Genome-Wide Identification and Expression Profiling of Sugar Transporter Protein (STP) Family Genes in Cabbage (Brassica oleracea var. capitata L.) Reveals their Involvement in Clubroot Disease Responses.

Sugar transporter protein () genes are involved in multiple biological processes, such as plant responses to various stresses. However, systematic analysis and functional information of family genes in are very limited. A comprehensive analysis was carried out to identify genes and dissect their phylogenetic relationships and to investigate the expression profiles in different organs and in response to the clubroot disease. A total of 22 genes were identified in the genome and they were further classified into four clades based on the phylogenetic analysis. All the BoSTP proteins harbored the conserved sugar transporter (Sugar_tr, PF00083) domain, and the majority of them contained 12 transmembrane helices (TMHs). Rates of synonymous substitution in relative to indicated that genes of diverged from those of approximately 16.3 million years ago. Expression profiles of the genes in different organs derived from RNA-Seq data indicated that a large number of the genes were expressed in specific organs. Additionally, the expression of and genes were induced in roots of the clubroot-susceptible cabbage (CS-JF1) at 28 days after inoculation with , compared with mock-inoculated plants. We speculated that the two BoSTPs might be involved in monosaccharide unloading and carbon partitioning associated with colonization in CS-JF1. Subcellular localization analysis indicated that the two BoSTP proteins were localized in the cell membrane. This study provides insights into the evolution and potential functions of .