水稻质核互作雄性不育系选育的反向杂交法研究

不同的部分保持系可能存在不同的微效恢复基因,通过有性杂交,产生基因重组,能够获得完全保持系类型,但只有在不育细胞质中才能观察得到微效恢复基因是否存在以及它们的作用大小.反向杂交法以不育细胞质为选择背景,在杂交后代植株中直接观察到微效恢复基因的表达,获得的完全不育株,在一定程度上排除微效恢复基因,不育株再通过高温处理转换为可育后自交,来自不育株的微效恢复基因可以进一步排除掉,从而产生出没有(或很少)微效恢复基因的"亲本",利用该"亲本"高温处理后仍可转换为可育的特性,作为父本进行杂交或回交育种,在其后代中获得没有微效恢复基因的完全保持系.该研究为Cp 26不育细胞质源创造出了完全保持系.如果在田间鉴定出优异的完全不育株,对其进行单倍体育种(诱导孤雌生殖或花培),选择到没有(或很少)微效恢复基因的纯合不育株.再对其进行花培,筛选可育的突变体;或者利用纯合不育株的原生质体与一个已破坏细胞核的可育系原生质体融合,都可能得到具有纯合不育株细胞核和可育细胞质的保持系,而能够完善和改进反向杂交法.反向杂交法不但能够为所谓不能保持的不育细胞质源创造出保持系,而且有利于加强新不育系选育的目标性和预见性,提高不育系配合力和培育不同类型优异不育系.

Breeding Techniques to Obtain Elite CMS Lines by Reverse Crossing

Elite maintainers of some CMS are difficult to obtain in rice or other crops. And there have been no precise methods to test maintainers, unless testers' chromosomes are all introduced into the male sterile cytoplasm. To overcome these difficulties, a new breeding method was studied in this program. Its breeding procedure includes: (a) screen elite male sterile plants from segregating populations of male sterile cytoplasm; (b) treat the elite CMS plants under high temperature at pollen developing stage to make their panicles fertile; (c) select male sterile offspring plants from fertile panicles, repeat the high temperature treatment and repeat the selection, until some plants having no minor fertility genes are obtained; (d) use those fertile panicles from male sterile offspring plants as male parent to pollinate a maintainer, repeat the process in next generations, until some plants of normal cytoplasm having no minor fertility genes are obtained; (e) screen elite maintainers of CMS from genetically stable plants of normal cytoplasm having no minor fertility genes. Based on the method, we obtained a complete maintainer (Cd-1 B) of Cp 26. Cp 26 is a new male sterile cytoplasm and had no complete maintainers before.In the future, to improve this method we may change the procedure as follows: (a) screen elite male sterile plants from segregating populations of male sterile cytoplasm, then get genetically stable CMS lines by anther culture or parthenogenesis inducing; (b) select target CMS lines by identifying CMS lines' combinability, outcrossing habit, restorability, quality and resistance to pests and diseases, etc. and identify its best hybrids; (c) transfer target CMS lines into maintainers: (1) test fertile mutations from target CMS lines by anther culture; (2) irradiate to protoplasts of a normal variety to destroy their nuclei, retain their normal cytoplasm; treat Corresponding author the protoplasts of target CMS lines with iodoacetamide, fuse the two kinds of protoplasts to form cybrid cells and screen fertile plants as maintainers.