Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2004
Publication Date: 4/23/2004
Citation: Aluko, G., Martinez, C., Tohme, J., Castano, C., Bergman, C.J., Oard, J.H. 2004. QTL mapping of grain quality traits from the interspecific cross Oryza sativa X O. glaberrima. Journal of Theoretical and Applied Genetics. 109:630-639. Interpretive Summary: In the U.S., grain quality improvement is a demanding focus of rice breeders. These scientists develop improved cultivars of the type of rice known as Oryza sativa, while in some African countries Oryza glaberrima is the kind that is primarily cultivated. The latter represents a genetic resource that has not been evaluated for its potential to help improve Oryza sativa grain quality. This report describes the development and study of a population of rice derived from crossing an Oryza sativa cultivar with an Oryza glaberrima cultivar. The offspring from this cross were evaluated to determine various aspects of grain quality (i.e., grain yield after milling, grain shape, cooking properties, and protein and bran contents). Individual progeny were identified that had different levels (greater than and less than) of each of these characteristics compared to their parents. That indicates that Oryza glaberrima types may offer U.S. breeders a new source of parents for use in improving U.S. rice grain quality. Also, areas of the rice genome that control the variation in these grain traits were identified using genetic markers known as microsatellites. Knowledge of which genomic regions impact grain quality will assist rice breeders in their efforts to decrease the time required to develop improved cultivars.
Technical Abstract: Rice grain quality improvement is a focus of most rice breeders across the world, specially those developing cultivars whose grain will be sold in the world's export market. A potential source of improved quality traits for Oryza sativa development is the African cultivated rice O. glaberrima. A population of 312 doubled haploid lines derived from the BC3F1 of an interspecific cross of O. sativa x O. glaberrima was used to identify quantitative trait loci (QTLs) associated with several grain quality traits. A linkage map using 100 polymorphic microsatellite markers was constructed and used in composite and interval analyses to identify 27 QTLs associated with nine grain quality characteristics. Several of these associations agreed with previous reports, while those for milling quality and protein content mapped to different genomic regions. Three QTLs found to be associated with rice bran content are the first to be reported for this trait. Results from this study suggest that O. glaberrima germplasm offers rice breeders additional genetic resources for use in improving rice grain quality.