A 252-bp insertion in BoCER1 is responsible for the glossy phenotype in cabbage (Brassica oleracea L. var. capitata)

Bright green of leaf head is an important characteristic in cabbage breeding. Wax-less cabbage shows glossy phenotype on leaf surface, which facilitates the brilliant green cabbage breeding. In this study, we identified a spontaneous glossy mutant g21-3 in cabbage. Genetic analyses showed that its glossy phenotype is controlled by a single recessive gene. Further analysis indicated that the glossy phenotype of g21-3 and a known glossy cabbage mutant 10Q-961 was controlled by a same locus. According to the fine-mapping of glossy-controlled gene in 10Q-961, BoCER1 was identified as a candidate gene which was found to be closely related to the glossy phenotype in g21-3. Sub-cellular localization showed that BoCER1 protein is localized to the endoplasmic reticulum. Sequence analysis revealed that a 252-bp insertion was included in the fourth intron of BoCER1 in g21-3, but not in the wild-type 21-3. The insertion significantly inhibited the expression of BoCER1. A marker designed to distinguish between the BoCER1 alleles in g21-3 and wild-type cabbage co-segregated perfectly with glossy/waxy phenotypes in backcross population, confirming that the insertion mutation of BoCER1 is responsible for the glossy phenotype. The allele-specific marker is effective for marker-assisted selection of the glossy cabbage.