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

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 <i>ALMT1</i> 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 <i>ALMT1</i> 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 <i>ALMT1</i>, plays a negative regulatory role in plant resistance to aluminum toxicity.