title: Two GRAS proteins, SCARECROW-LIKE21 and PHYTOCHROME A SIGNAL TRANSDUCTION1, function cooperatively in phytochrome A signal transduction.
abstract: Photoreceptors, especially the far-red light-absorbing phytochrome A, play a crucial role in early seedling development, triggering the transition from etiolated to photomorphogenic growth. Here, we describe the biological functions of two GRAS proteins from Arabidopsis (Arabidopsis thaliana), SCARECROW-LIKE21 (SCL21) and PHYTOCHROME A SIGNAL TRANSDUCTION1 (PAT1), which are specifically involved in phytochrome A signal transduction. Loss-of-function mutants show an elongated hypocotyl under far-red light and are impaired in other far-red high-irradiance responses. The SCL21 transcript itself is down-regulated by far-red light in a phytochrome A- and PAT1-dependent manner. Our results demonstrate that both SCL21 and PAT1 are positive regulators of phytochrome A signal transduction for several high-irradiance responses. Genetic and biochemical evidence suggest a direct interaction of the two proteins.
authors.affiliation: Lehrstuhl für Molekularbiologie der Pflanzen, Department Biologie I, Ludwig-Maximilians-Universität München, D-82152 Planegg-Martinsried, Germany.
authors.forename: Patricia
authors.initials: P
authors.lastname: Torres-Galea
authors.forename: Birgit
authors.initials: B
authors.lastname: Hirtreiter
authors.forename: Cordelia
authors.initials: C
authors.lastname: Bolle
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D004843:Epistasis, Genetic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D018546:Hypocotyl / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D008969:Molecular Sequence Data; D010641:Phenotype; D055519:Photoreceptors, Plant / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010834:Phytochrome / Q000235:genetics / Q000378:metabolism*; D051942:Phytochrome A / Q000235:genetics / Q000378:metabolism*; D025941:Protein Interaction Mapping; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C409842:PAT1 protein, Arabidopsis; C497973:PHYA protein, Arabidopsis; D055519:Photoreceptors, Plant; D051942:Phytochrome A; D012333:RNA, Messenger; D010834:Phytochrome