Cryptochromes and phytochromes synergistically regulate Arabidopsis root greening under blue light.
To increase their fitness, plants sense ambient light conditions and modulate their developmental processes by utilizing multiple photoreceptors such as phytochrome, cryptochrome and phototropin. Even roots, which are normally not exposed to light, express photoreceptors and can respond to light by developing chloroplasts. In the present study, root greening was observed in Arabidopsis thaliana. Seedlings were grown under monochromatic light and chlorophyll levels in the roots were determined. It was found that blue light was far more effective at inducing chloroplast development in Arabidopsis roots than was red light, and this response was under the control of a strong synergistic interaction between phytochromes and cryptochromes. As expected, the cry1 mutant was deficient in this response. Interestingly, the phyAphyB double mutant failed to respond to blue light under these conditions. This strongly suggests that either phytochrome A or phytochrome B, in addition to cryptochrome, was required for this blue light response. It was further demonstrated that the expression of photosynthetic genes was regulated in the same way. Dichromatic irradiation experiments indicated that this interaction depends on the level of phyB P(FR). Analysis of the cop1, det1 and hy5 mutants indicated that the corresponding factors were involved in the response.
Usami
Takeshi
T
Department of Botany, Graduate School of Science, Kyoto University, Sakyo-Ku, Kyoto, 606-8502 Japan.
Mochizuki
Nobuyoshi
N
Kondo
Maki
M
Nishimura
Mikio
M
Nagatani
Akira
A
D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics; D050976:Basic-Leucine Zipper Transcription Factors; D002734:Chlorophyll / Q000096:biosynthesis / Q000528:radiation effects; D056931:Cryptochromes; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D007425:Intracellular Membranes / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D047908:Intracellular Signaling Peptides and Proteins; D008027:Light; D046529:Microscopy, Electron, Transmission; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D010788:Photosynthesis / Q000235:genetics / Q000528:radiation effects*; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D018087:Plastids / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D044767:Ubiquitin-Protein Ligases
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C538962:CRY1 protein, Arabidopsis; D056931:Cryptochromes; C088435:DET1 protein, Arabidopsis; D005420:Flavoproteins; C109254:HY5 protein, Arabidopsis; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D010834:Phytochrome; D002734:Chlorophyll; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases