Assessing the physiological responses and uptake patterns of lanthanum and yttrium in rice and Phytolacca americana L.

Abstract

The effects of rare earth elements (REEs) on plant physiology and bioaccumulation characteristics vary significantly. As a result, considerable attention has been directed towards the effects and toxicity of REEs on plants. REEs migrate and transform in the environment and are absorbed by plant roots. However, different plants exhibit varying capacities to absorb REEs, leading to diverse impacts on their growth. In our study, we subjected seedlings of rice and Phytolacca americana L. to a gradient of lanthanum and yttrium (La + Y) concentrations to evaluate the physicochemical effects and uptake patterns of these elements. We meticulously measured variables such as biomass, root length, and elemental concentrations of La and Y, as well as macronutrients (P, Na, K, Mn, Fe, Mg, Ca) and micronutrients (Cu, Zn) to decode the physiological responses to varying levels of La + Y exposure. Based on the known dualistic nature of REEs interaction with plants, our results reveal that the threshold of REEs to different plants is different, and this conclusion can serve well for the formulation of rare earth pollution remediation strategies. Importantly, the accumulation of La and Y in P. americana L. roots was significantly greater than in rice roots, by an order of magnitude, reflecting the unique uptake capacities of hyperaccumulators. Additionally, this research found that nutrient dynamics and the absorption patterns of La and Y within the plants diverged, suggesting that La uptake in P. americana L. may occur via Ca²⁺ ion channels. These insights enhance our understanding of REE-plant interactions and have broader implications for agriculture and environmental health.