Effect of the Methylation Level on the Grape Fruit Development Process

Grapevine
is extensively grown for fresh table grapes, wine, and other processed
products worldwide. DNA methylation levels are regulated by DNA methylation
maintenance and DNA methylation removal involved in the grapevine
growth. We comprehensively analyzed the transcriptome and metabolome
of the ‘Kyoho’ fruit with or without demethylation and
screened for a large number of differential genes and metabolites.
Color, hardness, and aroma are the most obvious traits reflecting
the ripening of grapes. We used gas chromatography–mass spectrometry
and high-performance liquid chromatography to understand the changes
in metabolites during ripening. We cloned many key genes selected
by transcriptome analysis and found that intron retention was observed
in VvCHS, VvDFR, and VvGST. The imbalance of methylation levels affects the alternative splicing
of pre-mRNA, which makes the translation process abnormal and affects
gene expression. In addition, analyzing promoters of some genes, such
as proVvGST4 and proVvUFGT, found
that the promoters of these genes after demethylating were more difficult
to methylate. Taken together, this study will provide new insights
into comprehension of the molecular mechanism of methylation during
ripening of grape berries. In addition, the study provides some genetic
information to help guide our improvement, cultivation, and management
of grapes in the future.