Introduction

The alarming population growth, global warming, continued overexploitation of natural resources have led to severe threats to food security. Innovative product development and improved sustainable farming methods can bridge the massive gap of food scarcity from limited natural resources (Ashraf and Akram 2009). Traditional breeding has a limited scope; instead, it can be tackled within the realm of genetic engineering (Brookes and Barfoot 2015). Transgenic technology is used to deploy the gene(s) of interest either from the primary gene pool or even unrelated organisms and deliver to the host plant genome with the desired trait expression (Alsadon et al. 2021). Vegetables are significant sources of essential nutrients for human health. Besides, it serves as a source of income, and as such, its cultivation is economically viable owing to the short cropping period and prime demand in each household. Thus, the vegetable sector has significantly improved human health, livelihood and the economy of a country.

However, the pace of crop improvement is much slower in vegetables than what has been achieved in cereals. Farmers stress upon optimal yield coupled with resistance to biotic and abiotic stresses, while the products' appearance, nutritional value, quality, and shelf-life are of paramount importance in turns of consumers' perspectives (Dias and Ryder 2011). Vegetables are the most perishable food items. Hence, there is a need to re-orient the breeding strategy in vegetable crops for ease in cultivation and meet the requirement of marketing and general consumption (Dias and Ryder 2011). One important strategy to mitigate the shortage of nutrients is bio-fortification which makes zinc, iron, carotenoids and provitamin-A breeding extremely vital (Hotz and McClafferty 2007). In combination with the knowledge available about genes and their

Fig. 1: Area (Million ha) under vegetable cultivation across vegetable growing countries (Statistica 2021)

Fig. 2: Production and consumption of vegetables across some vegetable growing countries (Statistica 2021)

Fig. 3: Global vegetable cultivated on arable land as compared to other crops (Statistica 2021)

properties, plant biotechnologists can develop various genetically modified vegetable crops using plant transformation protocols. This can solve the issue of the most difficult biotic and abiotic limitations faced by farmers worldwide. In this review, the global scenario of vegetables and the strategies for genetic modification using transgenic technology are elaborated with its prospects.

Global vegetable production scenario

Fig. 4: Important vegetables cultivated in India (Vegetable Statistics 2021)

Vegetables are cultivated on diverse land and climate on both small and large scales around the world. Over the last decade, the world's vegetable production has undergone a considerable increment accounting for a turnover of about 3% annually (FAOSTAT Database 2013). The total vegetable production around the globe reached 1 billion tons in 2011 (FAOSTAT Database 2013). From 52.7 million ha, Asia has produced 671 million tons of vegetables and has covered a share of about 74.7% of the total vegetable production across the globe. Among the countries in the world, China is the largest producer of vegetables, sharing 50% of global export (FAOSTAT Database 2013). A survey on different countries in which vegetable crops are cultivated for the year 2017–2018 revealed that China has the prominent area of vegetable growing, which is 19.96 million ha, followed by India, which has 1.02 million ha (Fig. 1). Suppose the production and consumption (Fig. 2) of vegetable crops is considered in 2017–2018. In that case, China stands for the first position, followed by India, the USA, Turkey, Russia, Nigeria, Vietnam, Mexico, Egypt and Iran. This analysis revealed that vegetables are the most important crops that need to be addressed for more cultivation and production (Vasileva and Dinev 2021). Global vegetables cultivated on arable land are grown at 31% (Fig. 3) per year, followed by fiber crops, fruits, cereals, root crops, and pulses (FAOSTAT Database 2013). India stands second in the list of vegetable-producing countries, but it represents six times lower than China.

Nevertheless, in the last three decades, India has made remarkable progress on the agricultural point of view. Potato is ranked first (Fig. 4), subsequently followed by other essential vegetable crops, such as cabbage, cauliflower, tomato, brinjal and onion. Among a total of 1,596 high-yielding varieties and horticultural crop hybrids, 485 are vegetables alone. In both developed and developing countries, the quick adoption of transgenic crops reflects the multiple advantages gained by all classes of farmers, enabling commercial cultivation of transgenic crops (James 2015). This favourable adoption rate is the norm, giving both small and large farmers and consumer’s resilience, longevity and significant benefits. According to the ISAAA (International Service for the Acquisition of Agri-biotech Applications) GM approval database, the highest number of major GM vegetable crop events is approved by the USA, followed by Canada, Australia and New Zealand (ISAAA 2021). Maximum crop events are approved for potatoes, followed by tomatoes and minor events approved for eggplant globally. Recently only one event has been in progress in Canada for genetically modified eggplants. According to the same GM approval database of ISAAA, for commercial traits in GM vegetables, the events are approved in more numbers for potatoes followed by tomatoes and eggplants (ISAAA 2021).

Need of the transgenic vegetable production

By the end of this century, the dramatic global climate change would lead the way towards an increase of surface air temperature of about 1.8–4.0°C, thereby increasing the frequent occurrence of extreme climate events such as droughts, heat, floods and cold waves (Pimentel et al. 1997). Global climate change, resulting in high temperature increases and severe weather conditions has a significant adverse impact on diverse horticultural crops so also nutritional security provided by them which, in turn, hampers sustainable farm revenue. Therefore, considering and promoting adaptation measures is very important by implementing acceptable cultural strategies such as differential crop growing times, use of resistance varieties, regular crop rotation, adequate irrigation and drainage facilities. Identification of the resistance gene (s) and the QTLs (quantitative trait loci) for resistance towards biotic and abiotic stresses will overcome the problems of resolving the issues associated with biotic and abiotic stresses. Usually, plants become infested with pathogens and pests. Sometimes, dramatic reduction in yield has been recorded by several bacteria, fungi and viruses; those are well known to cause different plant diseases.

In the world, there are more than 70,000 insect species, 10 percent of which are considered serious pests (Pimentel et al. 1997). Despite of the ubiquitous use of pesticides, varied diseases, insects and weeds have continued the crop yield reduction that is close enough to 40 percent (Tarafdar et al. 2014). Several pre-harvest crop losses comprised of 15% from insect pests, diseases covering 13% while 12% noted from weeds (Pimentel et al. 1997). Vegetables are quite sensitive and difficult as compared to that of field crops because of their frequency of production, disease and pests. Climate change, a growing population and slow growth have led to major challenges for the population. By 2025, the entire population around the globe is expected to reach about 8.5 billion. A major problem is feeding the rising population with inadequate land, water and limited natural resources. Several works have been carried out via conventional breeding programmes in the production of novel crop cultivars, but they are quite slow-going processes consuming of about 8–10 years of time or more. The parental gene and the recipient's origin and life serve as the deciding factor for the time taken in order to pass the desired gene into the crop plants (Jauhar 2006). The secondary and tertiary gene pool consists of some wild crops and landraces, which are rich gene pools for several agronomic characteristics such as resistance to diseases or pests whose genes can be used for improvement. However, between donor and crop species, pre and post fertilization barriers may impede sexual hybridization which can worsen the issue of alien gene transmission (Jauhar 2006). In such instances, the integration of a certain characteristic by conventional means may not even be possible because a suitable donor may not be available. Genetic engineering technology therefore gives access, leaving aside the limitations of sexual compatibility to a broader gene pool.

Timeline of development and the current global status of transgenic vegetables

In 1994, the first transgenic vegetable approved to be cultivated commercially in the United States was the FlavrSavr tomato (Bruening and Lyons 2000). Bt potato (AMFLORA potato) resistant to insect pests and squash and papaya virus-resistant was subsequently approved for commercial cultivation. Bt brinjal was also approved for commercial production in Bangladesh for the first time on October 30, 2013. The timeline of transgenic vegetable production and development is indexed in Fig. 5, which indicates the importance of transgenic vegetable for commercialization. In United States, the transgenic bruise-resistant potato cultivar has got approval in November 2014.

Potatoes are the world's fourth most significant food staple that plays a major role in strengthening the food security of Asian countries for instance China covering 6 million ha of potatoes, 2 million ha of potatoes covered in India whereas Bangladesh is having 0.5 million ha of potatoes. During the commercialization of transgenic technology in early 20 years (1996–2015), the required commitment of transgenic technology for the wellbeing of agriculture sector has been noted to be fulfilled satisfactorily (Qaim 2016). Transgenic crops have paved a way for significant economic, social, agricultural, health and environmental benefits not only to farmers but also to the society as a whole (Areal et al. 2013).

Criteria for trait selection for development of transgenic vegetable

Fig. 5: Timeline of transgenic vegetable production and development

An important approach to crop improvement is transgenic manipulation. Through different viewpoints, there are several biosafety issues associated with transgenic crops. However, by carefully selecting crops, their traits, techniques along with government policies, transgenic crops can be produced as well as implemented under the purview of biosafety standards to attain global agricultural goals. During the transgenic improvement of crop varieties, the following points should be considered.

Presence of wild relatives and vegetable landraces

Interbreeding between crop cultivars and their wild relatives may sometimes lead to pollen leakage. This poses a possibility for escape of transgene to wild relatives where genetically engineered crops are raised in crop origin or diversity centers. It is difficult to predict the accurate effects of such transgene escape on biodiversity and will be dependent on the characteristics bestowed by the transgenes as well as the climate. Keeping an eye on the poor consequences of transgenic escape, these modified crops are not authorized for commercial release in areas where wild relatives are being developed. Since India is considered to be one of the major centers of crop biodiversity, prioritization of transgenic development is needed. In transgenic crops, on the other hand, sufficient countermeasures should be implemented to avoid transgene escape.

Breeding behavior of vegetables

From the perspective of transgene motion, the biology of the crop plant presumes significance. The possibility of issue of escape of transgene in the case of plants propagated asexually such as pointed gourd, potato and sweet potato is wisely reduced. Similarly, restricted transgene movement has been found in the case of crops such as tomato, eggplant, peas, etc. which are highly autogamous or do self-pollination. In comparison, it presents severe challenges to prevent transgenic movement in crops such as maize, pearl millet, mustard etc. which exhibit allogamy or cross-pollination. Thus, crop choice from the transgene movement viewpoint would be propagated vegetative > autogamous > allogamous. Biotechnology provides new means of altering crop breeding activity and thus enables successful options for resolving transgenic movement concerns.

Achievements in transgenic vegetable approach

Enhancing shelf-life period of vegetables

Table 1: Transgenes for the improved storage period in vegetables

Target Gene	Target Trait	Crop	Reference
β-Glucuronidase, Pectin methylesterase, Polygalacturonase	Storage shelf-life, juice viscosity	Tomato	Powell et al. (2003); Moon and Callahan (2004)
β-Glucuronidase and Deoxyhypusine synthase, Polygalacturonase and expansin	Storage shelf-life, Postharvest softening delaying and senescence	Tomato and Pea	Kalamaki et al. (2003); Powell et al. (2003); Xiong et al. (2005); Ruma et al. (2009)
ACC synthase	Enrichment in production of Ethylene	Pea and Tomato	Romagnano (2008)
Deoxyhypusine synthase	Senescence, male sterility and Postharvest softening delaying	Tomato and Pea	Wang et al. (2005)
Pectin methylesterase	Juice viscosity enrichment and reduction in pectin hydrolysis	Tomato and Pea	Thakur et al. (1996)
hpRNAi ACO1 gene, LeERF1 and Nr gene overexpression	Low ethylene production, less sensitivity to ethylene, longer shelf life	Tomato and Pea	Ciardi et al. (2000); Li et al. (2007); Behboodian et al. (2012)
S-adenosylmethionine decarboxylase proenzyme	Lycopene content increment and increase in fruit juice quality	Tomato and Pea	Bapat et al. (2010)

Table 2: Transgenes for high nutritional quality in vegetables

Target Gene	Target Trait	Crop	Reference
Chalcone isomerase, S1MYB12	Flavonoid enrichment, solid soluble content, fruit color enrichment	Tomato	Ballester et al. (2010); Maligeppagol et al. (2013)
SlAco3b, L-Galactono-1,4-lactonedehydrogenase	Carboxylic acids and Ascorbic acid content enrichment	Tomato	Garza et al. (2007); Morgan et al. (2013)
Lycopene b-cyclase, Phytoene desaturase, Phytoene synthase	Increase in beta-carotene and lutein	Tomato	Rosati (2000); Fraser et al. (2002)
SAM decarboxylase, Phytoene synthase, ySAMdc; spe-2	High lycopene, improved juice quality, β- carotene	Tomato	Mehta et al. (2002); Kisaka and Kida (2003); Singh et al. (2015)
GaIUR, scax	Vitamin C and Calcium content	Carrot, Lettuce	Park and Kang (2004); Lim et al. (2008); Singh et al. (2015)
Or, Pr, MYB, Ore, IbMYB1	β- carotene, Anthocyanin	Cauliflower

The use of antisense RNA technology using the 1-aminocyclopropane-1-carboxylic acid deaminase gene that reduces 1-aminocyclopropane-1-carboxylic acid to ethylene and contributes to maturation and the suppression of the polygalacturonase enzyme that naturally takes place in the cell walls and induces vegetable and fruit softening (Gerszberg et al. 2015), which are two means to raising the shelf-life of vegetable crops. The first approved transgenic vegetable for commercial sale, FlavrSavr tomato, produced by Calgene in Davis, California, was attempted for a delayed ripening trait. However, the fruits remained firm after harvest. Some transgenic vegetables with enhanced shelf-life periods are indexed in Table 1 along with the target genes.

Improvement in quality and nutritional value of vegetables

Most individuals in developing countries suffer from micronutrient deficiency. This is one of the most significant risk factors that impact human health and the root cause of most illnesses. So, there has always been a need to combat such a deficiency problem more wisely. The use of recombinant DNA technology can now produce transgenic crops with improved nutritional value. Modifying plant nutritional value by transgenic technology can be accomplished by improving the purity, structure and nutrient (protein, carbohydrate and fatty acid along with antioxidants) levels of different crops (Gerszberg et al. 2015). A significant output of the transgenic approach for advanced nutritional value is golden rice to combat vitamin A deficiency. In addition, genes have been identified associated with superior fruit quality and nutritional value of vegetables (Table 2).

Transgenic vegetables for abiotic and biotic stress tolerance

The environmental stresses, referred to as abiotic stresses, most often led to a decrease in the growth and productivity of vegetable crops below optimum levels. Furthermore, abiotic stresses most often cross-talk, showing the result of an expected deficit of cellular water; also known as osmotic stress effects (Nandhakumar et al. 2020). These contribute to the minimization of cell turgor osmotic potential and retention. Till now, significant steps have been taken by the researchers for the identification and utilization of transgenes for combating several abiotic stresses (Table 3). A significant prospect includes trans-grafting (Kharal et al. 2021), which exploits a genetically engineered climate-resilient genotype as rootstock grafted onto a commercial scion. Trans-grafting has the prospects to widen the traits facilitated by grafting since the advantages acquired from the transgenes can be utilized (Kharal et al. 2021). Thus, transgenic DNA free scion could enable the arrival of GE crops into commercial production since the deregulation of every scion cultivar would likely not be obligatory by USA, Turkey, Russia, Nigeria, Vietnam, Mexico, Egypt and Iran. This analysis revealed that vegetables are the most important crops that need to be addressed for more cultivation and production (FAO/WHO 2009; Vasileva and Dinev 2021;). Plant diseases including fungal, bacterial, viral diseases and insect pests pose significant challenges to growth and productivity of vegetables. Therefore, it is essential to target genes for resistance to biotic stress in vegetable crops (Table 4 and 5).

Ethical and biosafety issues for transgenic vegetables

Table 3: Transgenes for abiotic stress tolerance in vegetables

Crop	Genes Responsible	Target trait	Reference
Bean	P5CS	Drought stress	Chen et al. (2009a)
Tomato	ATHB-7	Drought stress	Mishra et al. (2012)
Potato	StPUB17	Salt stress	Ni et al. (2010a)
Tomato	Choline oxidase	Salt stress	Goel et al. (2011)
Tomato, Brinjal	MtlD	Drought stress	Khare et al. (2010)
Tomato	BcZAT12	Drought stress	Rai et al. (2013)
Tomato	cAPX	Temperature stress	Wang et al. (2006)
Tomato	GlyII	Salt stress	Viveros et al. (2013)
Tomato	SAMDC	Salt, cold and drought	Alcazar et al. (2010)
Tomato	LeERF2	Freezing stress	Zhang et al. (2010)
Tomato, Brinjal	PtADC	Drought stress	Wang et al. (2011)
Tomato	SpMPK1, SpMPK2, SpMPK3	Drought stress	Rai et al. (2013)
Tomato	Osmotin	Cold stress	Patade et al. (2013)
Tomato	MdVHA-B	Drought stress	Hu et al. (2012)
Tomato	CBF1	Cold and drought	Lee et al. (2003)
Tomato	Trehalose-6- phosphate synthase	Drought and oxidative stress	Cortina and Culianez- Macia (2005)
Tomato	HAL1 gene	Salt stress	Gisbert et al. (2000)
Tomato	NHX1	Salt stress	Zhang and Blumwald (2001)
Tomato	Betaine aldehyde dehydrogenase	Salt stress	Jia et al. (2002)
Tomato	Heat shock factor, hsfA1b	Chilling tolerance	Lee et al. (2003)
Tomato	Choline oxidase	Oxidative stress	Park and Kang (2004)
Tomato	sHSP (mitochondrial)	Temperature stress	Nautiyal et al. (2005)
Tomato	CAPX (cDNA)	Heat stress	Wang et al. (2006)
Tomato	Cys-2/His-2 zinc finger protein-TF	Cold stress	Seong et al. (2007)
Tomato	ACC deaminase	flooding stress	Grichko and Glick (2001)

Table 4: Transgenes for resistant to fungal, bacterial and viral disease in vegetables

Target Gene	Target microorganism	Crop	Reference
Endochitinase	Soil-borne fungus	Potato	Lorito et al. (1998)
Lactoferrin, Defensins	Ralstonia solanacearum	Tomato, potato	Gao et al. (2000)
Cathelicidin	Bacteria	Tomato	Jung (2013)
amiR-AV1-3	leaf curl virus	Tomato	Vu et al. (2013)
StPUB1, RB gene	Phytophthora infestans	Potato	Ni et al. (2010b)
Bs2 gene	Bacteria (Xanthomonas spp.)	Tomato	Horvath et al. (2012)
CHIAFP	Botrytis cinerea	Tomato	Chen et al. (2009a)
rep; AC1, TrAP; AC2, REn; AC3, and BC1	Golden mosaic virus	Common bean, Cucurbits	Aragao and Faria (2009)
Coat protein	Cucumber mosaic virus	Tomato	Fuchs et al. (1996)
Replicase	Ringspot virus	Papaya	Kumari et al. (2015)
Coat protein	Cucumber mosaic virus	Cucumber, melon	Nishibayashi et al. (1996)
Coat protein	Ringspot virus	Papaya	Davidson (2006)
N gene	Spotted wilt virus	Tomato	Goldbach et al. (2003)
ScFv antibodies	Cucumber mosaic virus	Tomato	Villani et al. (2005)
ScFv antibodies	Potato virus Y	Potato	Gargouri-Bouzid et al. (2006)
Serine acetyltransferase	Cucumber mosaic virus	Tomato	Stommel et al. (1998)
Stilbene synthase	Phytophthora infestans	Tomato	Thomzik et al. (1997)
Endochitinase	Verticillium dahliae	Tomato	Tabaeizadeh et al. (1999)
Oxalate decarboxylase	Sclerotinia sclerotiorum	Tomato	Kesarwani et al. (2000)
Nonexpresser of PR genes	Tomato Mosaic Virus resistance, bacterial wilt and fusarium wilt	Tomato	Lin et al. (2004)
Thi2.1	Ralstonia solanacearum and Fusarium wilt	Tomato	Chan et al. (2005)
Glucanase	Alternaria solani	Tomato	Schaefer et al. (2005)
Serine or threonine-protein kinase	Xanthomonas campestris pv. Vesicatoria, Cladosporium fulvum	Tomato	Tang et al. (1999)
Glycoprotein	Ralstonia solanacearum	Tomato	Lee et al. (2002)
Magainin	Pseudomonas syringae	Tomato	Alan et al. (2004)
Thi2.1	Ralstonia solanacearum and Fusarium oxysporum	Tomato	Chan et al. (2005)
Cys-2 or His-2 zinc finger protein-TF	Pseudomonas syringae	Tomato	Seong et al. (2007)
Ferredoxin-I protein	Ralstonia solanacearum	Tomato	Huang et al. (2007)
ToMV coat protein	Chimeric Tomato mosaic virus	Tomato	Motoyoshi and Ugaki (1993)
Capsid protein	Delayed disease symptoms	Tomato	Kunik et al. (1994)
CMV satellite RNA	Tolerance to CMV infection	Tomato	McGarvey et al. (1995)
Coat protein	Resistance to infection by CMV-WL and CMV-China	Tomato	Xue et al. (1994)
Nucleoprotein	A hypersensitive response	Tomato	Whitham et al. (1996)
TSWV nucleoprotein	High levels of resistance to Tomato spotted wilt virus	Tomato	Haan et al. (1996)
Capsid protein	Reduced infection of CMV under natural conditions	Tomato	Murphy et al. (1997)
rep protein	Tomato yellow leaf curl virus	Tomato	Brunetti et al. (1997)
Coat protein	CMV	Tomato	Kaniewski et al. (1999)
Coat protein	Physalis mottle tymo virus	Tomato	Vidya et al. (2000)
Truncate replicate gene	CMV stain Ta-8	Tomato	Nunome et al. (2002)
PR genes	ToMV, BW, FW, GLS, BS	Tomato	Lin et al. (2004)
Coat protein	TLCV	Tomato	Raj et al. (2005)
cDNA of RCC2	Botrytis cinerea	Cucumber	Tabei et al. (1998)

The cultivation of GM crops is consistently increasing (James 2015). With dramatic economic and environmental benefits, transgenic crops are an essential tool for disease and pest control (Brookes and Barfoot 2015). Transgenic technology caused increased agricultural productivity in developing countries, along with the development of nutritional quality and nutritious foods that also have an increased shelf life. These advantages of GM crops have improved food security for the poverty-stricken people (Parvaiz et al. 2012). Thus, GM food promoters are environmentally friendly, pose minor disadvantages to humans' health and are highly beneficial to general farmers (Andreasen 2014). The GM proteins are also being added to the soil through crop residues which may lead to the decline of spraying of pesticides (Godfrey 2000).

However, some GM crops have antibiotic resistance genes and as a result, GM foods face potential adverse health effects (Gilbert 2013). This poses several areas of concern regarding the use of GM crops. There may be the possibility of occasional gene flow from GM crop-to-weed, making the latter resistant to herbicides, which is a major problem for the adoption of GM crops. So, each country must create a solid bio-safety framework for the cultivation and use of GM species. However, specific regulations have been formulated by many advanced countries and few developing countries. The duty of government regulatory agencies should be solely to ensure that there should not be any adverse effect of GM crops on environmental factors and human health (Rigaud 2008).

Conclusion

Several studies reveal that the agronomic and economic benefits associated with GM crops are far-reaching. With the shrinking area under cultivation, the principle of growing productive crop per unit area is an inertial and imperative global phenomenon. In this context, GM crops offer enhanced yield along with reduction in pesticide uses. Transgenic candidate cultivars also proved to be potential for breaking the yield and quality barriers in vegetable crops and hence, can solve food and nutritional security. However, the malnutrition rate has risen to around 20 percent over the past decade, in consonance with the FAO of the United Nations, and is projected to remain constant until 2022. In 2012, over 870 million individuals were officially chronically malnourished, with almost 250 million citizens in India. To address this issue associated with malnutrition, there is an urgent need for a shift to transgenic agriculture.

Author Contributions

JPS and UM planned the first draft and wrote the manuscript. SPB, LB, LJ, SS, APM, MPD, PP and NP checked the grammatical error of the manuscript. SKT, KCS and DL corrected and approved the manuscript.

Conflict of Interest

The authors declare that they have no conflict of interest.

Data Availability

Not Applicable in this paper.

Ethics Approval

Not Applicable in this paper.

References

Abdeen A, A Virgos, E Olivella, J Villanueva, X Aviles, R Gabarra, S Prat (2005). Multiple insect resistance in transgenic tomato plants over-expressing two families of plant proteinase inhibitors. Plant Mol Biol 57:189‒202

Alan AR, A Blowers, ED Earle (2004). Expression of a magainin-type antimicrobial peptide gene (MSI-99) in tomato enhances resistance to bacterial speck disease. Plant Cell Rep 22:388‒396

Alcazar R, T Altabella, F Marco, C Bortolotti, M Reymond, C Koncz, AF Tiburcio (2010). Polyamines: Molecules with regulatory functions in plant abiotic stress tolerance. Planta 231:1237‒1249

Alsadon A, THI Solieman, MA Wahb-Allah, AA Helaly, AAM Ali, AA Ibrahim, MAO Saad (2021). Heterosis, potency ratio and correlation of vegetative, yield and quality traits in tomato genotypes and their performance under arid region. Ind J Agric Res 55:33‒41

Alyokhin A, M Baker, D Mota-Sanchez, G Dively, E Grafius (2008). Colorado potato beetle resistance to insecticides. Amer J Pot Res 85:395‒413

Andreasen M (2014). GM food in the public mind–facts are not what they used to be. Nat Biotechnol 32:25–26

Aragao FJ, JC Faria (2009). First transgenic geminivirus-resistant plant in the field. Nat Biotechnol 27:1086‒1088

Areal FJ, L Riesgo, E Rodriguez-Cerezo (2013). Economic and agronomic impact of commercialized GM crops: A meta-analysis. J Agric Sci 151:7‒33

Ashraf M, NA Akram (2009). Improving salinity tolerance of plants through conventional breeding and genetic engineering: An analytical comparison. Biotechnol Adv 27:744‒752

Ballester AR, J Molthoff, RD Vos, BTL Hekkert, D Orzaez, JP Fernández-Moreno, M Ykema (2010). Biochemical and molecular analysis of pink tomatoes: Deregulated expression of the gene encoding transcription factor SlMYB12 leads to pink tomato fruit color. Plant Physiol 152:71‒84

Bapat VA, PK Trivedi, A Ghosh, VA Sane, TR Ganapathi, P Nath (2010). Ripening of fleshy fruit: Molecular insight and the role of ethylene. Biotechnol Adv 28:94‒107

Behboodian B, ZM Ali, I Ismail, Z Zainal (2012). Postharvest analysis of lowland transgenic tomato fruits harboring hpRNAi-ACO1 construct. Sci World J 2012:1–9

Brookes G, P Barfoot (2015). GM Crops: Global Socio-economic and Environmental Impacts 1996–2013. PG Economics Ltd., Dorchester, UK

Bruening G, J Lyons (2000). The case of the FLAVR SAVR tomato. Calif Agric 54:6‒7

Brunetti A, M Tavazza, E Noris, R Tavazza, P Caciagli, G Ancora, S Crespi, GP Accotto (1997). High expression of truncated viral Rep protein confers resistance to tomato yellow leaf curl virus in transgenic tomato plants. Mol Plant-Microb Interact 10:571‒579

Chan YL, V Prasad, KH Chen, PC Liu, MT Chan, CP Cheng (2005). Transgenic tomato plants expressing an Arabidopsis thionin (Thi2. 1) driven by fruit-inactive promoter battle against phytopathogenic attack. Plant 221:386‒393

Chen SC, AR Liu, FH Wang, GJ Ahammed (2009a). Combined overexpression of chitinase and defensin genesin transgenic tomato enhances resistance to Botrytis cinerea. Afr J Biotechnol 8:5182‒5188

Chen Y, A Wang, L Zhao, G Shen, L Cui, K Tang (2009b). Expression of thymosin α1 concatemer in transgenic tomato (Solanum lycopersicum) fruits. Biotechnol Appl Biochem 52:303‒312

Ciardi JA, DM Tieman, ST Lund, JB Jones, RE Stall, HJ Klee (2000). Response to Xanthomonas campestris pv. vesicatoria in tomato involves the regulation of ethylene receptor gene expression. Plant Physiol 123:81‒92

Cortina C, FA Culianez-Macia (2005). Tomato abiotic stress enhanced tolerance by trehalose biosynthesis. Plant Sci 169:75‒82

Davidson SN (2006). The genetically modified (GM) PRSV-resistant papaya in Thailand: A case study for the agricultural biotechnology development in the GMS subregion. New Zealand, Agrifood Consulting International Inc., (AGRICO), USA and ANZDEC Ltd.

Dias JS, EJ Ryder (2011). World vegetable industry: Production, breeding, trends. Hortic Rev 38:299‒356

FAO (2013). Food and Agriculture Organisation of the United Nations, Rome, Italy. Available at: http://www.fao.org. (Accessed on: 11^th November 2021)

FAO/WHO (2009). Principles and methods for the risk assessment of chemicals in food. Environ Health Criteria 240:1‒34

Fraser PD, S Romer, CA Shipton, PB Mills, KW Kiano, N Misawa, RG Drake, W Schuch, PM Bramley (2002). Evaluation of transgenic tomato plants expressing an additional phytoene synthase in a fruit-specific manner. Proc Natl Acad Sci 99:1092‒1097

Fuchs M, R Provvidenti, JL Slightom, D Gonsalves (1996). Evaluation of transgenic tomato plants expressing the coat protein gene of cucumber mosaic virus strain WL under field conditions. Plant Dis 80:270‒275

Gao AG, SM Hakimi, CA Mittanck, Y Wu, BM Woerner, DM Stark, CM Rommens (2000). Fungal pathogen protection in potato by expression of a plant defensin peptide. Nat Biotechnol 18:1307‒1310

Gargouri-Bouzid R, L Jaoua, S Rouis, MN Saïdi, D Bouaziz, R Ellouz (2006). PVY-resistant transgenic potato plants expressing an anti-NIa protein scFv antibody. Mol Biotechnol 33:133‒140

Garza RIDDL, JF Gregory, AD Hanson (2007). Folate biofortification of tomato fruit. Proc Natl Acad Sci 104:4218‒4222

Gatehouse AM, GM Davison, JN Stewart, LN Gatehouse, A Kumar, IE Geoghegan, JA Gatehouse (1999). Concanavalin A inhibits the development of tomato moth (Lacanobia oleracea) and peach-potato aphid (Myzus persicae) when expressed in transgenic potato plants. Mol Breed 5:153‒165

Gerszberg A, K Hnatuszko-Konka, T Kowalczyk, AK Kononowicz (2015). Tomato (Solanum lycopersicum L.) in the service of biotechnology. Plant Cell Tiss Org Cult 120:881‒902

Gilbert N (2013). A hard look at GM crops. Nat News 497:24–36

Gisbert C, AM Rus, MC Bolarin, JM Lopez-Coronado, I Arrillaga, C Montesinos, M Caro, R Serrano, V Moreno (2000). The yeast HAL1 gene improves salt tolerance of transgenic tomato. Plant Physiol 123:393‒402

Godfrey J (2000). Do genetically modified foods affect human health? Lancet 355:414–414

Goel D, AK Singh, V Yadav, SB Babbar, N Murata, KC Bansal (2011). Transformation of tomato with a bacterial codA gene enhances tolerance to salt and water stresses. J Plant Physiol 168:1286‒1294

Goggin FL, L Jia, G Shah, VM Williamson, DE Ullman (2004). The tomato Mi-1.2 herbivore resistance gene functions to confer nematode resistance but not aphid resistance in eggplant. Mol Plant-Microb Interact 19:383‒388

Goldbach R, E Bucher, M Prins (2003). Resistance mechanisms to plant viruses: An overview. Vir Res 92:207‒212

Grichko VP, BR Glick (2001). Flooding tolerance of transgenic tomato plants expressing the bacterial enzyme ACC deaminase controlled by the 35S, rolD or PRB-1b promoter. Plant Physiol Biochem 39:19‒25

Haan PD, T Ultzen, M Prins, J Gielen, R Goldbach, MV Grinsven (1996). Transgenic tomato hybrids resistant to tomato spotted wilt virus infection. Tospovir Thrips Flor Veg Crops 431:417‒426

Horvath DM, RE Stall, JB Jones, MH Pauly, GE Vallad, D Dahlbeck, BJ Staskawicz, JW Scott (2012). Transgenic resistance confers effective field-level control of bacterial spot disease in tomato. PLoS One 7:1–9

Hotz C, B McClafferty (2007). From harvest to health: Challenges for developing biofortified staple foods and determining their impact on micronutrient status. Food Nutr Bull 28:271‒279

Hu DG, SH Wang, H Luo H, QJ Ma, YX Yao, CX You, YJ Hao (2012). Overexpression of MdVHA-B, a V-ATPase gene from apple, confers tolerance to drought in transgenic tomato. Sci Hortic 145:94‒101

Huang HE, CA Liu, MJ Lee, CG Kuo, HM Chen, MJ Ger, YC Tsai, YR Chen, MK Lin, TY Feng (2007). Resistance enhancement of transgenic tomato to bacterial pathogens by the heterologous expression of sweet pepper ferredoxin-I protein. Phytopathology 97:900‒906

ISAAA (2021). GM Approval Database. Available at: https://www.isaaa.org/gmapprovaldatabase/. (Accessed on: 1^st November 2021)

ISAAA (2008). Bt brinjal in India. Pocket K 35. International Service for Acquisition of Agri-Biotech Applications, Ithaca, NY

Ishimoto M, T Sato, MJ Chrispeels, K Kitamura (1996). Bruchid resistance of transgenic azuki bean expressing seed α-amylase inhibitor of common bean. Entomol Exp Appl 79:309‒315

James C (2015). Global status of commercialized biotech/GM crops. ISAAA

Jauhar PP (2006). Modern biotechnology as an integral supplement to conventional plant breeding: The prospects and challenges. Crop Sci 46:1841‒1859

Jia GX, ZQ Zhu, FQ Chang, YX Li (2002). Transformation of tomato with the BADH gene from Atriplex improves salt tolerance. Plant Cell Rep 21:141‒146

Jung YJ (2013). Enhanced resistance to bacterial pathogen in transgenic tomato plants expressing cathelicidin antimicrobial peptide. Biotechnol Bioproc Eng 18:615‒624

Kalamaki MS, MH Harpster, JM Palys, JM Labavitch, DS Reid, DA Brummell (2003). Simultaneous suppression of LePG and LeExp1 influences rheological properties of juice and concentrates from a processing tomato variety. J Agric Food Chem 51:7456‒7464

Kaniewski W, V Ilardi, L Tomassoli, T Mitsky, J Layton, M Barba (1999). Extreme resistance to Cucumber mosaic virus (CMV) in transgenic tomato expressing one or two viral coat proteins. Mol Breed 5:111‒119

Kesarwani M, M Azam, K Natarajan, A Mehtaand, A Datta (2000). Oxalate decarboxylase from Collybia velutipes: Molecular cloning and its overexpression to confer resistance to fungal infection in transgenic tobacco and tomato. J Biol Chem 275:7230‒7238

Kharal S, AK Shrestha, HN Giri, S Pandey (2021). Vegetable grafting: Methods, uses and opportunities for Nepal: A Review. Agric Rev 42:284‒291

Khare N, D Goyary, NK Singh, P Shah, M Rathore, S Anandhan, Z Ahmed (2010). Transgenic tomato cv. Pusa Uphar expressing a bacterial mannitol-1-phosphate dehydrogenase gene confers abiotic stress tolerance. Plant Cell Tiss Org Cult 103:267‒277

Kim YJ, JH Lee, CH Harn, CG Kim (2016). Transgenic cabbage expressing Cry1Ac1 does not affect the survival and growth of the wolf spider, Pardosa astrigera L. Koch (Araneae: Lycosidae). PLoS One 11:1–11

Kisaka H, T Kida (2003). Transgenic tomato plant carrying a gene for NADP-dependent glutamate dehydrogenase (gdhA) from Aspergillus nidulans. Plant Sci 164:35‒42

Kumari S, M Trivedi, M Mishra (2015). PRSV resistance in papaya (Carica papaya L.) through genetic engineering: A review. J Appl Hortic 17:243‒248

Kunik T, R Salomon, D Zamir, N Navot, M Zeidan, I Michelson, Y Gafni, H Czosnek (1994). Transgenic tomato plants expressing the tomato yellow leaf curl capsid protein are resistant to the virus. Biotechnology 12:500‒504

Lawrence SD, NG Novak (2006). Expression of poplar chitinase in tomato leads to inhibition of development in Colorado potato beetle. Biotechnology Lett 28:593‒599

Lee JT, V Prasad, PT Yang, JF Wu, TH David Ho, YY Charng, MT Chan (2003). Expression of Arabidopsis CBF1 regulated by an ABA/stress-inducible promoter in transgenic tomato confers stress tolerance without affecting yield. Plant Cell Environ 26:1181‒1190

Lee TJ, DP Coyne, TE Clemente, A Mitra (2002). Partial resistance to bacterial wilt in transgenic tomato plants expressing antibacterial lactoferrin gene. J Amer Soc Hortic Sci 127:158‒164

Li Y, B Zhu, W Xu, H Zhu, A Chen, Y Xie, Y Shao, Y Luo (2007). LeERF1 positively modulated ethylene triple response on etiolated seedling, plant development and fruit ripening and softening in tomato. Plant Cell Rep 26:1999‒2008

Lim S, LM Cortina, VJ Magley (2008). Personal and workgroup incivility: Impact on work and health outcomes. J Appl Psychol 93:95‒107

Lin WC, CF Lu, JW Wu, ML Cheng, YM Lin, NS Yang, CP Cheng (2004). Transgenic tomato plants expressing the Arabidopsis NPR1 gene display enhanced resistance to a spectrum of fungal and bacterial diseases. Trans Res 13:567‒581

Lison P, I Rodrigo, V Conejero (2006). A novel function for the cathepsin D inhibitor in tomato. Plant Physiol 142:1329‒1339

Lorito M, SL Woo, IG Fernandez, G Colucci, GE Harman, JA Pintor-Toro, S Tuzun (1998). Genes from mycoparasitic fungi as a source for improving plant resistance to fungal pathogens. Proc Natl Acad Sci 95:7860‒7865

Maligeppagol M, GS Chandra, PM Navale, H Deepa, PR Rajeev, R Asokan, NK Kumar (2013). Anthocyanin enrichment of tomato (Solanum lycopersicum L.) fruit by metabolic engineering. Curr Sci 105:72‒80

McGarvey PB, J Hammond, MM Dienelt, CD Hooper, FZ Fu, B Dietzschold, H Koprowski, FH Michaels (1995). Expression of the rabies virus glycoprotein in transgenic tomatoes. Biotechnology 13:1484‒1487

Mehta RA, T Cassol, N Li, N Ali, AK Handa, AK Mattoo (2002). Engineered polyamine accumulation in tomato enhances phytonutrient content, juice quality and vine life. Nat Biotechnology 20:613‒618

Mishra KB, R Iannacone, A Petrozza, A Mishra, N Armentano, GL Vecchia, L Nedbal (2012). Engineered drought tolerance in tomato plants is reflected in chlorophyll fluorescence emission. Plant Sci 182:79‒86

Moon H, AM Callahan (2004). Developmental regulation of peach ACC oxidase promoter–GUS fusions in transgenic tomato fruits. J Exp Bot 55:1519‒1528

Morgan MJ, S Osorio, B Gehl, CJ Baxter, NJ Kruger, RG Ratcliffe, LJ Sweetlove (2013). Metabolic engineering of tomato fruit organic acid content guided by biochemical analysis of an introgression line. Plant Physiol 161:397‒407

Motoyoshi F, M Ugaki (1993). Production of transgenic tomato plants with specific TMV resistance. Jap Agric Res Quart 27:122‒125

Murphy J, E Sikora, K Lovins, M Andrianifahanana (1997). Transgenic tomato withstands CMV epidemic in North Alabama. Highlights Agric Res 44:3

Nandhakumar P, VS Vasantha, P Veilumuthu, G Christopher (2020). 7, 8-Dihydroxyflavone, an effective natural product reduce Ralstonia solanacearum populations and control tomato bacterial wilt. Ind J Agric Res 54:731‒737

Nautiyal PC, M Shono, Y Egawa (2005). Enhanced thermotolerance of the vegetative part of MTsHSP transgenic tomato line. Sci Hortic 105:393‒409

Ni SQ, PH Lee, S Sung (2010a). The kinetics of nitrogen removal and biogas production in an anammox non-woven membrane reactor. Bioresour Technol 101:5767‒5773

Ni X, Z Tian, J Liu, B Song, J Li, X Shi, C Xie (2010b). StPUB17, a novel potato UND/PUB/ARM repeat type gene, is associated with late blight resistance and NaCl stress. Plant Sci 178:158‒169

Nishibayashi S, T Hayakawa, T Nakajima, M Suzuki, H Kaneko (1996). CMV protection in transgenic cucumber plants with an introduced CMV-O cp gene. Appl Genet 93:672‒678

Nunome T, F Fukumoto, F Terami, K Hanada, M Hirai (2002). Development of breeding materials of transgenic tomato plants with a truncated replicase gene of cucumber mosaic virus for resistance to the virus. Breed Sci 52:219‒223

Park YK, YH Kang (2004). Effects of single cells of carrot and radish on the fecal excretion properties, mineral absorption rate and structure of small intestine and colon in rats. J Kor Soc Food Sci Nutr 33:505‒511

Parvaiz K, S Yang, Y Hernandez, A Winter, A Turchanin, X Feng, K Müllen (2012). Nitrogen-doped graphene and its iron-based composite as efficient electrocatalysts for oxygen reduction reaction. ACS Nano 6:9541‒9550

Patade VY, D Khatri, M Kumari, A Grover, SM Gupta, Z Ahmed (2013). Cold tolerance in Osmotin transgenic tomato (Solanum lycopersicum L.) is associated with modulation in transcript abundance of stress-responsive genes. SpringerPlus 2:117

Pimentel D, C Wilson, C McCullum, R Huang, P Dwen, J Flack, B Cliff (1997). Economic and environmental benefits of biodiversity. BioScience 47:747‒757

Powell AL, MS Kalamaki, PA Kurien, S Gurrieri, AB Bennett (2003). Simultaneous transgenic suppression of LePG and LeExp1 influences fruit texture and juice viscosity in a fresh market tomato variety. J Agric Food Chem 51:7450‒7455

Qaim M (2016). Genetically Modified Crops and Agricultural Development. In: Palgrave Studies in Agricultural Economics and Food Policy. Springer

Rai AC, M Singh, K Shah (2013). Engineering drought-tolerant tomato plants over-expressing BcZAT12 gene encoding a C2H2 zinc finger transcription factor. Photochemistry 85:44‒50

Raj SK, R Singh, SK Pandey, BP Singh (2005). Agrobacterium-mediated tomato transformation and regeneration of transgenic lines expressing Tomato leaf curl virus coat protein gene for resistance against TLCV infection. Curr Sci 88:1674‒1679

Rhim SL, HJ Cho, BD Kim, W Schnetter, K Geider (1995). Development of insect resistance in tomato plants expressing the δ-endotoxin gene of Bacillus thuringiensis subspp. tenebrionis. Mol Breed 1:229‒236

Rigaud N (2008). Biotechnology: Ethical and social debates. In: OECD International Futures Project on “The Bioeconomy to 2030”, pp:1‒89

Romagnano JF (2008). Ethylene Synthesis and Sensitivity in Crop Plants. Ph.D. Dissertation.

Rosati JA (2000). The power of human cognition in the study of world politics. Intl Stud Rev 2:45‒75

Ruma D, MS Dhaliwal, A Kaur, SS Gosal (2009). Transformation of tomato using biolistic gun for transient expression of the β-glucuronidase gene. Ind J Biotechnol 8:363‒369

Schaefer SC, K Gasic, B Cammue, W Broekaert, EJMV Damme, WJ Peumans, SS Korban (2005). Enhanced resistance to early blight in transgenic tomato lines expressing heterologous plant defense genes. Planta 5:858‒866

Seong ES, KH Baek, SK Oh, SH Jo, SY Yi, JM Park, YH Joung, S Lee, HS Cho, D Choi (2007). Induction of enhanced tolerance to cold stress and disease by over-expression of the pepper CAPIF1 gene in tomato. Physiol Plant 129:555‒566

Singh U, PK Patel, AK Singh, V Tiwari, R Kumar, N Rai, B Singh (2015). Screening of tomato genotypes under high temperature stress for reproductive traits. Veg Sci 42:52‒55

Statistica (2021). Vegetables: Statistics & facts. Available at: https://www.statista.com/topics/1611/vegetables/https://www.statista.com/topics/1611/vegetables/. (Accessed on: 1^st November 2021)

Stommel JR, ME Tousignant, T Wai, R Pasini, JM Kaper (1998). Viral satellite RNA expression in transgenic tomato confers field tolerance to cucumber mosaic virus. Plant Dis 82:391‒396

Tabei Y, S Kitade, Y Nishizawa, N Kikuchi, T Kayano, T Hibi, K Akutsu (1998). Transgenic cucumber plants harboring a rice chitinase gene exhibit enhanced resistance to gray mold (Botrytis cinerea). Plant Cell Rep 17:159‒164

Tabaeizadeh Z, Z Agharbaoui, H Harrak, V Poysa (1999). Transgenic tomato plants expressing a Lycopersicon chilense chitinase gene demonstrated improved resistance to Verticillium dahliae race 2. Plant Cell Rep 19:197‒202

Tang X, M Xie, YJ Kim, J Zhou, DF Klessig, GB Martin (1999). Overexpression of Pto activates defense responses and confers broad resistance. Plant Cell 1:15‒29

Tarafdar A, M Kamle, A Prakash, JC Padaria (2014). Transgenic plants: Issues and future prospects. Biotechnology 2:1‒47

Thakur BR, RK Singh, DM Tieman, AK Handa (1996). Tomato product quality from transgenic fruits with reduced pectin methylesterase. J Food Sci 61:85‒87

Thomzik JE, K Stenzel, R Stocker, PH Schreier, R Hain, DJ Stahl (1997). Synthesis of a grapevine phytoalexin in transgenic tomatoes (Lycopersicon esculentum mill.) conditions resistance against Phytophthora infestans. Physiol Mol Plant Pathol 51:265‒278

Vasileva VH, NS Dinev (2021). Mineral content and quality parameters of tomato fruits as affected by different potassium fertilization treatments and cultivar specifics. Ind J Agric Res 55:169‒174

Vegetable Statistics (2021). Vegetable Statistics. Available at: https://iivr.icar.gov.in/sites/default/files/Technical%20Bulletins/Vegetable%20Statistics%20Final.pdfhttps://iivr.icar.gov.in/sites/default/files/Technical%20Bulletins/Vegetable%20Statistics%20Final.pdf. (Accessed on: 1^st November 2021)

Vidya CSS, M Manoharan, CTR Kumar, HS Savithri, GL Sita (2000). Agrobacterium-mediated transformation of tomato (Lycopersicon esculentum var. Pusa ruby) with coat-protein gene of Physalis mottle tymovirus. J Plant Physiol 156:106‒110

Villani ME, P Roggero, O Bitti, E Benvenuto, R Franconi (2005). Immunomodulation of cucumber mosaic virus infection by intrabodies selected in vitro from a stable single-framework phage display library. Plant Mol Biol 58:305‒316

Viveros MFÁ, C Inostroza-Blancheteau, T Timmermann, M González, P Arce-Johnson (2013). Overexpression of GlyI and GlyII genes in transgenic tomato (Solanum lycopersicum Mill.) plants confers salt tolerance by decreasing oxidative stress. Mol Biol Rep 40:3281‒3290

Vu T, NR Choudhury, SK Mukherjee (2013). Transgenic tomato plants expressing artificial microRNAs for silencing the pre-coat and coat proteins of a begomovirus, tomato leaf curl New Delhi virus, show tolerance to virus infection. Vir Res 172:35‒45

Wang AY, BM Wisniewski, CR Meilan, AM Cui, AL Fuchigami (2006). Transgenic tomato (Lycopersicon esculentum) overexpressing cAPX exhibits enhanced tolerance to UV-B and heat stress. J Appl Hortic 8:87‒90

Wang BQ, QF Zhang, JH Liu, GH Li (2011). Overexpression of PtADC confers enhanced dehydration and drought tolerance in transgenic tobacco and tomato: Effect on ROS elimination. Biochem Biophys Res Commun 413:10‒16

Wang TW, CG Zhang, W Wu, LM Nowack, E Madey, JE Thompson (2005). Antisense suppression of deoxyhypusine synthase in tomato delays fruit softening and alters growth and development. Plant Physiol 138:1372‒1382

Whitham S, S McCormick, B Baker (1996). The N gene of tobacco confers resistance to tobacco mosaic virus in transgenic tomato. Proc Natl Acad Sci 93:8776‒8781

Xiong AS, QH Yao, RH Peng, X Li, PL Han, HQ Fan (2005). Different effects on ACC oxidase gene silencing triggered by RNA interference in transgenic tomato. Plant Cell Rep 23:639‒646

Xue B, C Gonsalves, R Provvidenti, JL Slightom, M Fuchs, D Gonsalves (1994). Development of transgenic tomato expressing a high level of resistance to cucumber mosaic virus strains of subgroups I and II. Plant Dis 78:1038‒1041

Zhang H, M Liu, Y Li, Y Zhao, H He, G Yang, C Zheng (2010). Oral immunogenicity and protective efficacy in mice of a carrot-derived vaccine candidate expressing UreB subunit against Helicobacter pylori. Protein Expr Purif 69:127–131

Zhang HX, E Blumwald (2001). Transgenic salt-tolerant tomato plants accumulate salt in foliage but not in fruit. Nat Biotechnol 19:765‒768