Expression, divergence and evolution of the caleosin gene family in Brassica rapa

Abstract

Caleosins (CLO) are oil body-associated proteins encoded by a small gene family. To investigate the expression, functional diversity and evolutionary modes of CLO genes, we isolated and integrally analyzed in silico a total of 11 CLO genes from Brassica rapa. According to phylogeny and sequence analyses, 11 BrCLO genes were classified into 3 groups, and each group shared highly conserved sequence features. Syntenic analysis revealed that all members of the BrCLO gene family distributed on 7 chromosomes were expanded mainly by segmental duplications. Evolutionary analysis showed that CLO proteins were controlled by purifying selection in B. rapa. Interestingly, functional divergence studies indicated that site-specific relaxed functional constraints were present between the different clusters of caleosins. Expression pattern suggested that 6 BrCLO genes were potentially associated with oil body formation. Our findings provide valuable clues for an investigation of the evolutionary history and cellular functions of the CLO gene family in plants.

Keywords

• Brassica rapa
• caleosin
• functional divergence
• evolution
• expression