Functional analysis of Arabidopsis F-box proteins involved in drought stress response

Abstract

F-box proteins regulate various cellular processes by degradation of target proteins by ubiquitination in Skp1-Cullin-F-box protein (SCF) complexes of ubiquitin/26S proteasome pathway. Recent studies showed that ~700 F-box protein genes are present in Arabidopsis thaliana genome, and that the F-box proteins play critical roles in various aspects of plant growth and development. However, no reports have been published on the F-box proteins involved in drought stress response.
Recently, we identified the genes encoding 4 Stress-Inducible F-box Proteins (SIF1~4) and 5 Recovery-Inducible F-box Proteins (RIF1~5) by microarray analyses (Oono et al. 2003, 2006). Expression of the SIF1 gene was up-regulated by drought, high-salinity and ABA treatments. Knock-out mutants of the SIF1 gene showed hypersensitivity to osmotic stress (200mM sorbitol). The roles of SIF1 in the stress responses will be presented.