Identification of differentially expressed transcripts in groundnut genotypes subjected to different levels of mid-season moisture stress

Abstract

Groundnut is mostly cultivated under rainfed situation in India and drought tolerance is one of the major breeding objectives. Irrespective of the drought tolerance levels in groundnut genotypes, a significant increase in proline concentration under drought stress situation and progressively higher level of proline was accumulated in drought sensitive genotypes like Kadiri 6 and Narayani than the drought tolerant genotypes like TCGS 1157 and Kadiri 1725. Transcriptome analysis by cDNA-RAPD revealed a total of 712 drought responsive Transcript Derived Fragments (TDFs) were identified in four groundnut genotypes with 20 RAPD primers among the four genotypes at different levels of moisture stress and in comparison with their respective control. Out of 712 TDFs, 180 TDFs were quantitatively expressed, 514 TDFs were qualitatively expressed and 18 TDFs were showed without any difference in the level of expression. Two moisture stress responsive transcripts were identified with OPA2 (700 bp TDF) and OPA4 (450 bp TDF) markers only under drought stress in resistant genotypes (TCGS1157 & Kadiri1725) and absent susceptible genotypes (Kadiri 6 & Narayani). Further, characterization of these transcripts by sequencing will greatly helps in understanding nature of the genes and the mechanism by which groundnut plants respond to drought stress. These genes will be highly useful for the development of drought tolerant groundnut genotypes through molecular breeding.