Identification and breeding exploitation of dBrGMSP related to early bolting in Brassica rapa

Bolting is an important agronomic trait for stalk type of vegetable crops. Early bolting is a favorable characteristic for stalk type of Chinese cabbage variety, which has the advantage of early market supply. In the present study, we screened an EMS-mutagenized Chinese cabbage population and isolated a dominant gain-of-function early bolting mutant ebm16 which exhibited remarkable earlier bolting trait than its WT. BrGMSP, encoding a galactose mutarotase-like superfamily protein, was identified as the candidate gene via MutMap and KASP analysis. A C-T mutation existed in exon of BrGMSP in ebm16. Both transient overexpression in the WT and stable transgenic overexpression in Arabidopsis thaliana for the mutated gene dBrGMSP verified the function of BrGMSP in regulating early bolting. BrGMSP was localized in the nucleus. LCA proved that BrGMSP could interact with BrPGM1 controlling photosynthetic carbon flow. VIGS verified that BrPGM1 had the function on promoting bolting in Chinese cabbage. It was proved that dBrGMSP could be applied in breeding for stalk type of Chinese cabbage.