Abstract
BackgroundMelatonin can regulate plant growth, development and biotic responses by causing global changes in gene expression; however, the melatonin-induced changes in gene expression via the modification of DNA methylation remain unclear in plants.ResultsA total of 1,169,852 and 1,008,894 methylated cytosines (mCs) were identified in the control and melatonin-treated grape berries, respectively, and mCs occurred primarily at CG sites, followed by CHG sites and CHH sites. Compared to the control, melatonin treatment broadly decreased methylation levels at CHG and particularly CHH sites in various gene regions. Melatonin treatment generated a total of 25,125 differentially methylated regions (DMRs), which included 6517 DMR-associated genes. RNA-Seq demonstrated that 2479 genes were upregulated, and 1072 genes were repressed by melatonin treatment. The evaluation of the interconnection of the DNA methylome and transcriptome identified 144 genes showing a negative correlation between promoter methylation and gene expression, which were primarily related to biotic stress responses and flavonoid biosynthesis. Additionally, the application of 5́-azacytidine and melatonin led to similar effects on mycelial growth of B. cinerea, berry decay rate and flavonoid biosynthesis. Moreover, EDS1 was used to show that melatonin increased gene expression by decreasing promoter methylation levels.ConclusionOur results demonstrated that melatonin broadly decreased DNA methylation and altered gene expression in grape berries. We propose that melatonin increases disease resistance and flavonoid biosynthesis by decreasing the methylation levels of the promoters of the genes involved.
Highlights
Melatonin can regulate plant growth, development and biotic responses by causing global changes in gene expression; the melatonin-induced changes in gene expression via the modification of DNA methylation remain unclear in plants
In the ‘Merlot’ grape berries, anthocyanins began to accumulate at 80 days after bloom (DAB), and coloring began at 90 DAB (Fig. 1a, b)
Veraison occurred at approximately 80 DAB, and melatonin treatment was performed at this time point
Summary
Melatonin can regulate plant growth, development and biotic responses by causing global changes in gene expression; the melatonin-induced changes in gene expression via the modification of DNA methylation remain unclear in plants. Strategies for improving quality and disease resistance are a key focus of grapevine cultivation. Gao et al BMC Plant Biology (2020) 20:231 melatonin content activated by MeRAV1 and MERAV2 enhances plant disease resistance against cassava bacterial blight [4]. Both exogenous treatment with and endogenous induction of melatonin increase abiotic stress tolerance in many plants. It has been reported that melatonin alleviates salt damage in grapes [5] and enhances the drought tolerance of apple plants [6]. Increasing melatonin via the overexpression of ASMT1 significantly enhances the drought tolerance of Arabidopsis plants [7]
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