LAUSR

Abstract The grass pea (Lathyrus sativus L.) is an attractive legume which grows traditionally in drought-stricken, rain-fed and poor fertile soils. Globally drought is a major constraint for agriculture. Regulatory mechanism such as non-coding RNA is an important molecule to control gene expression in every domain of life. Therefore, identification and characterization of drought-responsive miRNAs of this plant can be very useful genomic resource to understand the molecular mechanisms of drought stress tolerance in plants. In this study we identified 143 and 128 conserved miRNAs by sequencing small RNA libraries from control (LC) and moisture-stressed (LD) leaf tissues. Additionally, 5 and 11 novel miRNAs were also found in LC and LD library respectively, among which 2 miRNAs were common. Further, we observed that 8 and 12 known miRNAs were up- and down- regulated under drought stress. Importantly, complementary miRNA (feeder) stands were also found for all the mature miRNAs. Expressions of few known and novel miRNAs were validated by qPCR in the tolerant genotype of grass pea under drought stress. The predicted target sequence of differentially expressed miRNAs were found to be either transcription factors such as F-box, U-Box or protein coding genes involved in proline, betain and osmolyte biosynthesis pathway indicating that these miRNAs may have specific role in imparting drought tolerance. These findings provide valuable information to understand the function of miRNAs in an inherently drought tolerant plant.