Gene Expression and Protein-Protein Interaction Analysis for Understanding Drought Tolerance Mechanism in Chickpea (Cicer arietinum L.)

Plant responses to abiotic stresses involve expression of genes participating in signalling, regulatory pathways and stress induced protein-protein interactions (PPI) contributing to stress tolerance. To understand the mechanisms of drought tolerance in chickpea, both, gene expression and protein-protein interaction studies have been undertaken.  Transcription factors (TFs), although known to have significant roles in drought tolerance signalling pathways, have not been well studied in legumes.  Selected 8 TFs, that were found to be differentially expressed for drought tolerance in chickpea, were validated using quantitative real time PCR (qRT-PCR) on root tissues of four drought responsive chickpea genotypes.  Of these, the Myb1R1-like, that encodes for the MYB1R1-like TF showed higher differential expression between tolerant and sensitive genotypes.  Myb1R1-like was cloned and subjected to yeast two-hybrid (Y2H) analysis, which involved screening a library of drought responsive genes, isolated from root tissue of the drought tolerant chickpea genotype, ICC 4958.  The MYB1R1-like TF showed interaction with four components at their C-terminus, which include a protein involved in the biosynthesis of sugar (galactinol-sucrose galactosyltransferase), two CBL (Calcineurin B-like)-interacting serine/threonine-protein like kinases, (a CIPK-11 like and a CIPK-25 like) and an ABA responsive like protein (ABR17-like). The PPI observed between MYB1R1-like TF and the four components identified may be important in enzyme regulation, phosphorylation events and cross-talk with other pathways, which could be significant in the drought tolerance mechanism of ICC 4958, with the involvement of the ABA-dependent stress signaling pathway.