Development and utilization of one new cytoplasmic male sterile line of Chinese leaf mustard (Brassica juncea var. rugosa Bailey)

Highlight
- The hau CMS was transferred to leaf mustard (Brassica juncea var. rugosa Bailey) for harvesting vegetative mass by hybridization and saturated back-crossing of 8 generations, and one new CMS line 0912A was developed.
- We evaluated the application prospect of the new sterile line 0912A comprehensively in terms of plant fertility, pollen activity, seed setting, cytological structure of anther development, and heterosis potential.
- The newly bred CMS line had a good promise in leaf mustard hybrid breeding.

A novel cytoplasmic male sterility (CMS) designated as hau CMS (00-6-102A) was identified in Brassica juncea previously. In present study, the hau CMS was transferred to leaf mustard (B. juncea var. rugosa Bailey) for harvesting vegetative mass by hybridization and saturated back-crossing of 8 generations and one new CMS line 0912A was developed. 0912A and its maintainer line 0912B showed similar phenotype, including leaf shape and color except stamen fertility, and they also had no significant difference on seed setting under open-pollination. The investigation of pollen fertility of the CMS line showed that its flowers without pollen grains were completely male sterile, and the seeds harvested following pollinations with the maintainer line 0912B gave rise to 100% sterile progeny. The dissection of anther development indicated that the anther abortion occurred at the early stage of stamen sporogonium differentiation, for no butterfly anthers appeared. The heterosis potential was tested for its F1 hybrids with five representative cultivars selected from 45 inbred lines, and the hybrids gave obvious heterosis for vegetative mass, especially the average HPH value of plant weight reached up to 15.20%. These results showed that the newly bred CMS line had a good promise in leaf mustard hybrid breeding.