The Brassica ‐specific gene MS5 mediates early meiotic progression, and its allelic variants contribute to a valuable genic male sterility three‐line hybrid production system in rapeseed (Brassica napus L.). However, the underlying mechanisms of its triallelic inheritance are poorly understood. Herein, we show that the restorer allele MS5a and the maintainer allele MS5c, are both necessary for male fertility in Brassica napus . The functional divergence of the MS5a and MS5c is strongly related to the sequence variations in their coding region and less strongly to their promoter regions. The male‐sterile allele MS5b encodes a chimeric protein containing only the complete MS5 coiled coil (CC) domain, having lost the MS5 superfamily domain. Both MS5a and MS5c can form homodimers in the nucleus via the CC domain. MS5b can competitively interact with MS5a or MS5c to form nonfunctional heterodimers. Owing to the close transcript levels of the MS5b and MS5c in the MS5bMS5c , these heterodimers induced a dominant‐negative effect of MS5b on the MS5c, resulting in a male‐sterile phenotype. The extremely high transcript abundance of the MS5a maintains sufficient MS5a homodimers in the MS5aMS5b , causing the recovery of the male sterility. These findings provide substantial genetic and molecular evidence to improve our understanding of the mechanisms underlying the multiallelic inheritance of MS5 , and enable the construction of a solid foundation for the improved use of the MS5 ‐controlled GMS system in Brassica species.

全文链接：https://onlinelibrary.wiley.com/doi/10.1111/tpj.14857