Gene expression reveals differences between symptomatic and asymptomatic infection in tobacco

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Pectobacterium atrosepticum is a bacterium that causes blackleg in potatoes, visible as a black rotting of stem bases. Despite being highly visible, it can be hard to spot in plants as it can be asymptomatic for long periods. Vladimir Gorshkov and colleagues compared the physiology and biochemistry of symptomatic and asymptomatic infections. The botanists had identified jasmonates as a key sign of symptomatic infections. These chemicals are the product of a lipoxygenase cascade that triggers many other reactions in the plant. The team studied the lipoxygenase cascade in symptomatic and asymptomatic infections to understand how plants and pectobacteria interact.

Three leaves with many acronyms and arrows on them. The letters are larger on the infected leaves, with the typical infection leaf having a large JA for Jasmonic Acid, that the other two leaves lack. — Schematic representation of the modulation of the lipoxygenase cascade during typical and latent *Pectobacterium atrosepticum* infections compared to control non-infected plants. Image: Gorshkov *et al*. 2022.

Gorshkov and colleagues used three groups of tobacco plants. The first were mock-inoculated so that they were a control group. The other two groups were either infected with wild-type P. atrosepticum or a mutant that produced a latent, asymptomatic infection. The scientists then measured the expression levels of target lipoxygenase cascade-related genes. They found that latent, asymptomatic P. atrosepticum infection is associated with decreased levels of 9-lipoxygenase branch products and jasmonic acid and an increased level of cis-12-oxo-10,15-phytodienoic acid.

In a commentary on the article, Claus Wasternack said that Gorshkov and colleagues have demonstrated that the oxylipin signature provides a powerful heuristic for unravelling the plant-pathogen interactions that determine whether a given infection event proceeds along a latent or symptomatic trajectory.

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Gorshkov, V.Y., Toporkova, Y.Y., Tsers, I.D., Smirnova, E.O., Ogorodnikova, A.V., Gogoleva, N.E., Parfirova, O.I., Petrova, O.E. and Gogolev, Y.V. (2022) “Differential modulation of the lipoxygenase cascade during typical and latent Pectobacterium atrosepticum infections,” Annals of Botany, https://doi.org/10.1093/aob/mcab108

READ THE COMMENTARY

Wasternack, C. (2022) “Deciphering the oxylipin signatures of necrotrophic infection in plants. A commentary on: Differential modulation of the lipoxygenase cascade during typical and latent Pectobacterium atrosepticum infections,” Annals of Botany, https://doi.org/10.1093/aob/mcab142