Genetic Diversity, Population Structure, and Interspecific Hybridization of Oryza longistaminata

O. longistaminata is an undomesticated relative of cultivated Asian rice, O. sativa. Here, we characterized genetic diversity and population structure of O. longistaminata and described the phylogenetic relationship of O. longistaminata to O. sativa, O. barthii, and O. glaberrima. We also explored evidence for recent and historical hybridization between O. longistaminata and O. sativa. The materials genotyped in this study include most O. longistaminata accessions available from the International Rice Research Institute Genebank, interspecific O. sativa / O. longistaminata hybrids, an O. sativa / O. longistaminata RIL population, and control accessions of O. sativa, O. barthii, and O. glaberrima.O. longistaminata has been used to introgress valuable agronomic traits into O. sativa, including disease resistance, self-incompatibility, perennial habit, nitrogen use efficiency, and increased yields. O. longistaminata is a self-incompatible species native to a broad range of environments across sub-Saharan Africa. Improved understanding of genetic diversity and population structure in O. longistaminata will aid breeding efforts to improve O. sativa with O. longistaminata germplasm and also conservation of O. longistaminata. Crossing O. sativa and O. longistaminata is complicated by a substantial breeding barrier, and the interspecific hybrids described here (recovered from the IRRI genebank) can be used in breeding or to understand the genetic basis of crossability between the species.