Whole-Genome Identification and Expression Pattern of the Vicinal Oxygen Chelate Family in Rapeseed (Brassica napus L.)

Abstract

Vicinal oxygen chelate proteins (VOC) are members of the metalloenzyme superfamily, which plays roles in many biological reactions. Some members of the VOC superfamily have been systematically characterized but not in <i>Brassica napus</i>. In this study, 38 <i>VOC</i> genes were identified based on their conserved domains. The present results revealed that most of the <i>BnaVOC</i> genes have few introns, and all contained the typical VOC structure of βαβββ modules. The <i>BnaVOC</i> genes are distributed unevenly across 15 chromosomes in <i>B. napus</i> and occur as gene clusters on chromosomes C5 and A6. The synteny and phylogenetic analyses revealed that the <i>VOC</i> gene family is a consequence of mesopolyploidy events that occurred in <i>Brassica</i> evolution, and whole-genome duplication and segmental duplication played a major role in the expansion of the <i>BnaVOC</i> gene family. The expression profile analysis indicated that the expression of most <i>BnaVOC</i>s was increased in the leaves and late stage seeds. Further results indicated that seeds of <i>B. napus</i> with a high oil content show higher expression levels under drought stress conditions, suggesting that BnaVOCs not only respond to abiotic stress but may also affect lipid metabolism in drought stress. This present study provides a comprehensive overview of the <i>VOC</i> gene family and provides new insights into their biological function in <i>B. napus</i> evolution.