Wi, Soo Jin , Park, Ky Young .
Effect of ethylene and polyamines on gene expression of pathogenesis-related proteins against biotic stress.
To investigate the contributions of ethylene in response to biotic stress, the fungal pathogen, Phytophthora parasitica, was treated in transgenic tobacco plants suppressed ethylene biosynthesis with antisense of ACC oxidase gene. It was showed that a significant resistance against this fungal pathogen was induced in these transgenic plants. When we analyzed the gene expression with northern blot for pathogenesis-related (PR) protein genes, the transcript levels of PR-4b, PR-5 and SAR8.2 accumulated slightly more in transgenic plants than wild-type plants without pathogen infection. The treatment with ACC, the precursor of ethylene biosynthesis, caused the more resistance in wild-type and transgenic plants. RNA blot analysis revealed that the expression of PR-4b, PR-5 and TLP genes were increased by ACC treatment, whereas SAR8.2 transcripts were reduced. The transcript levels of chitinase, SAR8.2 and PIII were more strongly induced in the treatment wit AVG, an inhibitor of ACC synthase. Ethylene biosynthetic pathway has a same precursor, SAM, with polyamine biosynthesis, being contrary to each other for senescence and stress resistance in plants. The increased resistance against fungal pathogen was observed in SAMDC-overexpressing transgenic plant S16-S-4 than wild-type plant. Spermidine treatment induced more amounts of the transcripts for chitinase, PR-4b, PR-5, and PIII genes, but reduced the expression of SAR8.2 gene in both type of plants. It can not be concluded that ethylene is a negative effecter for the resistance against biotic stress. It was suggested that each of ethylene or polyamines induced specifically the responsible genes. The defense response in plants might be interpreted the specificity and the superintendence between ethylene and specific PR genes.
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1 - Korea Basic Science Institute, Sunchon Branch, Sunchon National University, 315 Maegok, Sunchon, Chonnam, 540 742, Korea
2 - Sunchon National University, Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM