Functional analysis and intracellular localization of rice cryptochromes.
Blue-light-receptor cryptochrome (CRY), which mediates cotyledon expansion, increased accumulation of anthocyanin, and inhibition of hypocotyl elongation, was first identified in Arabidopsis. Two Arabidopsis cryptochromes (AtCRY1 and AtCRY2) have been reported to be localized to the nucleus. However, there is no information on the cryptochromes in monocotyledons. In this study, we isolated two cryptochrome cDNAs, OsCRY1 and OsCRY2, from rice (Oryza sativa) plants. The deduced amino acid sequences of OsCRY1 and OsCRY2 have a photolyase-like domain in their N termini and are homologous to AtCRY1. To investigate the function of OsCRY1, we overexpressed a green fluorescence protein-OsCRY1 fusion gene in Arabidopsis and assessed the phenotypes of the resulting transgenic plants. When the seedlings were germinated in the dark, no discernible effect was observed. However, light-germinated seedlings showed pronounced inhibition of hypocotyl elongation and increased accumulation of anthocyanin. These phenotypes were induced in a blue-light-dependent manner, indicating that OsCRY1 functions as a blue-light-receptor cryptochrome. We also examined the intracellular localization of green fluorescence protein-OsCRY1 in the transgenic plants. It was localized to both the nucleus and the cytoplasm. We identified two nuclear localization domains in the primary structure of OsCRY1. We discuss the relationship between the function and intracellular localization of rice cryptochromes by using additional data obtained with OsCRY2.
Matsumoto
Nanako
N
Graduate School of Humanities and Sciences, Ochanomizu University, Bunkyo-ku, Tokyo 112-8610, Japan.
Hirano
Tomoharu
T
Iwasaki
Toshisuke
T
Yamamoto
Naoki
N
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000254:growth & development; D029681:Arabidopsis Proteins; D001683:Biological Clocks; D017124:Conserved Sequence; D056931:Cryptochromes; D018076:DNA, Complementary / Q000235:genetics; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D049452:Green Fluorescent Proteins; D018546:Hypocotyl / Q000254:growth & development; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000378:metabolism*; D017956:Photoreceptor Cells, Invertebrate; D030821:Plants, Genetically Modified / Q000254:growth & development; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; D018076:DNA, Complementary; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D008164:Luminescent Proteins; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; C119828:cry protein, Drosophila; D049452:Green Fluorescent Proteins