Evolution of GID1-dependent gibberellin signaling pathway in plants

Abstract

Although some types of ferns and mosses produce endogenous gibberellins (GAs), it has been unknown whether they possess the GID1-dependent GA signal transduction pathway as seen in seed plants. We analyzed the GA signaling pathway in a fern (Selaginella moellendorffii) and in a moss (Physcomitrella patens) to explore when plants came to utilize GA as a plant hormone. In rice, the GA receptor (OsGID1) and DELLA protein (SLR1) interact in a GA dependent manner resulting in degradation of SLR1 by OsGID2. Then, degradation of SLR1 induces some GA actions.
Interaction between GID1 and DELLA of P. patens was not found by Y2H assay. In contrast, S. moellendorffi contains SmGID1s (SmGID1a and SmGID1b), SmDELLA1 and SmGID2 involved in GA perception and signaling. SmGID1a has similar function of OsGID1, whereas SmGID1b shows some different characters from OsGID1, suggesting an existence of a fern specific GA receptor.