The most dominant vegetables in the global food economy are tomato, cucurbits, (pumpkin, squash, cucumber and gherkin), allium (onion, shallot, garlic) and chili. These vegetables are consumed in nearly all countries although with much variation in shape, size, color and taste, while the marketing of global vegetables accounts for significant revenue streams, traditional vegetables often have superior nutritional properties. Biodiversity is considered essential for food security and nutrition and can contribute to the achievement through improved dietary choices and positive health impacts Through conventional breeding approach, it is possible to develop new vegetable varieties or integrate the favorable genes for neutraceuticals, bioactive compounds and edible color into cultivated varieties. Advances in molecular biology and recombinant technology have paved the way for enhancing the pace of special trait variety development using marker assisted breeding and designing new vegetable crop plants following transgenic approach.
- conventional breeding
Vegetables are increasingly recognized as an essential source for food and nutrition security. Vegetable production provides a promising economic opportunity for reducing rural poverty and unemployment in developing countries and is a key component of farm diversification strategies. Vegetables are mankind’s most affordable source of vitamins and minerals needed for good health. Today, neither the economic nor nutritional power of vegetables has not been sufficiently realized. To tap the economic power of vegetables, Governments will need to increase their investment in farm productivity (including improved varieties, alternatives to chemical pesticides, and the use of protected cultivation), good postharvest management, food safety, and market access. To tap the nutritional power of vegetables consumers need to know how vegetable consumption must therefore be nurtured through a combination of supply side interventions and communication emphasizing the importance of eating vegetables, governments and donors will need to give vegetables for good nutrition and health, to fully tap the economic and nutritional power of vegetables, much greater priority than they currently receive. Now is the time to prioritize investments in vegetables, providing increased economic opportunities for smallholder farmers and providing healthy diets for all.
Fruits and vegetables are essential sources for the micronutrients needed for healthier diets. Potassium in vegetables helps to maintain healthy blood pressure, their dietary fiber content reduces blood cholesterol levels and may lower the risk of heart disease, folate reduces the risks of birth defects, and vitamin A keeps eyes and skin healthy, while vitamin C not only keeps teeth and gums healthy but also aids in iron absorption. Recognizing the important nutritional benefits of fruits and vegetables, the World Health Organization (WHO) recommends a minimum intake of 400 g per day to prevent chronic diseases (especially heart diseases, cancers and diabetes) and supply needed micronutrients (especially calcium, iron, iodine, vitamin A and Zinc). However, consumers today even those with higher incomes, are believed to be missing this target. More attention in filling this dietary gap and enabling consumers to take the nutritional power of vegetables is required.
2. Vegetables in global food economy
The most dominant vegetables in the global food economy are tomato, cucurbits, (pumpkin, squash, cucumber and gherkin), allium (onion, shallot, garlic) and chili. These vegetables are consumed in nearly all countries although with much variation in shape, size, color and taste, while the marketing of global vegetables accounts for significant revenue stream, traditional vegetables often have superior nutritional properties. For instance, 100 g of leaves of amaranth or vegetable cowpea can provide over 100% of the vitamin A needs of pregnant women. Globally, a one per cent increase in per capita income in developing countries is associated with a 0.5% increase in per capita vegetables availability. It follows that the bulk of the global supply of fruit and vegetables (77% of total value) is produced in populous middleincome countries. China accounts for 45% of the global value of vegetable production. India comes second, accounting for eight per cent of global vegetable production. Vegetables play a major role in world agriculture by providing food and offering nutritional and economic security.
3. Health promoting nutrient compounds in vegetables
Macro carotene, nutraceuticals, phyto-chemicals are bioactive compounds which are either plant pigments (lycopene, ß carotene, anthoyanin, lutein, capsanthin, zeaxanthin
4. Antinutrient factors
Plants produce many defense strategies to protect themselves from predators and many of these, such as resveratrol and glucosinate, which are primarily pathogen- protective chemicals also have demonstrated beneficial effects for human health. Many, however, have the opposite effect. For example, phytate, a plant phosphate storage compound, is an antinutrient as it strongly chelates iron, calcium, zinc and other divalent mineral ions making them unavailable for uptake. Different antinutrient compounds (phytates, oxalates, trypisn inhibitors, lectins etc.), food allergens (albumins, globluins etc.) and toxins (glycoalkaloids, cynogenic glucosides, phyto-hemaglutinins) in crop plants need to be reduced to enhance nutrient potential of the vegetables.
5. Breeding nutrient rich varieties
Vegetables are valued for their extrinsic and intrinsic quality traits. Diet rich in vegetables provide micronutrients and health promoting phytochemicals that alleviate malnutrition. The beneficial health effects are mainly attributed to diverse antioxidant compounds such as vitamins, carotenoids, phenolics. Alkaloids, nitrogen containing compounds, organouslphur compounds etc. Although, chief long term breeding objective will continue to be increasing yield to meet the food requirement of ever increasing population, in order to ensure health security to our countrymen and multipurpose utility of the varieties for fresh market and industry suitability, it is imperative that nutraceutical, edible color and bioactive compound rich vegetable varieties are bred ensuring high remuneration to farmers. Quality in vegetables is a complex character influenced by both genetical and environmental factors. Breeding for quality has been unsystematic and often empirical but significant progress has been made in several vegetable crops. Conventional breeding in conjunction with molecular biology has bright prospects of developing vegetable varieties high in neutraceuticals, edible colors and bioacticve compounds suitable for fresh market as well as developing functional fusions food industry.
Conventional breeding uses inherent properties of the crop, having far reaching impact on communities and has fewer regulatory constraints compared to genetically modified varieties. Breeding efforts targeting improved micronutrient content and composition began in the 1940s and 1950’s, with research describing the inheritance and development of tomato breeding stocks high in pro-vitamin A carotenoids and vitamin C. Similar research leading to the development of darker orange and consequently high pro-vitamin A, carrots began in the 1960s. Since then genetic improvement to increase levels of specific micronutrient has been pursued primarily in several vegetables.
A significant genetic component of iron and zinc content of edible plant parts has been noted, but parallel investigations for calcium are not widely reported for many plant species and even less is known about magnesium. As progress is made in breeding for crop yield, mineral content usually is reduced. Furthermore, breeding for improved mineral use efficiency usually does not alter mineral content of edible plant parts. Success in breeding for higher mineral content must consider not only mineral concentration but also organic components in plants that can be abundant and either reduce (phytate, phenolic compounds) or increase (vitamin C) bioavailability. Recent studies have exhibited a broad range of calcium, iron, and zinc content across a range of Andean potato cultivars .
5.1 Genetic resources
Biodiversity is considered essential for food security and nutrition and can contribute to the achievement through improved dietary choices and positive health impacts. However, it is seldom included in nutrition programmes and interventions. Dietary diversity depends not only on a diversity of crops but also on diversity within crops. There is an increasing body of evidence of wide variation in nutrient contents within species, but data are lacking on nutrient composition and dietary intake for many underutilized species as well as for cultivars within species. Such information is needed both to enhance use of more nutritious cultivars in diets and to make them available for use in breeding programme aimed at increasing the nutrient content of more commonly used varieties for the same species, eliminating the need for transgenic modifications.
Genetic resources are the foundation block that are essentially required for evolving improved crop varieties when the breeder aim at adding more desirable traits to an otherwise acceptable varieties. This necessitates availability of the desired variability to the breeder within the land races, putative ancestral form, primitive cultivars and obsolete cultivars, heirloom cultivars of these crops or its wild forms and other elated species constituting primary, secondary and tertiary gene pools. The utilization of plant genetic resources to enhance the chemical composition of horticultural crops through biotechnology or conventional breeding has led to the development of varieties with enhanced levels of micronutrients, such as enhanced beta-carotene sweet potatoes, potato, carrot. Pavithra
5.2 Breeding for nutraceutical bioactive compounds
Nutraceutical bioactive and edible colors are natural compounds which are regulated by several biochemical pathways and controlled by genetical and environmental factors. From early times people knowingly or unknowingly selected several vegetable crops for their food purpose. There are many or cultivated vegetables which are rich in these beneficial compounds. The biochemical pathway and synthesis of these compounds are controlled by one or many genes which are scattered in the available or unknown germplasm of particular vegetable crop. India is endowed with diverse agroclimatic regions ranging from tropical to temperate making it possible to grow all kinds of vegetable crops in one or the other corners of the country. Besides, there is plenty of diversity in different vegetable crops which can be exploited for development of special varieties. Through convention breeding, it is possible to develop new vegetable varieties or integrate the favorable genes for nutraceuticals, bioactive compounds and edible color into cultivated varieties, advances in molecular biology and recombinant technology have paved the way for enhancing the pace of special trait variety development using marker assisted breeding and designing new vegetable crop plants following transgenic approach.
5.3 Breeding techniques
Breeding method in any crops depends upon the breeding system and genetic architecture resulting from natural selection as well as human selection during the course of cultivation. The genetic architecture or the pattern of inheritance of characters is another important consideration while determining the most appropriate breeding procedure applicable to any particular crops. The choice of breeding method would be largely guided by nature of gene action and relative magnitude of additive genetic variance, dominance variance and epistasis in a breeding population. The efficient breeding procedure should be effective in manipulation and selection of favorable gene combination, additive genetic variance, exploitation of dominance variance and achieving close relationship between expected genetic gain and realized progress from selection. Development of F1 hybrid is very suitable for enhancing nutraceuticals and edible colors. The beta-carotene content in muskmelon has increased manifold in F1 hybrid .
5.4 Advanced breeding techniques
5.4.1 Mutation breeding
In a simple way, mutation is a random or directed change in the structure of DNA or the chromosome which often result in a visible or detectable chance in specific character or trait. In self-pollinated crops, it is well known whereas in cross pollinated crops its application is more difficult and identification of the origin of the desirable genotypes is difficult. Sapir et al.  reported in tomato that
5.4.2 Polyploidy breeding
Polyploid can be induced due to aberration in cell division. This may occur both in the mitosis as well as in meiosis. This method can be used successfully in vegetable breeding as a means of enhancing nutraceuticals and colors in vegetables. Tetraploids in radish, pumpkin, and watermelon are highly productive and have improved quality. Zhang
5.4.3 Haploidy breeding
The development of haploids in a number of plant species is now recognized as the most rapid route to the achievement of homozygosity and production of pure lines. Currently, little breeding effort is going on for improvement of
5.5 Biotechnological approaches
5.5.1 Molecular markers and marker assisted selection (MAS)
Molecular markers such as RAPD, ISSR, SSR, SCAR, CAPS are used to study linkage with gene(s) responsible for high neutraceuticals, bioactive compounds and edible colors using mapping population. Of late, use of SNP marker is becoming more common. In Marker Assited Selection, a marker (morphological, biochemical or DNA) is used for indirect selection of a trait of interest. The mapping populations such as Near Isogenic Lines (NILs), Recombinant Inbred Lines (RILs) are used to identify the molecular markers linked to genes of interest. Ripley and Roslinsky  identified an ISSR Marker for 2 propenyl glucosinolate content in
5.5.2 Quantitative trait loci (QTL) analysis
QTL analysis is the study of the alleles that occur in a locus and the phenotypes. Most traits of interest are governed by more than one gene, defining and studying the entire locus of genes related to a trait gives hope of understanding the effect genotype of an individual. The advent of molecular maps and the derived quantitative trait locus (QTL) mapping technology has provided strong evidence that despite the inferior phenotype, exotic germplasm is likely to contain QTLs that can increase the quality of elite breeding lines. Bin 3-C has previously been described as harboring a single gene mutation
5.5.3 Advanced backcross QTL analysis
The AB-QTL strategy has so for been tested in tomato and pepper. The most extensive experiments have been conducted in tomato, where populations involving crosses with five wild
5.5.4 Introgression line (IL) libraries
IL libraries contain homogenous genetic backgrounds, only differing from one another by the introgressed donor segment. A tomato introgression line population that combines single chromosomal segments introgrossed from the wild, green fruited species
Marker assisted backcross breeding has been used successfully to incorporate genes or QTL for both qualitative and quantitative traits in a number of crop species especially tomato, cucumber, potato, in some cases leading to the development of improved cultivars. Of late Indian cauliflowers are being introgressed with semi-dominant mutant
Interspecific crosses with wild species transferred the ability to produce small quantities of anthocyanins into the peel of cultivated tomatoes. For example, the dominant gene Anthocyanin fruit (
The common cucumbers always develop white fruit with lower carotenoid, 22 48 μg/100 g fresh weight. While Xishuangbanna gourd (
SCAR markers linked to the
6. Transgenic approach
Three genes, encoding phytoene synthase (
One of the most obvious benefits of enhancing carotenoid levels is the increase in pigmentation, which can lead to more deeply colored vegetables that are often preferred by consumers. Thus, increasing levels of carotenoid is doubly beneficial, both in terms of nutrition and esthetics. There are a range of other approaches to enhance the carotenoid levels in potatoes and other root vegetables. Diretto
The extent to which vegetable brassicas protect against cancer probably depend on genotype of the consumer, in particular the allele present at the GSTM 1 locus. This gene codes for the enzyme glutathione transferase, which catalyzes the conjugation of glutathione with isothiocyanates. Approximately, 50% of humans carry a deletion on the GSTM1 gene which reduces their ability to conjugate, process and excrete isothiocyanates. Individuals with two null alleles for GSTM1 might gain less protection from these cultivars of vegetable. The most commonly consumed
A 10 fold increase in the level of 4-methylsulphinylbutyl glucosinolate was obtained by crossing broccoli cultivars with selected wild taxa of the
Vegetables of the
Miraculin rich vegetables: For reduction of bitterness in lettuce, the gene for sweetness and taste modifying protein miraculin, from the pulp of berries of West African shrub
Protein rich potato: The genetically modified potato developed at CPRI in collaboration with NIPGAR “Protato” contains 60% enhanced protein content. This has been achieved by introducing
Vegetables are nutritional powerhouses, key sources of micronutrients needed for good health. They add diversity, flavor and nutritional quality to diets. A strengthened focus on vegetables may be the most direct affordable way to deliver better nutrition for all. Intensified vegetable production has the potential to generate more income and employment than other segments of the agricultural economy, making vegetable an important element of any agricultural growth strategy. Today neither the economic nor the nutritional power of vegetables is sufficiently realized. With a growing understanding of the linkages between dietary quality and health, policy makers must also be prepared to support additional interventions to promote vegetable consumption. Breeding for improved taste, convenience, nutritive value and consumer appeal has already contributed in increase per capita vegetable consumption with the development of products such as baby carrots, yellow and orange peppers, cherry and pear tomatoes, seedless watermelons and lettuces with different with different color, texture and flavor. Therefore conventional breeding in conjunction with molecular biology has bright prospects of developing high yielding vegetable varieties with high neutraceutcials and bio active compounds suitable to offer nutritional security.
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