Seminar IJPB/ SPS Dr David Cannella

During evolution, plants have developed sophisticated mechanisms to sense threats. Primarily the sensing of pathogens associated molecular patterns, guarantee the plants the possibility of recognizing aggressors by detecting their derived molecules or outlay structures. In the last decades investigations focused on the perception of plant derived cell wall fragments, an hallmark event during pathogen attacks.

Several of these fungi display redox enzymes active as poly- or oligo-saccharide oxidases as virulent factors and key components of the enzymatic arsenal which ultimately degrade plant cell wall. In my research group we investigate their implications in several pathosystems, for example Botrytis cinerea display several lytic polysaccharide monooxygenases (LPMOs) upregulated during Arabidopsis infection. LPMOs when degrading plant cell wall leaves behind a mixtures of native and oxidized cellodextrines (COS), that where demonstrated to effectively trigger plant immunity up to discrete levels of protection, and without triggering the common ROS-signalling pathway. Successful plant protection was also achieved by the treatments with the sole oxidized COS.

Moreover in collaborations with F. Sabbadin, Université de York, we reported the functional characterisation of a group of P. infestans berberine bridge enzyme-like proteins (BBEs) and their role in plant infection. We demonstrate that BBE-encoding genes are upregulated during early infection and that the secreted enzymes specifically oxidise fragments of pectin, the most abundant charged polysaccharide in the plant cell wall. We further show that these enzymes preferentially oxidise longer pectin fragments, which evade detection by the plant contrary to the cellulose oxidized oligos, yet failing to trigger ROS signalling. Combined with the reduced infection observed upon silencing of the encoding BBE-genes, these findings point to a key role for this enzyme class in host penetration and colonisation.

Deciphering which of the several components of the cell wall derived oligosaccharides may play a role of immune-evasion or signalling, it will enables the design of functional (perhaps pathogen tailored) plant vaccines for future field application. In this regards the EU-founded ZELDA projects aim at combining and design a new generation of plant elicitors combining several plant wall components. These will be tested on several crops in the lab as well in field trials.

Reference
Welsh LRJ, Avrova AO, Besser K et al. Oomycetes manipulate plant innate immunity through galacturonide oxidases. Nat Commun 16, 9093 (2025)
https://doi.org/10.1038/s41467-025-64189-1


David Cannella, CPBL group, Bioengineering group, Université libre de Bruxelles -ULB

Invitation: Massimiliano Corso, "Seed - Development, Regulation, and Metabolism" SEED-DREAM team


Seminar in connection with the research developed at the Institute Jean-Pierre Bourgin for Plant Sciences.