WRKY61 Negatively Regulates Aluminum Resistance by Inhibiting the Expression of ALMT1 in Arabidopsis thaliana

TL;DR

This study shows that the WRKY61 gene in Arabidopsis reduces plant resistance to aluminum toxicity by suppressing the ALMT1 gene, which helps plants tolerate aluminum.

Contribution

The paper identifies WRKY61 as a negative regulator of aluminum resistance through its repression of ALMT1 expression.

Findings

Loss of WRKY61 function increases aluminum resistance in Arabidopsis.

WRKY61 represses ALMT1 by binding to its promoter region.

Increased malate secretion in WRKY61 mutants reduces aluminum uptake.

Abstract

Aluminum (Al) toxicity is a major constraint on crop production in acidic soils. A key mechanism for aluminum resistance in many plants involves the ALMT1-mediated exudation of malate from the root system. This process hinges on the precise regulation of ALMT1 expression, which is therefore critical for plant tolerance to aluminum toxicity. In a screen for Arabidopsis mutants with altered aluminum resistance, we found that the loss-of-function mutant of the WRKY61 transcription factor exhibited significantly enhanced resistance to aluminum toxicity, indicating that WRKY61 is involved in the plant’s response to aluminum toxicity. Further research revealed that WRKY61 binds to the W-box in the ALMT1 promoter to repress its expression. Mutation of WRKY61 resulted in increased malate secretion from mutant roots, which chelated aluminum ions, leading to a significant reduction in aluminum content within the plant. This, in turn, significantly enhances malate secretion under aluminum toxicity, ultimately conferring heightened aluminum resistance. These results clearly indicate that WRKY61, as a transcriptional repressor of ALMT1, plays a negative regulatory role in plant resistance to aluminum toxicity.

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