Identification of QTLs for domestication-related and agronomic traits in an Oryza sativa x O-rufipogon BC1F7 population

Asian cultivated rice was domesticated from the wild rice, Oryza rufipogon and throughout the domestication process, a wide range of morphological and physiological changes altered the ancestral form. This study was conducted to identify the genetic basis of changes associated with the domestication process. An recombinant inbred line (RIL) population consisting of 120 lines was developed from a cross between the japonica cultivar, 'Hwayeongbyeo' and a presumed wild progenitor, O. rufipogon Griff. Acc.01944. The population was genotyped with 124 simple sequence length repeat (SSR) markets. providing an average interval size of 15 cM, and also evaluated for 20 traits related to domestication and agricultural performance. A total of 63 quantitative trait locus (QTLs) and one locus associated with qualitative variation for pericarp coloration were identified using single point and composite interval analysis. The number of QTLs per trait ranged from one to seven. Phenotypic variation associated with each QTL ranged from 3.7 to 40.4%, with an average of 15.3%. The results indicated that most domestication-related traits clustered in chromosomal blocks, and the positions of many of these clusters were consistent with those reported it,, previous studies and with skewed segregation ratios in these BC1F7 RILs. For 13 (20.6%) of the QTLs identified in this study, the O. rufipogon-derived allele contributed a desirable agronomic effect despite the overall undesirable characteristics of the wild phenotype. Favourable alleles from O. rufipogon were detected for particle length, spikelets per particle, days to heading and leaf discoloration associated with cold stress. When compared with previous studies involving interspecific crosses, it can be concluded that O. rufipogon is useful as a source of valuable alleles for rice improvement and that many of the introgressed regions contain genes that have a favourable impact on phenotype in different genetic backgrounds and different environments.