A SNARE-protein has opposing functions in penetration resistance and defence signalling pathways

Ziguo Zhang, Angela Feechan, Carsten Pedersen, Mari-Anne Newman, Qiu Jin-long, Karen L. Olesen, Hans Thordal-Christensen

    Research output: Contribution to journalJournal articleResearchpeer-review

    138 Citations (Scopus)

    Abstract

    Penetration resistance is often the first line of defence against fungal pathogens. Subsequently induced defences are mediated by the programmed cell death (PCD) reaction pathway and the salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) signalling pathways. We previously demonstrated that full penetration resistance in Arabidopsis against the non-host barley powdery mildew fungus (Blumeria graminis f.sp. hordei) requires the syntaxin SYP121 (PEN1). Here we report that SYP121, together with SYP122, functions as a negative regulator of subsequently induced defence pathways. The SA level in the syntaxin double mutant syp121-1 syp122-1 is dramatically elevated, resulting in necrosis and dwarfism. This phenotype is partially rescued by introducing the SA-signalling mutations eds1-2, eds5-3, sid2-1 and npr1-1 as well as the NahG transgene. These partially rescued triple mutants have an unknown defence to Pseudomonas syringae pv. tomato, and have increased HR-like responses to non-host and host powdery mildew fungi. The HR-like responses cause efficient resistance to the latter. These defence pathways are SA-independent. Furthermore, the JA/ET signalling marker, PDF1.2, is highly upregulated in the triple mutants. Thus SYP121 and SYP122 are negative regulators of PCD, SA, JA and ET pathways through a molecular function distinct from that of SYP121 in penetration resistance. Our data suggest that individual cells preferentially express either penetration resistance or the subsequently induced defences.

    Original languageEnglish
    JournalPlant Journal
    Volume49
    Issue number2
    Pages (from-to)302-312
    Number of pages11
    ISSN0960-7412
    DOIs
    Publication statusPublished - 2007

    Keywords

    • Former LIFE faculty
    • syntaxins, penetration, salicylic acid, jasmonic acid, powdery mildew, programmed cell death.

    Cite this