Development and evaluation of Oryza glaberrima Steud. chromosome segment substitution lines (CSSLs) in the background of O. sativa L. cv. Koshihikari

Oryza saliva and O. glaberrima are the cultivated forms of rice in Asia and Africa, respectively. While both possess important agricultural traits, genes that are unique to either species can be used to improve the other. To explore the genetic potential of the African rice as a genetic resource for the improvement of O. saliva, 34 chromosome segment substitution lines of O. glaberrima in the background of the elite japonica cultivar Koshihikari were developed and used to identify QTLs associated with 10 traits related to grain yield, plant stature and maturity. More than 90% of the entire genome of the donor parent was represented in contiguous or overlapping chromosome segments in the CSSL set. A total of 105 putative QTLs were identified, 84 of which had positive and 21 had negative effects on the traits examined. Of the 84 QTLs with positive effects, 64 were associated with increase in grain length, grain width, grain thickness, 100-grain weight, grain number per panicle and number of primary branches per panicle whereas 20 QTLs control plant stature. These results suggest that alleles from the African rice may be useful in improving traits related to grain yield and plant stature in existing cultivars of O. saliva.