BAS1: A Gene Regulating Brassinosteroid Levels and Light Responsiveness in Arabidopsis

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 26; pp. 15316 - 15323
• Main Authors: Neff, Michael M., Nguyen, Serena M., Malancharuvil, Elizabeth J., Fujioka, Shozo, Noguchi, Takahiro, Seto, Hideharu, Tsubuki, Masayoshi, Honda, Toshio, Takatsuto, Suguru, Yoshida, Shigeo, Chory, Joanne
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 21.12.1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Series: Inaugural Article
• Subjects: 26-hydroxybrassinolide; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - radiation effects; Arabidopsis Proteins; Arabidopsis thaliana; BAS1 gene; Biological Sciences; Biology; Biosynthesis; Brassinosteroids; Cholestanols - pharmacology; Complementary DNA; Cryptochromes; CYP72B1 gene; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Drosophila Proteins; Eye Proteins; Flavoproteins - genetics; Flowers & plants; Genes; Genes, Plant; Genetic mutation; Hypocotyls; Light; Mutation; Nicotiana - genetics; Peroxidases - genetics; Peroxiredoxins; Phenotypes; Photoreceptor Cells; Photoreceptor Cells, Invertebrate; Photoreceptors; phyA gene; phyB gene; Phytochrome - genetics; Phytochrome B; Phytosterols - biosynthesis; Plants; Plants, Toxic; Receptors, G-Protein-Coupled; Seedlings; Signal Transduction; Steroids, Heterocyclic - pharmacology; Suppression, Genetic; Transcription Factors; Transformation, Genetic
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.26.15316

The Arabidopsis bas1-D mutation suppresses the long hypocotyl phenotype caused by mutations in the photoreceptor phytochrome B (phyB). The adult phenotype of bas1-D phyB-4 double mutants mimics that of brassinosteroid biosynthetic and response mutants. bas1-D phyB-4 has reduced levels of brassinosteroids and accumulates 26-hydroxybrassinolide in feeding experiments. The basis for the mutant phenotype is the enhanced expression of a cytochrome P450 (CYP72B1). bas1-D suppresses a phyB-null allele, but not a phyA-null mutation, and partially suppresses a cryptochrome-null mutation. Seedlings with reduced BAS1 expression are hyperresponsive to brassinosteroids in a light-dependent manner and display reduced sensitivity to light under a variety of conditions. Thus, BAS1 represents one of the control points between multiple photoreceptor systems and brassinosteroid signal transduction.