Bioinformatic identification of phosphoenolpyruvate carboxylase (PEPC) gene family in Brassica napus

Phosphoenolpyruvate carboxylase (PEPC) gene family is essential in regulating plant growth and abiotic stress response. Based on the sequenced Brassica napus genomes, a comprehensive analysis of PEPC homolog genes identified 15 in B. napus. These genes were categorized into four subgroups: PTBC-II, PTPC-III, PTPC-IV, and PTPC-V; genes in each subgroup displayed conserved gene structures and motifs. Segmental duplication and whole genome duplication (WGD) events yielded the expansion of PEPC genes. Expression assays showed that the duplicated PEPC genes displayed diverse expression patterns, indicating that they experienced functional divergence. Cis-elements and expression analyses revealed that BnaPEPC homologs might respond to abiotic stresses. The expression of a few BnaPEPC genes (BnaPEPC2, BnaPEPC4, BnaPEPC6, BnaPEPC9) was induced in response to IAA, ABA, JA, and GA in leaf while in root BnaPEPC6 and BnaPEPC9 was significantly responsive to all applied hormone stresses. BnaPEPC2, BnaPEPC4, BnaPEPC6, BnaPEPC9, and BnaPEPC10 showed significant responses to cold, heat, drought, and salinity in leaf tissues, while BnaPEPC1, BnaPEPC2, BnaPEPC6, and BnaPEPC9 exhibited highest expression levels in root tissues under cold, heat, drought, and salt stress. The present study provides new information to decipher the evolution and function of PEPC genes in B. napus.