Spatial ionomics provides new insights into the accumulation and transport of mineral ions in rice (Oryza sativa L.) under Cadmium stress

The distribution of various elements in different organs is spatially specific, and the distribution of elements in different organs of rice under Cadmium (Cd) stress and nutrient deficiency conditions is unknown, these limit the creation of ideal crops. In this study, spatially-specific ionomics study was applied to the spatial distribution of ions in different organs of 14 different varieties of hybrid rice seedlings under Cd stress. Under Cd stress, magnesium (Mg), manganese (Mn), zinc (Zn), copper (Cu), and iron (Fe) were found to accumulate mainly in the nodes, while Ca accumulated mainly in the mature leaves, and K mainly in the leaf sheaths and new leaves. Under Cd stress, the contents of Mg and Mn in all organs and Mg, Mn, Zn, Ca, Cu, and Fe in nodes decreased, but the accumulation of Fe in roots increased. In all organs, the concentrations of calcium (Ca), Mg, Mn, and Fe were almost positively correlated. Moreover, the ion transfer factors of Mg/Mn, Mg/Cu, and Zn/potassium (K) all showed positive correlations, indicating that these elements had similar chemical properties or biological functions. The accumulation of Cd in different organs of 4 varieties under Cd stress and K/Mn/Ca/Mg deficiency treatments was studied. Under Mg deficiency stress, the Cd concentration increased significantly. Under Ca deficiency stress, Cd transport was reduced. In conclusion, spatial ionomics was used to investigate the transport and accumulation of elements in different organs of O. sativa L., and these results provided theoretical support for the creation and production of ideal crops under Cd stress.