Creation of fertility-restored materials for Ogura CMS inBrassica oleraceaby introducingRfogene fromBrassica napusvia an allotriploid strategy

摘要

Key message Ogura CMS fertility-restored materials, with 18 chromosomes, normal seed setting, stable fertility and closer genetic background to the parent Chinese kale, were successfully developed inB. oleraceavia a triploid strategy for the first time. Ogura cytoplasmic male sterility (CMS) is the most widely used sterile type in seed production for commercial hybrids ofBrassica oleraceavegetables. However, the natural Ogura CMS restorer line has not been found inB. oleraceacrops. In this study, the triploid strategy was used with the aim to create euploidB. oleraceaprogenies with theRfogene. The allotriploid AAC hybrid YL2 was used as a male parent to backcross with Ogura CMS Chinese kale. After successive backcrosses, the BC(2)Rfo-positive individual 16CMSF2-11 and its BC(3)progenies, with 18 chromosomes, were developed, which were morphologically identical to the parent Chinese kale. Compared with F(1)and BC(1)plants, it showed stable fertility performance, and regular meiosis behavior and could produce seeds normally under natural pollination. The genomic composition analysis ofRfo-positive progenies by using molecular markers showed that more than 87% of the C-genome components of BC(3)Rfo-progenies recovered to the parent Chinese kale, while most or all of theA(n)-genome segments were lost in 16CMSF2-11 and its progenies. The results suggested that the genetic background ofRfo-positive individuals was closer to that of the parent Chinese kale along with backcrossing. Hereof, the Ogura CMS fertility-restored materials of Chinese kale were successfully created via triploid strategy for the first time, providing a bridge for utilizing the Ogura CMSB. oleraceagermplasm in the future. Moreover, our study indicates that the triploid strategy is effective for transferring genes fromB. napusintoB. oleracea.