In Silico Analysis of the MAPK Gene Family in Cabbage and Its Expression during Development and Stress Response

Cabbage is often affected by an adverse environment and pathogens during its growth, resulting in a decline in yield and quality. Mitogen-activated protein kinases (MAPKs) play crucial roles in the development process, hormones, abiotic and biotic stresses, and cell division. So far, MAPKs have been characterized in various species. However, no systematic analysis of the MAPK family in cabbage has been performed. A total of 24 <i>BoMAPK</i> genes were identified and renamed according to Arabidopsis homologs; they were unevenly distributed on nine chromosomes. According to the conserved domain and phylogenetic relationship, <i>BoMAPKs</i> were divided into four subgroups, of which three belonged to subgroup A, four to subgroup B, three to subgroup C, and fourteen to subgroup D, respectively. There were 13 segmental duplication events in the cabbage genome. The Ka/Ks ratios for duplicated gene pairs of the MAPK family were less than 0.2, indicating that these <i>BoMAPK</i> genes have undergone purification selection in evolution. There were various <i>cis</i>-acting elements associated with stress, hormones, and development found in the promoter regions of most <i>BoMAPK</i> genes. Transcriptome data showed a high expression of <i>BoMAPK3</i>, <i>BoMAPK4.1</i>, and <i>BoMAPK6.1</i> genes in various tissues. <i>BoMAPK17.2</i>, <i>BoMAPK20.1</i> and <i>BoMAPK20.2</i> were significantly induced by <i>Plasmodiophora brassicae</i>, as evidenced in the quantitative PCR (RT-qPCR) analysis, revealing their enormous potential to regulate stress response. RT-qPCR results showed how the transcriptional levels of <i>BoMAPK</i> genes varied substantially under abiotic stress at different time points. These analysis results provide a reference to further explore the function and evolution of <i>BoMAPK</i> genes in cabbage.