Genome-Wide Identification and Characterization of the ABA Receptor PYL Gene Family in Broomcorn Millet (Panicum miliaceum L.)

Pyrabactin resistance-like (PYL) proteins are core abscisic acid (ABA) receptors, but their organization and stress-responsive functions remain poorly understood in broomcorn millet (Panicum miliaceum L.). Here, we identified PmPYL genes genome-wide and characterized their phylogeny, gene structure, conserved motifs, chromosomal distribution, synteny, selection pressure, promoter cis-elements, predicted regulatory networks, tissue expression, and responses to ABA, salinity, and osmotic stress. Fifteen PmPYL genes were identified, with eight located in the A subgenome and seven in the B subgenome. Phylogenetic analysis placed 11 PmPYL proteins in Group II and four in Group III, with none in Group I. Sequence and structural analyses revealed broad conservation of receptor features associated with ABA perception and PP2C interaction. Collinearity analysis identified seven synteny-supported A/B homoeologous pairs, while the examined duplicate pairs showed low Ka/Ks ratios. Promoter analyses revealed abundant hormone- and stress-responsive elements, while predicted protein interactions supported a conserved PYL–PP2C–SnRK2 signaling module. Pairwise promoter and tissue-expression comparisons indicated regulatory variation among retained homoeologs. qRT-PCR analysis of seedling leaves further showed distinct treatment- and time-dependent expression patterns, with PmPYL10, PmPYL8, and PmPYL12 showing pronounced changes under the examined conditions. These findings reveal a conserved ABA receptor framework with substantial regulatory diversification and identify candidate PmPYL genes for functional analysis of stress adaptation in broomcorn millet.