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Cadmium (Cd) toxicity poses a serious threat to plant growth and endangers human health via the food chain. The plant cell wall, composed primarily of cellulose, hemicellulose (HC), and pectin, serves as a critical barrier against abiotic stresses. However, how the cell wall mitigates ion accumulation and alleviates toxicity, particularly how pectin modification mediates responses to heavy metals, remains unclear. Here, we show that a subset of pectin methylesterase (PME) genes, with PME11 as a key member, is transcriptionally repressed by WRKY76. PME11 deficiency suppresses pectin demethylesterification, reduces pectin abundance, and diminishes Cd sequestration within the pectin matrix and cell wall, all of which ultimately reduces Cd accumulation and improves Cd tolerance in roots. Our study not only advances understanding of plant responses to heavy metals through cell wall dynamics but also identifies WRKY76 and PMEs as promising targets for engineering rice with reduced Cd accumulation and enhanced Cd tolerance.
Zhang et al. (Tue,) studied this question.