PhD defence: Disease-associated shifts in the rhizosphere microbiome towards a soy-borne legacy

Plants are continuously exposed to various microorganisms, both above- and belowground. These microorganisms, primarily bacteria and fungi, form the plant microbiome, which plays a crucial role in plant growth and health. For instance, the plant microbiome facilitates nutrient uptake and strengthens the plant immune system, making plants more resistant to diseases. In case of disease or stress, such as drought, the plant microbiome can adapt to provide long-term protection for the host.

In my research, I investigated how plants recruit specific microorganisms from the soil to combat pathogens. This process can lead to the development of so-called “disease-suppressive soils,” where beneficial microorganisms in the soil protect the plant against pathogens. Such disease suppression only occurs after repeated disease outbreaks, and plants seems to play a key role in this process.

I studied this phenomenon in thale cress, a model plant for biological research, and discovered that certain compounds, called coumarins, as well as the plant hormone salicylic acid, play an important role in creating this disease protection. I also examined the impact of infectious diseases on the microbiome of soybean plants, where I observed that viral and fungal infections are associated with various changes in the root microbiome, potentially affecting the growth and health of the soybean plant.

My research highlights that the plant microbiome is dynamic and can be utilized by plants to combat diseases. Knowledge of the underlying mechanisms could aid in the development of effective biological crop protection agents, providing a sustainable alternative to chemical pesticides.