Effect of drought stress on morphological, biochemical, physiological traits and expression analysis of microRNAs in drought-tolerant and sensitive genotypes of chickpea

Abstract

Drought stress poses a global threat for sustainable growth and productivity of major legumes, including chickpea. There was severe reduction in biomass of the chickpea plants subjected to drought and the effect on leaves was most apparent. However, there was not much difference in the root volume(s) suggesting a drought tolerance mechanism other than the root traits in Pusa 362, a drought tolerant genotype as compared to SBD377, a drought sensitive genotype. The proline accumulation was significantly higher in Pusa 362 as compared to SBD377. Recently miRNAs (21-24 nt in length, endogenous, noncoding RNAs) have emerged as major regulatory molecules which have been shown to regulate gene expression during drought stress conditions. Among the 16 validated miRNAs, expression of miR167, miR168 and miR171 showed significant upregulation (>3-fold) in root tissue of drought tolerant genotype. These miRNAs targets auxin response factors, WD-repeat and scarecrow-like transcription factors, respectively which are known to play important role in drought stress in plants suggesting direct role of these miRNAs during drought tolerance in chickpea. miR390 and miR2118 were up-regulated in shoot samples in Pusa 362. Among the novel miRNAs, nov_miR8 in root and nov_miR2 in shoot tissue showed maximum expression in Pusa 362. Nov_miR2 targets GMP synthase and nov_miR8 targets gene encoding laccase. GMP synthase are involved in synthesis of purine nucleotides which among other functions play key role as secondary messenger in signal pathways activated during stress conditions. These drought-responsive miRNAs are likely to provide novel insights into post transcriptional gene regulation under drought stress conditions in chickpea at molecular level.