Of shy specialized metabolites: A role for non-proteinaceous effectors in plant-fungal interactions? – ShySM

The JCJC ANR project ‘ShySM’ aims to understand the role of specialized metabolites produced by fungal hemibiotrophic plant pathogens specifically during host infection. The project will focus on those molecules produced during initial biotrophic growth in living plant cells, when they are most likely involved in manipulating plant defences to setup the infection, prior to the switch to destructive necrotrophic growth. Preliminary transcriptomic analyses indicate that such metabolites are cryptic or ‘shy’ in that they are not produced under lab conditions. The data also indicate that these molecules are produced in successive waves corresponding to the different stages of infection: initial host penetration, biotrophic phase. These characteristics represent a major bottleneck. The structural elucidation of these molecules requires their purification in milligram quantities, which is extremely challenging from infected tissues. Likewise, identifying their biological activities and deciphering their modes of action also require large quantities of the molecules.
With this pluridisciplinary project, we propose to combine synthetic biology, metabolomics and proteomics in an innovative way to produce the specialized metabolites of interest in sufficient amounts for their structural elucidation and characterization of their mode of action. The latter point will involve the identification of their plant protein target(s) using untargeted methods. The protein-specialized metabolite interactions will then be validated using in planta screens including reporter lines and biochemical assays. The JCJC project ‘ShySM’ will uncover the role of fungal specialized metabolites in establishing the early stages of infection and will provide the basic knowledge required for the rational design of novel disease control strategies.