title: Phototropin 1 and cryptochrome action in response to green light in combination with other wavelengths.
abstract: Genetic studies have shown the effects of various photoreceptors on early photomorphogenic processes, defining the precise time course of red (RL), far-red (FrL) and blue light (BL) action. In this study, the effect of green wavebands in conjunction with these responses is examined. Longer-term (end point; 24-96 h) analysis of hypocotyl elongation in enriched green environments shows an increase in growth compared to seedlings under blue, red or both together. The effect was only observed at lower fluence rates (<10 μmol/m² s). Genetic analyses demonstrate that cryptochromes are required for this GL effect, consistent with earlier findings, and that the phy receptors have no influence. However, analysis of early (minutes to hours) stem growth kinetics indicates that GL cannot reverse the cryptochrome-mediated BL effect during early stem growth inhibition, and instead acts additively with BL to drive cryptochrome-mediated inhibition. Green light (GL) treatments antagonize RL and FrL-mediated hypocotyl inhibition. The GL opposition of RL responses persists in phyA, phyB, cry1cry2 and phot2 mutants. The response requires phot1 and NPH3, suggesting that this is not a GL response, but instead a response to extremely low-fluence rate BL. Tests with dim BL (<0.1 μmol/m² s) confirm a previously uncharacterized phot1-dependent promotion of stem growth, opposing the effects of RL. These findings demonstrate how enriched green environments may adjust RL and BL photomorphogenic responses through both the crys and phot1 receptors, and define a new role for phot1 in stem growth promotion.
authors.affiliation: Horticultural Sciences Department, University of Florida, 1301 Fifield Hall, PO Box 110690, Gainesville, FL 32611, USA.
authors.forename: Yihai
authors.initials: Y
authors.lastname: Wang
authors.forename: Stefanie A
authors.initials: SA
authors.lastname: Maruhnich
authors.forename: Melissa H
authors.initials: MH
authors.lastname: Mageroy
authors.forename: Jessica Rodean
authors.initials: JR
authors.lastname: Justice
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Folta
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics; D056931:Cryptochromes / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D007700:Kinetics; D008027:Light; D008565:Membrane Proteins; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D010750:Phosphoproteins / Q000235:genetics; D056949:Phototropins / Q000235:genetics*; D051942:Phytochrome A / Q000235:genetics; D051939:Phytochrome B / Q000235:genetics; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases; D020133:Reverse Transcriptase Polymerase Chain Reaction; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C538962:CRY1 protein, Arabidopsis; C103618:CRY2 protein, Arabidopsis; D018797:Cell Cycle Proteins; D056931:Cryptochromes; C109254:HY5 protein, Arabidopsis; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C400222:NPH3 protein, Arabidopsis; D009687:Nuclear Proteins; C423903:PHOT2 protein, Arabidopsis; C497973:PHYA protein, Arabidopsis; C497952:PHYB protein, Arabidopsis; C485609:PKS1 protein, Arabidopsis; D010750:Phosphoproteins; D056949:Phototropins; D051942:Phytochrome A; C118571:SPA1 protein, Arabidopsis; D051939:Phytochrome B; C103646:NPH1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases