The utilization of heterosis is a crucial way for oilseed rape breeding. Male-sterile mutants provide useful pollination control method in hybrid production. However, the molecular mechanism of male sterility in oilseed rape remains elusive.

Yi3A is a spontaneous male sterile mutant found in Brassica napus in the 1970s, and has been well used as a male sterile line for hybrid reproduction. The male sterility of Yi3A is controlled by a multiallelic gene, MS5, with three different alleles, MS5^b being the male-sterile allele, MS5^a being the fertility restorer allele, and MS5^c being the maintainer allele.

The researchers from CHENG Zhukuan’s lab at the Institute of Genetics and Developmental Biology of Chinese Academy of Sciences, collaborating with YANG Guangsheng’s lab at Huazhong Agricultural University, found that MS5 participates in the progression of meiosis during early prophase I and regulates gametogenesis in Brassica napus.

MS5 is preferentially expressed in reproductive organs and encodes a Brassica-specific protein with unknown function. MS5 has the richest transcript and protein abundance in MS5^aMS5^a and a medium-low accumulation in MS5^cMS5^c, while it has an extremely low expression level in MS5^bMS5^b. Thus, the fertility transition regulated by different alleles of MS5 depends on their significant differences in protein levels, which provides a promising strategy for pollination control for heterosis breeding.

This study entitled “MS5 mediates early meiotic progression and its natural variants may have applications for hybrid production in Brassica napus” was published in The Plant Cell. It was supported by the National Natural Science Foundation of China.

Figure 1: Fertility performances of plants with different MS5 alleles (Image by XIN Qiang et al.)

Figure 2: Meiosis Progression is arrested in MS5^bMS5^b pollen mother cells. (Image by XIN Qiang et al.)