The Inheritance Of The Fertility Restoration For Cytoplasmic Male Sterility In Rice(Oryza Sativa L.)

The inheritance of fertility restoration of cytoplasmic male sterility (CMS) in rice and DNA marker based gene mapping for fertility restoration were undertaken, by using three test-cross populations of Xieqingzao A / (Xieqingzao BlMilyang 46)F6 , Xieqingzao A / (Zhenshan 97 B/Milyang 46)F6 and Zhenshan 97A1(Zhenshan 97B/Milyang 46)F6. Genes for the fertility restoration of dwarf-abortive CMS were mapped for the first time. Comparisons among the mapping results from the three populations were also made to study the influence of the genetic background on the fertility restoration, and to analyze the relationship of fertility restoration of the same restorer line Milyang 46 on different CMS. Segregation analyses indicated that the spikelet fertility behaved as a qualitative- quantitative trait in the three populations . It was also suggested that the fertility restoration was affected by the genetic background in the ways of variation on genes of minor effects and gene by gene interactions. A linkage map consisting of 95 RFLP and 20 SSLP markers was constructed from Xieqingzao BlMilyang 46 F6 recombinant inbred line (RJL) populations. It spanned for 1 572.a cM with a average distance of 15.57 between markers . Four main effect QTL for fertility restoration were detected in the test-cross population , including one major gene on chromosome 10, and 3 minor genes on chromosomes 1, 8 and 10, respectively. One additional QTL for spikelet fertility was detected on chromosome 3 , but its heterozygote had an effect for reducing the trait value. On comparison between QTL for spikelet fertility detected in Xieqingzao A / (Xieqingzao B / Milyang 46)F6 test-cross population and Xieqingzao B / Milyang 46 RIL population, it was shown that the additive effect of the paternal allele hardly contributed to the fertility restoration . All these results were in accordance with the phenomenon observed in the fertility segregation. Four main effect QTL for fertility restoration were detected in each of the populations Xieqingzao A / (Xieqingzao B / Milyang 46)F6 and Xieqingzao A / (Zhenshan 97 B / Milyang 46)F6. The major gene qRf-1O-2 was detected in both populations . Of the three minor genes, the two QTL having greater effects, qRf-1 and qRf-1O-1 , were also detected in both populations . Only the QTL displaying smallest effects among those detected in the same population were not detected in the other populations . This indicated that the fertility restoration genes having small effects were greatly affected by the genetic background. With the advance of the replacement of Xieqingzao B constitution in the populations by 4 Zhenshan 97B, the fertility restoration was gradually enhanced. In the test-cross population of Zhenshan 97A1(Zhenshan 97B/Milyang 46)F6, the major gene qRf-1 0-2 and the two minor genes of substantial effects (qRf-1 and qRf-1 0-]) were detected. No more main effect QTL were detected, but 4 significant digenic interactions were found. The epistatic QTL contributed 12.6% to the phenotype variation in the Zhenshan 97A1(Zhenshan 97B/Milyang 46)F6 population , which was much higher that the epistasis contribution of 1.8% in Xieqingzao A1(Xieqingzao BlMilyang 46)F6, and that of 3.9% in Xieqingzao AI(Zhenshan 97B/Milyang 46)F6. On conclusion, the influence of the genetic background on the fertility restoration, and the variation of fertility restoration of the same restorer line on different CMS were shown in...