Genome-Wide Identification and Molecular Characterization of Core ABA Signaling Components Under Abiotic Stresses and During Development in Chickpea

Abscisic acid (ABA) signaling is vital for plant's response to abiotic stresses and development. Core components of ABA signaling include ABA receptors PYR/PYL/RCAR, group-A PP2Cs (PP2C-As) and SnRK2 serine/threonine kinases. These have been well studied in Arabidopsis, but their knowledge in the legume crop chickpea is missing. Here, we identified 8 PYLs, 11 PP2C-As and 13 SnRK2s genes in the chickpea genome. Gene duplication events have been found to drive their evolution and expansion in chickpea. Protein homology modeling revealed three-dimensional structure, and arrangements of alpha-helix, beta-sheets and p-loops in respective families. In-planta subcellular localization analysis revealed that CaPYL3 and CaPYL5 proteins were localized at the plasma membrane, and CaPP2CA-1 and CaSnRK2.7 were localized in the cytoplasm and the nucleus. RNA sequencing data analysis indicated the regulatory role of CaPYLs, CaPP2C-As and CaSnRK2s in developmental stages particularly, stages of early embryogenesis to seed maturity. Through RT-qPCR analysis drought, salt and ABA responsive CaPYL, CaPP2C-A and CaSnRK2 genes, which might regulate abiotic stress response in chickpea were identified. Importantly, key genes like CaPYL4, CaPP2C-A4, CaPP2C-A11 and CaSnRK2.9 with overlapping expression in drought, ABA and seed development were identified, which might determine chickpea crop yield. In-silico interaction analysis revealed specific and overlapping interaction among ABA signaling proteins indicating their functional relevance. Overall, core ABA signaling components are crucial for abiotic stress tolerance and development in chickpea. These genes will be functionally validated in the future and will be utilized to generate abiotic stress resilience and high-yielding chickpea varieties.