Importance of Lewis A Epitopes for Pseudomonas syringae Infection of Arabidopsis

As sessile organisms, plants are constantly exposed to a plethora of different environmental stresses which affect productivity of crop plants and constitute a major issue of contemporary agriculture and worldwide food security. In particular, rapidly emerging pathogens provide an increasing threat to global crop production as they can cause devastating plant diseases. In order to cope with these unfavorable stress conditions, plants have developed diverse defense mechanisms. Understanding the molecular principles underlying the stress response of plants is fundamental for strategies to engineer disease-resistant plants and improve the agricultural production of quality crops. In human cells, infection by pathogens involves specific molecular recognition events between components from the invader and the host cell. The recognition and subsequent adhesion events are very frequently mediated by highly-specific carbohydrate-protein interactions and depend on distinct glycan structures that are exposed on the cell surface and recognized by carbohydrate- binding proteins. While these glycan-dependent processes are well characterized for several human pathogens, relatively little information is available on comparable processes during pathogen infection and defense response in plants. Here, in this project we aim to investigate the contribution of a distinct carbohydrate structure called Lewis A epitope and its potential binding partner during bacterial infection. We hypothesize that the Lewis A epitope plays a crucial role during infection of the model plant Arabidopsis thaliana with the bacterial plant pathogen Pseudomonas syringae. To examine this interaction and the role of a specific plant carbohydrate-binding protein (called F-box-Nictaba) we will carry out numerous bacterial infection assays in different genetic backgrounds. The influence of the bacterial infection on glycosylation and subcellular localization of the involved factors will be carefully monitored by different approaches including mass spectrometry and confocal laser scanning microscopy. These experiments will be supported by in vitro binding studies and glycan profiling of plant and bacterial extracts. Our results will for the first time reveal the function of a specific carbohydrate epitope during infection and the plant response against a bacterial pathogen. Since this carbohydrate epitope is highly conserved in plants we propose that our discoveries will be of direct relevance for crop species and lead to the identification of novel targets for engineering of disease-resistant crops in order to meet growing demands for high-quality food.

Importance of Lewis A epitopes for Pseudomonas syringae pv tomato DC3000 infection of Arabidopsis thaliana As sessile organisms, plants are constantly exposed to a plethora of different environmental stresses which affect productivity of crop plants and constitute a major issue of contemporary agriculture and worldwide food security. Rapidly emerging pathogens provide an increasing threat to global crop production as they can cause devastating plant diseases. In order to cope with these unfavorable stress conditions, plants have developed diverse defense mechanisms. Understanding the molecular principles underlying the stress response of plants is fundamental for strategies to engineer disease-resistant plants and improve the agricultural production of quality crops. In human cells, infection by pathogens involves specific molecular recognition events between components from the invader and the host cell. The recognition and subsequent adhesion events are very frequently mediated by highly specific carbohydrate-protein interactions and depend on distinct glycan structures that are exposed on the cell surface and recognized by carbohydrate-binding proteins. While these glycan-dependent processes are well characterized for several human pathogens, relatively little information is available on comparable processes during pathogen infection and defense response in plants. Here, in this project we characterized the contribution of a distinct carbohydrate structure called Lewis A epitope to plant pathogen defense. A systematic analysis of disease symptoms and pathogen growth in the model plant Arabidopsis thaliana revealed that plant glycoproteins carrying the Lewis A epitope are not involved in defense against the bacterial plant pathogen Pseudomonas syringae. To obtain further insights into the biological role of the highly conserved Lewis A epitope we identified glycoproteins from different plant species that carry this specific protein modification. The identified glycoproteins form the basis to dissect the role of the Lewis A epitope in future studies.