Pathogen Suppression by Plant-Associated Microbiota

Plants interact with a broad spectrum of microorganisms. While pathogens have received the most attention due to their detrimental effects on plant growth, development, and productivity, they represent only a small fraction of the microbial community. By contrast, non-pathogenic microorganisms are abundant and may establish mutualistic relationships with their plant hosts. The symbiosis between plants and beneficial microorganisms is key to promoting plant productivity, health, and resilience to stress. In recent years, non-pathogenic microorganisms have garnered increasing attention for their positive effects on plants, aligning with the demand to develop sustainable strategies to mitigate the impact of the current climate crisis. Several examples of microorganism-plant symbiotic relationships have been explored. For instance, the well-known associations of plant roots with mycorrhizal fungi and nitrogen-fixing bacteria enhance nutrient uptake and thus improve plant fitness. In addition, the plant microbiota can prevent dysbiosis and suppress pathogen proliferation.

In terms of modes of action, pathogen suppression can be classified into two main categories. The first involves antagonism between symbiotic microbes and pathogens with overlapping niches, causing direct interactions such as parasitism, chemical warfare through the production of antibiotics, competition for resources, or priority effects. The second mode of action is through priming, in which microbes induce a resistance response in plants that can counteract a subsequent pathogenic invasion. However, this may also impact the proliferation of beneficial microorganisms. Crop disease outbreaks depend not only on the host plant and pathogen virulence but also on environmental conditions such as soil characteristics, microbial activity, and community composition. Under certain circumstances, diseases are suppressed due to the collective interactions among microbes, between plants and microbes, or within the plant-microbiome-environment system.

We are interested in unraveling the complex interaction mechanisms of plants associated with bacterial and fungal microbes involved in pathogen suppression, with particular emphasis on symbiotic interactions.

This Research Topic aims to gather recent discoveries and innovative approaches across various aspects of microbial-pathogen suppression. Its focus will be on unraveling the ecological, physiological, cellular, and molecular mechanisms associated with pathogen suppression by plant-associated microbiota.

To gather further insights into the complex interactions between plants and their associated microbiota, we welcome articles addressing, but not limited to, the following themes:

• Interactions between single plant-pathogen-beneficial species
• Interactions involving synthetic communities and plants, with a focus on how these communities influence plant responses to pathogens
• Comparative plant microbiome studies (changes in the microbiome induced by the environment, management, ectopic microbes, among others), particularly how these changes affect the plant's vulnerability or resistance to pathogens
• Studies on microbe protection or plant defense induction mechanisms within these interactions

We strongly encourage studies involving the functional analysis of key genes activated during these symbiotic interactions and multidisciplinary approaches.