Development of New Type of CMS Source from Dongxiang Wild Rice (Oryza rufipogon)

This study was conducted to develop and characterize a novel new cytoplasmic male sterile (CMS) source which was identified from Dongxiang wild rice by crossing Dongxiang wild rice as female with Zhongzao 35, an indica inbred variety, as male and continuous backcrosses with Zhongzao 35. Observation under optical microscope manifested that this novel CMS belongs to typical abortion type with fewer number of pollens compared with CMS-WA. Sequential planting showed that this novel CMS has complete and stable male sterility. Testcross experiment showed that all the 24 testers including B and R lines of CMS-WA and CMS-HL and other indica inbred varieties are the maintainers with complete maintaining ability, suggesting that this novel CMS has fertility restoration totally different from CMS-WA and CMS-HL and belongs to a novel type of CMS. So far, we only discovered a unique fertility restoration source for this novel CMS. Inheritance analysis showed that the fertility restoration for this CMS showed that it was governed by three pairs of independent dominant genes, which is the first report that fertility restoration in CMS rice is controlled by three pairs of independent dominant genes. Prospect for use of this novel CMS system in hybrid rice breeding was also discussed.