Plant hormone signaling in flowering: An epigenetic point of view.

Reproduction is one of the most important phases in an organism's lifecycle. In the case of angiosperm plants, flowering provides the major developmental transition from the vegetative to the reproductive stage, and requires genetic and epigenetic reprogramming to ensure the success of seed production. Flowering is regulated by a complex network of genes that integrate multiple environmental cues and endogenous signals so that flowering occurs at the right time; hormone regulation, signaling and homeostasis are very important in this process. Working alone or in combination, hormones are able to promote flowering by epigenetic regulation. Some plant hormones, such as gibberellins, jasmonic acid, abscisic acid and auxins, have important effects on chromatin compaction mediated by DNA methylation and histone posttranslational modifications, which hints at the role that epigenetic regulation may play in flowering through hormone action. miRNAs have been viewed as acting independently from DNA methylation and histone modification, ignoring their potential to interact with hormone signaling - including the signaling of auxins, gibberellins, ethylene, jasmonic acid, salicylic acid and others - to regulate flowering. Therefore, in this review we examine new findings about interactions between epigenetic mechanisms and key players in hormone signaling to coordinate flowering.