Le Ru, A. | bioRxiv Science

bioRxiv2021

Pathogen-derived mechanical cues regulate the spatio-temporal implementation of plant defense

How immune responses are activated and regulated is a central question in immunology. In addition to molecular signaling, recent work has shown that physical forces regulate the immune response of vertebrates by modifying transmembrane protein conformation and cell contact. Mechanical stress and strain produced by forces constitute physical cues perceived by cells instructing gene expression. Whether mechanical cues generated by pathogens during host colonization can trigger adaptive responses in plant cells remains elusive. We found that local and progressive variations of plant cell wall tension caused by fungal pathogen attacks are transmitted to neighboring healthy tissue around the infection site and trigger immunity in distal cells. This thigmoimmunity process requires the reorganization of cortical microtubules and contributes strongly to Arabidopsis disease resistance. One-Sentence SummaryActivation of plants immunity depends on fluctuations of mechanical tension caused by a fungal pathogen.

plant biology↗

bioRxiv2020

A DEAD BOX RNA helicase from Medicago truncatula is hijacked by an RNA-binding effector from the root pathogen Aphanomyces euteiches to facilitate host infection

Microbial effectors from plant pathogens are molecules that target host components to facilitate colonization. While eukaryotic pathogens are virtually able to produce hundreds of effectors, the molecular mechanisms allowing effectors to promote infection are still largely unexplored. Here we show that the effector AeSSP1256 from the soilborne oomycete pathogen Aphanomyces euteiches is able to interact with plant RNA. Heterologous expression of AeSSP1256 delays Medicago truncatula host roots development and facilitate pathogen colonization. Transcriptomic analyses of AeSSP1256-expressing roots show a downregulation of genes implicated in ribosome biogenesis pathway. A yeast-two hybrid approach reveals that AeSSP1256 associates with a nucleolar L7 ribosomal protein and a M. truncatula RNA helicase (MtRH10) orthologous to the Arabidopsis RNA helicase RH10. Association of AeSSP1256 with MtRH10 impaired the capacity of MtRH10 to bind nucleic acids. Promoter:GUS composite plants revealed that MtRH10 is expressed preferentially in the meristematic root cells. Missense MtRH10 plants displayed shorter roots with developmental delay and are more susceptible to A. euteiches infection. These results show that the effector AeSSP1256 facilitates pathogen infection by causing stress on plant ribosome biogenesis and by hijacking a host RNA helicase involved in root development and resistance to root pathogens.

plant biology↗