The NAC transcription factor ANAC017 regulates aluminum tolerance by regulating the cell wall-modifying genes

The membrane-bound NAC transcription factor ANAC017 acts upstream of Xyloglucan Endotransglucosylase-Hydrolase31 in regulating Al resistance via modulating the cell wall xyloglucan content. Aluminum (Al) toxicity is one of the key factors limiting crop production in acid soils; however, little is known about its transcriptional regulation in plants. In this study, we characterized the role of a NAM, ATAF1/2, and cup-shaped cotyledon 2 (NAC) transcription factors (TFs), ANAC017, in the regulation of Al tolerance in Arabidopsis (Arabidopsis thaliana). ANAC017 was localized in the nucleus and exhibited constitutive expression in the root, stem, leaf, flower, and silique, although its expression and protein accumulation were repressed by Al stress. Loss of function of ANAC017 enhanced Al tolerance when compared with wild-type Col-0 and was accompanied by lower root and root cell wall Al content. Furthermore, both hemicellulose and xyloglucan content decreased in the anac017 mutants, indicating the possible interaction between ANAC017 and xyloglucan endotransglucosylase/hydrolase (XTH). Interestingly, the expression of XTH31, which is responsible for xyloglucan modification, was downregulated in the anac017 mutants regardless of Al supply, supporting the possible interaction between ANAC017 and XTH31. Yeast one-hybrid, dual-luciferase reporter assay, and chromatin immunoprecipitation-quantitative PCR analysis revealed that ANAC017 positively regulated the expression of XTH31 through directly binding to the XTH31 promoter region, and overexpression of XTH31 in the anac017 mutant background rescued its Al-tolerance phenotype. In conclusion, we identified that the tTF ANAC017 acts upstream of XTH31 to regulate Al tolerance in Arabidopsis.

Automated summary

The membrane-bound NAC transcription factor ANAC017 plays a crucial role in regulating Al resistance by modulating the cell wall xyloglucan content. Loss of function of ANAC017 enhances Al tolerance accompanied by reduced root and root cell wall Al content. ANAC017 positively regulates XTH31 expression through directly binding to the XTH31 promoter region.