REVIEW INTERNATIONAL JOURNAL “Advancements in Life Sciences” ARTICLE Invited Review: Date Published Online: 25/05/2014 Genetically Modified Foods: Engineered tomato with extra advantages Arfan Ali*1, Adnan Muzaffar1, Mudassar Fareed Awan1, Salah ud Din1, Idrees Ahmad Nasir1, Tayyab Husnain1 Citation: Ali A, Muzaffar A, Awan MF, Din S, Nasir IA, Husnain T. (2014). Genetically Modified Foods: Engineered tomato with extra advantages. Adv. life sci., 1(3). pp. 139-152. Key words: Transgenic tomato, Transformation, RNAi, Cry1Ac, CsiHPL1, SlSHINE3, N gene, LeMYC2, Wasabi defensing gene, Glycine betaine, Chilling stress, Photosynthesis, Metabolic rate, Salinity, Drought tolerance, Fast ripening, Floral developments, Female sterility Abstract Currently, genetically modified crops are among the most important constituents in all aspect of our life. Recent controversies about genetically modified crops in United Kingdom and other European countries indicate the apparent differences in public opinion on this subject across the Atlantic, where people do seem untroubled with GMO as compared to other countries. Among plants after potato, tomato is the model plant for genetic changes. A number of genetic modifications of tomato are available especially against different insects, pests and fungus. Gene silencing techniques against viruses have been applied for silencing the expression of damage causing gene. Genetic modifications inducing significant events regarding fruits ripening and growth in tomato and vaccines are of the particular importance. In this review article, we have covered genetic modifications which cause insect, virus and fungus resistance; confer fast growth, chilling, salinity and drought tolerance, increased and improved nutrients, yield, fruit ripening, quality and color of the tomato. Factors affecting photosynthesis and metabolic rate are also discussed in this review. *Corresponding Author: Arfan Ali (Email: [email protected]) 1-National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan 139 | Advancements in Life Sciences Vol. 1, Issue 3 Review Article Introduction important events related to tomato fruit development and ripening; insects and During the process of crop development, viruses resistance; chilling and soil salinity tomato (Solanum lycopersicun) evolved resistance. from Solanum pimpinellifolium [1,2]. Tomato is among the most important Methods vegetables and extensively used as raw or cooked [3]. Beside a source of antioxidants, Search Strategy and Selection Criteria minerals, fibers and vitamins it is also an The following key terms were provided in excellent model system for genetic studies, Google Scholar, PubMed and PubMed fruit development and ripening process Central for mining the scholarly literature [4,5]. Insect pest and other different many relevant. Research papers with specific kind of microbial pathogens outbreak focus on tomato pathogens (insects, fungus tomato. Microbial pathogens include and viruses), tomato growth, nutrition and lepidopteron, Helicoverpa armigera and fruit ripening were included. Most of the common fruit borers which mainly attack on included articles were published during fruit while Spodoptera litura destroy leaves 2013-2014. But exceptions were made for [6,7]. Incorporation of Bt genes in tomato, few articles published back in 1990s based cotton, and sugarcane has showed upon strong relevancy to topic. A total of 51 considerable resistance against lepidoternans research articles were consulted to construct [8-10]. Tomato has served as an excellent this review. model for fleshy fruit development and Discussion ripening [11,12]. Well characterized ripening mutants, high density genetic maps, Against Insects: small genome size, short life cycle, efficient Transformation of Cry1Ac gene against and stable transformation made tomato an lepidopteron pest in Tomato excellent model for studying viruses, Tomato is the part and parcel of our daily development and fruit ripening process food. Importance of tomato in food industry through genetic modification [13-16]. Cold, can also not be undermined because it is heat and soil salinity are the major involved in production of other food environmental factors that significantly products. Presently, there are many yield affect the productivity and quality of tomato limiting factors for tomato crop but and other crops [16-18]. Chilling, drought lepidopteron insects pose a serious threat in and salinity stress have been found devastating this precious crop. In order to interconnected in effecting water relations at check the attack of these insects, modified cellular, tissue, organ and whole plant level BT genes (Cry1Ab) were transformed in leading to physiological, morphological high yielding commercial tomato variety by biochemical and molecular changes [19-22]. Agrobacterium mediated transformation A lot of genetic modifications in tomato method. This transformation played a have been done. The aim of this review is pivotal role in reducing the attack of not to explain all of them but to mention the lepidopteron insects. The results of this 140 | Advancements in Life Sciences Vol. 1, Issue 3 Review Article study indicate the effective control of this Tobacco mosaic virus has become a major problem [23]. threat for the production of tomato plant. Studies show that resistance can be created Transformation of Tea Hydro peroxide Lyase in tomatoes by genetic transformation of Gene, CsiHPL1 in tomato virus resistant genes. In a recent study, viral Tomato crop is an attractive crop for many resistant N gene has been isolated from insects and other pest organisms causing transgenic tobacco plant, cloned and several problems in it. Defense system of transferred in commercial tomato variety tomato plant is highly sensitive and ultimately created resistance against tobacco vulnerable to insect attack ultimately mosaic virus in tomato [26]. triggers the occurrence of dangerous diseases in tomato. Chloroplast localized tea Against Viruses: gene, CsiHPL1 is found to be highly effective in strengthening the defense Transformation of Coat protein gene system of tomato crop. Moreover, from Tobacco Mosaic Virus in tomato transformation of CsiHPL1 not only protects Viruses are the natural enemies of living tomato crop against all fungal attacks but organisms. Similarly plants are also among also create herbivore resistance in tomato the easy victims of viral infection. Tobacco [24]. mosaic virus (TMV) and tomato mosaic virus (ToMV) have been causing losses in The transcription factor SlSHINE3 tomato crop. Yield losses about 25-30% modulates defense responses in tomato have been reported in tomato crop due to plants this viral attack. Coat protein genes (CP Cuticle is an important part of plant leaf. genes) are found producing more than 90% Several transcription factors are involved in resistance in tomato plants against TMV and cuticle production, like SlSHINE3, an ToMV. Integration of CP genes in tomato ortholog of the Arabidopsis WIN/SHN3. genetic makeup was done through Interaction of pathogens with their Agrobacterium mediated transformation to surroundings and acting as a barrier against create viral resistance. These CP gene has no physical stresses and pathogens are all the negative impact on fruit yield [27]. functions of leaf cuticle. Moreover, it also acts as chemical deterrent in enhancing and Genetic transformation of Tomato Yellow regulating the plant defense system. Many Leaf Curl Virus against virus transcription factors are said to be involved Like other viral diseases, Tomato Yellow in enhancing the production of cuticle in Leaf curl Virus (TYLCuV) also cause huge leaves making tomato plant resistant against fruit losses in tomato crop. This viral disease all types of stresses [25]. was controlled by the genetic transformation The N gene of tobacco confers resistance of TYLCuV genes which encode Capsid to tobacco mosaic virus in transgenic proteins (VI). This strategy has against this tomato virus has reduced the risk of leaf curling in esculentum spp [28]. 141 | Advancements in Life Sciences Vol. 1, Issue 3 Review Article Transformation of glycoprotein Hence Fungus can be controlled effectively producing gene in tomato plants by WD genes [30]. Preparation of vaccine for protection against any disease is an uphill task now a day. Growth and Nutrition: Biotechnologists and molecular biologists Transformation of LeMYC2 gene in utilize different means and mediums for tomato manufacturing valuable products. Most From commercial point of view, tomatoes interestingly, transgenic tomato plants have having shorter stature are more acceptable as been used for this purpose. Glycoprotein compared to taller ones because (which coats the outer surface of rabies reproductive growth is more important than virus) producing gene is transferred in vegetative growth. Many genetic promoters tomato plants through Agrobacterium are reported which enhance reproductive mediated transformation procedure. growth while discourage vegetative Analysis through electron microscopy and development. LeMYC2 and MYC2 are the other techniques show cell organelles like promoters responsible for root growth and Golgi bodies, plasma cells, vesicles and cell repressing vegetative length. They are also walls of parenchyma tissues contain reported to enhance fruit development Glycoprotein proteins. In this way, ultimately increasing the yield of tomato transgenic tomato plants can be used as a crop. Hence their transformation