title: Phytochrome A-mediated inhibition of seed germination in tomato.
abstract: Far-red light (FR) inhibition of seed germination of tomato (Solanum lycopersicum L.) was studied with the phytochrome (phy)-hypersensitive mutants, hp-1w, hp-1w,fri1, a phyA-deficient double mutant, and hp-1w,tri1, a phyB1-deficient double mutant. Seeds of all mutants germinated readily in the dark at 25 degrees C, and the germination was retarded by a single 100-s FR pulse given 1-3 h after sowing. The effect of an FR pulse was red-light reversible in all mutants used. After 24 h where a single FR pulse was no longer effective, prolonged FR exposure or hourly FR pulses suppressed germination in hp-1w and hp-1w,tri1, whereas in hp-1w,fri1 the suppressive effect of FR was almost absent. The effect of the prolonged FR was greater than that of the hourly 3-min FR pulses having equal photon fluence, and was fluencerate dependent. Thus we conclude that the germination inhibition by FR in tomato seed consists of a low-fluence response and a high irradiance response (HIR); the latter is controlled by phyA, but not phyB1. This is the first indication of phyA being involved in the HIR of seed germination inhibition.
authors.affiliation: Department of Biology, Faculty of Science, Kobe University, Japan. shichijo@biol.kobe-u.ac.jp
authors.forename: C
authors.initials: C
authors.lastname: Shichijo
authors.forename: K
authors.initials: K
authors.lastname: Katada
authors.forename: O
authors.initials: O
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
mesh_terms: D001059:Apoproteins / Q000235:genetics / Q000378:metabolism; D018525:Germination / Q000528:radiation effects*; D008027:Light; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D009154:Mutation; D010786:Photoreceptor Cells; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism*; D051942:Phytochrome A; D051939:Phytochrome B; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D012639:Seeds / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D013997:Time Factors; D014157:Transcription Factors
chemical_list: D001059:Apoproteins; C116403:PHYB1 protein, Lycopersicon esculentum; D045322:Photosynthetic Reaction Center Complex Proteins; D051942:Phytochrome A; D010940:Plant Proteins; D014157:Transcription Factors; D010834:Phytochrome; D051939:Phytochrome B