ANALYSIS OF METABOLITE PROFILES IN LEAF TISSUES OF TRANSGENIC GROUNDNUT PLANTS MODIFIED FOR RESISTANCE AGAINST TOBACCO STREAK VIRUS Sara Shomo, H. Shifa, C. Senthilraja, Madem Gurivi Reddy, V. Paranidharan and R. Velazhahan* Department of Plant Pathology, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore-641 003, India. *Agricultural College and Research Institute, Tamil Nadu Agricultural University, Eachangkottai, Thanjavur - 614 902, India e-mail: velazhahan@hotmail.com (Accepted 26 June 2016) ABSTRACT : The metabolic profile of transgenic groundnut (Arachis hypogaea L.) plants transformed with a gene construct encoding hairpin RNA (hpRNA) of Tobacco streak virus - coat protein gene sequence was compared with that of non-transformed control plants by using gas chromatography coupled to electron impact ionization-time of flight-mass spectrometry (GC/EI- TOF-MS). A total of 38 metabolites were identified and annotated using the Golm Metabolome Database and Tag Finder software. Several resistance- related metabolites such as benzoic acid, methionine, myristic acid, myo-inositol, oleic acid and D-fructose were detected in both transgenic and wild-type plants. The metabolites such as lauric acid, L-arabitol, threitol, mannose, glucose and sorbose were detected in the transgenic plant, whereas the metabolites viz., mannobiose, galactose and L-tryptophan were detected in the non-transgenic control plant. However these compositional differences did not cause any unintended changes in plant growth and yield of transgenic groundnut plant. The results showed that expression of dsRNA of TSV- CP gene sequence and two antibiotic marker genes had no undesirable effect on vital metabolic activities of transgenic groundnut plant. Key words : Arachis hypogaea, RNA interference, transgenic plant, metabolomics. TMV-7) harbouring a hairpin RNA (hpRNA) construct targeting coat protein gene of TSV (Senthilraja et al (Unpublished). Analysis of the transgenic lines for TSV resistance revealed that transgenic lines showed better resistance than the untransformed control lines. Several reports indicate the occurrence of abnormal phenotypes in transgenic plants expressing functional viral proteins (Lucas et al, 1996; Herbers et al, 1997; Hou et al, 2000). It has been reported that transgenic Nicotiana tabacum plants expressing the 30-kDa movement protein of Tobacco mosaic virus (Lucas et al, 1993; Lucas et al, 1996) or the 17-kDa movement protein of Potato leafroll virus (Herbers et al , 1997) have abnormal phenotypes, such as chlorosis and stunted growth, as well as an altered plasmodesmal structure and/ or size exclusion limit. An important issue in assessment of the safety of genetically modified crops is identification of undesirable changes in genetically modified crops. One approach to address this concern is the use of metabolomics. The identification of metabolites is very important for understanding the physiology of plants including plant growth, development and defense mechanisms. In the present study, the metabolites profile of transgenic groundnut plants was compared with that of non-transformed control plants by using gas chromatography coupled to electron impact ionization- Biochem. Cell. Arch. Vol. 16, No. 2, pp. 245-250, 2016 www.connectjournals.com/bca ISSN 0972-5075 INTRODUCTION Peanut stem necrosis disease (PSND) caused by Tobacco streak virus (TSV) is one of the important viral diseases affecting groundnut (Arachis hypogaea L.) production in India. The virus infection causes severe necrosis of shoots leading to death of the affected plant, and plants that survive are malformed, with severe reduction in pod yield. TSV belongs to the genus Ilarvirus in the family of Bromoviridae. TSV has a tripartite positive-strand RNA genome consisting of RNA1, RNA2 and RNA3 (Reddy et al , 2002). In nature, TSV is transmitted by thrips viz., Frankliniella schultzei and Scirtothrips dorsalis (Prasada Rao et al, 2003; Shukla et al, 2005). Currently, all commercial groundnut cultivars in India are susceptible to TSV, and the only available method to control this disease is through application of insecticides to control thrips vectors that spread viruses within and between fields. However, this is becoming less acceptable since it conflicts with the public concern about environmental pollution, build-up of resurgence in insect population and insecticide residues. Due to lack of suitable PSND-resistant sources in groundnut germplasm, transgenic resistance by exploiting the concept of pathogen-derived resistance (PDR) is being explored to manage the disease (Bag et al, 2007; Mehta et al, 2013). Recently, we generated transgenic groundnut lines (cv.