Integrated multi-omics analysis reveals drought stress response mechanism in chickpea (Cicer arietinum L.)

Drought is one of the major constraints for crop productivity across the globe. Chickpea (Cicer arietinum L.) is mainly cultivated in the arid and semi-arid tropical regions under rain-fed conditions and drought stress is one of the major constraints, which causes up to 50% yield losses annually. In this study, transcriptomics, proteomics and metabolomics datasets from root tissues of contrasting drought responsive chickpea genotypes, ICC 4958 (drought-tolerant), JG 11 (drought-tolerant); an introgression line, JG 11+ (drought-tolerant) and ICC 1882, (drought-sensitive) under control and stress conditions were generated. The integrated analysis of these multi-omics data revealed complex molecular mechanism underlying drought stress response in chickpea. Transcriptomics integrated with proteomics data identified enhancement of hub proteins encoding isoflavone 4’-O-methyltransferase (Ca_06356), UDP-D-glucose/UDP-D-Galactose 4-epimerase (Ca_15037) and delta-1-pyrroline-5-carboxylate synthesis (Ca_24241). These proteins highlighted the involvement of critical pathways such as antibiotic biosynthesis, galactose metabolism and isoflavonoid biosynthesis in activating drought stress response mechanism. Subsequently, integration of metabolomics data identified six key metabolites (fructose, galactose, glucose, myo-inositol, galactinol and raffinose) that showed enhanced correlation with galactose metabolism. Further, integration of root -omics data together with genomic dataset of the “QTL-hotspot” region harbouring several drought tolerance related traits revealed involvement of candidate genes encoding aldo keto reductase family oxidoreductase (Ca_04551) and leucine rich repeat extensin 2 (Ca_04564). These results from integrated multi-omics approach provided a comprehensive understanding and new insights into the drought stress response mechanism of chickpea.