101. Blocking the QB-binding site of photosystem II by tenuazonic acid, a non-host-specific toxin of A lternaria alternata, activates singlet oxygen-mediated and EXECUTER-dependent signalling in Arabidopsis.
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CHEN, SHIGUO, KIM, CHANHONG, LEE, JE MIN, LEE, HYUN‐AH, FEI, ZHANGJUN, WANG, LIANGSHENG, and APEL, KLAUS
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ARABIDOPSIS , *PHOTOSYSTEMS , *ALTERNARIA alternata , *MYCOTOXINS , *APOPTOSIS - 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 A lternaria alternata, on A rabidopsis 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 (1 O 2). 1 O 2 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 1 O 2-mediated and EX-dependent signalling is activated as indicated by the rapid and transient up-regulation of 1 O 2-responsive genes in wild type, and its suppression in ex 1/ ex 2 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 1 O 2-mediated and EX-dependent signalling is superimposed by other events that also contribute to lesion formation. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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