GIBBERELLIN INSENSITIVE DWARF1 encodes a soluble receptor for gibberellin.
Ueguchi-Tanaka, Miyako 1*; Ashikari, Motoyuki 1*; Nakajima, Masatoshi 2*; Itoh, Hironori 1; Katoh, Etsuko 3; Kobayashi, Masatomo 4; Chow, Teh-yuan 5+; Hsing, Yue-ie C. 5; Kitano, Hidemi 1; Yamaguchi, Isomaro 2,6; Matsuoka, Makoto 1
[Article]
Nature.
437(7059):693-698, September 29, 2005.
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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.
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