title: A role for IAA in the infection of Arabidopsis thaliana by Orobanche aegyptiaca.
abstract: BACKGROUND
  Vascular continuity is established between a host plant and the root parasite broomrape. It is generally accepted that the direction of vascular continuity results from polar flow of auxin. Our hypothesis was that chemical disruptions of auxin transport and activity could influence the infection of the host by the parasite.
  
  
  METHODS
  A sterile system for the routine infection of Arabidopsis thaliana seedlings in Nunc cell culture plates by germinated seeds of Orobanche aegyptiaca was developed. This method permitted a quantitative assay of the rate of host infection. The three-dimensional structure of the vascular contacts was followed in cleared tissue. IAA (indole acetic acid) or substances that influence its activity and transport were applied locally to the host root.
  
  
  RESULTS
  The orientation of the xylem contacts showed that broomrape grafts itself upon the host by acting hormonally as a root rather than a shoot. Local applications of IAA, PCIB (p-chlorophenoxyisobutyric acid) or NPA (naphthylphthalamic acid) all resulted in drastic reductions of Orobanche infection
  
  
  CONCLUSIONS
  Broomrape manipulates the host by acting as a sink for auxin. Disruption of auxin action or auxin flow at the contact site could be a novel basis for controlling infection by Orobanche.
authors: Department of Plant and Environmental Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors: Nurit
authors: N
authors: Bar-Nun
authors: Tsvi
authors: T
authors: Sachs
authors: Alfred M
authors: AM
authors: Mayer
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects* / Q000469:parasitology*; D049109:Cell Proliferation / Q000187:drug effects; D002995:Clofibric Acid / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000494:pharmacology*; D031672:Orobanche / Q000502:physiology*; D010797:Phthalimides / Q000494:pharmacology; D010935:Plant Diseases / Q000469:parasitology*; D018517:Plant Roots / Q000187:drug effects / Q000469:parasitology; D052584:Xylem / Q000166:cytology / Q000187:drug effects / Q000469:parasitology
chemical_list: D007210:Indoleacetic Acids; D010797:Phthalimides; C002687:alpha-naphthylphthalamic acid; D002995:Clofibric Acid; C030737:indoleacetic acid