Tomato epigenome fruit set

Developmental changes are associated with major transcriptomic reprogramming in all living organisms. The fruit-to-flower transition provides a remarkable example of a developmental shift allowing to address the contribution of DNA methylation and histone marking to the regulation of the fruit set transcriptomic program. The study emphasizes the tight correlation between epigenome reprogramming and global changes in gene expression during fruit initiation and reveals that H3K9ac and H3K4me3 histone marks synergistically promote gene transcription, whereas H3K27me3 marking has a repressive effect. Moreover, changes in histone marks rather than in DNA methylation are the main drivers of genetic reprogramming with H3K9ac and H3K4me3 marks being the primary players in this control mechanism. Consistently, the expression level of fruit set-associated genes is tightly correlated with changes in H3K9ac or H3K4me3 marking. The data provide new insight into the control of gene expression reprogramming and identifies a set of genes as the main actors of epigenetic reprogramming.