Coordinated regulation of Arabidopsis thaliana development by light and gibberellins.
Light and gibberellins (GAs) mediate many essential and partially overlapping plant developmental processes. DELLA proteins are GA-signalling repressors that block GA-induced development. GA induces degradation of DELLA proteins via the ubiquitin/proteasome pathway, but light promotes accumulation of DELLA proteins by reducing GA levels. It was proposed that DELLA proteins restrain plant growth largely through their effect on gene expression. However, the precise mechanism of their function in coordinating GA signalling and gene expression remains unknown. Here we characterize a nuclear protein interaction cascade mediating transduction of GA signals to the activity regulation of a light-responsive transcription factor. In the absence of GA, nuclear-localized DELLA proteins accumulate to higher levels, interact with phytochrome-interacting factor 3 (PIF3, a bHLH-type transcription factor) and prevent PIF3 from binding to its target gene promoters and regulating gene expression, and therefore abrogate PIF3-mediated light control of hypocotyl elongation. In the presence of GA, GID1 proteins (GA receptors) elevate their direct interaction with DELLA proteins in the nucleus, trigger DELLA protein's ubiquitination and proteasome-mediated degradation, and thus release PIF3 from the negative effect of DELLA proteins.
Feng
Suhua
S
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104, USA.
Martinez
Cristina
C
Gusmaroli
Giuliana
G
Wang
Yu
Y
Zhou
Junli
J
Wang
Feng
F
Chen
Liying
L
Yu
Lu
L
Iglesias-Pedraz
Juan M
JM
Kircher
Stefan
S
Schäfer
Eberhard
E
Fu
Xiangdong
X
Fan
Liu-Min
LM
Deng
Xing Wang
XW
D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D005875:Gibberellins / Q000494:pharmacology*; D018546:Hypocotyl / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects
D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D005875:Gibberellins; D009687:Nuclear Proteins; D012097:Repressor Proteins; C109555:GAI protein, Arabidopsis; C116162:PIF3 protein, Arabidopsis; C508468:RGA protein, Arabidopsis