Insight into the mechanism of indium toxicity in rice

• Published in: Journal of hazardous materials 2022-05, Vol.429, p.128265-128265, Article 128265
• Main Authors: Cheah, Boon Huat, Liao, Pei-Chu, Lo, Jing-Chi, Wang, Yu-Tsen, Tang, I-Chien, Yeh, Kuo-Chen, Lee, Dar-Yuan, Lin, Ya-Fen
• Format: Article
• Language: English
• Subjects: Emerging contaminants; Gene Expression Regulation, Plant; Heavy metal; Indium; Indium - toxicity; Oryza - metabolism; Phosphate starvation; Phosphates - metabolism; Phosphorus - metabolism; Plant Roots - metabolism; Rice
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.128265

Indium is widely used in the technology industry and is an emerging form of environmental pollution. The presence of indium in soil and groundwater inhibits shoot and root growth in crops, thus reducing yields. However, the underlying mechanisms are unknown, making it difficult to design effective countermeasures. We explored the spatiotemporal effects of excess indium on the morphological, physiological and biochemical properties of rice (Oryza sativa L.). Indium accumulated mainly in the roots, severely restricting their growth and causing the acute perturbation of phosphorus, magnesium and iron homeostasis. Other effects included leaf necrosis and anatomical changes in the roots (thinned sclerenchyma and enlarged epidermal and exodermal layers). Whole-transcriptome sequencing revealed that rice immediately responded to indium stress by activating genes involved in heavy metal tolerance and phosphate starvation responses, including the expression of genes encoding phosphate-regulated transcription factors and transporters in the roots. Direct indium toxicity rather than phosphate deficiency was identified as the major factor affecting the growth of rice plants, resulting in the profound phenotypic changes we observed. The application of exogenous phosphate alleviated indium toxicity by reducing indium uptake. Our results suggest that indium immobilization could be used to prevent indium toxicity in the field. [Display omitted] •Indium causes severe growth inhibition and anatomical changes in rice roots.•Indium also causes acute phosphate deficiency in rice.•Indium toxicity more than phosphate deficiency causes the observed phenotypes.•Exogenous phosphate restores rice growth by reducing indium uptake.•Indium immobilization techniques could reduce the impact of indium in the field.