title: Phytochrome modulation of blue light-induced chloroplast movements in Arabidopsis.
abstract: Photometric analysis of chloroplast movements in various phytochrome (phy) mutants of Arabidopsis showed that phyA, B, and D are not required for chloroplast movements because blue light (BL)-dependent chloroplast migration still occurs in these mutants. However, mutants lacking phyA or phyB showed an enhanced response at fluence rates of BL above 10 micromol m-2 s-1. Overexpression of phyA or phyB resulted in an enhancement of the low-light response. Analysis of chloroplast movements within the range of BL intensities in which the transition between the low- and high-light responses occur (1.5-15 micromol m-2 s-1) revealed a transient increase in light transmittance through leaves, indicative of the high-light response, followed by a decrease in transmittance to a value below that measured before the BL treatment, indicative of the low-light response. A biphasic response was not observed for phyABD leaves exposed to the same fluence rate of BL, suggesting that phys play a role in modulating the transition between the low- and high-light chloroplast movement responses of Arabidopsis.
authors: Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
authors: Stacy L
authors: SL
authors: DeBlasio
authors: Jack L
authors: JL
authors: Mullen
authors: Darron R
authors: DR
authors: Luesse
authors: Roger P
authors: RP
authors: Hangarter
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D002736:Chloroplasts / Q000502:physiology* / Q000528:radiation effects; D017353:Gene Deletion; D007700:Kinetics; D008027:Light; D009068:Movement; D016296:Mutagenesis; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects
chemical_list: D010834:Phytochrome