Tang_2026_Theor.Appl.Genet_139_146

BrDAD1 encodes a phospholipase A1 family protein and was precisely localized using MutMap technology. Allelic mutations and functional complementation experiments using Arabidopsis T-DNA insertion mutants demonstrated that BrDAD1 regulates petal opening and anther dehiscence by controlling jasmonic acid synthesis in Chinese cabbage. Flower opening and anther dehiscence are crucial for the successful reproduction of cross-pollinated crops. The role of jasmonic acid (JA) in floral organ development and fertility regulation has been extensively documented. However, its function in Chinese cabbage (Brassica rapa L. ssp. pekinensis) remains poorly characterized. In this study, three mutant plants, M5068, M5036 and M5088, with defects in flower opening and anther dehiscence were screened from a Chinese cabbage ethyl methane sulfonate-induced mutation library. Through genetic analysis, allelic tests, and MutMap, we identified that these three mutants each harbored non-synonymous mutations at distinct sites within the BrDAD1 gene, which encodes a phospholipase A1 family protein critical for JA biosynthesis. The mutation led to a significant reduction in JA in the M5068 mutant. Notably, exogenous application of methyl jasmonate can completely restore the phenotype of M5068. In addition, overexpression of BrMYB108 rescued the delayed flower opening and impaired anther dehiscence phenotypes in dad1, which results from JA deficiency in Arabidopsis thaliana. Further evidence from yeast one-hybrid, dual-luciferase reporter, and electrophoretic mobility shift assays revealed that BrMYB108 regulates flower opening and anther dehiscence by activating the promoter activity of BrSWEET15. This study identifies a novel regulatory mechanism of JA in flower opening and anther dehiscence, providing new insights into molecular mechanisms underlying floral organ development in Chinese cabbage. It also offers new targets and strategies for the application of male sterile lines in hybrid breeding.