title: Gravity Persistent Signal 1 (GPS1) reveals novel cytochrome P450s involved in gravitropism.
abstract: OBJECTIVE
  Gravity is an important environmental factor that affects growth and development of plants. In response to changes in gravity, directional growth occurs along the major axes and lateral branches of both shoots and roots. The gravity persistent signal (gps) mutants of Arabidopsis thaliana were previously identified as having an altered response to gravity when reoriented relative to the gravity vector in the cold, with the gps1 mutant exhibiting a complete loss of tropic response under these conditions.
  
  
  METHODS
  Thermal asymmetric interlaced (TAIL) PCR was used to identify the gene defective in gps1. Gene expression data, molecular modeling and computational substrate dockings, quantitative RT-PCR analyses, reporter gene fusions, and physiological analyses of knockout mutants were used to characterize the genes identified.
  
  
  RESULTS
  Cloning of the gene defective in gps1 and genetic complementation revealed that GPS1 encodes CYP705A22, a cytochrome P450 monooxygenase (P450). CYP705A5, a closely related family member, was identified as expressed specifically in roots in response to gravistimulation, and a mutation affecting its expression resulted in a delayed gravity response, increased flavonol levels, and decreased basipetal auxin transport. Molecular modeling coupled with in silico substrate docking and diphenylboric acid 2-aminoethyl ester (DBPA) staining indicated that these P450s are involved in biosynthesis of flavonoids potentially involved in auxin transport.
  
  
  CONCLUSIONS
  The characterization of two novel P450s (CYP705A22 and CYP705A5) and their role in the gravity response has offered new insights into the regulation of the genetic and physiological controls of plant gravitropism.
authors.affiliation: Department of Environmental and Plant Biology, 317 Porter Hall, Ohio University, Athens, Ohio 45701, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Withers
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Shipp
authors.forename: Sanjeewa G
authors.initials: SG
authors.lastname: Rupasinghe
authors.forename: Poornima
authors.initials: P
authors.lastname: Sukumar
authors.forename: Mary A
authors.initials: MA
authors.lastname: Schuler
authors.forename: Gloria K
authors.initials: GK
authors.lastname: Muday
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Wyatt
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D056426:Genetic Loci / Q000235:genetics; D018522:Gravitropism / Q000187:drug effects / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D010710:Phosphates / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D010710:Phosphates; D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System; C581568:GPS1 protein, Arabidopsis