Gibberellins and Seed Germination

Abstract Gibberellins (GA) promote seed germination, but they are not simple 'Go Ahead' (GA) molecules as the insight gained into the molecular mechanisms underlying their role in seeds appears to be complex. This chapter covers their central role in mediating the environmental and developmental control of seed germination, and how this differs from vegetative growth processes. Spatiotemporal patterns of GA metabolism and GID1‐type receptor signalling in the key seed compartments determine tissue interactions and germination timing in response to ambient environmental cues. Gibberellins are key players in seed temperature responses; during thermoinhibition they interact with other hormonal pathways. Allelochemicals such as myrigalone A inhibit seed germination by specific interference with GA metabolism and signalling. This reveals important ecophysiological roles for GAs in seeds and suggests that they are fundamental for studying species adaptation and interaction in natural and agricultural ecosystems upon climate change.