Jochen Bogs

1.) New disease-resistant grapevine varieties: The grapevine’s defense mechanisms against pathogens

• Investigation of the resistance mechanisms of new, fungus-resistant grapevine varieties through molecular, biochemical, and microscopic analyses.
• Development and testing of combined, holistic plant protection strategies to reduce the use of pesticides in viticulture.

Background and Problem Statement:

The pathogens causing powdery mildew (Erysiphe necator) and downy mildew (Plasmopara viticola) are the most dangerous and economically significant pathogens in viticulture worldwide and can cause a total crop failure under optimal climatic conditions. Consequently, significant amounts of fungicides are required in viticulture to prevent damage caused by these pathogens. Fungicide use in viticulture far exceeds that in cereal production or other crop cultivation and must be urgently reduced (Eurostat, 2007). One way to reduce fungicide use is to increase the cultivation of new, resistant grape varieties (fungus-resistant grape varieties, “Piwis”). Despite the ecological and economic advantages, as well as the now high wine quality of these new grape varieties, Piwi varieties account for only about 2% of the total vineyard area in Germany (Source: EU Vineyard Register 2011). Reasons for this very small area under cultivation of resistant grape varieties include the continuing difficulty in marketing them, limited oenological experience, and the limited scientific knowledge regarding the resistance characteristics of the new varieties and the associated adapted plant protection strategies.

Research and Approaches:

The goals of the research projects in the working group are to investigate the genetic differences between various resistant and susceptible grape varieties in order to understand the molecular physiology of successful defense and to identify the relevant genes. At the same time, the stability of the various defense mechanisms against isolates of the pathogen with varying levels of virulence is being investigated to support the targeted combination of different resistance mechanisms and, thereby, the sustainability of resistance breeding.

At the same time, the potential for reducing pesticide use in new, resistant grapevine varieties is being intensively investigated in field trials involving different pesticide application strategies and resistant grapevine varieties. The results of these studies are intended to provide winegrowers with well-founded insights and strategies—and thus recommendations for action—regarding sustainability in plant protection for resistant grapevine varieties, which will sensibly reduce the use of fungicides in viticulture.

2.) Components of the wine grape and their effects on grape quality

• Environmental influences (terroir)
• Genetics (varieties) and regulation of metabolic pathways
• Impact of viticultural practices on grape quality
• Development of practical methods and parameters for assessing grape quality

The quality of wine is determined by the value-adding components of the wine berries, such as aroma, color, and flavor compounds, whose content is influenced by environmental factors, viticultural practices, and the grape variety. Ongoing research projects are investigating the genetic and environmental influences on the synthesis of color and flavor compounds (flavonoids, stilbenes).

Flavonoids and stilbenes are phenolic compounds found in fruits and plant-based products such as wine, fruit juices, and tea, which contribute significantly to their quality, color, flavor, and health-promoting effects. Due to their quality-enhancing properties, these classes of compounds hold great potential for optimizing a wide variety of plant-based products such as wine and fruit juices. Ongoing research projects are investigating the genetic basis as well as the influence of environmental factors and viticultural practices on flavonoid and stilbene biosynthesis. The results of these projects are intended to contribute to a better understanding of flavonoid and stilbene biosynthesis in grapes and, thereby, to the development of improved grapevine breeding strategies and adapted cultivation methods that lead to the optimization of flavonoid and stilbene content in grapes.