Multi-elemental bioimaging of freshly exposed Oryza sativa (L.) rhizospheres grown in flooded soils

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was employed to generate multi-elemental spatial profiles of the rhizosphere and vascular tissues of paddy rice ( Oryza sativa L.). Plants were cultivated under flooded conditions in soil-filled segmented tubes, which were sectioned post-sampling to expose fresh soil interfaces for imaging. High-resolution elemental maps revealed localized enrichment of arsenic, cadmium, calcium, iron, and phosphorus within the rhizosphere. External certified reference materials enabled systematic inter-run standardization and ensured quantitative accuracy, with bulk soil concentrations comparable to conventional ICP-MS and X‑ray Fluorescence (XRF) analyses. The spatial profiles provided novel insights into arsenic mobilization, highlighting calcium’s inhibitory role in rhizosphere arsenic accumulation. Additionally, iron plaque adjacent to roots was identified as a cadmium reservoir. Despite pronounced heterogeneity in soil elemental composition, rice root vascular tissues maintained elemental homeostasis. Furthermore, depletion of rhizosphere silicon stores by roots was observed. These findings demonstrate the utility of LA-ICP-MS imaging for elucidating element dynamics in plant-soil interfaces and advancing understanding of nutrient and contaminant interactions in flooded agroecosystems. • LA-ICP-MS mapped elements in freshly exposed rice rhizospheres • Calcium reduced arsenic buildup; iron plaque stored cadmium near roots • Rice roots maintained homeostasis despite soil elemental variability