Basic Study On Genetic Improvement Of Restoring Lines To Nian-Type Cytoplasmic Male Sterility

Heterosis is a universal phenomenon in living nature. Wheat, like other crops, has obvious competitive advantage since suitable hybridized combination is made up. But the heterosis of wheat is not utilized extensively after more than 40 years'research activities. At present, the restrictions on the promotion of hybrid wheat into practice are: (1) The cost of hybrid seed made by CHA is too high to exhibit it's competitive advantage. (2) There are still difficulties in the selection of restorer to NIAN-CMS. In order to combine the two ways'advantages, this paper conducted in-depth research on the restoring mechanisms of NIAN-CMS and pyramid effects of restoring genes. NILs with the same cytoplasm and similar genetic background as the NIAN-CMS (k)-5-1 were created by backcross and used in SSR analysis of restoring gene. The main results obtained were as follows:1. Fertility data of B₁, B₂ and F₁ populations derived from cross between male sterility line (k)-5-1 and restoring line 5253 were adopted to investigate the inheritance of fertility restoration. Through mixed major gene plus polygene inheritance model analysis, the results showed that, fertility restoration was controlled by 1 major gene. It's heritability in B2 was 73.27%. Polygene was also detected. It's heritability in B2 was 21.03%.2. The study on the pyramid effects of restoring genes showed that different combination or pyramid generation of restoring lines held restoring capacity in diversity. 5906, WN9888, V1 and Xichun 2 had higher middle seed setting rates. Pyramid effects of such varieties were better than others. WN9888 and 5451 had better complementary on restoring gene sites. It would be much possible to obtain fine restoring lines from this combination. The results indicated that, pyramiding high middle seed setting rate character to restoring lines was one effective way to improve restoring capacity (IM), solve the current difficulties in breeding restoring lines, and promote the utilization of NIAN-CMS in hybrid wheat practice.3. In Vitro germination liquid medium and system for wheat were established. In Vitro germination rate was used as an index for wheat fertility during the creation of NILs of restoring gene. A series of BC4F1 were obtained through backcross in greenhouse.4. Primers of 18 SSR located on chromosome 1BS were adopted to analysis restoring gene in BC4F1. The results showed that genetic backgrounds of the BC4F1were similar to (k)-5-1. Three SSR(barc8,gwm18,gwm11)diversity existed in fertile BC4F1 and (k)-5-1. They were speculated to be relative to restoring gene.