Plant microbiome: the extended immune system

The plant microbiome functions as an extension of the immune system, reshaping our understanding of plant health. Rather than being solely intrinsic, plant immunity is actively influenced by microbial communities, forming a dynamic, multilayered defense system. Beyond immunity, plant microbiota enhance nutrient uptake, growth, and resilience to abiotic stress. At Utrecht University’s Plant-Microbe Interactions group, research focuses on bidirectional signaling along the microbiome-root-shoot axis (Trends Plant Sci. 26: 169-183). Using 16 Arabidopsis structural and chemical defense barrier mutants, we uncovered distinct and complementary roles of chemical (coumarins, camalexin, glucosinolates) and structural (cutin, callose, lignin, endodermal barriers) defenses in root-microbiome interactions. Additionally, we demonstrated that Arabidopsis roots recruit a protective microbial consortium in response to foliar infection by the downy mildew pathogen. This recruited microbiota establishes a soilborne legacy, protecting future plant generations against pathogens (Nature Microbiol. 8: 2349-2364). Our research aims to develop microbiome-based strategies for disease-resistant crops that optimize beneficial root microbiome functions. One example is a microbiome-informed prediction model based on the potato seed tuber microbiome, which accurately forecasts seed potato vigor in the next growing season (Nature Microbiol. 10: 28-40). Understanding the mechanistic basis of plant-microbiome interactions will lay the foundation for microbiome-assisted crop systems that enhance productivity while reducing reliance on fertilizers and pesticides.