Bioimaging of multiple elements by high‐resolution LA‐ICP‐MS reveals altered distribution of mineral elements in the nodes of rice mutants

Abstract

Inter-vascular transfer in rice (Oryza sativa) nodes is required for delivering mineral elements to developing tissues, which is mediated by various transporters in the nodes. However, the effect of these transporters on distribution of mineral elements in the nodes at a cellular level is still unknown. Here, we established a protocol for bioimaging of multiple elements at a cellular level in rice node by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), and compared the mineral distribution profile between wildtype (WT) rice and mutants. Both relative comparison of mineral distribution normalized by endogenous 13 C and quantitative analysis using spiked standards combined with soft ablation gave valid results. Overall, macro-nutrients such as K and Mg were accumulated more in the phloem region, while micro-nutrients such as Fe and Zn were highly accumulated at the inter-vascular tissues of the node. In mutants of nodal Zn transporter OsHMA2, Zn localization pattern in the node tissues did not differ from that of WT; however, Zn accumulation in the inter-vascular tissues was lower in uppermost node I but higher in the third upper node III compared with the WT. In contrast, Si deposition in the mutants of three nodal Si transporters Lsi2, Lsi3 and Lsi6 showed different patterns, which are consistent with the localization of these transporters. This improved LA-ICP-MS analysis combined with functional characterization of transporters will provide further insight into mineral element distribution mechanisms in rice and other plant species.

A transporter for delivering zinc to the developing tiller bud and panicle in rice

“…To examine the tissue accumulation of Zn in WTs and mutants, we applied the newly established bioimaging technique, laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) (Yamaji and Ma, 2019). Higher Zn accumulations in basal node and lower Zn accumulations in shoot apical meristems were observed in the oszip4 mutants relative to that of WTs under the Zn‐sufficient condition (Figure S7a–d).…”

Spatial Heterogeneity of Cadmium Effects on Salvia sclarea Leaves Revealed by Chlorophyll Fluorescence Imaging Analysis and Laser Ablation Inductively Coupled Plasma Mass Spectrometry

“…Among the different techniques that have been developed for elemental imaging, including secondary ion mass spectrometry, X-ray fluorescence, scanning electron microscopy with energy-dispersive X-ray analysis, and LA-ICP-MS, the latter one has emerged as the prevailing, with high sensitivity and more comprehensible tool for bioimaging of mineral elements in plant tissues [55,56].…”

A Vacuolar Phytosiderophore Transporter Alters Iron and Zinc Accumulation in Polished Rice Grains

“…2, G and H). In these tissues, Fe and Zn are also highly accumulated (Yamaguchi et al, 2012;Moore et al, 2014;Zhao et al, 2014;Yamaji and Ma, 2019). Since DMA chelates both Fe and Zn (Suzuki et al, 2008;Nishiyama et al, 2012), increased DMA in the cytosol and/or apoplast due to lack of vacuolar sequestration results in more Fe and Zn deposited in the PCBs to be solubilized in the mutant before loading to the grains through the phloem.…”