5-AzaC enhances the Aluminum tolerance of grapes by reducing the DNA methylation level

Abstract

Purpose 5-Azacitidine (5-AzaC) is a base analog with a reduced methylation level of the genome generated by removing the methyl group from methylated cytosine in the DNA. However, the mechanism of exogenous 5-azaC mediating Al accumulation in grapes at the methylation level remains unclear. Methods Using 5-azaC treatment solution to spray the ‘crystal’ grape seedlings under Al stress, and then, observing the agronomic traits of grape, detecting the activity of SOD, POD and MDA, the content of H2O2 and Al, and the rate of oxygen free radical production. Meanwhile, the whole genome bisulfite sequencing (WGBS) was used to generate high-coverage cytosine methylation profiles of the grape genome. Results After treatment with 5-azaC of the ‘crystal’ grape seedlings under Al stress, the methylation rates of all chromosomes decreased, the DNA methylation level decreased, and the DNA methylation level of promoter increased at CG, CHG, and CHH sites, so that transcription factors could trigger the promoter and induce upregulation of hypo-differentially methylated regions (DMRs) in the genome to counteract Al stress. Gene Ontology enrichment analysis of DMRs demonstrated that 5-azaC treatment could effectively reduce the Al toxicity in grape plants under Al stress by upregulating related genes and effectively reducing the Al stress-induced DNA methylation level of the grape genome. Conclusion 5-azaC treatment leads to reduced DNA methylation level of the grape genome, and elucidation of the methylation features helped to clarify the molecular mechanism behind the response of grapes to Al stress.