Molecular Plant Pathology (2006) 7, 325-339

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Shigehito Takenaka, Yumi Nakamura, Tamaki Kono, Hiroyuki Sekiguchi, Akira Masunaka and Hideki Takahashi (2006)
Novel elicitin-like proteins isolated from the cell wall of the biocontrol agent Pythium oligandrum induce defence-related genes in sugar beet
Molecular Plant Pathology 7 (5), 325-339
Abstract: We previously reported that cell wall protein fractions (CWPs) of the biocontrol agent Pythium oligandrum have elicitor properties in sugar beet and wheat. Here we have examined the effect of treatment with the D-type of CWP, a fraction that contains two major forms (POD-1 and POD-2), on the induction of defence-related genes in sugar beet. Using PCR-based cDNA library subtraction, we identified five genes that were highly expressed in response to CWP treatment. The five genes are probably of oxalate oxidase-like germin (OxOLG), glutathione S-transferase (GST), 5-enol-pyruvylshikimate-phosphate synthase (EPSPS), phenylalanine ammonia-lyase (PAL) and aspartate aminotransferase (AAT). In addition, we purified and characterized POD-1 and POD-2 and found that POD-1 induced all five genes, whereas POD-2 induced three of the genes, but not OxOLG or GST. A sugar beet bioassay indicated that CWP, POD-1 and POD-2 are each sufficient to induce resistance to sugar beet seedling disease caused by Aphanomyces cochlioides. Although carbohydrate analyses indicated that POD proteins were glycoproteins with similar carbohydrate compositions, containing approximately 15.0% carbohydrate by weight, their peptide portions have elicitor activity. Furthermore, cDNAs of POD-1 and POD-2 proteins were cloned, and the deduced amino acid sequences were found to be 82.9% identical. Characterization of their molecular structures indicated that they have an elicitin domain followed by a C-terminal domain with a high frequency of Ser, Thr, Ala and Pro, which is structurally similar to class III elicitins. However, phylogenetic analysis with 22 representative elicitin and elicitin-like proteins showed that POD-1 and POD-2 are distinct from previously defined elicitin and elicitin-like proteins. Therefore, POD-1 and POD-2 are novel oomycete cell wall elicitin-like glycoproteins.
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Link to article at publishers website
Database assignments for author(s): Shigehito Takenaka, Hideki Takahashi

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Aphanomyces cochlioides Beet/sugarbeet (Beta vulgaris)
Pythium oligandrum (antagonist) Aphanomyces cochlioides Beet/sugarbeet (Beta vulgaris)