New Phytologist (2020) 226, 189-204

Andree Schmidt, Rebecca Mächtel, Alexandra Ammon, Timo Engelsdorf, Jessica Schmitz, Veronica G. Maurino and Lars M. Voll (2020)
Reactive oxygen species dosage in Arabidopsis chloroplasts can improve resistance towards Colletotrichum higginsianum by the induction of WRKY33
New Phytologist 226 (1), 189-204
Abstract: - Arabidopsis plants overexpressing glycolate oxidase in chloroplasts (GO5) and loss-of-function mutants of the major peroxisomal catalase isoform, cat2-2, produce increased hydrogen peroxide (H₂O₂) amounts from the respective organelles when subjected to photorespiratory conditions like increased light intensity.
- Here, we have investigated if and how the signaling processes triggered by H₂O₂ production in response to shifts in environmental conditions and the concomitant induction of indole phytoalexin biosynthesis in GO5 affect susceptibility towards the hemibiotrophic fungus Colletotrichum higginsianum.
- Combining histological, biochemical, and molecular assays, we found that the accumulation of the phytoalexin camalexin was comparable between GO genotypes and cat2-2 in the absence of pathogen. Compared with wild-type, GO5 showed improved resistance after light-shift-mediated production of H₂O₂, whereas cat2-2 became more susceptible and allowed significantly more pathogen entry. Unlike GO5, cat2-2 suffered from severe oxidative stress after light shifts, as indicated by glutathione pool size and oxidation state.
- We discuss a connection between elevated oxidative stress and dampened induction of salicylic acid mediated defense in cat2-2. Genetic analyses demonstrated that induced resistance of GO5 is dependent on WRKY33, but not on camalexin production. We propose that indole carbonyl nitriles might play a role in defense against C. higginsianum.
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Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

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