Cloning and expression analysis of a pathogenesis-related protein gene BoPR2 from Brassica oleracea var. italica

Pathogenesis-related protein genes comprise a gene family in plants, and they play a key role in disease resistance. In this study, a gene designated BoPR2 was isolated from broccoli material using the PCR method. Sequencing results indicated that the full-length genomic DNA was 1 188 bp with an intron, and its coding sequence was 1 092 bp encoding 351 amino acids. Sequence comparison and phylogenetic analysis results showed that higher similarities were found between BoPR2 and PR2 proteins from Brassica oleracea var. oleracea and B. rapa subsp. chinensis, and they were clustered into the same clade. The lowest similarities were seen between BoPR2 and PR2s from both Camelina sativa and Capsella rubella, indicating their distinct relationships. Real-time quantitative PCR results revealed that the expression of BoPR2 gene was induced by Plasmodiophora brassicae, and the highest relative expression level was detected at 10 d after incubation with an approximately 6-fold increase. However, the expression of BoPR2 was not affected by Sclerotinia sclerotiorum. Isolation and expression analysis of BoPR2 provide evidence for further studies on disease resistance mechanism and broccoli molecular breeding.