Institut für Pflanzenschutz in Obst- und Weinbau
Potato tuber wilt syndrome is associated with different pathogens transmitted by leafhopper vectors. In the classical case, it is caused by Candidatus Phytoplasma solani (CaPsol; Stolbur phytoplasma). Associated with a host switch of the vector leafhopper Pentastiridius leporinus from sugar beet to potato, the gamma-proteobacterium Candidatus Arsenophonus phytopathogenicus is appearing with increasing frequency in diseased potatoes, but infestation by CaPsol has also increased sharply. This is associated with serious damage to potato crops. The project focuses on the question of the causes for the strong spread of CaPsol in potato cultivation, which was previously of particular importance in viticulture as a pathogen of Bois noir disease. The aim of the project is to investigate transmission cycles and phytoplasma-host plant-vector interactions in order to identify targets for agricultural practice to interrupt the transmission pathways and thus reduce the infection pressure on potato.The CaPsol pathosystem is characterized by a high genetic diversity of phytoplasmas, a wide host range of wild and cultivated plants, and different leafhopper species as vectors. Due to specific host-plant-pathogen-vector combinations, more or less distinct epidemiological cycles exist, but these cycles may be linked by vectors and often branch out to crops such as vines, potatoes and other solanaceous plants, sugar beets, maize, lavender, or strawberries. Because of the multiple interactions, prevention and control of CaPsol-associated diseases are often difficult. Effective and sustainable management approaches should aim at interrupting transmission cycles and therefore require detailed knowledge of the respective epidemiological situation, which mostly varies from region to region.To clarify the open questions, the elements of the stolbur pathosystem in potato crops are investigated. This includes the survey of wild host plants in the vicinity of affected crops as well as the occurrence and dominance structure of known and potential CaPsol vectors in potato fields and their surroundings. The importance of potato as an acquisition host for P. leporinus will be investigated by recording the seasonal variation in infection frequency of adult leafhoppers as well as the infection frequency of larval populations in the fall and adults of the subsequent generation appearing in the spring. The significance of PCR detections of CaPsol in leafhoppers with respect to transmission risk will be investigated by single-animal transmission experiments. Comparative analysis of genetic variability of CaPsol isolates from wild host plants, potato, sugar beet, and leafhoppers (MLST analysis) will identify transmission cycles and routes of spread relevant to potato infection.
Bundesland Rheinland-Pfalz
