Curcumin leads to responses of grapes to aluminum stress by inducing whole genome hypo-methylation

Aluminum (Al) is the most abundant element in the earth crust. Due to the abuse of phosphate fertilizer, acid rain has been frequently observed in recent years, resulting in the conversion of non-toxic aluminosilicates in the soil into Al ions, thereby causing stress to plants. As a DNA methylation inhibitor, curcumin can effectively counteract the Al stress on plants, while the epigenetic mechanism remains unclear. This study discusses the epigenetic mechanism of curcumin counteracting Al stress on grape. The results demonstrated that curcumin could significantly relieve the Al stress symptoms of grapes and reduce its whole genome methylation level. Al stress and curcumin treatment did not cause variations in the methylation level in each chromosome. While Al stress led to a slight increase in the average methylation level of each chromosome, and treatment by curcumin led to a significant decrease in the average methylation level of each chromosome. Specifically, the sites of CG and CHG were decreased significantly, and the site of CHH was increased or decreased significantly. Analysis of differentially-methylated regions (DMRs) revealed that treatment by curcumin led to an increase in hypo-DMRs in the whole genome of grape, and analysis of differentially-methylated genes (DMGs) also identified differentially related genes of hypo-DMRs in the whole genome of grapes, suggesting that curcumin triggers responses to Al stress by regulating hypo-methylation mode of the whole genome of grape. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis demonstrated that DMGs of grapes generate responses to Al stress by participating in galactose metabolism, ascorbate, and aldarate metabolism, and amino sugar and nucleotide sugar metabolism pathways of carbohydrate metabolism in the KEGG subclass.