Abstract
Many toxic secondary metabolites produced by phytopathogens can subvert host immunity, and some of them are recognized as pathogenicity factors. Fusarium head blight and Verticillium wilt are destructive plant diseases worldwide. Using toxins produced by the causal fungi Fusarium graminearum and Verticillium dahliae as screening agents, here we show that the Arabidopsis P4 ATPases AtALA1 and AtALA7 are responsible for cellular detoxification of mycotoxins. Through AtALA1-/AtALA7-mediated vesicle transport, toxins are sequestered in vacuoles for degradation. Overexpression of AtALA1 and AtALA7 significantly increases the resistance of transgenic plants to F. graminearum and V. dahliae, respectively. Notably, the concentration of deoxynivalenol, a mycotoxin harmful to the health of humans and animals, was decreased in transgenic Arabidopsis siliques and maize seeds. This vesicle-mediated cell detoxification process provides a strategy to increase plant resistance against different toxin-associated diseases and to reduce the mycotoxin contamination in food and feed.
Highlights
Many toxic secondary metabolites produced by phytopathogens can subvert host immunity, and some of them are recognized as pathogenicity factors
To investigate whether defects in AtALA1 and AtALA7 could affect the accumulation of toxins in vacuoles, we treated ala[1] and ala[7] mutants with DON labeled with 5-carboxyfluorescein (DON5-FAM) and cinnamate acetate (CIA) labeled with fluorescein-isothiocyanate-isomer (CIAFITC), which did not impair the toxicity of either DON (Supplementary Fig. 3a, b) or CIA (Supplementary Fig. 3c, d)
With DON5-FAM treatment, no obvious fluorescent signal was observed in the vacuoles of cells of ala[1] mutant, whereas the signal appeared obvious in the vacuoles of other mutants (Fig. 1d, e and Supplementary Fig. 2c, d)
Summary
Many toxic secondary metabolites produced by phytopathogens can subvert host immunity, and some of them are recognized as pathogenicity factors. The concentration of deoxynivalenol, a mycotoxin harmful to the health of humans and animals, was decreased in transgenic Arabidopsis siliques and maize seeds This vesicle-mediated cell detoxification process provides a strategy to increase plant resistance against different toxinassociated diseases and to reduce the mycotoxin contamination in food and feed. The fungus produces epoxy-sesquiterpenoid compounds, named trichothecenes, including deoxynivalenol (DON), T-2 toxin, HT-2 toxin, and nivalenol[7,12] These mycotoxins can evoke the rapid generation of reactive oxygen species that stimulate apoptosis-like processes and result in chlorotic and necrotic lesions, growth cessation, or even plant death[13,14,15,16,17]. It was found that Fhb[7] encodes a glutathione-S-transferase (GST)
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