1. Alternaria TeA toxin activates a chloroplast retrograde signaling pathway to facilitate JA-dependent pathogenicity.
- Author
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Shi J, Wang H, Li M, Mi L, Gao Y, Qiang S, Zhang Y, Chen D, Dai X, Ma H, Lu H, Kim C, and Chen S
- Subjects
- Tenuazonic Acid metabolism, Singlet Oxygen metabolism, Virulence, Chloroplasts metabolism, Plants metabolism, Signal Transduction, Alternaria metabolism, Arabidopsis genetics
- Abstract
The chloroplast is a critical battleground in the arms race between plants and pathogens. Among microbe-secreted mycotoxins, tenuazonic acid (TeA), produced by the genus Alternaria and other phytopathogenic fungi, inhibits photosynthesis, leading to a burst of photosynthetic singlet oxygen (
1 O2 ) that is implicated in damage and chloroplast-to-nucleus retrograde signaling. Despite the significant crop damage caused by Alternaria pathogens, our understanding of the molecular mechanism by which TeA promotes pathogenicity and cognate plant defense responses remains fragmentary. We now reveal that A. alternata induces necrotrophic foliar lesions by harnessing EXECUTER1 (EX1)/EX2-mediated chloroplast-to-nucleus retrograde signaling activated by TeA toxin-derived photosynthetic1 O2 in Arabidopsis thaliana. Mutation of the1 O2 -sensitive EX1-W643 residue or complete deletion of the EX1 singlet oxygen sensor domain compromises expression of1 O2 -responsive nuclear genes and foliar lesions. We also found that TeA toxin rapidly induces nuclear genes implicated in jasmonic acid (JA) synthesis and signaling, and EX1-mediated retrograde signaling appears to be critical for establishing a signaling cascade from1 O2 to JA. The present study sheds new light on the foliar pathogenicity of A. alternata, during which EX1-dependent1 O2 signaling induces JA-dependent foliar cell death., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)- Published
- 2024
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