Phototropins Mediate Blue and Red Light-Induced Chloroplast Movements in Physcomitrella patens

• Published in: Plant physiology (Bethesda) Vol. 135; no. 3; pp. 1388 - 1397
• Main Authors: Kasahara, Masahiro, Kagawa, Takatoshi, Yoshikatsu Sato, Kiyosue, Tomohiro, Wada, Masamitsu
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.07.2004; American Society of Plant Physiologists
• Subjects: Base Sequence; Biological and medical sciences; blue light; Bryophyta; Bryophyta - classification; Bryophyta - drug effects; Bryophyta - physiology; Bryophyta - ultrastructure; Cell Biology and Signal Transduction; Cell motility; Cell motion; Cell physiology; Chloroplasts; Chloroplasts - drug effects; Chloroplasts - physiology; classification; Cloning, Molecular; complementary DNA; Cryptochromes; DNA; DNA Primers; drug effects; flavoproteins; Flavoproteins - genetics; Flavoproteins - physiology; Fluence; Fundamental and applied biological sciences. Psychology; Gene Deletion; Gene Expression Regulation, Plant; Gene Expression Regulation, Plant - genetics; Genetic vectors; genetics; Irradiation; Light; Lighting; metabolism; Microbeams; Models, Biological; Molecular Sequence Data; mosses and liverworts; Movement; Movement - drug effects; Movement - physiology; mutants; Mutation; nucleotide sequences; Photoreceptors; Phylogeny; Physcomitrella patens; physiology; Plant cells; Plant physiology and development; Plant Proteins; Plant Proteins - genetics; Plant Proteins - physiology; Receptors; Recombinant Proteins; Recombinant Proteins - metabolism; red light; ultrastructure; Intracellular movement; Musci; Arabidopsis; Photoreceptor; Phototropism; Red light; Bryophyta; Stomata; Complementary DNA; Gene; Cruciferae; Dicotyledones; Angiospermae; Phytochrome; Spermatophyta; Blue light; Chloroplast; Aminoacid sequence
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.042705

Phototropin is the blue-light receptor that mediates phototropism, chloroplast movement, and stomatal opening in Arabidopsis. Blue and red light induce chloroplast movement in the moss Physcomitrella patens. To study the photoreceptors for chloroplast movement in P. patens, four phototropin genes (PHOTA1, PHOTA2, PHOTB1, and PHOTB2) were isolated by screening cDNA libraries. These genes were classified into two groups (PHOTA and PHOTB) on the basis of their deduced amino acid sequences. Then phototropin disruptants were generated by homologous recombination and used for analysis of chloroplast movement. Data revealed that blue light-induced chloroplast movement was mediated by phototropins in P. patens. Both photA and photB groups were able to mediate chloroplast avoidance, as has been reported for Arabidopsis phot2, although the photA group contributed more to the response. Red light-induced chloroplast movement was also significantly reduced in photA2photB1photB2 triple disruptants. Because the primary photoreceptor for red light-induced chloroplast movement in P. patens is phytochrome, phototropins may be downstream components of phytochromes in the signaling pathway. To our knowledge, this work is the first to show a function for the phototropin blue-light receptor in a response to wavelengths that it does not absorb.