Gravity persistent signal 1 (GPS1) reveals novel cytochrome P450s involved in Gravitropism

John C. Withers, Matthew J. Shipp, Sanjeewa G. Rupasinghe, Poornima Sukumar, Mary A. Schuler, Gloria K. Muday, Sarah E. Wyatt

Research output: Contribution to journalArticlepeer-review

Abstract

Premise: Gravity is an important environmental factor that affects growth and development of plants. In response to changes in gravity, irectional 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 gpsl 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 di-phenylboric acid 2-aminoethyl ester (DBPA) staining indicated that these P450s are involved in biosynthesis of flavonoids potentially involved in auxin transport. Conclusion: 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.

Original languageEnglish (US)
Pages (from-to)183-193
Number of pages11
JournalAmerican journal of botany
Volume100
Issue number1
DOIs
StatePublished - Jan 1 2013

Keywords

  • Arabidopsis thaliana
  • Brassicaceae
  • Cytochrome P450
  • Flavonoids
  • Gravitropism
  • Gravity
  • Monooxygenases
  • Signal transduction

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Plant Science

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