Is There Still Room to Improve Medicinal Herbs (Functional Herbs) by Gene Editing for Health?

Abstract

Herbs have a wide variety of chemical compounds that can support food quality, medicines, and biotechnology approaches. Over the years, extensive research has been carried out in genetic engineering of foods, including improving the feasibility of herbs. The story behind the herbal genetic technology relates to food allergy, the pharmaceutical industry, and of course, the growing food shortage that is the biggest nutritional issue of this century. Researchers have highlighted that in genome editing, creating synthetic biology is a good strategy. Furthermore, the production of secondary metabolites in herbs may be enhanced through genetic methods. The researchers investigated the plants’ secondary metabolic pathways as well as their genetic alterations. Yet there are some herbal remedies used in genetic engineering. This chapter begins with a discussion of our studies of functional foods and their effects on human and animal health. Next, we will highlight the importance of genome editing in herbs and methodologies. Additionally, the differences between natural functional foods and genome editing herbs will try to prove efficacy on humans and animals. Consequently, we will attempt to reveal if genomic foods have protective effects on health and particularly on pandemic diseases.

1. Introduction

Genetic engineering, which is a branch of biotechnology, is the most important innovation in the present century. Since the 1990s, this technology has provided genetic and biological research to several novelties for human, animal, plant, health, agriculture, and nutrition (Figure 1). However, researchers are still interested in exciting new approaches to improving the technology.

Figure 1.

The possible benefits of genomic editing technologies.

Global population is expected to grow by 10 billion in the coming decades, along with climate change and drought. In addition to the shortage of crops, vegetables, and fruits, it is inevitable to increase inadequate nutrition and malnutrition. Following this problem, biotechnology approaches based on genome modification have been highlighted. In particular, editing the plant genome may be the most significant innovation for this purpose.

New genome editing technologies make it possible for researchers to know exactly and quickly the desired characteristics of the plant. These technologies could be a model of effectiveness that could change and enhance genes in crop production. In order to achieve this goal, several tasks are required between many disciplines, including plant breeders, molecular biologists, nutritionists, and even social scientists. Most authorities focus on global food security as well as malnutrition. In this chapter, we will attempt to present the importance of genome modification in herbs, methodologies, and correlation with health.

2. Is an herb a savior as a medicine for health?

Being part of the new global strategies on agricultural challenges and diseases, improving food products, quality of herbs and herbal medicines are very important. In particular, nowadays in pandemic diseases, herbs, natural foods, phytogenic ingredients, essential oils, and antioxidants have been studied by researchers in human and animal health [1].

It’s well known that the use of natural foods or natural additives is good for health as well as life quality. Among these additives, algae, spirulina, ginger, thyme, yeasts, Echinacea, sage tea, and green tea are the most interested ones. As a matter of fact, the relationship between natural herbs and health is evaluated on their ingredients. The most known compounds are polyphenols, flavonoids, phycocyanin, vitamins, carotene, and glutathione. These compounds have a broad range of health effects, such as antioxidants, anticancer, immunomodulatory, antivirals, and others [2, 3, 4, 5, 6, 7].

Natural foods may alternate several processes in the body, especially oxidative balance, inflammation, genetic changes, immune stimulation, and growth factors. Along with literatures, especially class of antioxidant compounds has radical scavenging properties. Flavonoids, flavones and anthocyanins, the most important antioxidant compounds, are enormously aware of the health benefits. They are all health-oriented and promote efficacy and functional activity against diseases due to the presence of multiple hydroxyl groups [1, 8, 9, 10]. What is more, certain nutraceuticals, such as phenylpropanoids, would have a role against environmental stress. However, certain important herbs can maintain homeostasis by reducing high fever [11, 12], may have metabolic effects through inhibition of cancer cell proliferation [13, 14], or act as a chemical quench [15]. Nonetheless, scientific studies have been investigated that several herbs and compounds are used to enhance immunity by inhibiting activation of specific cytokines [1, 10, 16, 17, 18]. In addition, certain herbs and their compounds have antiviral effects that are dependent on the inhibition of viral protein synthesis and viral replication [19].

Previously, the preventive role of the health and quality of life of herbs and their compounds were assessed. In addition, the association between these herbs and the target mechanism in humans and animals has been sought to identify. Several natural foods and their components have been used over the years. Especially nowadays, people try to protect their health in a natural way that is natural foods or their compounds, even if it is a natural medication or natural supplement. In fact, there is enormous complexity about this use knowingly or unknowingly. Thus, the use of traditional herbs and their effects have been researched over the years. In addition, new strategies have been identified for natural foods and their health-enhancing compounds.

3. In the near future: the importance of genome editing in herbs and the methodologies

Genome editing technologies have potential for nutrition due to climate change, reduced agricultural fields, and increased plant stressors. New global agriculture and food production strategies indicate that the revision of the food genome has been important. Actually, the history of genome editing was established over the 1980s as plant breeding. This innovation has supported both nutrition and the food and pharmaceutical industries.

Genome editing technology is a type of genetic engineering in which DNA is inserted, suppressed, altered, or replaced in the genome of a living organism. Genetic material is randomly inserted into the genome of a host by focusing on specific locations. However, it has been reported that random insertion of DNA into the host genome is a disadvantage of this technology because of disruption or alteration of other genes in the organism [20]. So, there was a concern about genetically modified products. Nevertheless, in the 2000s, genome editing has been successfully accomplished for both animal and plant systems with the use of artificial or natural region-specific nucleases and genome editing technologies. Genome editing technology has become a powerful method for functional genomics and crop selection studies in comparison with the randomized method [21].

Some plant transformation techniques are used for genome editing; administration of polyethylene glycol in protoplasts [22], microparticle bombardment [23], WHISKERS™ [24], and Agrobacterium [25]. They can deliver these genome editing reagents to plant cells [26, 27]. More recently, genome editing methods have started to be used to improve our understanding of plant gene functions and the alteration and enhancement of plant genes. The genome editing allows the addition, removal, or modification of the desired genes in the genome by creating double-strand breaks (DSBs) with the specific nucleases of the region. There are four ways to accomplish this: 1. Meganucleases; 2. Zinc finger nucleases (ZFNs); 3. Transcription activator-like effector nucleases (TALENs) and 4. Clustered regularly interspaced short palindromic repeats (CRISPR).

Meganucleases are regarded as the most specific naturally occurring restriction enzymes that are also mobile genetic compounds. They are synthesized in mitochondrial and chloroplast genomes. Despite the identification of several meganucleases, it is naturally impossible to find a suitable enzyme for each region. A new enzyme model is needed for each study. Meganucleases have been successfully used to target DNA insertions in various plants, such as maize, tobacco, and Arabidopsis species [28].

Zinc finger nucleases (ZFNs) are artificial restriction enzymes generated by merging a DNA-binding domain from a zinc finger to a DNA cleavage domain. ZFNs are synthetic nucleases, which were first discovered in TFIIIA from Xenopus laevis frogs. The zinc finger protein motif encounters transcribing factors and recognizes the DNA sequences. In fact, ZFNs can be designed to bind and divide any of the DNA sequences. However, for each region of the genome, ZFN must be regenerated. This increases costs and is time-consuming. Several studies have been carried out on plant genome modification using ZFNs, in particular Arabidopsis plants, tobacco, maize, and soybeans [29, 30, 31, 32]. Additionally, genome editing in microalgae with ZFNs was first reported for Chlamydomonas reinhardtii, which was the adapted model strain [33, 34].

Transcription activator-like effector nucleases (TALENs) are similar to those in ZFN. The targeting strategy is delivered by linking pairs to two tightly spaced DNA sequences in both systems. The TALEN proteins were obtained from the phytopathogenic bacterium Xanthomonas. The TALENs method was considered to be successful for Arabidopsis, rice, tobacco, barley, Brachypodium, and corn [35]. Nonetheless, the microalgae Phaeodactylum tricornutum was highlighted by the TALENs method to improve lipid accumulation [36]. It was also reported that genome editing in P. tricornutum and Chlamydomonas has been established by TALENs [37, 38].

Clustered regularly interspaced short palindromic repeat (CRISPR) is the most important method for plant biotechnology whose working principle is based on RNA-mediated nucleases [39]. This is a system discovered from Streptococcus pygonese and named CRISPR/Cas9 system. Clustered regularly interspaced short palindromic repeats (CRISPRs)-case-mediated immunity in bacteria provides bacterial populations with protection from pathogens. However, they are also exposed to the dangers of autoimmunity by developing protection that targets their own genomes. CRISPR/Cas vectors have a replication origin and marker gene and also have a power promotor with Cas genes. This makes it possible to target several genes, and consequently, this technology costs less than others. The scientists reported that the Cas9 system could be used to modify the human genome as well as the plant genome [39, 40]. There are two main strategies: using RNA as vectors or transferring a functional nuclease directly into the cells of plants.

Besides its applicability in plant biology, the main focus of CRISPR/Cas system is producing heritable mutations within NHEJ-mediated (NHEJ: nonhomologous end joining) in many species. Also, it’s possible to add a DNA fragment via HDR (HDR: homology directed recombination) to a desired region in the plant genome with the CRISPR system; however, a few number of studies have been conducted [41, 42]. Several plant genomes have been modified with CRISPR technology: rice, wheat, corn, tomato, potatoes, cucumber, orange, soybean, tobacco, lemon, and microalgae [32, 43]. The studies provided comparative data, including mutagenesis, efficiency, truncation specifications, potential for generating chromosomal deletions, or adding CRISPR genes [39, 44]. Also, it was reported that there have been several studies; nontoxicity mutation with mediated-CRISPR such as microalgae [45], basic biological studies such as on the opium poppy [46], and improving the quality of products such as tomatoes [47]. The CRISPR system is a multiplex engineering of the genome, which means that multiple genes may be targeted.

In addition, the main advantage of the CRISPR system is that it prevents the gene from moving between organisms and problems related to gene transporting. Also, no difference occurs in the next generation of organism, biallelic may be provided, and heterozygous and homozygous mutations may be generated [48]. Svitashev et al. [49] and Woo et al. [50] have conducted studies with lettuce, rice, and corn to get successful mutations and modified fields with no alien DNA and marker. In addition, some microalgae, namely C. reinhardtii, Chlamydomonas, and P. tricornutum, have been edited successfully without cytotoxic effects [45, 51, 52]. According to the literature, genome editing with CRISPR/Cas engineering for single nucleotide resolution editing, multiple gene editing, transcriptional regulation, and genome-wide modifications of Saccharomyces cerevisiae have been shown [53, 54]. S. cerevisiae is an important eukaryotic yeast for the biosynthesis and biofuels [55, 56]. However, there are still some limitations and challenges, in particular the application of CRISPR could limit the effectiveness of yeast processing.

All these technologies have been reported for improving plant micronutrients, such as flavonoids, phenols, saponins, tannins, etc. [57]. These are bioactive compounds known as medicines that are important to health. In particular, the CRISPR/Cas9 technology can be used to target genes in medicinal plants and their compounds. In addition, this technology can tolerate environmental stress along with quality and performance. There have been successful studies about plant biosynthetic pathways with CRISPR/Cas9, such as tomato for gamma-aminobutyric acid, banana, and rice for beta carotene [58, 59, 60, 61]. Also, CRISPR/Cas9 is an effectible technology for bacterial resistance of herbs and plant-derived products and against climate changes [62, 63]. Genome editing technology involves more controlled mutations, and genetic improvement is less time-consuming.

Biotechnology approaches have been interpreted in the context of genome editing technologies over the years. Secondary plant metabolites that belong to genome technology are pharmacologically important as well as nutritional (Table 1). However, the editing of the genome is still in its beginnings in plants and their contents. As new and interesting results are obtained in this field, new technologies will emerge.

Plants	Methods	Improved trait
Rice	TALENs	Increased fragrance content
Rice	CRISPR/Cas9	Functional metabolites (amylose, Proanthocyanidins, anthocyanidins, beta carotene)
Wheat	CRISPR/Cas9	Increased protein (reduce gliadins)
Corn	ZFNs	Antinutrient (reduce the phytic acid content)
Corn	TALEN	Antinutrient (reduce the phytic acid content)
Corn	CRISPR/Cas9	Protein (reduce zein protein)
Potato	TALEN	Reduced browning, antinutrient (reduce steroidal glycoalkaloids); Toxic substance (reduce sugar and acrylamide)
Potato	CRISPR/Cas9	Reduced browning, starch (amylose), anti-nutrient (absence of steroidal glycoalkaloids)
Oilseed	CRISPR/Cas9; TALEN	Reduced oil content,; Reduced polyunsaturated fatty acids,
Tobacco	Meganuclease	Reduced nicotine levels
Tomato	TALEN	Functional metabolite (increased anthocyanin)
Tomato	CRISPR/Cas9	Functional metabolite (increased anthocyanin, aminobutyric acid content)
Tomato	ZFN	Antinutrient (reduced anti-nutrient oxalic acid)
Grape	CRISPR/Cas9	Antinutrient (reduced tartaric acid level)
Sage (Salvia miltiorrhiza)	CRISPR/Cas9	Decreased phenolic acid contents
Pomegranate	CRISPR/Cas9	Changes the galloyl-glucose conjugates
Grapevine	CRISPR/Cas9	Lack of pigments phenotypes
Papaver	CRISPR/Cas9	Biosynthesis flux of morphine, thebaine, etc.
Banana	CRISPR/Cas9	Functional metabolites (Beta carotene)

Table 1.

Some nutritional quality-improved foods by gene-editing technologies (Prepared according to literatures; Ku and Ha [64], Scarano et al. [65], Dey et al. [66]).

4. The differences between functional foods and herbs with edited genomes

Scientific evidence shows a great relationship between functional foods and improvement of physiological condition. It is also important to achieve health-related results, particularly in the case of chronic diseases and pandemics. Several studies and clinical trials for herbal nutrition exist. In fact, functional foods have been accepted as mainstream medicine for generations. Based on the literature review, it may be suggested that functional foods are safe to use. They have several health benefits such as preventing adverse effects, increasing the beneficial effect on health, and improving health status [1, 2, 9, 10, 15].

Genome editing of herbs is an exciting innovation for agricultural, nutritional, and pharmacological areas. Some foods designed to modify the genome have been in use for 25 years. This technology is addressed in the cultivation of first-generation transgenic crops, and it permits gene deletion, insertion, silencing, and gene knock-out. The main problem in genome editing is off-target effect. The off-target effect results in inadequacy and typing error, and undesired mutations occur. These off-target activities may change in organisms. However, any such mismatches can be guessed through computer programs [67]. There have been several studies to decrease these effects [68, 69].

Unlike random recombinant methods, CRISPR/Cas9 editing technology is accepted as target-specific. On the contrary, especially in rice, the off-target sites of CRISPR/Cas9 editing are still unknown [70]. However, studies have shown that there are no nontarget DNA changes in rice mutants generated by CRISPR/Cas9, which should be important for the regulation of gene-modified breeding [71, 72]. In addition, it was reported that besides rice, Arabidopsis, cotton, and tobacco have indicated off-target mutations rarely [73]. However, some studies have indicated that off-target mutations are possible. Thus, genome editing still leaves room for improvement for the future.

5. Future perspectives: genomic foods have protective effects on health or not?

Most national authorities consider the need for a specific evaluation of genetically modified foods. Certain specific systems for assessing foods intended to modify genes for humans and the environment have been improved. Therefore, the World Health Organization’s (WHO’s) The Department of Food Safety and Zoonoses requests national authorities to implement risk assessment procedures and recommend safety assessment approaches.

Theoretical discussions were raised regarding the effectiveness of editing the food genome. However, discussing the potentials for stimulating allergenicity, gene transfer and outcrossing are the fact of the matter. For allergenicity, The Food and Agriculture Organization of the United Nations (FAO) and WHO have evaluated the protocols for testing of genome editing of foods, and no allergic effects were found right now on marketing. It was reported that plant breeding could cause high toxins and allergen concentration in plants. Also, a number of food poisoning could be done due to new varieties into food chain [74]. Gene transfer technology is encouraged with antibiotic resistance genes because of the concern of transferred genetic material from genome-edited foods to humans. Outcrossing is the migration of genes from genome editing plants into conventional crops, which is also mixing of crops from conventional seeds with genome editing crops. This has an indirect effect on food security. There are studies reporting that genome modification cultures for animal feed have been determined to products for humans in a low value. In this way, several countries have adopted major strategies aimed at reducing the mixing and separation of fields where genome editing and conventional crops are grown.

In addition, antibiotic resistance, immunosuppression, cancer, and loss of nutrition can also be counted for unexpected effects and health risks of genome editing technology. It can be said that all genome-edited foods contain antibiotic resistance markers to help identify the transferring of new genetic material into host food. Food and Drug Administration (FDA) introduces these antibiotic markers into the food on a widespread basis. Because of this, some important antibiotics against human illnesses could be made unnecessary. Even though the FDA ignored the issue, the British Medical Association (BMA) has concluded that antibiotic marker genes in the modification of the food genome should constitute a risk to human health and the development of microorganisms is going to be a very important issue in the twenty-first century. In addition, some researchers have shown that changes in the potato genome have significant negative effects on immunity and organ development in rats. They found a valid link between changing the food’s genome and immunosuppression [75]. Also, in 1993, a study about engineering recombinant bovine growth hormone (rBGH) resulted in concerns. Researchers showed that levels of hormone called insulin-like growth factor-1 (IGF-1) are increased in dairy cows treated with rBGH. This hormone, IGF-1, is an important factor for breast cancer, colon cancer, or prostate cancer [76]. Another concern was that modifying the genome may alter the nutritional value of foods. Researchers reported that some foods are in “undesirable alteration in the level of nutrients” and noted the nutritional changes. However, these findings were not considered by the FDA in their studies. Nevertheless, the WHO has pointed out that the modification of the genome of foods currently available on the international market is safe and does not pose a risk to human health. In addition, it was indicated that the principles of Codex Alimentarius must be applied on an ongoing basis and that post-market monitoring should ensure the safety of foods for genome editing [77].

6. Conclusion

Introducing new genetic material from a plant may produce certain chemicals. New technologies are necessary to test toxicity with safe boundaries. This means that risk assessment and food safety are important. There is a need to provide food safety, biological severity, feed, renewable resources for fuel and the environment. Genome editing technologies may improve the ability of these objectives. In this regard, some countries have regulatory policies restricting the editing of the food genome; in particular, about the traceability of plants or food with technologies, or resistance to genetic transformations.

The state of being natural for food is important for health, life, and the environment. There are several points about genetically modified foods. Researchers continue to investigate these and new technologies. But everyone agrees that there is still work to be done.

Conflict of interest

“The authors declare no conflict of interest.”

Acronymes and abbreviations

DNA

deoxyribonucleic acid

RNA

ribonucleic acid

ZFNs

zinc finger nucleases

TALENs

transcription activator-like effector nucleases

CRISPR

clustered regularly interspaced short palindromic repeats

TFIIIA

transcription factor IIIA

Cas9

a protein plays a vital role in the immunological defense of certain bacteria against DNA viruses and plasmids

NHEJ

nonhomologous end joining

HDR

homology directed recombination

WHO

the World Health Organization

FAO

the Food and Agriculture Organization of the United Nations

FDA

Food and Drug Administration

BMA

British Medical Association

rBGH

recombinant bovine growth hormone

IGF-1

insulin-like growth factor-1

Appendices and nomenclature

Antioxidants

proanthocyanidins, anthocyanidins, beta carotene, phenolic acid

Microalgae

Spirulina

Algae

Phaeodactylum tricornutum

Algae

Chlamydomonas reinhardtii

Yeast

Saccharomyces cerevisiae

Agrobacterium

plant bacteria

Bacteria

Streptococcus pygonese