Mapping QTLs and gene validation studies for Mg uptake and translocation using a MAGIC population in rice.

Magnesium (Mg) is an essential element for plant growth and development. Rice is an important food crop in the world, but there are few studies on the uptake and translocation of Mg in rice. We used a multi-parent advanced generation inter-cross (MAGIC) population constructed using four parental lines and genotyped by a 55 K rice SNP array for association analysis to locate QTLs related to Mg uptake and translocation in rice at the seedling stage. Four QTLs ( and ) were detected for the root Mg concentration, which explained 11.45-13.08% of the phenotypic variation. The Mg transporter gene, , was within the region of . Three QTLs ( and ) were detected for the shoot Mg concentration, which explained 4.30-5.46% of the phenotypic variation. Two QTLs ( and ) were found to affect the translocation of Mg from the roots to the shoots, and explained 10.91% and 9.63% of phenotypic variation. and might be the same, since they are very close to each other on chromosome 3. Analysis of candidate genes in the region of and through qRT-PCR, complementation assay in the yeast Mg transport-defective mutant CM66, and sequence analysis of the parental lines suggested that may play important roles in Mg uptake, translocation and accumulation in rice. Overexpression of can significantly increase the Mg concentration in rice seedlings, especially under the condition of low Mg supply.