Genome-Wide Identification and Expression Profiling of PYL Genes in Brassica napus Under ABA and Drought-Stress Treatments

Brassica napus L. is a major oilseed crop whose productivity is significantly affected by abiotic stresses such as drought. PYR/PYL/RCAR (PYL) proteins act as key abscisic acid (ABA) receptors and play central roles in stress responses. However, a comprehensive genome-wide analysis of the PYL gene family in B. napus is still lacking, limiting our understanding of their functions in plant and stress adaptation. This study reports the first comprehensive genome-wide analysis of the PYL gene family in B. napus (rapeseed), cultivar ZS11, identifying 25 BnPYL genes grouped into four subfamilies, I (four genes), I-II (five genes), II (five genes), III (11 genes), and their encoded proteins were predicted to be mainly localized in the chloroplast. Structural analysis revealed diverse exon–intron organization and 10 conserved motifs. All identified BnPYLs contained Polyketide_cyc2 domains (PF10604), supporting their annotation as members of the PYL family. Promoter analysis identified cis-regulatory elements related to light response, stress regulation, and hormonal signaling. Computational analysis of post-translational modifications suggested that phosphorylation sites are mainly localized at serine and threonine residues. Tertiary structure modelling revealed conserved three-dimensional architectures among BnPYL proteins, suggesting potential functional conservation. Expression profiling and RT-qPCR analyses revealed that several BnPYL genes respond to ABA-mediated drought stress, with BnPYL15 and BnPYL22 exhibiting the highest induction (4–5-fold) and BnPYL2, BnPYL5, BnPYL6, BnPYL17, BnPYL18, and BnPYL25 showing significant upregulation (2.0–4.5-fold), suggesting potential roles in enhancing drought tolerance in B. napus.