Epigenetics plays pivotal role in tomato ripening
Zhong and others found that tomato fruits undergo a major epigenetic overhaul during ripening, losing cytosine DNA methylation in many locations on the genome, particularly in promoters targeted by RIN. What's more, this epigenetic reprogramming does not happen in tomato mutants that are deficient in ripening.
"This change in DNA methylation, and specifically of promoters of ripening genes, is what makes the fruit respond to ethylene and then ripen," says Giovannoni. "We believe we have identified a new component of the ripening switch -- one that may serve as an additional target or tool to regulate tomato shelf life and quality."
The group is following up on the findings. "We want to check whether this is a general pattern" in other types of fruits, Fei says. If so, it may eventually be possible to improve other fruit crops by targeting methylation on ripening genes, fine-tuning the process to achieve a better product.