Molecular Characterization and in silico Analysis of Drought Resistance Genes in Oryza Sativa

Abstract

The success of the Green Revolution in closing the gap between world population newlineand food production was principally achieved by increasing crop productivity in newlinefavorable areas. However, this success has been limited in the rainfed systems, which are newlineprone to frequent droughts and other abiotic stresses. Worldwide, drought affects newlineapproximately 23 million hectares of rainfed rice. Varieties combining improved drought newlineresistance with high yield under favorable conditions and quality characteristics preferred newlineby farmers are the most promising and deliverable technologies for alleviating poverty in newlinecommunities dependent on rainfed rice production. Drought is one of the major newlinelimitations to food production worldwide and is endemic particularly in the semi-arid newlinetropics. Improving drought tolerance and productivity is one of the most difficult tasks newlinefor cereal breeders. The difficulty arises from the diverse strategies adopted by plants newlinethemselves to combat drought stress depending on the timing, severity and stage of crop newlinegrowth. Compounding the problem further are the many loci that show efficacy only in a newlinesubset of circumstances (Lebreton et al 1995; Ribaut et al 1996, 1997; Tunistra et al newline1996; Nguyen et al 2004). Candidate genes (CGs) are sequenced genes of known newlinebiological function associated with the manifestation of the trait. They may be structural newlinegenes or genes in a regulatory or biochemical pathway which affect trait expression. One newlineCG hypothesis states that a significant proportion of the quantitative trait loci (QTL) newlineaffecting trait variation are in fact CGs associated with that trait (Rothschild and Soller newline1997). The CG approach involves choosing the CG, obtaining primer sequences to newlineamplify the gene, uncovering polymorphism, developing a convenient procedure for newlinelarge-scale genotyping, identifying a population for association studies, carrying out an newlineassociation study of the CG with trait phenotype and verifying the uncovered newlineassociations. newlineIn the present study, CGs directly related to drought resistance and productivity newlinegenetic and phenotypic levels were identified and polymerase chain reaction (PCR) newlineprimers designed. These were used to genotype diverse cultivars of rice. Reporting the newlinepresence of targeted 3 genes involved in drought resistance in selected varieties of Oryza newlineand Insilico studies of selected genes and their products involving Evolutionary study, newlineGene annotation and Structural analysis are the objectives of the study. newlineThe current research was undertaken to detect/identify the presence of three of the newlinedrought resistant genes DREB, LEA and OsDHODH1 among 19 varieties of paddy. The newlineresults of amplification showed that DREB was present in all the varieties except newlineRajshree, Kala namak-3, Gotra Bidhan and NDR-97 while LEA could not be detected in newlineMalviya Dhan-2, PNR-301, Lalat and NDR-97. OsDHODH1 was comparatively much newlinerare than these two genes and was not identified in Pusa-1612, Rajshree, Annada, Lalat newlineand Gotra Bidhan.The samples in which all these three genes were identified were newlinePratikshaa, Rajendra Mehsuri, Komal-1, NDR-2064, MTU-Swarna/7029, Prabhat, Pusa newlinesugandha-5 and Sarju-52. newlineConventional breeding approaches towards developing drought tolerant rice newlinevarieties are resulting in slow progress due to complex nature of drought toleranceiv newlinemechanism(s). In this context, Biotechnology offers us a powerful means of manipulating newlinedrought tolerance in rice through QTL mapping and genetic transformation. newline