Genetic Dissection Of S₁, A Hybrid Sterility Locus, And Detecting Allelic Variation Of Agronomy-Related Traits Between Oryza Sativa L. And Oryza Glaberrima Steud

Identification, cloning, and functional analysis of genes related to rice development is the base to purposefully pyramid and scheme originally and functionally different genes for development of better varieties. Relatives of Oryza sativa are usually inferior in their phenotype but they bear positive alleles for genetic improvement. O. glaberrima, another cultivated species in genus Oryza, has been cultivatied for more than3500years in West Africa, and it is poor potential in yield. It is difficult to raise genetic populations to conduct further investigations because of severe reproductive barriers, especially hybrid sterility between O. sativa and O. glaberrima, which result in rare researches conferring alleles mining from O. glaberrima.S1, on the short arm of chromosome6, is a hybrid sterility locus between O. sativa and O. glaberrima. In this study, Accessions of O. glaberrima were used to raise advanced backcrossed populations, and fifteen BC7F1, one BC3F2populatons were used to dissected genetic base of the S1.1) S1was a ubiquitous hybrid sterility locus between O. sativa and O. glaberrima;2) It induced both male and female gamete abortion, and responded to typical and spherical, or emptive pollen abortion.3) Both male and female gametes carrying S1α allele were killed incompletely in sterile plants with heterozygous S1locus, and of9.06%male gametes and26.33%female gamates with S1α genotype were remained when BC3F1sterile plant produced male and female gametes.4) Interaction between S1and other two loci on chromosome1,4, which suppressed the express of S1, were identified.5) In sterile BC6F1plants with heterozygous S1locus, not only a majority of the female gametes carrying S1α allele, but a quite part of those carrying S1g (O.glaberrima allele in S1) could not be transmitted to their offsprings, the abnormal transmission of female gametes illustrated the complexity of reproductive isolation mechanism caused by S1, and can not be simply explained by’one locus, sporo-gametal interaction’ model only. Twenty-six BC7F1, one BC3F2, and two BC3F5populations were employed to identify loci of agronomic important traits. A total of26loci/QTL were identified, eight of them responded to number of grain per panicle; two to grain length; one to grain width; two to grain weight; six to plant height; two to presence of awn; one to awn length of the topmost grain in the panicle; three to spreading panicle type; and one to erect and dense panicle type. Sixteen loci/QTL were with positive effect from O. glaberrima, and ten loci/QTL were beneficial to genetic improvement of O. sativa:qnpl-1, qnp7-1, qnp10-1, qnp10-2, qgwd6-1, qgw6-1, qph6-1, qph6-3, qph10-1, and DEP4. This result illustrated that there were some constructive loci of O. glaberrima for breeding programs, although the exterior performance of O. glaberrima is inferior to modern varieties of O. sativa. Further research for mining usefull genes/loci from O. glaberrima is deserved.