Regulatory network of fruit ripening: current understanding and future challenges.

Fruit ripening is a developmental process that is spatio-temporally tuned at multiple levels. Molecular dissections of the mechanisms underlying the ripening process have revealed a network encompassed by hormones, transcriptional regulators, epigenomic modifications and other regulatory elements that directly determine fruit quality and the postharvest commodity of fresh produce. Many studies have addressed the important roles of ethylene, abscisic acid (ABA) and other hormones in regulating fruit ripening. Recent studies have shown that some spontaneous mutants for tomato transcription factors (TFs) have resulted from loss-of-function or dominant-negative mutations. Unlike in DNA methylation variation, the histone mark H3K27me3 may be conserved and prevents the transcriptional feedback circuit from generating autocatalytic ethylene. These observations of a network of partially redundant component indicate the need to improve our current understanding. Here, we focussed on the recent advances and future challenges in investigations of the molecular mechanisms of fruit ripening. We also identified several issues that still need to be addressed in future studies.