Identification of stress-induced genes from the drought tolerant semi-arid legume crop horsegram (Macrotyloma uniflorum (Lam.) Verdc.) through analysis of subtracted expressed sequence tags

Abiotic stresses adversely affect the agricultural productivity worldwide. Horsegram (Macrotyloma uniflorum (Lam.) Verdc.) is a legume crop that can tolerate severe adverse environmental conditions such as drought, salinity and heavy metal contamination. As a first step towards characterization of genes that contribute to combating abiotic stresses, construction and analysis of subtracted cDNA library is reported here. Using this strategy a total of 1050 ESTs were isolated, sequenced, 959 high quality ESTs were obtained and clustered. Further, our analysis revealed that of these 531 sequences are unique and 30% of these have no homology to known proteins in the database. This observation has great relevance since horsegram is a stress-adapted legume crop. Further, to validate the identified differentially expressed genes, expression profiles of selected clones were analyzed using reverse-northern, northern blot analysis and we show that indeed these clones are differentially expressed under various abiotic stress conditions. The implications of the analyzed genes in abiotic stress tolerance also discussed.