GIBBERELLIN INSENSITIVE DWARF1 encodes a soluble receptor for gibberellin

Abstract

Gibberellins (GAs) are phytohormones that are essential for many developmental processes in plants. It has been postulated that plants have both membrane-bound and soluble GA receptors; however, no GA receptors have yet been identified. Here we report the isolation and characterization of a new GA-insensitive dwarf mutant of rice, gid1. The GID1 gene encodes an unknown protein with similarity to the hormone-sensitive lipases, and we observed preferential localization of a GID1-green fluorescent protein (GFP) signal in nuclei. Recombinant glutathione S-transferase (GST)-GID1 had a high affinity only for biologically active GAs, whereas mutated GST-GID1 corresponding to three gid1 alleles had no GA-binding affinity. The dissociation constant for GA4 was estimated to be around 10(-7) M, enough to account for the GA dependency of shoot elongation. Moreover, GID1 bound to SLR1, a rice DELLA protein, in a GA-dependent manner in yeast cells. GID1 overexpression resulted in a GA-hypersensitive phenotype. Together, our results indicate that GID1 is a soluble receptor mediating GA signalling in rice.

Genetic Characterization and Functional Analysis of the GID1 Gibberellin Receptors inArabidopsis

“…By contrast, several GA signaling components in rice (Oryza sativa) are encoded by single genes, making it a powerful system for studying this pathway. This is emphasized by a recent study by Ueguchi-Tanaka et al (2005) in which they identified the elusive GA receptor in rice. The identity of the GA receptors provides an important opportunity to dissect the GA signaling cascade in Arabidopsis (Nakajima et al, 2006).…”

“…A major breakthrough in our understanding of the GA signaling cascade was the recent identification of GID1 as a soluble GA receptor in rice (Ueguchi-Tanaka et al, 2005). Genetic analysis of the gid1 mutants does not support the existence of other GA receptors in rice.…”

The Gibberellin perception system evolved to regulate a pre-existing GAMYB-mediated system during land plant evolution

“…Previous anatomical and in silico studies suggest that, similar to flowering plants, present-day bryophytes, including mosses, and lycophytes (lycopods) contain sporopollenin-containing outer walls on the surface of their spores and microspores [9][10][11] , and genes encoding CYP703 homologues have been detected in these genomes 12 . Curiously, however, one of the basal vascular plants, Selaginella, contains a functional GA perception system that is mediated by a GA receptor, GIBBERELLIN-INSENSITIVE DWARF1 (GID1), and suppressor proteins (DELLAs), whereas one of the basal land plants, Physcomitrella patens, does not contain this system [13][14][15][16] . These observations led us to speculate that the ancestral land plants developed sporopollenin-containing outer walls on their spores, which protected the spores from dryness and ultraviolet radiation on land, in association with CYP703-like enzymes, and that GA signalling pathway then evolved to control the development of the spore outer wall via the modulation of CYP703-like expressions during the evolution from mosses to lycopods.…”

SUMO proteases OTS1 and 2 control filament elongation through a DELLA-dependent mechanism

“…DELLA degradation initiates when GA binds to the soluble receptor GID1 (Ueguchi-Tanaka et al 2005;Griffiths et al 2006;Murase et al 2008). This event stimulates GID1-DELLA binding and recruitment of the E3 ubiquitin-ligase SLEEPY1 (Silverstone et al 2001;Willige et al 2007;Wang et al 2009).…”