Genetic Analysis For Inter-subspecific Hybrids Sterility In Rice (Oryza Sativa L.)

Partial spikelet and pollen sterility were detected in hybrid progeny derived from wide compatibility variety, N22, containing neutral alleles of 5-5, 5-7, S-8, S-15 and S-16, and USSR5 (a japonica variety). In this study, Two molecular linkage maps were constructed with BC1F1 population and F2 population, derived from USSR5/N22/AJSSR5 and USSR5/N22. With the two maps, QTL analysis for spikelet and pollen sterility were performed.BC1F1 population and F2 population derived from USSR5/N22//USSR5 and USSR5/N22 respectively were used to construct molecular linkage maps, and QTL mapping and analysis of spikelet and pollen sterility were performed. The results as follow:1. Construction of molecular linkage mapA molecular map comprised of 101 markers was constructed using BC1F1 population containing 97 individuals derived from USSR5/N22//USSR5, covering 1560.5cM on all chromosomes with an average 15.5cM, another map comprised of 103 markers was constructed using F2 population containing 189 individuals derived from USSR5/N22, covering 1921.0cM on all chromosomes with an average 18.7cM.2. Detection of distorted segregation in the linkage mapAnalysis genotype frequency of SSR markers was conducted based on molecular linkage map, to detect distorted segregation. The results show that:42 markers and 32 markers fell into distorted segregation in BCiFi and F2 population respectively. The former were distributed on all chromosomes, with harboring region on 1,2, 3, 6, 7 and 12; and the latter were distributed on all chromosomes except 5, with harboring region on 1, 3 and 10 chromosome.3. Mapping of QTL controlling hybrid pollen and spikelet sterility between indica and japonicaBased on the molecular linkage maps constructed, QTL controlling hybrid pollen andspikelet sterility were detected using software MAPMAKER/QTL 1.1. The results indicated:(1) Detection of QTL for hybrid spikelet sterilityThree putative QTL (qSS-1, qSS-2 and qSS-7) linked to marker RM490 on chromosome 1, RM341 on chromosome 2 and RM1335 on chromosome 7 were detected in BCiFi population respectively, with variation explained 22.5%. 36.2% and 19.1% by each. Likewise, Two putative QTL (qSS-1 and qSS-5) linked to marker RM490 on chromosome 1 and RM169 on chromosome 5 were detected in F2 population, with variation explained 48.2% and 6.1% by each.(2) Detection of QTL for hybrid pollen sterilityTwo putative QTL (qSS-1 and qSS-10) linked to marker RM490 on chromosome 1 and RM467 on chromosome 10 were detected in F2 population respectively, with variation explained was 7.6% and 11.5% by each.4. Relation between spikelet fertility and pollen fertilityCoefficient between spikelet fertility and pollen fertility in BC1F1 population was low (0.27), but significant at 0.05, while that (0.26) in F2 population was significant at 0.01.By comparison, mutual QTL linked to RM490 on chromosome 1 was detected controlling pollen sterility and spikelet sterility simultaneously.