GIBBERELLIN INSENSITIVE DWARF1 encodes a soluble receptor for gibberellin.
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.
Ueguchi-Tanaka
Miyako
M
Bioscience and Biotechnology Center, Nagoya University, Nagoya 464-8601, Japan.
Ashikari
Motoyuki
M
Nakajima
Masatoshi
M
Itoh
Hironori
H
Katoh
Etsuko
E
Kobayashi
Masatomo
M
Chow
Teh-yuan
TY
Hsing
Yue-ie C
YI
Kitano
Hidemi
H
Yamaguchi
Isomaro
I
Matsuoka
Makoto
M
D000595:Amino Acid Sequence; D001667:Binding, Competitive; D003001:Cloning, Molecular; D004843:Epistasis, Genetic; D017343:Genes, Plant / Q000235:genetics; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012995:Solubility; D002787:Sterol Esterase / Q000737:chemistry
D005875:Gibberellins; D010940:Plant Proteins; D002787:Sterol Esterase