The Study of Arabidopsis thaliana Trichomes for Source of Chemical Defense Against Pathogens
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Date
2009-06
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The Ohio State University
Abstract
Trichomes on plants, such as Arabidopsis, may provide a physical barrier to pathogen infection. Evidence for Arabidopsis trichomes to secrete chemicals or signals to inhibit pathogen attack is not presently available. The pathogenesis-related protein, PR-1 is expressed in several plant species after infection with Pseudomonas syringae pv. phaseolicola (P. s. pv. phaseolicola) or its hrp mutant. Mutations in Pseudomonas in the hypersensitive response and pathogenicity genes are called hrp mutants, which is a Type Three Secretion System deficient (TTSS-) strain. The main objective of this study is to observe the induction of PR-1 proteins in trichomes, Columbia wildtype leaves, and Columbia gl1 (GLABROUS 1) mutant leaves when inoculated with P. s. pv. phaseolicola. The hrp mutant serves as the control with little or no induction of PR-1. Previous studies show P. s. pv. phaseolicola and the hrp mutant induce PR-1 proteins in Arabidopsis Columbia wildtype leaves. Testing of the objective will be accomplished by growing Arabidopsis Columbia wildtype and gl1 mutant seedlings and inoculating with P. s. pv. phaseolicola, hrp mutant, or distilled water as control treatment. RNA from leaves and trichomes will be analyzed by performing real time Reverse-Transcription Polymerase Chain Reaction (RT-PCR). A technique was established to efficiently isolate trichomes from the surface of Arabidopsis’s leaves and study PR-1 in trichomes specifically. PR-1 is expressed in wildtype trichomes after induced by P. s. pv. phaseolicola independent of TTSS. P. s. pv. phaseolicola induced PR-1 in wildtype leaves at significantly high levels (one sided t-test, p<0.05). Hrp mutant (TTSS-) induced significantly high level of PR-1 in gl1 mutant leaves (one sided t-test, p<0.05). Evidence of PR-1 in trichomes strongly suggests that trichomes have a defense mechanism to detect pathogen infection. This study provides evidence for loss of the GL1 genes to play a role in defense mechanisms against pathogens. Results from this study and future studies will be applicable to pathogen induced trichome defense mechanisms.
Description
First place at CFAES Forum in Environmental and Plant Sciences Division
Third place at Denman Forum in Agriculture/Environmental Science Division
Third place at Denman Forum in Agriculture/Environmental Science Division
Keywords
Arabidopsis trichomes as defense mechanism against pathogen