Biology and epidemiology
TASK 3.1: Environmental requirements and disease epidemiology What are the environmental requirements critical in pathogen (Psa, Xap, Xf) life cycles and disease epidemiology in fruit orchards? A sufficient knowledge of the pathogen biology and epidemiology is fundamental in order to develop effective sustainable control strategies; however for Psa, Xap and Xf information was very scarce before the DROPSA project was initiated. Therefore it aims in identifying primary/secondary inoculum sources and inoculum reservoirs in agricultural systems in order to determine their epidemiological significance. To assess the invasion risks across a diversity of European agro-ecosystems, a comprehensive picture of pathogen behaviour on individual plants, within orchards and across geographic regions will be carried out. It will provide a foundation for control strategies. Essential climatic influences on critical points in life cycle/epidemiology will also be taken into consideration in order to help the development of forecasting models and decision support systems.
TASK 3.2: Pathogen source tracking (see pathways of introduction)
How can the mechanisms of spread of these bacterial pathogens and their evolutionary risks be analysed?
A first necessary step is the development of quantitative and on-site detection tools for all these pathogens in order to properly determine inoculum reservoirs and invasion routes impacting disease outbreaks. The establishment of molecular fingerprinting methods is being carried out in order to perform further genotyping of the collected isolates thus allowing their fine characterization, also known as subtyping. Additionally, in several other pathosystems, these genotyping tools always proved to be very useful in performing source-tracking of a pathogen outbreak thus allowing the determination of the origin of contamination. Although these tools can also provide insights concerning pathogen evolutionary risks like emergence of pathogen resistance to control products, the gold-standard for this purpose is still the determination of the whole genome sequence of the pathogen using Next Generation Sequencing, some techniques that will also be used within DROPSA.
TASK 3.3: Virulence factors and ecological fitness
Are there known conditions modulating the virulence and the fitness of these pathogens?
The influence of growth stage of the plant and of cultural management practices on the infection process and disease development will be determined in parallel to the influence of environmental conditions. However it is obvious that a big part of these influences also resides on the pathogen side. The identification of virulence factors and fitness determinants thus needs first to be performed within DROPSA. This is of particular interest as a better understanding of these and more especially of their modulating conditions could provide ways to interfere with them and thus to probably prevent infection.
TASK 3.4: interactions with host plants and host resistance
How are the plants responding to these pathogens?
As they were mainly unknown so far, the mechanisms that the plant adopts to counteract the infection are being studied within DROPSA. Next Generation Sequencing currently provides the mean to identify and understand gene regulation associated with the interactions with, and resistance of, the host plant. In depth transcriptomic and metabolic studies of the different phases of the host responses to pathogen infection will thus be performed within DROPSA. These results should help the development of marker assisted breeding tools but also the screening of resistance boosting control products or the establishment of durable integrated pest management strategies.
TASK 3.5: interactions with insect pollinators and Drosophila suzukii
Can these pathogens be vectored by insect pollinators or by Drosophila suzukii?
The potential, frequency and predisposing conditions for pathogen vectoring by insects will be determined within DROPSA. For this purpose, passive surface vectoring and internalised gastrointestinal colonisation will be evaluated. All these experiment s will be really helped by the advances made with the development of quantitative and on-site detection tools for these pathogens. Indeed these tools will allow testing a lot of samples in a relatively short time for the presence of the bacteria.
Environmental Genomics and Systems Biology Research Group
Institute of Natural Resource Sciences
Zurich University of Applied Sciences ZHAW Life Sciences and Facility Management (Switzerland)