Implications of oligomeric forms of POD-1 and POD-2 proteins isolated from cell walls of the biocontrol agent Pythium oligandrum in relation to their ability to induce defense reactions in tomato

Shigehito Takenaka, Keishi Yamaguchi, Akira Masunaka, Syu Hase, Tsuyoshi Inoue, Hideki Takahashi

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    The cell wall protein fraction (CWP) isolated from the biocontrol agent Pythium oligandrum induces defense reactions in tomato. CWP contains two novel elicitin-like proteins, POD-1 and POD-2, both with seven cysteines. To determine the essential structure in the defense-eliciting components of CWP, five fractions (F1, F2, F3, F4 and F5) were fractionated from CWP using cation chromatography and their components and disulfide bond compositions were analyzed. The expression levels of three defense-related genes (PR-6, LeCAS and PR-2b) were determined in tomato roots treated with each of the five fractions. Of the five fractions, F4 containing a heterohexamer of POD-1 and POD-2, and F5 containing a homohexamer of POD-1, both with disulfide bonds formed between all cysteine residues, induced the expression of three genes. F4 treatment also induced the accumulation of ethylene in tomato. The predicted three-dimensional structures of POD-1 and POD-2, and the results of SEC and MALDI-TOF MS analyses suggest that F4 consists of three POD-1 and POD-2 disulfide-bonded heterodimers that interleave into a hexameric ring through noncovalent association. These results suggest that this structure, which F5 also appears to form, is essential for stimulating defense responses in tomato.

    Original languageEnglish
    Pages (from-to)1972-1979
    Number of pages8
    JournalJournal of Plant Physiology
    Volume168
    Issue number16
    DOIs
    Publication statusPublished - 2011 Nov 1

    Keywords

    • Biocontrol agent
    • Cell wall protein
    • Elicitor
    • Induced resistance
    • Pythium oligandrum
    • Tomato

    ASJC Scopus subject areas

    • Physiology
    • Agronomy and Crop Science
    • Plant Science

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