摘要
CRYPTOCHROMES （CRYs） are photolyase-like ultraviolet-A/blue light photoreceptors that mediate various light responses in plants. The signaling mechanism of Arabidopsis CRYs （CRY1 and CRY2） involves direct CRY-COP1 interaction. Here, we report that CRY1G380R, which carries a Gly-to-Arg substitution of the highly conserved G380 in the photo-lyase-related （PHR） domain of Arabidopsis CRY1, shows constitutive CRY1 photoreceptor activity in Arabidopsis. Transgenic plants overexpressing CRY1G380R display a constitutively photomorphogenic （COP） phenotype in darkness, as well as a dramatic early flowering phenotype under short-day light conditions （SD）. We further demonstrate that CRY1G380R expression driven by the native CRY1 promoter also results in a COP phenotype in darkness. Moreover, over- expression of either the Arabidopsis homolog CRY2G377R or the rice ortholog OsCRYlbG388R of CRY1G380R in Arabidopsis results in a COP phenotype in darkness. Cellular localization studies indicate that CRY1G380R co-localizes with COP1 in the same nuclear bodies （NBs） in vivo and inhibits the nuclear accumulation of COP1 in darkness. These results suggest that the conserved G380 may play a critical role in regulating the photoreceptor activity of plant CRYs and that CRY1G380R might constitutively phenocopy the photo-activated CRY1 in darkness and thus constitutively mediate CRY1 signaling.
CRYPTOCHROMES （CRYs） are photolyase-like ultraviolet-A/blue light photoreceptors that mediate various light responses in plants. The signaling mechanism of Arabidopsis CRYs （CRY1 and CRY2） involves direct CRY-COP1 interaction. Here, we report that CRY1G380R, which carries a Gly-to-Arg substitution of the highly conserved G380 in the photo-lyase-related （PHR） domain of Arabidopsis CRY1, shows constitutive CRY1 photoreceptor activity in Arabidopsis. Transgenic plants overexpressing CRY1G380R display a constitutively photomorphogenic （COP） phenotype in darkness, as well as a dramatic early flowering phenotype under short-day light conditions （SD）. We further demonstrate that CRY1G380R expression driven by the native CRY1 promoter also results in a COP phenotype in darkness. Moreover, over- expression of either the Arabidopsis homolog CRY2G377R or the rice ortholog OsCRYlbG388R of CRY1G380R in Arabidopsis results in a COP phenotype in darkness. Cellular localization studies indicate that CRY1G380R co-localizes with COP1 in the same nuclear bodies （NBs） in vivo and inhibits the nuclear accumulation of COP1 in darkness. These results suggest that the conserved G380 may play a critical role in regulating the photoreceptor activity of plant CRYs and that CRY1G380R might constitutively phenocopy the photo-activated CRY1 in darkness and thus constitutively mediate CRY1 signaling.
基金
This work was supported by funds from the National Natural Science Foundation of China，National Special Grant for Transgenic Crops，Science and Technology Commission of Shanghai Municipality，and the Shanghai Leading Academic Discipline Project
