The japonica rice in Northeast China is famous because of its high quality. Eating and cooking qualities (ECQs) are the most important factors that determine cooked rice quality. However, the genetic basis of ECQ of japonica varieties in Northeast China needs further study. In this study, 200 japonica varieties that are widely distributed in Northeast China were collected to evaluate the physicochemical indices of grain ECQs. The distribution of each trait was concentrated without large variations. Correlation analysis indicated that gel consistency (GC) had a significantly negative correlation with gelatinization temperature (GT). By integrating various analyses including kinship calculation, principal component analysis (PCA), linkage disequilibrium (LD) analysis, and original parent investigation, we found that the japonica varieties in Northeast China exhibited a narrow genetic basis. An association study for grain ECQs was performed and eight quantitative trait loci (QTLs) were detected. ALK was the major locus that regulated GT and also significantly affecting GC. Through the linkage disequilibrium (LD) and expression pattern analysis, one possible candidate gene (LOC_Os02g29980) was predicted and required further research for validation. Additionally, a different allele of Wx was identified in the variety CH4126, and ALK was not fixed in these japonica varieties. These results further elucidate the genetic basis of ECQs of japonica varieties in Northeast China and provide local breeders some assistance for improving ECQs of rice grain in rice breeding.
Discussion on strategy of grain quality improvement for super high yielding japonica rice in Northeast China
