[RFLP analysis on wide compatibility genes in rice variety dular of ecotype aus]

Dular is one of the typical wide compatibility varieties in ecotype Aus of rice. Genetic analysis on wide compatibility genes (WCG) from Dular based on triple crosses (indica//++Dular/japonica) was conducted. In the condition of being shaded for 7 days, the individual spikelet fertility segregated obviously, and the continuous distributions of spikelet fertility with a handful of peaks were observed. This suggested that the segregation of spikelet fertility in triple cross populations was controlled by one or more major genes, also modified by some minor genes. Based on 109 individuals of triple cross Nanjing 11 (indica)//++Dular/2533(japonica, a marker gene line, Rc and g), fertile and semisterile pools were set up by bulked segregant analysis, the RFLP analysis of the two pools led to the discovery of three chromosomal segments co-segregating with fertility. The one is on the interval RG213-C235 on chromosome 6. According to the previous studies, it may be the wide compatibility gene S5n. The other two were on the interval RG901-RG413 and G402-RG651 on chromosome 12, temporarily designated as Sd1(t)n and Sd2(t)n, respectively. Because of the continuous distribution for spikelet fertility, we also used a quantitative model to evaluate the effects of those three loci. On the basis of interval analysis with Mapmaker/QTL, 32.3% of the phenotypic variance associated with spikelet fertility was explained by the S5n (LOD = 9.03), and the other two chromosomal segments were responsible for 10.5%(LOD = 2.61) and 10.9%(LOD = 2.14) phenotypic variance, respectively. The results demonstrated that the wide compatibility variety Dular contained three WCGs. To introgress the three WCGs into a restorer line or an abortive line will overcome the hybrid sterility barrier of indica/japonica crosses, and the precise RFLP mapping will be useful for breeders to accumulate a few genes of interest into one cultivar by means of molecular marker assisted selection.