Construction And Gene Effect Analysis Of The Near-isogenic Lines (NILs) Of Fertility Restorer Genes For Wheat Male Sterile Line With Ae.kotschyi Cytoplasm

Wheat male sterile line with Ae.kotschyi cytoplasm has the best potential application and was controlled by two pairs of major fertility restorer genes. The effect analysis of the two restorer genes is helpful to select good restoring lines and develop hybrid wheat varieties. The population was constructed using sterile line Yumai 3 with Ae.kotschyi cytoplasm which don't induced haploid, maintainer line Yumai 3 and restorer line Yumai 2 which have two pairs of major restorer genes. The gene effect analysis of the near-isogenic lines (NILs) of fertility restorer genes for wheat male sterile line with Ae.kotschyi cytoplasm was conducted by marker assistant selection with backcross breeding instead of conventional breeding. The results showed as follows:1. The breeding program of marker assistant selection combining with conventional backcross breeding method was adopted. The sterile line was used as recurrent parent and the restorer line Yumai 2 as non-recurrent parent. The NILs population was constructed by Yumai 3 crossing with Yumai 2, then backcrossing four times and selfing once. Fertility segregation in backcross populations and 10 flanking markers were used to select for the two restorer genes. The combination of phenotypic selection and SSR markers, polymorphism between Yumai 2 and Yumai 3, were used to select for the genetic background of Yumai 3. In BC1F1 and BC2F1 populations, the selection was carried by phenotypic difference and agronomic traits of Yumai 3. In BC3F1 population, the foreground and agronomic characters selection were used, and then the background selection was screened by SSR markers. The BC4F1 and BC4F2 populations were screened by MAS method for foreground and background selection.2. The 3 populations of Yumai 2 NILs were obtained. Of which the 2 NILs populations contained restoring gene Rfk1 on chromosome 1B and Rfk2 on chromosome 2B with Yumai 2 gene pool. The other NILs population has both two restorer genes of Rfk1 and Rfk2. In generation BC4F1, the plants only with Rfk1 on 1B were H-3-1-3-2,H-12-2-4-1,H-15-2-26-4,H-17-2-11-1 and H-17-4-24-3, and the plants H-1-2-13-2,H-6-1-3-2,H-6-1-19-4,H-2-1-8-2 and H-17-4-8-3 only contained Rfk2 on 2B. Meanwhile, the plants H-7-1-10-5,H-17-3-3-3,H-17-4-8-2 and H-17-4-8-5 contained both restorer genes Rfk1 and Rfk2. The NILs populations can constructed that contained 1 pair and two pairs of restorer genes respectively with the plants mentioned above by selfing.3. The restorating degree of each restoring genes in different backcross generations indicated that the Rfk1 in 1B chromosome had the stronger restoring ability than Rfk2 in 2B chromosome. There were cumulative effects between the two pairs of restoring genes. The restoring ability of all the restoring genes were enhanced with the increase of backcross generation, which indicated that maybe there were minor gene that inhibited fertility restoration in Yumai 2 background or there were minor gene in Yumai 3 background that promote fertility restoration.