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bioRxiv · 10.1101/2023.12.01.569535

The pathogenic coronatine toxin hijacks host redox signalling to suppress plant immunity

Frungillo, L.·Oka, N.·Lee, S.-U.·Nomoto, M.·Yun, B.-W.·Tada, Y.·Spoel, S. H.
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Abstract

Reciprocal antagonism between the hormones salicylic acid (SA) and jasmonic acid (JA) is particularly important during infection by the bacterial pathogen Pseudomonas syringae. P. syringae secretion of the virulence-promoting toxin, coronatine, is thought to suppress SA-induced immune responses by manipulating host JA signalling. Here, we report an unexpected JA-independent role of coronatine in promoting pathogen virulence. While JA induced resistance to P. syringae, coronatine promoted pathogen virulence by suppressing cellular accumulation of glutathione, a vital antioxidant required for immunity. Coronatine-mediated suppression of glutathione levels prevented activation of NPR1, a redox-sensitive master regulator of SA-responsive immune genes. Moreover, the accrual of nitric oxide (NO) restored virulence of coronatine-deficient P. syringae, but was counteracted by expression of the host S-nitrosothiol reductase, Thioredoxin h5. Thus, our findings indicate P. syringae utilises coronatine to suppresses host immunity by precisely manipulating glutathione- and NO-mediated redox signalling networks.

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Frungillo, L., Oka, N., Lee, S.-U., Nomoto, M., Yun, B.-W., Tada, Y., Spoel, S. H.. 2023-12-01. The pathogenic coronatine toxin hijacks host redox signalling to suppress plant immunity. https://doi.org/10.1101/2023.12.01.569535

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