To Grow or not to Grow?

The seed to seedling transition in plants is initiated following the termination of seed dormancy. Here, I present a simplified developmental framework describing the events underlying this transition. I discuss putative mechanisms of signal integration and their relation to a global developmental fate switch in seeds within this framework. I delineate the events that occur before and after the flipping of this switch, marking an important distinction between these different developmental states. To end, I propose that the final fate switch resides within the embryo, and is informed by the endosperm in arabidopsis (Arabidopsis thaliana). This framework can serve as a template to focus future research in seed science.

TrendsEnvironmental signal integration in seeds is mediated by the relative abundance of the hormones abscisic acid (ABA) and gibberellins (GA). The dynamic regulation of hormone synthesis and degradation is regulated by exogenous cues.An irreversible developmental fate switch underlies the commitment to make the transition from seed to seedling. Both hormone and protein thresholds likely represent components of this switch.Events downstream of the flipping of the switch include the transcriptional induction of GA synthesis and cell wall-modifying gene expression. These act as downstream molecular markers indicating the developmental fate switch has been previously flipped.Current evidence suggests that the final switch resides within the embryo, where the decision to germinate is ultimately reached.