Myosin‐binding protein 13 mediates primary seed dormancy via abscisic acid biosynthesis and signaling in Arabidopsis

SUMMARY Dormancy is an essential characteristic that enables seeds to survive in unfavorable conditions while germinating when conditions are favorable. Myosin‐binding proteins (MyoBs) assist in the movement of organelles along actin microfilaments by attaching to both organelles and myosins. In contrast to studies on yeast and metazoans, research on plant MyoBs is still in its early stages and primarily focuses on tip‐growing cells. In this study, we found that Arabidopsis MyoB13 is highly expressed in dry mature seeds. The myob13 mutant, created using CRISPR/Cas9, exhibits a preharvest sprouting phenotype, which can be mitigated by after‐ripening treatment, indicating that MyoB13 plays a positive role in primary seed dormancy. Furthermore, we show that MyoB13 negatively regulates ABA biosynthesis and signaling pathways. Notably, the expression of MyoB13 orthologs from maize and soybean can completely restore the phenotype of the Arabidopsis myob13 mutant, suggesting that the function of MyoB13 in ABA‐induced seed dormancy is evolutionarily conserved. Therefore, the functional characterization of MyoB13 offers an additional genetic resource to help prevent vivipary in crop species. Significance Statement Our research indicates that MyoB13, a myosin‐binding protein, plays a positive role in the regulation of primary seed dormancy in Arabidopsis. Additionally, orthologues of MyoB13 from maize and soybean exhibit analogous functions. Furthermore, the results demonstrate that MyoB13 negatively influences abscisic acid (ABA) biosynthesis and signaling pathways. This study represents the first instance of establishing a connection between MyoB proteins and the seed germination process.