Engineering of novel cell-wall derived oligosaccharides for plant protection – WALLDERIVE

We are studying two pathosystems (plant/pathogen) as follows: wheat/Zymoseptoria tritici and tomato/Botrytis cinerea. Infections are carried out in the laboratory. About twenty different tomato varieties and ten wheat varieties are being studied. These varieties show varying degrees of resistance to their respective pathogens, and during infection, sugar molecules of various chemical natures can be released. The approach is therefore to compare the production of sugar molecules between plants that are resistant or susceptible to pathogen attack and to correlate the presence of certain molecules with the results of phytopathological tests. For example, we will select sugar molecules that are present in high quantities in plants resistant to pathogens and absent in those susceptible to pathogens.

To achieve this, pathogens are brought into contact with the plants, and the sugar molecules are then identified using analytical chemistry methods. These methods first allow us to separate the degraded molecules based on their size and to obtain their chemical formulas, and therefore their structures.

Next, using available metadata, we will select the enzymes that seem most likely to be involved in the production of these molecules. Through biochemical approaches, these enzymes will be produced and studied.

Finally, using these enzymes, we will develop a strategy to mimic the production of the previously selected sugar molecules in the laboratory. To do this, we will identify bio-based substrates through the company Elicityl, upon which our enzymes will act. The molecules thus released will be characterized, purified, and then tested for their protective effects

The wheat and tomato plants were respectively produced by the Cyrille Saintenac’s team and the Samantha Vernhettes’s team. We first analyzed the composition of the wheat and tomato tissues. Then, we identified the sugar molecules produced during the attack of different wheat varieties by Zymoseptoria tritici and also during the attack of different tomato varieties by Botrytis cinerea. Comparing the varieties allowed us to demonstrate the existence of a wide range of sugar molecules and to show that the nature of these molecules is correlated to the variety studied, and therefore to the chemical characteristics of the plant tissue. We also showed that pathogens adapt their cellular machinery according to the plant varieties encountered in order to optimize their infections and degrade plant tissues.

We have already selected two types of molecules for the protection of tomatoes, and we are currently analyzing the data to find more molecules for both tomatoes and wheat. For the first molecule, we are currently establishing a production process. To this end, the company Elicityl has produced several types of substrates for us, and the Jerome Pelloux’s team has produced several enzymes that will be mixed with these substrates to mimic the production of this molecule.

In the Samantha Vernhettes ‘s team, we have also produced an enzyme from Botrytis cinerea that is capable of producing sugar molecules that have not been described until now. This new enzyme will allow the production of new molecules that potentially have new biological activities. This work has recently been accepted for publication.

We will continue to identify sugar molecules produced in the two pathosystems under study. For this, the teams of Cyrille Saintenac and Samantha Vernhettes will continue to produce leaves from different wheat and tomato varieties at various stages.

We will also keep testing the substrates provided by Elicityl. Elicityl is currently working on improving the quality of their substrates. Jérôme Pelloux’s team is producing new fungal-origin enzymes and characterizing their activities. We need to implement solutions to purify certain sugar molecules that are sometimes found in mixtures.

We are setting up phytopathology and molecular biology tests in order to assess, in the future, the ability of certain sugar molecules to elicit defense mechanisms. We will also be able to test the activity of the new sugar molecules we have identified.

If one of the molecules proves to be highly effective in protecting against Zymoseptoria tritici or Botrytis cinerea, we will propose a process for large-scale production.