Fine Mapping And Candidate Gene Analysis Of BoGL-3 Gene Conferring Dominant Wax-less Trait In Cabbage

Cabbage?Brassica oleracea L.var.capitata L.?,belonging to Brassica of Cruciferous,is an important cultivated vegetable which contains a lot of nutrients and has strong environmental adaptability.Bright green of leaf head is an important characteristic in cabbage breeding.Wax-less cabbage shows glossy phenotype on leaf surface,which displays good economic characteristics.The study of waxy-less mutants is of great significance for understanding the regulatory pathway of wax synthesis and the innovation of bright green cabbage germplasm.In this study,the dominant wax-less gene BoGL-3 was fine mapped and the candidate genes in the mapped region were analyzed in mutant cgl-3.The main results in this research are as follow:1.Six generation populations were constructed through cgl-3 and Chinese Kale DH lines 939.All the individuals in F₁and BC₁P₁population show the wax-less phenotype.In F₂and BC₁P₂population,the ratio of glossy to waxy plants was confirmed to be 3:1 and 1:1 by the Chi-square test.The results showed that the wax-less phenotype in cabbage mutant cgl-3 is controlled by one single dominant gene.2.Polymorphic markers were screened from these primers by BSA method.F₂recessive plants were used in the fine mapping of wax-less gene BoGL-3 and the result showed that all the markers were located on the same side of the target gene.The genetic distance between the nearest molecular marker and the target gene was 0.2 cM,The wax-less gene BoGL-3 was mapped in the region of 83kb at the end of chromosome 8.3.After Illumina sequencing of mRNA from cgl-3 and wild type,a total of 8340 GEGs were obtained,of which 3187 DEGs were significantly up-regulated and 5153DEGs were significantly down-regulated in cgl-3.These DEGs are mainly involved in biosynthesis of secondary metabolites,synthesis and degradation of ketone bodies,glucosinolate biosynthesis,wax biosynthesis and and so on.In the candidate region,Bo8g118320 was homologous to wax-related gene CER1 in Arabidopsis,which was down-regulated in mutant.Thus Bo8g118320 was identified as candidate gene of BoGL-3.4.Bioinformatics analysis of protein sequence revealed that the target protein is a membrane protein in endoplasmic reticulum.The results of qPCR showed that expression of Bo8g118320 in cgl-3was significantly inhibited,but the nucleotide sequence of the gene and itspromoter region did not change significantly.We speculated that BoGL-3 may inhibit the synthesis of wax by inhibiting the expression of Bo8g118320.