Blocking the QB-binding site of photosystem II by tenuazonic acid, a non-host-specific toxin of Alternaria alternata, activates singlet oxygen-mediated and EXECUTER-dependent signalling in Arabidopsis

Shiguo Chen, Chanhong Kim, Je Min Lee, Hyun Ah Lee, Zhangjun Fei, Liangsheng Wang, Klaus Apel

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Necrotrophic fungal pathogens produce toxic compounds that induce cell death in infected plants. Often, the primary targets of these toxins and the way a plant responds to them are not known. In the present work, the effect of tenuazonic acid (TeA), a non-host-specific toxin of Alternaria alternata, on Arabidopsis thaliana has been analysed. TeA blocks the QB-binding site at the acceptor side of photosystem II (PSII). As a result, charge recombination at the reaction centre (RC) of PSII is expected to enhance the formation of the excited triplet state of the RC chlorophyll that promotes generation of singlet oxygen (1O2). 1O2 activates a signalling pathway that depends on the two EXECUTER (EX) proteins EX1 and EX2 and triggers a programmed cell death response. In seedlings treated with TeA at half-inhibition concentration 1O2-mediated and EX-dependent signalling is activated as indicated by the rapid and transient up-regulation of 1O2-responsive genes in wild type, and its suppression in ex1/ex2 mutants. Lesion formation occurs when seedlings are exposed to higher concentrations of TeA for a longer period of time. Under these conditions, the programmed cell death response triggered by 1O2-mediated and EX-dependent signalling is superimposed by other events that also contribute to lesion formation.

Original languageEnglish
Pages (from-to)1069-1080
Number of pages12
JournalPlant, Cell and Environment
Volume38
Issue number6
DOIs
StatePublished - 1 Jun 2015

Keywords

  • Arabidopsis thaliana
  • Necrotrophic pathogens
  • Photosynthetic electron transport
  • Programmed cell death

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