Association Mapping of Quantitative Trait Loci for Mineral Element Contents in Whole Grain Rice (Oryza sativa L.)

Mineral elements in brown rice grain play an important role in human health. In this study, variations in the content of iron (Fe), zinc (Zn), selenium (Se), cadmium (Cd), and lead (Pb) in 378 accessions of brown rice were investigated, and association mapping was used to detect the quantitative trait loci (QTLs) responsible for the variation. Among seven subpopulations, the mean values of Zn and Cd in the japonica group were significantly higher than in the indica groups. The population structure accounted for from 5.7% (Se) to 22.1% (Pb) of the total variation. Correlation analyses showed that Pb was positively correlated with the other minerals (P < 0.001) except for Se. For the five mineral elements investigated, 20 QTLs, including some previously reported and new candidate loci, were identified. Particularly, three cases of QTL colocalization, i.e. Cd and Pb on chromosome 5, Zn and Pb on chromosome 7, and Se and Pb on chromosome 11, were observed. This study suggested that the identified markers could feasibly be used to enhance desired micronutrients while reducing the heavy metal content in whole rice grain by marker-assisted selection (MAS).