The functional analysis of photomorphogenetic transcription factor, ZAT9, of which nuclear localization is regulated by light irradiation.

Abstract

We are investigating the Arabidopsis mutant showing abnormal photomorphogenesis isolated from gain-of-function mutant lines, which have glucocorticoid receptor (GR)-mediated induction system. The mutant isolated from these lines showed long hypocotyl and small cotyledons phenotypes by application of dexamethasone (DEX) under light condition. These phenotypes were observed under red and/or far-red light conditions, but not under blue and dark conditions.
The corresponding gene encoded C2H2 type zinc finger transcription factor, ZAT9. Interestingly, nuclear localization of ZAT9-GFP fusion protein was observed under blue, red and far-red light conditions, but not under dark condition. These results suggest light dependent transport of ZAT9 into nucleus. We also practiced microarray analysis to investigate genes regulated by ZAT9. As a result, the expression of several genes related with phytochrome dependent signal was affected in the mutant by application of DEX. We will discuss the functions of ZAT9 in light signal transductions.