Deciphering ABA Receptor PYL Gene Family in Sugar Beet: Evolutionary Analysis and Drought Stress Response

Abscisic acid (ABA) receptors (PYL) play a pivotal role in plant responses to abiotic stress. However, functional characterization of PYL genes in sugar beet response to stresses remains unexplored. Here, 11 BvPYL genes were identified in the sugar beet genome, and they were classified into three subgroups. A comprehensive analysis of their gene structures, sequence features, chromosomal distributions, and promoter cis-elements was conducted. Furthermore, their evolutionary relationships, predicted interaction networks, and expression patterns under drought stress were investigated. qRT-PCR and transcriptomics data revealed expression profiles of the BvPYL family from two perspectives: short-term response and long-term adaptation to drought. Most BvPYL members were up-regulated under both conditions. Subcellular localization analysis showed that BvPYL8 is nuclear-localized. Protein interaction screening and molecular docking predicted that BvPYL8 interacts with multiple PP2C proteins (e.g., PP2C8, PP2C24, PP2C37, PP2C50, PP2C51 and PP2C56) through hydrogen bonding with a key asparagine residue (ASN-148), and their interaction was experimentally verified using the Y2H and BiFC assay. A molecular mechanism for the BvPYL8-PP2Cs-BvSnRK2s-TFs pathway in the ABA signaling pathway under drought stress was proposed. These results may serve as a springboard for further functional exploration of the BvPYL gene family in sugar beet and its related species, and provide important target genes for improving crop drought tolerance through genetic engineering and molecular breeding.