Crop plants transport irregularly shaped mineral particles from root to shoot: Tracking and quantifying.

Mineral particles, ubiquitous in soils, influence crop plant growth by carrying nutrients and pollutants. While the uptake of dissolved mineral nutrients is well-established, the direct incorporation of irregular mineral particles into plants remains unclear. This study investigated the uptake and transport of kaolin particles, representative of minerals, by wheat and lettuce seedlings using hydroponic and soil cultures. Covalent labeling and advanced microscopy revealed that kaolin enters root steles at lateral root emergence sites, followed by transport to shoots. Fluorescent dyes and lanthanum (La)-labeled kaolin particles demonstrated that wheat surpassed lettuce in kaolin uptake in hydroponics, but both plants showed similar levels of particles in the shoots. Translocation factors (TFs) for kaolin were significantly higher in soil (0.089 for wheat, 0.039 for lettuce) compared to hydroponics (0.001 for wheat, 0.003 for lettuce). These findings provide compelling evidence for the direct uptake and transport of kaolin particles in crop plants. This opens new avenues for research on the interactions between plant and mineral particles, including other colloidal particles, in terrestrial ecosystems.