Poster #15

Understanding the biochemistry of polysaccharides opens ways to prevent the spread of an invasive fungus causing dieback of ash trees.
O. KUTINOVA, Ł. WICZOŁEK, A. LISZKA, E. ARKORFUL, K. NAWROT-CHORABIK, D. LATOWSKI, J.J. LYCZAKOWSKI.
Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland

Ash dieback is a widespread problem among European forest ecosystems. The disease is caused by an invasive fungal pathogen (Hymenoscyphus fraxineus) that was introduced to Europe around 30 years ago from Asia. Infections result in over 60% mortality among trees. It is known that fungi can stimulate plant cellular responses by components of their cell walls. Such fungal active molecules are called pathogen-associated molecular patterns (PAMPs).In our work we discovered that H. fraxineus produces a unique exopolysaccharide (EPS) that acts as a PAMP on ash cells. Through biochemical studies using Polysaccharides analysis by carbohydrate gel electrophoresis (PACE) and HPLC we showed that this EPS is mainly composed of mixed-linkage glucan (MLG). Purification of the MLG secreted by H. fraxineus enabled us to analyse its impact on ash callus. We observed changes in gene expression profiles and plant cell wall reprogramming which may mimic these present at the early stages of the infection process. This discovery showed that the unique EPS may be a key to improve our understanding of the pathogen infection and may help prevent dieback of ash. Moreover, we showed that callus is a remarkable model for studying the interaction between fungus and a plant. This work was supported by National Science Centre Poland (grant 2021/43/D/NZ9/01978).