Characterization of a Major Quantitative Trait Locus for the Whiteness of Rice Grain Using Chromosome Segment Substitution Lines
Lulu Chen,
Yujia Leng,
Caiyun Zhang,
Xixu Li,
Zhihui Ye,
Yan Lu,
Lichun Huang,
Qing Liu,
Jiping Gao,
Changquan Zhang,
Qiaoquan Liu
Affiliations
Lulu Chen
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Yujia Leng
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Caiyun Zhang
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Xixu Li
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Zhihui Ye
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Yan Lu
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Lichun Huang
Key Laboratory of Plant Functional Genomics of the Ministry of Education/Zhongshan Biological Breeding Laboratory, Yangzhou University, Yangzhou 225009, China
Qing Liu
Key Laboratory of Plant Functional Genomics of the Ministry of Education/Zhongshan Biological Breeding Laboratory, Yangzhou University, Yangzhou 225009, China
Jiping Gao
Key Laboratory of Plant Functional Genomics of the Ministry of Education/Zhongshan Biological Breeding Laboratory, Yangzhou University, Yangzhou 225009, China
Changquan Zhang
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou 225009, China
Qiaoquan Liu
Key Laboratory of Plant Functional Genomics of the Ministry of Education/Zhongshan Biological Breeding Laboratory, Yangzhou University, Yangzhou 225009, China
The whiteness of rice grains (WRG) is a key indicator of appearance quality, directly impacting its commercial value. The trait is quantitative, influenced by multiple factors, and no specific genes have been cloned to date. In this study, we first examined the correlation between the whiteness of polished rice, cooked rice, and rice flour, finding that the whiteness of rice flour significantly correlated with both polished and cooked rice. Thus, the whiteness of rice flour was chosen as the indicator of WRG in our QTL analysis. Using a set of chromosome segment substitution lines (CSSL) with japonica rice Koshihikari as the recipient and indica rice Nona Bokra as the donor, we analyzed QTLs for WRG across two growth environments and identified six WRG QTLs. Notably, qWRG9 on chromosome 9 displayed stable genetic effects in both environments. Through chromosomal segment overlapping mapping, qWRG9 was narrowed to a 1.2 Mb region. Additionally, a BC4F2 segregating population confirmed that low WRG was a dominant trait governed by the major QTL qWRG9, with a segregation ratio of low to high WRG approximating 3:1, consistent with Mendelian inheritance. Further grain quality analysis on the BC4F2 population revealed that rice grains carrying the Indica-type qWRG9 allele not only exhibited lower WRG but also had significantly higher protein content. These findings support the fine mapping of the candidate gene and provide an important QTL for improving rice grain quality through genetic improvement.
