Grape vine is the crop plant that generates the greatest yield in € per area. In our region, wine growing is a culture technique and tradition that has been growing over two millennia, resulting in very high quality standards. However, quality comes at a price: in Europe, approximately 70% of the total amount of fungicides is used in the wine growing industry.
Consumers are increasingly demanding food that is produced in a way that is sustainable and preserves natural resources.
We will only be able to meet these demands if we manage to develop novel, sustainable techniques for plant protection. In wine production, observation, knowledge and experience have always been of great importance. The same holds true for good science. When it comes to connecting science and wine growing, our region has always been one step ahead. This tradition shall be continued in Vitifutur to face the challenges of the future.
The cultivation of fungus resistant grape varieties is one of the most effective approaches to sustainable viticulture. Resistance against the pathogens that cause downy mildew (vine Peronospora) and powdery mildew (Oidium), which were imported from North America, are based on genetic factors that were attained by crossing grape cultivars with mostly North American wild vines. It took several decades of breeding efforts to separate this resistance from the “foxton” in American wild vines which lowers the quality of the wine. The use of these Piwi varieties allows us to drastically reduce the use of fungicides.
However, nature doesn’t stand still and it is on us to secure this success story. New strains of Peronospora that are capable of overcoming the resistance in Piwi-varieties have already appeared. We are therefore in search of novel resistance factors that can be used to secure the resistance of the Piwi varieties.
We are using cutting-edge molecular, biochemical and microscopic techniques to investigate what happens when these novel strains encounter vulnerable grape vines as well as Piwi-varieties. We are furthermore developing probes that diagnose the novel strains and track their spread. At the same time, we test the efficiency of novel resistance factors, originating for instance from Asian wild grape. We will then introduce this resistance into Piwi varieties through cross-breeding. Molecular investigations help us to achieve faster and more precise results in plant breeding without the need to use genetic engineering.
Based on this newly-gained knowledge, we are subsequently developing novel procedures to interrupt the chain of infection and thereby reduce the amount of fungicides that need to be used. Our findings can as a result be translated into concrete recommendations for the winegrowing practice or may be integrated into forecasting tools, such as the online application Vitimeteo (http://www.vitimeteo.de/), which was developed in our region and is used by numerous wine growers.
Viruses are not alive. However, they use other forms of life to reproduce and to spread. Grape vine infecting viruses use predominantly insects, as well as nematodes. Due to globalization and climate change, new insects that carry previously unknown viruses are appearing in our region. Which viruses do they carry and how do these novel viruses spread?
To gain a better understanding on the occurrence and spread of viruses, samples are taken in collaboration with our partners from the vine industry and tested for relevant, already known viruses using molecular and serological methods. Mapping the occurrences allows us to locate the epicenter of the spread. At the same time, we gain information on the susceptibility of the cultivated grape varieties.
In addition to known viruses, newly introduced as well as completely unknown viruses exist and cannot be identified by any of the available detection method.
We are therefore working on innovative ways to detect these viruses using new innovations and technologies. For example, novel antibodies, so called Nanobodies, allow us to distinguish between virus strains on the basis of minor differences in their envelope proteins. Simultaneously, differences in the viral RNA are detected by molecular differential diagnosis.
These novel methods do not only allow us to shed light on the spread of these viruses, but they further allow us to understand the transmission of viruses to plants and the infestation of new plants.
In order to track the spread of viruses in real time, different grape varieties were planted in virus-contaminated areas. Some of the plants contain novel rootstocks that are presumed to be virus resistant. Our findings can be immediately translated into practice, as concrete recommendations on which species are best to be used in infested areas can be given to the respective wine growers.
Unlike downy mildew and powdery mildew that have been introduced from North America, wood decaying fungi have presumably always been present in our region. It is however a new phenomenon, that they increasingly kill the trunk of grape vines. It is estimated that 15% of all French vineyards are infested with the disease and are likely to increase. The situation in Germany is not any better.
We only have a rudimental understanding on what is happening here. We do not even know which fungal strain is responsible for Esca and other wood decaying diseases. However, first field trials have revealed that grape varieties differ in their susceptibility to wood diseases. The next step is to scientifically verify our initial findings in experiments in which the different grape varieties are infected under controlled conditions. This will give us information on which grape varieties to plant in the affected areas.
However, nature has taken its own precautions in form of the last population of European wild grape vine. This population of grape vines, which can withstand an infection with wood decaying fungi relatively well, is located on the peninsula Ketsch between Karlsruhe and Mannheim in Southern Germany. This endangered mother-strain of the grape vine possesses genetic factors that can be used in breeding efforts to generate a new generation of resistant grape vines.
Nonetheless, there is still a long way to go. We therefore simultaneously try to identify the factors that allow the fungi to have its deadly effect on its host plant. In lab experiments with cell cultures of different grape varieties as well as in experiments using whole plants, we seek for possibilities to activate the plant’s immune system and prevent the fungi from producing its deadly toxin.
Identifying these signals will allow us to give recommendations on how to prevent the disease to break out in the viticultural practice.