Genetic characterization and functional analysis of the GID1 gibberellin receptors in Arabidopsis.
We investigated the physiological function of three Arabidopsis thaliana homologs of the gibberellin (GA) receptor GIBBERELLIN-INSENSITIVE DWARF1 (GID1) by determining the developmental consequences of GID1 inactivation in insertion mutants. Although single mutants developed normally, gid1a gid1c and gid1a gid1b displayed reduced stem height and lower male fertility, respectively, indicating some functional specificity. The triple mutant displayed a dwarf phenotype more severe than that of the extreme GA-deficient mutant ga1-3. Flower formation occurred in long days but was delayed, with severe defects in floral organ development. The triple mutant did not respond to applied GA. All three GID1 homologs were expressed in most tissues throughout development but differed in expression level. GA treatment reduced transcript abundance for all three GID1 genes, suggesting feedback regulation. The DELLA protein REPRESSOR OF ga1-3 (RGA) accumulated in the triple mutant, whose phenotype could be partially rescued by loss of RGA function. Yeast two-hybrid and in vitro pull-down assays confirmed that GA enhances the interaction between GID1 and DELLA proteins. In addition, the N-terminal sequence containing the DELLA domain is necessary for GID1 binding. Furthermore, yeast three-hybrid assays showed that the GA-GID1 complex promotes the interaction between RGA and the F-box protein SLY1, a component of the SCF(SLY1) E3 ubiquitin ligase that targets the DELLA protein for degradation.
Griffiths
Jayne
J
Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom.
Murase
Kohji
K
Rieu
Ivo
I
Zentella
Rodolfo
R
Zhang
Zhong-Lin
ZL
Powers
Stephen J
SJ
Gong
Fan
F
Phillips
Andrew L
AL
Hedden
Peter
P
Sun
Tai-ping
TP
Thomas
Stephen G
SG
D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D025461:Feedback, Physiological / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000494:pharmacology; D016254:Mutagenesis, Insertional; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects; D020798:Two-Hybrid System Techniques
D029681:Arabidopsis Proteins; C512225:GID1a protein, Arabidopsis; C512226:GID1b protein, Arabidopsis; C512227:GID1c protein, Arabidopsis; D005875:Gibberellins; C508468:RGA protein, Arabidopsis; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012097:Repressor Proteins; D019883:Alkyl and Aryl Transferases; C476121:SLY1 protein, Arabidopsis