Abstract
EARLY FLOWERING 3 (ELF3) in Arabidopsis thaliana is thought to be not only an evening specific repressor of the light signals but also a required component of the core circadian clock. In the elf3 mutant under continuous light (LL), circadian rhythms of several gene expressions, hypocotyl elongation and root water content are obscure. In this study, we focused on circadian regulation of aquaporins which are water channel proteins in the biological membranes. First, we analyzed the expression levels of two aquaporin genes, AtPIP1;2 and AtPIP2;1 in Ler, elf3-1 mutant and Col(gl1) under LL. As a result, both AtPIP1;2 and AtPIP2;1 mRNAs in Ler and Col(gl1) seedlings increase at subjective dawn and decrease at subjective evening. However, the circadian rhythms of the aquaporin mRNAs were not observed in the elf3 mutant. The results suggest that aquaporin gene expressions are modulated by a circadian clock through ELF3. Both PIP1 and PIP2 proteins in Ler roots increased at dawn and decreased at evening under LD cycles and the rhythms were similar to the PIP1;2 and PIP2;1 mRNAs. Immunoblotting of aquaporin proteins in Col(gl1) and elf3 mutant under LL is in progress.
