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Abstract

Phosphorus (P) starvation severely limits the growth and yield of rapeseed (Brassica napus). The ATP-binding cassette B subfamily (ABCB), also known as P-glycoproteins (PGPs), is widely involved in auxin transport and plant abiotic stress responses; however, their role in rapeseed response to low-P stress remains unclear. To our knowledge, the present study is the first comprehensive genome-wide analysis of the ABCB/PGP transporter subfamily in B. napus, providing novel insights into their structural diversity, evolutionary expansion, and potential roles in phosphorus starvation responses. In this study, 48 BnaPGP genes with conserved ABCB domains were identified and phylogenetically categorized into five major clades, each exhibiting conserved intron–exon structures and motif composition. Chromosomal localization analysis revealed that BnaPGP genes are unevenly distributed across 19 chromosomes and exhibit extensive segmental duplication events, suggesting that the expansion of this gene family occurred via gene duplication. Collinearity analysis revealed that the BnaPGP genes in rapeseed and Arabidopsis shared higher homology than those in B. rapa and B. oleracea. Promoter cis-regulatory element analysis revealed that members of this family possess multiple regulatory elements related to hormone and stress responses. Expression profiling under phosphorus deficiency revealed that multiple BnaPGP genes were significantly upregulated in roots, suggesting their potential involvement in root structural remodeling and phosphorus acquisition. Our study provides a foundation and genetic resources for subsequent functional validation and molecular breeding of high-P-efficient rapeseed varieties

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