Indexed on: 10 Sep '19Published on: 09 Sep '19Published in: Journal of experimental botany
Excessive cadmium (Cd) accumulation in rice poses a potential threat to human health. Rice varieties vary in their Cd content, which depend mainly on root-to-shoot Cd translocation. However, the cultivars accumulating high Cd in the natural population have not been completely investigated. In this study, we analyzed the variation in Cd accumulation in a diverse panel of 529 rice cultivars. We observed that only a small proportion (11 of 529) showed extremely high root-to-shoot Cd transfer rates, and seven of them were caused by two known OsHMA3 alleles. Using quantitative trait loci (QTL) mapping, we identified a new OsHMA3 allele that was associated with high Cd accumulation in three of the remaining cultivars. Using heterologous expression in yeast and comparative analysis among different rice cultivars, we observed that this new allele was weak at both transcriptional and protein levels compared to the functional OsHMA3 genotypes. The weak Cd transport activity was further demonstrated to be caused by Gly to Arg substitution at the 512th position. Our study comprehensively analyzed the variation in root-to-shoot Cd translocation rates in cultivated rice and identified a new OsHMA3 allele that caused high Cd accumulation in few rice cultivars. © The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Experimental Biology.