DNA methylation mediated by RdDM pathway and demethylation affects furanone accumulation through regulation of QUINONE OXIDOREDUCTASE in strawberry

Abstract

Recently, increasing evidence suggests that DNA methylation plays a crucial role in fruit ripening. However, the role of DNA methylation in regulating specific traits, such as flavor, remains unclear. Here, we report a role of DNA methylation in affecting furanone biosynthesis in strawberry. Strawberry quinone oxidoreductase (FaQR) is a key enzyme in furanone biosynthesis. There are four FaQR homologs in strawberry cultivar ‘Yuexin’, and one of them, FaQR3, contributes ∼50% of FaQR transcripts, indicating a major role of FaQR3 in furanone biosynthesis. Through characterization of levels of DNA methylation and FaQR3 transcript and furanone contents during fruit ripening and after the application of DNA methylation inhibitor, we found that the DNA methylation level of the FaQR3 promoter was negatively correlated with FaQR3 expression and furanone accumulation, suggesting that DNA methylation may be involved in furanone biosynthesis through adjusting FaQR3 expression, and responded to different temperatures consistently. In addition, transient expression of a gene in the RNA-directed DNA methylation (RdDM) pathway, FaAGO4, and enrichment analysis of the 24-nucleotide siRNAs suggested that DNA methylation in the FaQR3 promoter is mediated by the RdDM pathway. Transient RNA interference (RNAi) of FaDML indicated that the demethylation pathway may be involved in regulating furanone accumulation. These findings provide new insights into the role of DNA methylation and demethylation in affecting flavor quality in strawberry during fruit ripening.

Acknowledgements

We thank Jiangsu Academy of Agricultural Sciences for providing the leaves of ‘Camarosa’. This work was supported by the National Key Research and Development Program of China (2022YFD2100100), the National Natural Science Foundation of China (32002004), the 111 Project (B17039), and Fundamental Research Funds for the Central Universities.

Author contributions

Y. (Yunduan) L. performed most of the experiments and data analysis, and wrote the manuscript. J.L. and W.C. performed small-RNA analysis. Y. (Yichen) L., Y.S. (Sun) and Y.Z. contributed part of the experiments. Y.S. (Shi), Z.L., and K.C. provided guidance for the experiment and revised the manuscript. D.G. edited and polished the manuscript. X.Y. and G.J. created the new cultivar ‘Yuexin’ and performed field management. All authors read and approved the final manuscript.

Data availability

The datasets supporting the conclusions of this article are included in the article and additional files. The GenBank accession number of FaQR is AY158836.1 [7]. The accession numbers of AP2/ERF genes in strawberry referred to previous studies [10]. Accession numbers of the remaining genes are shown in Supplementary Data Table S2.

Conflict of interest

None declared.

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