Abstract
Onion is a shallow rooted crop predominantly grown under rainfed conditions, hence exposed to frequent drought during the crop growth period. Drought stress elicits complex cellular responses in plants involving a whole array of genes and regulatory elements. Therefore an understanding of the genes involved in the stress signaling network is important for developing crops tolerant to drought. In this study the enormous wealth of sequence data of model crop species (rice and Arabidopsis) available in the public database was used to design primers specific to the genes and regulatory elements. These primers were used to amplify the complementary sequences from onion leaf cDNA. The amplification products were sequenced and characterized using the BLASTx algorithm of NCBI site. Significant homology was obtained for Aquaporin, Calcium- dependent protein kinase (CDPK), Calcium Sensor homologue, Catalase, Dehydration responsive element binding protein (DREB), Heat shock protein (HSP), Hexose transporter, serine/threonine protein kinase (SAPK) and Ubiquitin. The crucial role played by these genes and regulatory elements in conferring drought tolerance in plants has been well established. The genes and transcriptional factors isolated from onion in this study should be valuable in delineating the regulatory network that controls the expression of drought induced genes in onion, which would in turn be useful in studying the drought tolerance mechanism operational in onion.
