Exploitation of novel cytoplasmic male sterility(CMS)is a main approach for widening the cytoplasmic genetic background of hybrid oilseed rape and avoiding epidemic risk in oilseed rape production.In this study,symmetric somatic hybrids between Brassicanapus var.Zhongshuang4 and Sinapis arvensis(Yeyou18)were produced by protoplast fusion.Two of the six established hybrids were male sterile showing trace or no pollen release upon flowering with non-or slightly extended stamens.Using Zhongshuang4 as a recurrent parent to pollinate the male sterile plants,the ratio of male sterile plants increased with the number of backcrosses.As early as in BC3 generation,most of the sterile families had nearly 100%sterile plants.Up to BC4 generation,the male sterility became stable and no fertility segregation was observed.All F1 progenies from tested crosses using restorer and maintainer lines of Polima CMS were 100%sterile,indicating that the established CMS by somatic hybridization is different from Polima CMS.The origin of the cytoplasm and potential use of this hovel CMS in oilseed rape breeding were discussed.Key wotds:Oilseed rape,Protoplast fusion,Cytoplasmic male sterility,Sinapis arvensis