Pan-genomic analysis and abiotic stress expression of eight TPS gene families in Brassica napus

TPS transcription factors play crucial roles in plant growth, development, and responses to abiotic stress. In this study, we identified 90 BnTPS genes across the Brassica napus pan-genome comprising eight high-quality genomes, including 11 core, 2 near-core, 6 non-essential, and 3 private genes. Ka/Ks analysis revealed that BnTPS38, BnTPS41, and particularly BnTPS20 (frequently > 1), along with BnTPS19 (up to 11.38), showed strong signals of positive selection, suggesting adaptation during domestication. In contrast, BnTPS14 and BnTPS16 consistently exhibited Ka/Ks < 1, indicating purifying selection. Notably, BnTPS41 displayed moderate exon SNP variation causing missense mutations in the Gangan and Shengli cultivars, which correlated with distinct expression profiles. Expression analyses under different sowing stages and abiotic stresses showed that BnTPS17 and BnTPS45 maintained high expression in leaves across most stages and stresses except freezing, while BnTPS16 from the TPS-e subfamily was highly expressed in leaves and roots under stress and during various sowing stages (except in No2127). These findings deepen our understanding of the evolutionary dynamics and functional diversity of BnTPS genes and provide candidate genes for future genetic improvement of B. napus.