9-Lipoxygenase Oxylipin Pathway in Plant Response to Biotic Stress Metadata

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Title

  • Main Title 9-Lipoxygenase Oxylipin Pathway in Plant Response to Biotic Stress

Creator

  • Author: Nalam, Vamsi J.
    Creator Type: Personal

Contributor

  • Chair: Shah, Jyoti
    Contributor Type: Personal
    Contributor Info: Major Professor
  • Committee Member: Ayre, Brian G.
    Contributor Type: Personal
  • Committee Member: Chapman, Kent D.
    Contributor Type: Personal
  • Committee Member: Dickstein, Rebecca
    Contributor Type: Personal
  • Committee Member: Maier, Camelia G.-A.
    Contributor Type: Personal

Publisher

  • Name: University of North Texas
    Place of Publication: Denton, Texas
    Additional Info: www.unt.edu

Date

  • Creation: 2012-05

Language

  • English

Description

  • Content Description: The activity of plant 9-lipoxygenases (LOXs) influences the outcome of Arabidopsis thaliana interaction with pathogen and insects. Evidence provided here indicates that in Arabidopsis, 9-LOXs facilitate infestation by Myzus persicae, commonly known as the green peach aphid (GPA), a sap-sucking insect, and infection by the fungal pathogen Fusarium graminearum. in comparison to the wild-type plant, lox5 mutants, which are deficient in a 9-lipoxygenase, GPA population was smaller and the insect spent less time feeding from sieve elements and xylem, thus resulting in reduced water content and fecundity of GPA. LOX5 expression is induced rapidly in roots of GPA-infested plants. This increase in LOX5 expression is paralleled by an increase in LOX5-synthesized oxylipins in the root and petiole exudates of GPA-infested plants. Micrografting experiments demonstrated that GPA population size was smaller on plants in which the roots were of the lox5 mutant genotype. Exogenous treatment of lox5 mutant roots with 9-hydroxyoctadecanoic acid restored water content and population size of GPA on lox5 mutants. Together, these results suggest that LOX5 genotype in roots is critical for facilitating insect infestation of Arabidopsis. in Arabidopsis, 9-LOX function is also required for facilitating infection by F. graminearum, which is a leading cause of Fusarium head blight (FHB) disease in wheat and other small grain crops. Loss of LOX1 and LOX5 function resulted in enhanced resistance to F. graminearum infection. Similarly in wheat, RNA interference mediated silencing of the 9-LOX homolog TaLpx1, resulted in enhanced resistance to F. graminearum. Experiments in Arabidopsis indicate that 9-LOXs promote susceptibility to this fungus by suppressing the activation of salicylic acid-mediated defense responses that are important for basal resistance to this fungus. the lox1 and lox5 mutants were also compromised for systemic acquired resistance (SAR), an inducible defense mechanism that is systemically activated throughout a plant in response to a localized infection. the lox1 and lox5 mutants exhibited reduced cell death and delayed hypersensitive response when challenged with an avirulent strain of the bacterial pathogen Pseudomonas syringae pv tomato. LOX1 and LOX5 functions were further required for the synthesis as well as perception of a SAR-inducing activity present in petiole exudates collected from wild-type avirulent pathogen-challenged leaves. Taken together, results presented here demonstrate that 9-LOX contribute to host susceptibility as well as defense against different biotic stressors.

Subject

  • Keyword: LOX5
  • Keyword: 9-lipoxygenase
  • Keyword: green peach aphid
  • Keyword: Fusarium

Collection

  • Name: UNT Theses and Dissertations
    Code: UNTETD

Institution

  • Name: UNT Libraries
    Code: UNT

Rights

  • Rights Access: public
  • Rights Holder: Nalam, Vamsi J.
  • Rights License: copyright
  • Rights Statement: Copyright is held by the author, unless otherwise noted. All rights Reserved.

Resource Type

  • Thesis or Dissertation

Format

  • Text

Identifier

  • Archival Resource Key: ark:/67531/metadc115127

Degree

  • Academic Department: Biological Sciences
  • Degree Discipline: Molecular Biology
  • Degree Level: Doctoral
  • Degree Name: Doctor of Philosophy
  • Degree Grantor: University of North Texas
  • Degree Publication Type: disse

Note

  • Embargo Note: Restricted until June 1, 2017
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