Plant & Animal Genomes XIV Conference Plant & Animal Genomes XIV ConferenceJanuary 14-18, 2006
Town & Country Convention Center
San Diego, CA
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 been identified yet. Recently, we isolated a GA insensitive dwarf mutant of rice, gid1. The GID1encodes an unknown protein with similarity to the hormone sensitive lipases (HSL) and the GID1-GFP signal was observed preferentially in nuclei. Recombinant GST-GID1 had a high affinity only for bioactive GAs, while mutated GST-GID1 corresponding three gid1alleles, had no GA-binding affinity. The Kd value for GA4 was estimated to be around 10-7 M, enough to account for the GA dependency on 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. Taken together, these results indicate that GID1 is a soluble receptor mediating GA signaling in rice.