Nuclear proteome reprogramming and acquired thermotolerance in chickpea exposed to escalating high-temperature stress

Global chickpea (Cicer arietinum L.) production amounted to ∼17.55 MMT during 2024-2025, whose market size is valued at ∼$16.83 billion. Chickpea is highly susceptible to high-temperature stress (HTS), and its yield declines 10-15% with the rise in each degree of temperature. In this study, the HTS-responsive nuclear proteome of a thermotolerant chickpea cultivar ICC 1205 was investigated, leading to the identification of 2705 proteins, including 424 differentially regulated proteins designated as HTS-responsive (HRPs). Of these, 212 were shared between immediate (day-1) and later (day-4) stages of HTS, with 117 proteins specific to day-1 and 95 to day-4. Functional network analysis revealed a complex network of nuclear proteins involved in regulatory and stress-related functions. Detailed analysis of the proteome revealed several non-canonical proteins, suggesting HTS-responsive reprograming of the nuclear proteome landscape. The cross-species multiple abiotic stress responses recognized unique HRPs, reflecting genetic foundation that leads to crop adaptation. Comparison of protein and mRNA expression shed light on the intricate regulatory mechanisms of thermotolerance response in chickpea. The characterization of root-phototropism 2 protein (CaRPT2), a member of the NPH3 gene-family, showed significant regulations, particularly under dehydration stress and ABA treatments. Subcellular localization of CaRPT2 demonstrated its dual localization in both plasma membrane and nucleus. Analysis of physiological indices in atrpt2 loss-of function mutants in Arabidopsis demonstrated better germination rate, resilience and growth under progressive HTS, suggesting the putative role of RPT2 in regulating multiple stress-responsive genes.