Abstract
Two novel bZIP-LOV proteins are discovered in the xanthophycean coenocytic alga, Vaucheria frigida (heterokontophyta, Stramenopile). They have each one bZIP- and one LOV domain. They function as the photoreceptors for photo(cyto)morphogenesis, because the blue light-induced branching is completely inhibited or seriously delayed when their mRNA is knocked out by RNA interference (RNAi) (PCP meeting at Niigata 2005). The photoreceptor proteins are also involved in the regulation of sex-organ development. We hypothesize that they are functioning in Vaucheria as the blue light-regulated transcription factors (Fukamatsu et al. in this meeting). We found several orthologs in mRNA isolated from zygotes of Fucus (phaeophyta) and in the genome of the marine diatom, Thalassiosira pseudonana by BLAST search (Ishikawa et al. in this meeting). Xanthophyta, phaeophyta and diatoms are all belonging to heterokonts. We therefore name the bZIP-LOV photoreceptor AUREOCHROME, assuming that AUREOCHROME is a common and intrinsic blue light photoreceptor of heterokonts.
