9 How plants defend themselves II - Copy

9 How plants defend themselves II - Copy - PP 315 / 590J...

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Lecture 9 How plants defend themselves II Objectives Understand plant defense mechanisms against colonizing pathogens. Defense mechanisms may be  structurally preformed or induced as well as chemically preformed. Chemically induced defense  mechanisms are discussed in lecture 10. Resistance (defense) mechanisms in plants may be  structural (physical) or chemical . In each type,  there are  preformed  (present before infection) and  induced  (formed in response to infection)  mechanisms.  Structural Defense Mechanisms - Preformed 1)  Cuticle  - primary structural (physical) barrier that plants have to most organisms;       - waxes on surface may prevent wetting (a requirement for infection by most fungi) 2)  Trichomes  - prevent wetting of leaf surface Structural Defense Mechanisms -   1)  Cork layers  - production of several layers of cork cells beyond the point of infection; they stop  pathogen colonization by:      a) provide a physical barrier to pathogen      b) provide a barrier to movement of pathogen enzymes and toxins out of lesion      c) prevent movement of water and nutrients to pathogen      d) direct toxicity of wall precursors (e. g. phenols) to the          pathogen.
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This note was uploaded on 03/22/2008 for the course PP 315 taught by Professor Shew during the Spring '08 term at N.C. State.

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9 How plants defend themselves II - Copy - PP 315 / 590J...

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