Physiochemical interaction between osmotic stress and a bacterial exometabolite promotes plant disease

Dr. Michael Marner:

        »I am grateful to have been able to contribute to the understanding of the interactions between plant pathogenesis and bacterial natural products in the context of climate change as part of this great research team.«

Climate change leads to altered precipitation patterns and increased frequency of drought periods. This raises the salt concentration in the soil, thereby increasing salt stress for plants, which in turn affects their health and resilience. In this context, researchers from the Max Planck Institute for Plant Breeding Research, Justus Liebig University Giessen, and the Natural Products department of the Fraunhofer IME in Giessen investigated the interactions between osmotic stress and bacterial exometabolites. In this study, the authors discovered the natural product Brassicapeptin A in cultures of the bacterium Pseudomonas brassicacearum (R401). This previously unknown natural product was identified as a crucial factor that transforms the microorganism R401 from a beneficial member of the root microbiome into a plant pathogen under saltwater stress. Brassicapeptin A disrupts salt homeostasis in plants, thus increasing their sensitivity to osmotic stress and exacerbating disease symptoms.

The research emphasizes the diverse interdisciplinary collaboration by integrating knowledge from microbiology, natural product research, plant sciences, and biochemistry. Using advanced techniques, such as metabolomics and transcriptomics, the authors demonstrated how the production of Brassicapeptin induces transcriptional reprogramming in plant roots, impairing their ability to cope with osmotic stress. The findings illuminate the complex interplay between microbial metabolites, plant responses, and environmental factors, offering new perspectives on the emergence of plant diseases in natural and agricultural contexts.

In summary, the study reveals that Brassicapeptin A plays a key role in disease development and that the physiochemical interaction between environmental stressors and bacterial metabolites is crucial for understanding plant diseases in complex soils. The team uncovered novel mechanisms of microbial pathogenicity, with far-reaching implications for sustainable agriculture and plant resilience in saline soils.