Mutations in OsRZF1, encoding a zinc-finger protein, causes reduced magnesium uptake in roots and translocation to shoots in rice

Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of 2,825 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. For identifying causal gene for LMGC1, first, F2 progenies were developed by a cross LMGC1 with wild type Koshihikari. Then, Among 90 individuals of the F2, 10 individuals containing highest and low concentration of Mg were applied to MutMap+ approach as high and low bulk samples, respectively.