Genetic Analysis And Mapping Of Fertility Restoring Genes For AL-type Male Sterility In Wheat

Wheat is one of the most significant food crops, being closely associated with national economy growth and the maintenance of social stableness. Utilization of heterosis is an effective means to provide crop yields. AL-type cytoplasmic male sterile line was one great potential sterility types of applications. Getting molecular markers tightly linked with the restorer genes, it can provide an effective method of molecular-assisted selection for the restorer lines. This study surveyed the fertility of F₂ segregating population?sterile line AL18 A × restorer line 99AR144-1? planted in different growth environment. Chi-square test,self-pollinated crops homozygote rate formula, quantitative plant traits major gene plus polygenes model test were conducted for genetic analysis of the fertility restorer genes. SSR molecular marker technology and software IciMapping3.2 were used to map major restorer gene of F₂ segregating populations planted in Yangling field and greenhouse. Meanwhile,illumina wheat 90 k SNP chips were adopted to detect the DNA samples which collected from sterile line AL18 A, restorer line 99AR144-1, sterile pool and fertile pool. Main results were as follows.1. Bagged seed-setting rate was taken as fertile indicator, and seed-setting rate 0% was setted as the threshold value to differentiate fertile plants and sterile plants. ?2 test on four F₂ populations indicated that the segregating-ratio between fertile plants and sterile plants in the hybrid population was 15:1, complied with genetic separation rule of two pairs of genes,and found that fertility restorer gene was also affected by minor genes influence from the frequency distribution. Self-pollinated crops homozygote rate formula was calculated F₂ segregating populations planted the field and greenhouse cultivation K value. The results of the samples for the test have shown that AL-type CMS was controlled by two major genes.2. Mix main gene and polygene inheritance model quantitative traits were adopted to analyse the single F₂ generation fertility of the four groups.Those results demonstrated that alternative models were B-1, B-5, B-6, which indicated fertile restorer genes were controlled by two pairs of major genes. The optimal model determined was two pairs of completelydominant major genes model in F₂ generations planted Yangling greenhouse and field, while,the optimal model ascertained was two pairs of peer dominant major gene model in Xinjiang field trials. Those revealed that optimal models merely differ in allele effects in different growth environment.3. In this study, 1480 pairs of SSR primers distributed on 21 pairs of chromosomes were screened between sterile line AL18 A and restorer line 99AR144-1, and the SSR markers Xgwm413 and Xbarc8 had polymorphic differences between the fertile pool and sterile pool as well as two parents. Seven chain groups marked by 25 SSR markers were established and combined with the F₂ individual fertility survey in Yangling greenhouse population. A QTL qRf1B-1 of restorer genes was determined on 1B chromosome short arm through composite interval mapping. The QTL was flanked by microsatellite markers Xgwm413 and Xbarc8,with genetic distance of 4.97 cM and 0cM,respectively, which was proved to be 3.14 of LOD value. It could explain 6.36% of the phenotypic variation, and show 6.36 additive effect,being certified from restorer line 99AR144-1. Seven chain groups marked by 14 SSR markers were established and combined with the F₂ individual fertility survey planted Yangling field.The QTL was temporarily named as qRf1B-2, locating on 1B chromosome short arm through composite interval mapping.The site was located between molecular markers Xgwm413 and Xbarc8 with genetic distance of 2cM and 0.85 cM,respectively, which was proved to be 3.14 of LOD value. It could explain 22.43% of the phenotypic variation, and indicate that it was a major gene showing 18.87 additive effect and being certified from restorer line 99AR144-1.Wheat 90 k SNP chip was used to detect parents, fertile and sterile pools. The results of polymorphism analysis revealed that 1B, 1A, 4B, 5A, 7B chromosomes hade more locus of difference, which pave the way for seeking another major gene.