A glycogen synthase kinase-3 gene enhances grain yield heterosis in semi-dwarf rapeseed

Optimizing plant height is a key breeding objective in Brassica napus to enhance lodging resistance and increase yield potential. In the present study, we identified a semi-dwarf gene in rapeseed, BnDWARF5 (BnDF5), which encodes a glycogen synthase kinase 3, BRASSINOSTEROID-INSENSITIVE 2 (BnaC03.BIN2), primarily controlling the elongation of basal internodes by inhibiting the elongation of internode cells. Genetic mapping and cloning revealed that BnDF5 is governed by a semi-dominant/dominant gene located on chromosome C03. Sequencing uncovered an SNP in BnaC03.BIN2 due to an amino acid substitution, which was confirmed via kompetitive allele-specific polymerase chain reaction marker analysis, and expressing the mutated BnaC03.BIN2 in the wild type resulted in decreased plant height. Practical breeding applications showed that heterozygous BnDF5 plants exhibited optimal intermediate height and strong yield heterosis, making the semi-dwarf mutant a valuable genetic resource for developing semi-dwarf rapeseed varieties with improved lodging resistance and yield.