Phosphatase member TaPP2C62-2A cooperates with downstream partners to regulate drought response in wheat

Drought is a major limiting factor for growth, development, and yield in wheat. TaPP2C62-2A, a clade A type phosphatase (PP2C) member in T. aestivum, was identified as a mediator of drought response. TaPP2C62-2A expression was downregulated in tissues in response to drought and abscisic acid signaling, which is linked to a transcriptional silencer in the promoter region. Yeast two-hybrid, bimolecular fluorescence complementation, and co-immunoprecipitation assays revealed interaction between TaPP2C62-2A and SnRK2 kinase TaSnRK2.5-2D and that TaSnRK2.5-2D also interacted with bZIP transcription factor TaABI5-3B with both interactions occurring via distinct conserved domains to establish a regulatory module of TaPP2C62-2A with the above partners. Transgene analyses revealed that this module is essential in modulating drought responses. TaPP2C62-2A negatively regulates drought tolerance, whereas TaSnRK2.5-2D and TaABI5-3B positively regulate plant growth and agronomic traits under drought conditions. The modified drought response mediated by TaPP2C62-2A and its associated components was ascribed to their functions in regulating osmotic stress-related physiological processes, including stomatal movement, osmolyte biosynthesis, leaf water retention, root morphology, and homeostasis of reactive oxygen species. TaABI5-3B binds with the promoters of stress-responsive genes, including S-type channel gene TaSLAC1-3, P5CS gene TaP5CS1, PIP gene TaPIP2;1, PIN-FORMED gene TaPIN4, and catalase gene TaCAT6, leading to their transcriptional activation. Transgene analysis confirmed the positive roles of these stress-responsive genes in regulating drought tolerance. Significant correlations were observed between yield and TaPP2C62-2A transcription and its module genes in a wheat variety panel subjected to drought conditions, with haplotype TaPP2C62-2A_h1 enhancing drought adaptation capacity. Our study presents novel insights into plant drought response associated with PP2C regulatory module and provides substantial genetic resources for breeding drought-tolerant wheat cultivars.