniques, their application to large scale production is still limited to a few processes. Various stimulation and process strategies have been exercised to improve secondary metabolite production in plant tissue cultures. Elicitation has been widely applied for enhancement of secondary metabolite production in plant cell and organ cultures. The effects of various abiotic and biotic elicitors on secondary metabolite production in plant tissue cultures are dependent on the specific secondary metabolites. The exploration of the production of useful secondary metabolites through regulation of biosynthetic pathway of the various plant cell and tissue cultures of medicinal plants has been carried out by a group of plant scientists in several countries during the last decade. Although, elicitation enhances secondary metabolism in plant cells in vitro, but the exact mechanism is not exactly understood. There is a tremendous scope for the large–scale production of secondary metabolites in the plant tissue culture system by using the elicitors as an agent.
References
1.Wink M. Plant breeding: importance of plant secondary metabolites for protection against pathogens and herbivores. Theoretical and Applied Genetics. 1988;75:225–233.
2.Verpoorte R, Contin A, Memelink J. Biotechnology for the production of plant secondary metabolites. Phytochemistry Reviews. 2002;1:13–25.
3.Murthy HN, Lee EJ, Paek KY. Production of secondary metabolites from cell and organ cultures: strategies and approaches for biomass improvement and metabolite accumulation. Plant Cell Tissue and Organ Culture. 2014;118:1–16.
4.Dixon RA. Natural products and plant disease resistance. Nature. 2001;411:843–847.
5.Oksman–Caldentey1 KM, Inze D. Plant cell factories in the post–genomic era: new ways to produce designer secondary metabolites. Trends in Plant Science. 2004;9:9.
6.Mosihuzzaman M. Herbal medicine in healthcare—an overview. Natural Product Communications. 2012;7:807–812.
7.Cordell GA. Biodiversity and drug discovery—a symbiotic relationship. Phytochemistry. 2000;55:463–480.
8.Schmidt BM, Ribnicky DM, Lipsky PE, Raskin I. Revisiting the ancient concept of botanical therapeutics. Nature Chemical Biology. 2007;3:360–366.
9.Shaw D, Graeme L, Pierre D, Elizabeth W, Kelvin C. Pharmacovigilance of herbal medicine. Journal of Ethnopharmacology. 2012;140:513–518.
10.Cox PA, Balick MJ. The ethanobotanical approach to drug discovery. Scientific American. 1994;270(6): 82–87.
11.Pezzuto JM. Natural product cancer chemoprotective agents. In: Arnason JT, Mata R, Romeo JT, editors. Recent advances in phytochemistry. Phytochemistry of Medicinal Plants. New York: Plenum.1995. p. 19–45.
12.Vanisree M, Lee CY, Lo SF, Nalawade SM, Lin CY, Tsay HS. Studies on the production of some important secondary metabolites from medicinal plants by plant tissue cultures. Botanical Bulletin of Academia Sinica. 2004;45:1–22.
13.Anis M, Husain MK, Faisal M, Shahzad A, Ahmad N, Siddique I, Khan H, In: Kumar A, Sopory SK. editors. Recent Advances in Plant Biotechnology and its Application, New Delhi: IK International Pvt. Ltd; 2009. p. 397–410.
14.Anis M, Husain MK, Siddique I, Varshney A, Naz R, Perveen S, Khan MI, Ahmed MR, Husain MK, Khan PR, Aref IM. Biotechnological approaches for the conservation of forestry species. In: Jenkins JA. editor. Forest Decline: Causes and Impacts. USA: Nova Science Publishers Inc. 2011. p. 1–39.
15.Skrzypczak–Pietraszek E, Słota J, Pietraszek J. The influence of L–phenylalanine, methyl jasmonate and sucrose concentration on the accumulation of phenolic acids in Exacum affine Balf. f. ex Regel shoot culture. Acta Biochimica Polonica. 2014;61(1):47–53.
16.Rao RS, Ravishankar GA. Plant cell cultures: chemical factories of secondary metabolites, Biotechnology Advances. 2002;20:101–153.
17.Sarin R. Useful metabolites from plant tissue cultures. Biotechnology. 2005;4:79–93.
18.Radman R, Saez T, Bucke C, Keshavarz T. Elicitation of plant and microbial systems. Biotechnology and Applied Biochemistry. 2003;37:91–102.
19.Poulev A, O’Neal JM, Logendra S, Pouleva RB, Timeva V, Garvey AS, Gleba D, Jenkins IS, Halpern BT, Kneer R, Cragg GM, Raskin I. Elicitation, a new window into plant chemodiversity and phytochemical drug discovery. Journal of Medicinal Chemistry. 2003;46: 2542–2547.
20.Angelova Z, Georgiev S, Roos W. Elicitation of plants. Biotechnology and Biotechnological Equipment. 2006;20:72–83.
21.Namdeo AG. Plant cell elicitation for production of secondary metabolites: a review. Pharmacognosy Reviews. 2007;1:69–79.
22.Anasori P, Asghari G. Effects of light and differentiation on gingerol and zingiberene production in callus culture of Zingiber officinale Rosc. Research in Pharmaceutical Sciences. 2008;3:59–63.
23.Zhong JJT, Seki SI, Kinoshita, Yoshida T. Effect of light irradiation on anthocyanin production by suspended culture of Perilla frutescens. Biotechnology and Bioengineering. 1993;38:653–658.
24.Hagimori M, Matsumoto T, Obi Y. Studies on the production of Digitalis cardenolides by plant tissue culture III. Effects of nutrients on digitoxin formation by shoot–forming cultures of Digitalis purpurea L. grown in liquid media. Plant and Cell Physiology. 1982;23:1205–1211.
25.Liu CZ, Guo C, Wang Y, Ouyang F. Effect of light irradiation on hairy root growth and artemisinin biosynthesis of Artemisia annua L. Process Biochemistry. 2002;38:581–585.
26.Fett–Neto AG, Pennington JJ, Di Cosmo F. Effect of white light on taxol and baccatin III accumulation in cell cultures of Taxus cuspidata Sieb and Zucc. Journal of Plant Physiology. 1995;146:584–590.
27.Kumari RSB, Agrawal S, Singh NKD. Supplemental ultraviolet–B induced changes in essential oil composition and total phenolics of Acorus calamus L. (sweet flag). Ecotoxicology and Environmental Safety. 2009;72:2013–2019.
28.Rozema J, Bjorn LO, Bornman JF, Gaberscik A, Ha°der DP, Trost T, Germ M, Klisch M, Gro°niger A, Sinha RP, Lebert M, He YY, Buffoni–Hall R, Bakker NVJ, de Staaij J, van de Meijkamp BB. The role of UV–B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV–absorbing compound. Journal of Photochemistry and Photobiology B. 2002;66:2–12.
29.Bernard YKB, Christie AMP, Jacqueline VS, Ka–Yiu S. The effects of UV–B stress on the production of terpenoid indole alkaloids in Catharanthus roseus hairy roots. Biotechnology Progress, 2009;25:8615.
31.Wang LJ, Ma L, Xi HF, Duan W, Wang JF, Li SH. Individual and combined effects of CaCl2 and UV–C on the biosynthesis of resveratrols in grape leaves and berry skins. Journal of Agricultural and Food Chemistry. 2013;61:7135–7141.
32.Wang W, Tang K, Yang HR, Wen PF, Zhang P, Wang HL, Huang WD. Distribution of resveratrol and stilbene synthase in young grape plants (Vitis vinifera L. cv. Cabernet Sauvignon) and the effect of UV–C on its accumulation. Plant Physiology and Biochemistry. 2010;48:142–152.
33.Liu W, Liu CY, Yang CX, Wang LJ, Li SH. Effect of grape genotype and tissue type on callus growth and production of resveratrols and their piceids after UV–C irradiation. Food Chemistry. 2010;122:475–481.
34.Xu A, Zhan JC, Huang WD. Effects of ultraviolet C, methyl jasmonate and salicylic acid, alone or in combination, on stilbene biosynthesis in cell suspension cultures of Vitis vinifera L. cv. Cabernet Sauvignon plant cell tissue and organ culture. 2015;122:197–211.
35.Vasconsuelo A, Boland R. Molecular aspects of the early stages of elicitation of secondary metabolites in plants. Plant Science. 2007;172(5):861–875.
36.Zobayed SMA, Afreen F, Kozai T. Phytochemical and physiological changes in the leaves of St. John’s wort plants under a water stress condition. Environmental and Experimental Botany. 2007;59:109–116.
37.Verbruggen N, Hermans C. Proline accumulation in plants: a review. Amino Acids. 2008;35:753–759.
38.Xu J, Yin HX, Li X. Protective effects of proline against cadmium toxicity in micropropagated hyperaccumulator Solanum nigrum L. Plant Cell Reports. 2009;28:325–333.
39.Van den Berg L, Zeng YJ. Response of South African indigenous grass species to drought stress induced by polyethylene glycol (PEG) 6000. The South African Journal of Botany. 2006;72:284–286.
40.Pratibha G, Satyawati S, Sanjay S. Biomass yield and steviol glycoside production in callus and suspension culture of Stevia rebaudiana treated with proline and polyethylene glycol. Applied Biochemistry and Biotechnology. 2015; DOI: 10.1007/s12010–015–1616–0.
41.Omer Y, Bengi E. Effects of sucrose and polyethylene glycol on hypericins content in Hypericum adenotrichum. Eurasian Journal of Biosciences. 2013;7:101–110.
42.Liu CZ, Cheng XY. Enhancement of phenylethanoid glycosides biosynthesis in cell cultures of Cistanche deserticola by osmotic stress. Plant Cell Reports. 2008;27: 357–362.
43.Pavlik M, Vacek J, Klejdus B, Kuban V. Hypericin and hyperforin production in St. John’s wort in vitro culture: influence of saccharose, polyethylene glycol, methyl jasmonate, and Agrobacterium tumefaciens. Journal of Agricultural and Food Chemistry. 2007;55:6147–6153.
44.Bernstein N. Effects of salinity on root growth. In: Eshel A, Beeckman T. editors. Plant Roots: The Hidden Half, 4th ed. Boca Raton: CRC Press; 2013. p. 784.
45.Munns R, Tester T. Mechanisms of salinity tolerance. Annual Review of Plant Biology. 2008;59:651–681.
46.Haghighi Z, Karimi N, Modarresi M, Mollayi, S, Enhancement of compatible solute and secondary metabolites production in Plantago ovata Forsk. by salinity stress. Journal of Medicinal Plants Research. 2012;6:3495–3500.
47.Selmar D. Potential of salt and drought stress to increase pharmaceutical significant secondary compounds in plants. Agriculture and Forestry Research. 2008;58:139–144.
48.Winkel–Shirley B. Biosynthesis of flavonoids and effects of stress. Current Opinion in Plant Biology. 2002;5:218–223.
49.Misra N, Gupta AK. Effect of salinity and different nitrogen sources on the activity of antioxidant enzymes and indole alkaloid content in Catharanthus roseus seedlings. Journal of Plant Physiology. 2006;163:11–18.
50.Kennedy BF, De Filippis LF. Physiological and oxidative response to NaCl of the salt tolerant Grevillea ilicifolia and the salt sensitive Grevillea arenaria. Journal of Plant Physiology. 1999; 155:746–754.
51.Daneshmand F, Arvin MJ, Kalantari KM. Physiological responses to NaCl stress in three wild species of potato in vitro. Acta Physiologiae Plantarum. 2010;32:91–101.
52.Brachet J, Cosson L. Changes in the total alkaloid content of Datura innoxia Mill. Subjected to salt stress. Journal of Experimental Botany. 1986;37:650–656.
53.Krishnamurthy R, Bhagwat KA. Polyamines as modulators of salt tolerance in rice cultivars. Plant Physiology. 1989;91:500–504.
54.Varshney KA, Gangwar LP. Choline and betaine accumulation in Trifolium alexandrinum L. during salt stress. Egyptian Journal of Botany. 1988;31:81–86.
55.Fatima S, Mujib A, Dipti T. NaCl amendment improves vinblastine and vincristine synthesis in Catharanthus roseus: a case of stress signalling as evidenced by antioxidant enzymes activities Plant Cell Tissue and Organ Culture. 2015;121:445–458.
56.Xu Z, Zhou G, Shimizu H. Plant responses to drought and rewatering. Plant Signaling and Behavior. 2010;5:649–54. PMID:20404516. DOI: 10.4161/psb.5.6.11398.
57.Zhu Z, Liang Z, Han R, Wang X. Impact on fertilization on drought response in the medicinal herb Bupleurum chinense DC: growth and saikosaponin production. Industrial Crops and Products. 2009;29: 629–633.
58.Liu H, Wang X, Wang D, Zou, Z, Liang Z, Effect of drought stress on growth and accumulation of active constituents in Salviamiltiorrhiza Bunge. Industrial Crops and Products. 2011;33:84–88
59.Chen Y, Guo Q, Liu L, Liao L, Zhu Z. Influence of fertilization and drought stress on the growth and production of secondary metabolites in Prunella vulgaris L. Journal of Medicinal Plants Research 2011;5:1749–1755.
60.Li W, Hou J, Wang W, Tang X, Liu C, Xing D, Effect of water deficit on biomass production and accumulation of secondary metabolites in roots of Glycyrrhiza uralensis. Russian Journal of Plant Physiology. 2011;58:538–542.
61.de Abreu, IN, Mazzafera P. Effect of water and temperature stress on the content of active constituents of Hypericum brasiliense Choisy. Plant Physiology and Biochemistry. 2005;43:241–248.
62.Morison JIL, Lawlor DW. Interactions between increasing CO2 concentration and temperature on plant growth. Plant Cell and Environment. 1999;22:659–682.
63.Jochum GM, Mudge KW, Thomas RB. Elevated temperatures increase leaf senescence and root secondary metabolite concentration in the understory herb Panaxquinquefolius (Araliaceae). American Journal of Botany. 2007;94:819–826. PMID:21636451.
64.Yu K, Niranjana MH, Hahn E, Paek K. Ginsenoside production by hairy root cultures of Panaxginseng: influence of temperature and light quality. Biochemical Engineering Journal. 2005;23:53–56.
65.Chan LK, Koay SS, Boey PL, Bhatt A. Effects of abiotic stress on biomass and anthocyanin production in cell cultures of Melastoma malabathricum. Biological Research 2010;43:127–135. PMID:21157639.
66.Zobayed SMA, Afreen F, Kozai T. Temperature stress can alter the photosynthetic efficiency and secondary metabolite concentrations in St. John’s wort. Plant Physiology and Biochemistry. 2005;43:977–984.
67.Cai Z, Kastell A, Speiser C, Smetanska I. Enhanced resveratrol production in Vitis vinifera cell suspension cultures by heavy metals without loss of cell viability. Applied Biochemistry and Biotechnology. 2013;171:330–340.
68.Nasim SA, Dhir B. 2010 Heavy metals alter the potency of medicinal plants. Reviews of Environmental Contamination and Toxicology. 2010;203:139–149.
69.Zhao J, Zhu W, Hu Q. Selection of fungal elicitors to increase indole alkaloid accumulation in Catharanthus roseus suspension cell culture. Enzyme and Microbial Technology. 2001;28:666–672.
70.Singh S, Sinha S. Accumulation of metals and its effects in Brassica juncea (L.) Czern. (cv. Rohini) grown on various amendments of tannery waste. Ecotoxicology and Environmental safety. 2005;62:118 27. PMID:15978297.
71.Mizukami H, Konoshima M, Tabata M. Effect of nutritional factors on shikonin derivative formation in Lithospermum callus cultures. Phytochemistry. 1977;16:1183–1186.
72.Ohlsson AB, Berglund T. Effect of high MnSO4 levels on cardenolide accumulation by Digitalis lanata tissue cultures in light and darkness. Journa of Plant Physiology. 1989;135:505–507.
73.Trejo–Tapia G, Jimenez–Aparicio A, Rodriguez–Monroy M, De Jesus–Sanchez A, Gutierrez–Lopez G. Influence of cobalt and other microelements on the production of betalains and the growth of suspension cultures of Betavulgaris. Plant Cell Tissue and Organ Culture. 2001;67:19–23.
74.Thimmaraju BN, Ravishankar GA. In situ and ex situ adsorption and recovery of betalains from hairy root cultures of Beta vulgaris. Biotechnology Progress. 2004;20:777‑85. PMID:15176882. DOI: 10.1021/bp0300570.
75.Obrenovic S. Effect of Cu (11) D–penicillanine on phytochrome mediated betacyanin formation in Amaranthus caudatus seedlings. Plant Physiology and Biochemistry. 1990;28:639–646.
76.Saba PD, Iqbal M, Srivastava PS. Effect of ZnSO4 and CuSO4 on regeneration and lepidine content in Lepidium sativum. Biologia Plantarum. 2000;43:253–256.
77.Pitta–Alvarez SI, Spollansky TC, Giullietti AM. The influence of different biotic and abiotic elicitors on the production and profile of tropane alkaloids in hairy root cultures of Brugmansia candida. Enzyme and Microbial Technology. 2000;26:252–258. PMID:10689085.
78.Arehzoo Z, Christina S, Florian G, Parvaneh A, Javad A, Seyed H M, Christoph W. Effects of some elicitors on tanshinone production in adventitious root cultures of Perovskia abrotanoides Karel. Industrial Crops and Products, 2015;67:97–102.
79.Furze JM, Rhodes MJC, Parr AJ, Robins RJ, Withehead IM., Threlfall DR. Abiotic factors elicit sesquiterpenoid phytoalexin production but not alkaloid production in transformed root cultures of Datura stramonium. Plant Cell Reports. 1991;10(3):111–114.
80.Creelman RA, Mullet JE. Biosynthesis and action of jasmonates in plants. Annual Review of Plant Biology. 1997;48(1):355–381.
81.Sembdner G, Parthier B. The biochemistry and the physiological and molecular actions of jasmonates. Annual Review of Plant Biology. 1993;44(1):569–589.
82.Pauwels L, Inze´ D, Goossens A. Jasmonate–inducible gene: what does it mean? Trends in Plant Science. 2009;14:87–91.
83.Wasternack C, Parthier B. Jasmonate–signalled plant gene expression. Trends in Plant Science. 1997;2:302–307.
84.Krzyzanowska J, Czubacka A, Pecio L, Przybys M, Doroszewska T, Stochmal A, Oleszek W. The effects of jasmonic acid and methyl jasmonate on rosmarinic acid production in Mentha piperita cell suspension cultures. Plant Cell Tissue and Organ Culture. 2012:108;73–81.
85.Almagro L, Gutierrez J, Pedren˜o MA, Sottomayor M. Synergistic and additive influence of cyclodextrins and methyl jasmonate on the expression of the terpenoid indole alkaloid pathway genes and metabolites in Catharanthus roseus cell cultures. Plant Cell Tissue and Organ Culture. 2014;119:543–551.
86.Silja PK, Gisha GP, Satheeshkumar K. Enhanced plumbagin accumulation in embryogenic cell suspension cultures of Plumbago rosea L. following elicitation. Plant Cell Tissue and Organ Culture. 2014;119:469–477.
87.Curtin C, Zhang W, Franco C. Manipulating anthocyanin composition in Vitis vinifera suspension cultures by elicitation with jasmonic acid and light irradiation. Biotechnology Letters. 2003;25:1131–1135.
88.Gangopadhyay M, Dewanjee S, Bhattacharya S. Enhanced plumbagin production in elicited Plumbago indica hairy root cultures. Journal of Bioscience and Bioengineering 2011;111:706–710.
89.Belhadj A, Saigne C, Telef N, Cluzet S, Bouscaut J, Corio–Costet MF, Me´rillon JM. Methyl jasmonate induces defense responsesin grapevine and triggers protection against Erysiphe necator. Journal of Agricultural and Food Chemistry. 2006;54:9119–9125.
90.Tassoni A, Fornale S, Franceschetti M, Musiani F, Michael AJ, Perry B, Bagni N. Jasmonates and Na–orthovanadate promote resveratrol production in Vitis vinifera cv. Barbera cell cultures. New Phytologist. 2005;166:895–905.
91.Taurino M, Ingrosso I, D’amico L, Domenico1 S. D, Nicoletti I, Corradini D, Santino A, Giovinazzo G. Jasmonates elicit different sets of stilbenes in Vitis vinifera cv. Negramaro cell cultures. SpringerPlus. 2015;4:49.
92.Nopo–Olazabal C, Condori J, Nopo–Olazabal L, Medina–Bolivar F. Differential induction of antioxidant stilbenoids in hairy roots of Vitis rotundifolia treated with methyl jasmonate and hydrogen peroxide. Plant Physiology and Biochemistry. 2014;74:50–69.
93.Tassoni A, Durante L, Ferri M. Combined elicitation of methyl–jasmonate and red light on stilbene and anthocyanin biosynthesis. Journal of Plant Physiology. 2012;169:775–781.
94.Xiaolong H, Min S, Lijie C, Chao X, Yanjie Z, Guoyin K. Effects of methyl jasmonate and salicylic acid on tanshinone production and biosynthetic gene expression in transgenic Salviamiltiorrhiza hairy roots. Biotechnology and Applied Biochemistry. 2015;62(1):24–31. DOI: 10.1002/bab.1236.
95.Sivanandhan G, Dev G, K, Jeyaraj M, Rajesh M, Arjunan A, Muthuselvam M, Manickavasagam M, Selvaraj N, Ganapathi A. Increased production of withanolide A, withanone, and withaferin A in hairy root cultures of Withaniasomnifera (L.) Dunal elicited with methyl jasmonate and salicylic acid. Plant Cell Tissue and Organ Culture. 2013;114:121–129.
96.Sharma P, Yadav S, Srivastava A, Shrivastava N. Methyl jasmonate mediates upregulation of bacoside A production in shoot cultures of Bacopa monnieri. Biotechnology Letters. 2013;35:1121–1125.
97.Sharma SN, Jhaa Z, Sinhab RK, and Gedac AK. Jasmonate–induced biosynthesis of andrographolide in Andrographis paniculata. Physiologia Plantarum. 2015;153: 221–229.
98.Hayashi H, Huang P, Inoue K, Up–regulation of soyasaponin biosynthesis by methyl jasmonate in cultured cells of Glycyrrhiza glabra. Plant and Cell Physiology. 2003;44:404–411.
99.Ketchum REB, Tandon M, Gibson DM, Begley T, Shuler ML. Isolation of labeled 9–dihydrobaccatin III and related taxoids from cell cultures of taxus cell cultures of Taxus canadensis elicited with methyl jasmonate. Journal of Natural Products. 1999;62:1395–1398.
100.Pedapudi S, Chin CK, Pedersen H. Production and elicitation of benzalacetone and the raspberry ketone in cell suspension cultures of Rubus idaeus. Biotechnology Progress. 2000;16:346–349.
101.Hayat Q, Hayat S, Irfan M, Ahmad A. Effect of exogenous salicylic acid under changing environment: a review. Environmental and Experimental Botany. 2010;68:14–25.
102.Pieterse CMJ, van Loon LC. Salicylic acid–independent plant defense pathways. Trends in Plant Science. 1999;4:52–58.
103.Idrees M, Naeem M, Aftab T, Khan MM. Salicylic acid mitigates salinity stress by improving antioxidant defence system and enhances vincristine and vinblastine alkaloids production in periwinkle [Catharanthus roseus (L.) G. Don]. Acta Physiologia Plantarum. 2010;33:987–999.
104.Avancini G, Abreu IN, Saldan˜a MDA, Mohamed RS, Mazzafera P. 2003 Induction of pilocarpine formation in jaborandi leaves by salicylic acid and methyl jasmonate. Phytochemistry. 2003;63:171–175.
105.Bulgakov VP, Tchernoded GK, Mischenko NP, Khodakovskaya MV, Glazunov VP, Radchenko SV, Zvereva EV, Fedoreyev SA, Zhuravlev YN. Effect of salicylic acid, methyl jasmonate, ethephon and cantharidin on anthraquinone production by Rubia cordifolia callus cultures transformed with the rolB and rolC genes. Journal of Biotechnology. 2002;97:213–221.
106.Ali M, Yu KW, Hahn EJ, Paek KY. Methyl jasmonate and salicylic acid elicitation induces ginsenosides accumulation, enzymatic and non–enzymatic antioxidant in suspension culture Panax ginseng roots in bioreactors. Plant Cell Reports. 2006;25:613–620.
107.Shabani L, Ehsanpour A, Asghari G, Emami J. Glycyrrhizin production by in vitro cultured Glycyrrhiza glabra elicited by methyl Jasmonate and salicylic acid. Russian Journal of Plant Physiology. 2009;56:621–626.
108.Xu YW, Lv SS, Zhao D, Chen JW, Yang WT, Wu W. Effects of salicylic acid on monoterpene production and antioxidant systems in Houttuynia cordata. African Journal of Biotechnology. 2012;11:1364–1372.
109.Liang Z, Ma Y, Xu T, Cui B, Liu Y, Guo Z, Yang D. Effects of abscisic acid, gibberellin, ethylene and their interactions on production of phenolic acids in Salvia miltiorrhiza bunge hairy roots. PLoS One. 2013;8(9):e72806.
110.Hu X, Neill S, Cai W, Tang Z. Hydrogen peroxide and jasmonic acid mediate oligogalacturonic acid–induced saponin accumulation in suspension–cultured cells of Panax ginseng. Physiologia Plantarum. 2003;118:414–421.
111.Fukui H, Yoshikawa N, Tabata M. Induction of shikonin formation by agar in Lithospermum erythrorhizon cell suspension cultures. Phytochemistry. 1983;22:2451–2453.
112.Komaraiah P, Ramakrishna SV, Reddanna P, Kavi Kishor PB. Enhanced production of plumbagin in immobilized cells of Plumbago rosea by elicitation and in situ adsorption. Journal of Biotechnology. 2003;101:181–187.
113.Orlita A, Sidwa–Gorycka M, Paszkiewicz M, Malinski E, Kumirska J, Siedlecka EM, Łojkowska E, Stepnowski P. Application of chitin and chitosan as elicitors of coumarins and fluoroquinolone alkaloids in Ruta graveolens L. (common rue). Biotechnology and Applied Biochemistry. 2008;51:91–96.
114.Sonja GS, Oliver T, Stéphane M, Alain D, Eric L, Claude J, and Daniel H. Polysaccharide elicitors enhance phenylpropanoid and naphtodianthrone production in cell suspension cultures of Hypericum perforatum. Plant Cell Tissue and Organ Culture. 2015; DOI: 10.1007/s11240–015–0798–z.
115.Felix G, Grosskopf DG, Regenass M, Basse CW, Boller T. Elicitor–induced ethylene biosynthesis in tomato cells: characterization and use as a bioassay for elicitor action. Plant Physiology. 1991;97:19–25.
116.Stangarlin JR, Kuhn OJ, Assi L, Schwan–Estrada KRF. Control of plant diseases using extracts from medicinal plants and fungi. In: Mendez–Vilas A. editor. Science Against Microbial Pathogens: Communicating Current Research and Technological Advances. Formatex Research Center, Badajoz, Spain; 2011. p. 1033–1042.
117.Dixon RA, Achnine L, Kota P, Liu CJ, Reddy MKS, Wang L. The phenylpropanoid pathway and plant defence—a genomics perspective. Molecular Plant Pathology. 2002;3:371–390.
118.Lattanzio V, Lattanzio VM, Cardinali A. Role of phenolics in the resistance mechanisms of plants against fungal pathogens and insects. Phytochemistry Advances in Research. 2006;661:23–67.
119.Glazebrook J. Contrasting mechanisms of defense against biotrophic and necrotrophic pathogens. Annual Review of Phytopathology. 2005;43:205–227.
120.Leonard KJ, Bushnell WR. Fusarium Head Blight of Wheat and Barley. APS Press, USA; 2004.
121.Boerema GH, de Gruyter J, Noordeloos ME, Hamers MEC. Phoma Identification Manual. Differentiation of Specific and Intra–pecific Taxa in Culture. CABI Publishing, Wallingford; 2004.
122.Gill SS, Tuteja N. Reactive oxygen species and antioxidant machinery in abiotic stress tolerance in crop plants. Plant Physiology and Biochemistry. 2010;48:909–930.
123.Hano C, Addi M, Bensaddek L, Cronier D, Baltora–Rosset S, Doussot J, Maury S, Mesnard F, Chabbert B, Hawkins S, Laine´ E, Lamblin F. Differential accumulation of monolignol–derived compounds in elicited flax (Linum usitatissimum) cell suspension cultures. Planta. 2006;223:975–989.
124.Keen NT. Specific elicitors of plant phytoalex in production: determinants of race specificity in pathogens? Science. 1975;187:74–75.
125.Bostock RM, Kuc JA, Laine RA. Eicosapentaenoic and arachidonic acids from Phytophthora infestans elicit fungitoxic sesquiterpenes in the potato. Science. 1981;212(4490):67–69.
126.Sang MK, Kim JG, Kim KD. Biocontrol activity and induction of systemic resistance in pepper by compost water extracts against Phytophthora capsici. Phytopathology. 2010;100:774–783.
127.Namdeo A, Patil S, Fulzele DP. Influence of fungal elicitors on production of ajmalicine by cell cultures of Catharanthus roseus. Biotechnology Progress 2002;18:159–162.
128.Parchmann S, Gundlach H, Mueller MJ. Induction of 12–oxo–phytodienoic acid in wounded plants and elicited plant cell cultures. Plant Physiology. 1997;115:1057–1064.
129.Rokem JS, Schwarzberg J, Goldberg I. Autoclaved fungalmycelia increase diosgenin production in cell suspension cultures of Dioscorea deltoidea. Plant Cell Reports. 1984;3:159–160.
130.Balazova A, Bilka F, Blana´rikova´ V, Psena´k M. Effect of a fungal elicitor on levels of sanguinarine and polyphenoloxidase activity in a suspension culture of Papaver somniferum L. Ceská a Slovenská Farmacie. 2002;51:182–185.
131.Heinstein PF. Future approaches to the formation of secondary natural products in plant cell suspension cultures. Journal of Natural Products. 1985;48:1–9.
132.Eilert U, Ehmke A, Wolters B. Induced accumulation of acridone alkaloid epoxides in Ruta graveolens suspension cultures. Planta Medica. 1984;50:508–512.
133.Wang C, Wu J, Mei X. Enhancement of taxol production and excretion in Taxus chinensis cell culture by fungal elicitation and medium renewal. Applied Microbiology and Biotechnology. 2001;55:404–410.
134.Bhagwath SG, Hjortsø MA. Statistical analysis of elicitation strategies for thiarubrine A production in hairy root cultures of Ambrosia artemisiifolia. Journal of Biotechnology. 2000;80: 159–167.
135.Awad V, Kuvalekar A, Harsulkar A. Microbial elicitation in root cultures of Taverniera cuneifolia (Roth)Arn. for elevated glycyrrhizic acid production. Industrial Crops and Products. 2014;54:13–16.
136.Satdive RK, Fulzele DP, Eapen S. Enhanced production of azadirachtin by hairy root cultures of Azadirachta indica A. Juss by elicitation and media optimization. Journal of Biotechnology. 2007;128:281–289.
137.Baldi A, Singh D, Dixit VK. Dual elicitation for improved production of withaferin A by cell suspension cultures of Withania somnifera. Applied Biochemistry and Biotechnology. 2008;151:556–564.
138.Jung HY, Kang SM, Kang YM, Kang MJ, Yun DJ, Bahk JD, Yang JK, Choi MS. Enhanced production of scopolamine by bacterial elicitors in adventitious hairy root cultures of Scopoliaparviflora. Enzyme and Microbial Technology. 2003;33:987–990.
139.Manero FJ, Algar E, Martin Gomez MS, Saco Sierra MD, Solano BR. Elicitation of secondary metabolism in Hypericum perforatum by rhizospherebacteria and derived elicitors in seedlings and shoot cultures. Pharmaceutical Biology. 2012;50:1201–1209.
140.Onrubia M, Moyano E, Bonfill M, Cusido´ RM, Goossens A, Palazo´n J. Coronatine, a more powerful elicitor for inducing taxane biosynthesis in Taxus media cell cultures than methyl jasmonate. Journal of Plant Physiology. 2013;170:211–219.
141.Dicosmo F, Misawa M. Eliciting secondary metabolism in plant cell cultures. Trends in Biotechnology. 1985;3:318–322.
142.Ganapathi G, Kargi F. Recent advances in indole alkaloid production by Catharanthus roseus (Periwinkle). Journal of Experimental Botany. 1990;41:259–267.
143.Collinge DB, Susarenka AJ. Plant gene expression in response to pathogens. Plant Molecular Biology. 1987;9:389–410.
144.Mukandan U, Hjorosto MA. Effect of fungal elicitor on thiophene production in hairy root cultures of Tagetes patula. Applied Microbiology and Biotechnology. 1990;33:145–147.
145.Roewer IA, Cloutier N, Van der Heijden R. Transient induction of tryptophan decarboxylase (TDC) and strictosidine synthase, (SS) genes in cell suspension cultures of Catharanthus roseus. Plant Cell Reports. 1992;11(2): 86–89.
146.Jeong GA, Park DH. Enhanced secondary metabolite biosynthesis by elicitation in transformed plant root system. Applied Biochemistry and Biotechnology. 2007;130:436–446.
147.Dong J, Wan G, Liang Z. Accumulation of salicylic acid–induced phenolic compounds and raised activities of secondary metabolic and antioxidative enzymes in Salvia miltiorrhiza cell culture. Journal of Biotechnology. 2010;148:99–104.
148.Chodisetti B, Rao K, Gandi S, Giri A. Gymnemic acid enhancement in the suspension cultures of Gymnema sylvestre by using the signaling molecules—methyl jasmonate and salicylic acid. In Vitro Cellular and Developmental Biology—Plant. 2015;51:88–92.
149.Chodisetti B, Rao K, Gandi S, Giri A. Improved gymnemic acid production in the suspension cultures of Gymnema sylvestre through biotic elicitation. Plant Biotechnology Reports. 2013;7:519–525.
150.Zahra S, Mehrnaz K, Gholamreza A, Mustafa G. Improvement of atropine production by different biotic and abiotic elicitors in hairy root cultures of Datura metel. Turkish Journal of Biology. 2015;39:111–118.
151.Wungsintaweekul J, Choo–malee J, Charoonratana T, Niwat N. Methyl jasmonate and yeast extract stimulate mitragynine production in Mitragyna speciosa (Roxb.) Korth shoot culture. Biotechnology Letters. 2012;34:1945–1950.
152.Namdeo AG. Investigation on pilot scale bioreactor with reference to the synthesis of bioactive compounds from cell suspension cultures of Catharanthus roseus Linn. [thesis]. Indore: Devi Ahilya Vishwavidyalaya; 2004.
153.Rijhwani SK, Shanks JV. Effect of subculture cycle on growth and indole alkaloid production by Catharanthus roseus hairy root cultures. Enzyme and Microbial Technology. 1998;22(7): 606–611.
154.Gautam S, Mishra A, Tiwari A. Catharanthus alkaloids and their enhanced production using elicitors: a review. International Journal of Pharmacy and Technology. 2011;3(1):713–724.
155.Docimo T, Davis AJ, Luck K, Fellenberg C, Reichelt M, Phillips M, Gershenzon J, D’Auria JC. Influence of medium and elicitors on the production of cocaine, amino acids and phytohormones by Erythroxylum coca calli. Plant Cell Tissue and Organ Culture. 2015;120:1061–1075.
156.Anderson WC. Tissue culture propagation of Rhododendrons. In Vitro Journal of Tissue Culture Association. 1978;14:334.
157.Gamborg OL, Murashige T, Thorpe TA, Vasil IK. Plant–tissue culture media. In Vitro Journal of Tissue Culture Association. 1976;12:473–478.
158.Murashige T, Tucker DPH. Growth factor requirements of citrus tissue culture. In: Chapman HD, editor. Proceedings of the 1st international citrus symposium; University of California–Riverside Publication, Riverside. California; 1969. p. 1155–1161.
159.Scheible WR, Morcuende R, Czechowski T, Fritz C, Osuna D, Palacios–Rojas N, Schindelasch D, Thimm O, Udvardi MK, Stitt M. Genome–wide reprogramming of primary and secondary metabolism, protein synthesis, cellular growth processes, and the regulatory infrastructure of Arabidopsis in response to nitrogen. Plant Physiology. 2004;136:2483–2499.
160.Kova´cˇik J, Klejdus B, Babula P, Jarosˇova´ M. Variation of antioxidants and secondary metabolites in nitrogen–deficient barley plants. Journal of Plant Physiology. 2014;171:260–268.
161.Fritz C, Palacios–Rojas N, Feil R, Stitt M. Regulation of secondary metabolism by the carbon–nitrogen status in tobacco: nitrate inhibits large sectors of phenylpropanoid metabolism. Plant Journal. 2006;46:533–548.
162.Bensaddek L, Gillet F, Saucedo JEN, Fliniaux MA. The effect of nitrate and ammonium concentrations on growth and alkaloid accumulation of Atropa belladonna hairy roots. Journal of Biotechnology. 2001;85:35–40.
163.Tonelli M, Pellegrini E, D’Angiolillo F, Nali C, Pistelli L, Lorenzini G. Ozone–elicited secondary metabolites in shoot cultures of Melissa officinalis L. Plant Cell Tissue and Organ Culture. 2015;120:617–629.
164.Xu M, Yang B, Dong J, Lu D, Jin H, Sun L, Zhu Y, Xu X. Enhancing hypericin production of Hypericum perforatum cell suspension culture by ozone exposure. Biotechnology Progress 2011;27:1101–1106.
165.Sun L, Su H, Zhu Y, Xu M. Involvement of abscisic acid in ozone–induced puerarin production of Pueraria thomsnii Benth. suspension cell cultures. Plant Cell Reports. 2012;31:179–185.
166.Naik PM, Manohar SH, Praveen N, Murthy HN. Effects of sucrose and pH levels on in vitro shoot regeneration from leaf explants of Bacopa monnieri and accumulation of bacoside A in regenerated shoots. Plant Cell Tissue and Organ Culture 2010;100:235–239.
167.Praveen N, Murthy HN. Synthesis of withanolide A depends on carbon source and medium pH in hairy root cultures of Withania somnifera. Industrial Crops and Products. 2012;35:241–243.
168.Praveen N, Murthy HN. Establishment of cell suspension cultures of Withania somnifera for the production of withanolide A. Bioresource Technology. 2010;101:6735–6739.
169.Sara–Alsadat R, Ahmad M, Mokhtar JJ. Paclitaxel production is enhanced in suspension–cultured hazel (Corylus avellana L.) cells by using a combination of sugar, precursor, and elicitor. Engineering in Life Sciences. 2015;15:234–242.
170.Munish S, Ashok A, Rajinder G, Sharada M. Enhanced bacoside production in shoot cultures of Bacopa monnieri under the influence of abiotic elicitors. Natural Product Research. 2015;29(8):745–749.
171.Izabela G, Halina W. The effect of methyl jasmonate on production of antioxidant compounds in shoot cultures of Salvia officinalis L. Herba Polonica. 2009;55:238–243.
172.Firouzi A, Mohammadi SA, Khosrowchahli M, Movafeghi A, Hasanloo T. Enhancement of silymarin production in cell culture of Silybum marianum (L) Gaertn by elicitation and precursor feeding. Journal of Herbs, Spices and Medicinal Plants. 2013;19(3):262–274.
173.Li B, Wang B, Li H, Peng L, Ru M, Liang Z, Yan X, Zhu Y. Establishment of Salviacastanea Diels f. tomentosa Stib. Hairy root cultures and the promotion of tanshinone accumulation and gene expression with Ag+, methyl jasmonate, and yeast extract elicitation. Protoplasma. 2015; DOI: 10.1007/s00709–015–0790–9.
174.Yuan Y, Huang L, Cui G, Mao Y, He X. Effect of gibberellins and its synthetic inhibitor on metabolism of tanshinones. Chinese Journal of Experimental Traditional Medical Formulae. 2008;6:002.
175.Abbasi BH, Stiles AR, Saxena PK, Liu CZ. Gibberellic acid increases secondary metabolite production in Echinacea purpurea hairy roots. Applied Biochemistry and Biotechnology. 2012;168(7):2057–2066.
176.Patil JG, Ahire ML, Nitnaware KM, Panda S, Bhatt VP, Kishor PB, Nikam TD. In vitro propagation and production of cardiotonic glycosides in shoot cultures of Digitalis purpurea L. by elicitation and precursor feeding. Applied Microbiology and Biotechnology. 2013;97:2379–2393.
177.Coste A, Vlase L, Halmagyi A, Deliu C, Coldea G. Effects of plant growth regulators and elicitors on production of secondary metabolites in shoot cultures of Hypericum hirsutum and Hypericum maculatum. Plant Cell Tissue and Organ Culture. 2011;106:279–282.
178.Ajungla L, Patil PP, Barmukh RB, Nikam TD. Influence of biotic and abiotic on accumulation of hyoscyamine and scopolamine in root cultures of Datura metel L. Indian Journal of Biotechnology. 2009;8(3): 317–322.
179.Li J, Wang J, Li J, Li J, Liu S, Gao W. Salicylic acid induces the change in the adventitious root of Glycyrrhiza uralensis Fisch.: bioactive compounds and antioxidant enzymes. Research on Chemical Intermediates. 2015; DOI: 10.1007/s11164–015–2099–x.
180.Kracˇun–Kolarevic´ M, Dmitrovic´ S, Filipovic´ B, Peric´ M, Misˇic´ D, Simonovic´ A, Todorovic S. Influence of sodium salicylate on rosmarinic acid, carnosol and carnosic acid accumulation by Salvia officinalis L. shoots grown in vitro. Biotechnology Letters. 2015;37(8):1693–1701.
181.Purohit M, Pande D, Datta A, Srivastava PS. Enhanced xanthotoxin content in regenerating cultures of Ammi majus and micropropagtion. Planta Medica. 1995;61:481–482.
182.Sonja GS, Oliver T, Stéphane M, Alain D, Claude J, Daniel H. Effects of polysaccharide elicitors on secondary metabolite production and antioxidant response in Hypericumperforatum L. shoot cultures. Scientific World Journal. 2014;11:609–649.
183.Sonja GS, Oliver T, Ste´phane M, Christophe H, Alain D, Brigitte C, Fre´de´ric L, Eric L, Claude J, Daniel H. Fungal elicitor–mediated enhancement in phenylpropanoid and naphtodianthrone contents of Hypericum perforatum L. cell cultures. Plant Cell Tissue and Organ Culture. 2015;122:213–226.
184.Qianliang M, Chunyan S, Chengjian Z, Min J, Qiaoyan Z, Hong Z, Khalid R, Ting H, Luping Q. Elicitors from the endophytic fungus Trichoderma atroviride promote Salvia miltiorrhiza hairy root growth and tanshinone biosynthesis. Journal of Experimental Botany. 2013;64(18):5687–5694.
Written By
Poornananda M. Naik and Jameel M. Al–Khayri
Submitted: 08 April 2015Reviewed: 07 September 2015Published: 17 February 2016
Open access peer-reviewed chapter
