Breeding of Elite CMS Lines by Reverse Nuclear Substitution

It was very difficult to specifically identify the maintainability of a plant line unless it is genetically stable and its whole nuclear genome has completely replaced in the CMS (cytoplasmic male sterile) line. To overcome this problem, a breeding method was proposed in this paper. The breeding procedure includes: (1) screening elite male sterile plants from segregating populations using male sterile cytoplasm as background selection; 2) getting genetically stable CMS lines via anther culture or parthenogenesis; (3) selecting target CMS lines with good combinability, restorability, outcrossing habit, grain quality and resistance to pests and diseases; (4) converting target CMS lines into maintainers by the following approaches: (a) to obtain fertile mutants of target CMS lines by further anther culture; (b) to make the target CMS line fertile by high temperature treatment at young panicle stage, then to select maintainers through screening their offspring, or through nuclear substitution using their offspring as male recurrent parent; (c) to irradiate to the obtain hybrids between CMS cells and radiated normal cells via protoplast fusion and screen fertile plants as new maintainers.