PT  - JOURNAL ARTICLE
AU  - Fu, Xiangdong
AU  - Richards, Donald E.
AU  - Ait-ali, Tahar
AU  - Hynes, Llewelyn W.
AU  - Ougham, Helen
AU  - Peng, Jinrong
AU  - Harberd, Nicholas P.
TI  - Gibberellin-Mediated Proteasome-Dependent Degradation of the Barley DELLA Protein SLN1 Repressor
AID  - 10.1105/tpc.006197
DP  - 2002 Dec 01
TA  - The Plant Cell
PG  - 3191--3200
VI  - 14
IP  - 12
4099  - http://www.plantcell.org/content/14/12/3191.short
4100  - http://www.plantcell.org/content/14/12/3191.full
SO  - Plant Cell2002 Dec 01; 14
AB  - DELLA proteins are nuclear repressors of plant gibberellin (GA) responses. Here, we investigate the properties of SLN1, a DELLA protein from barley that is destabilized by GA treatment. Using specific inhibitors of proteasome function, we show that proteasome-mediated protein degradation is necessary for GA-mediated destabilization of SLN1. We also show that GA responses, such as the aleurone α-amylase response and seedling leaf extension growth, require proteasome-dependent GA-mediated SLN1 destabilization. In further experiments with protein kinase and protein phosphatase inhibitors, we identify two additional signaling steps that are necessary for GA response and for GA-mediated destabilization of SLN1. Thus, GA signaling involves protein phosphorylation and dephosphorylation steps and promotes the derepression of GA responses via proteasome-dependent destabilization of DELLA repressors.