Dissecting the multispecies interaction network at the A. thaliana root-soil interface

In nature, healthy and asymptomatic plants cohabit with a variety of microbes, such as bacteria, fungi, and oomycetes, forming complex microbial consortia that interact with each other and likely provide fitness benefits to the host plant. Advances in culture-independent methods have deepened our understanding on microbial communities’ distribution in nature and the environmental factors shaping these communities. However, there is still a lack of consensus between studies and a more holistic approach is needed, by studying several microbial groups under a variety of environmental conditions. Importantly, there is a significant part of the microbial variance that remains unexplained in host-associated microbiota studies. Decades of research have shown that microbes interact with each other, indicating that microbe-microbe interactions might represent a major, yet poorly described, force driving microbial community establishment in and outside plant roots. In order to assess microbial communities´ functions and assembly rules, microbiota reconstitution experiments in gnotobiotic plant systems are needed. By linking microbial community profiling data from natural Arabidopsis thaliana populations (chapter I) with reconstruction experiments with synthetic microbial communities and germ-free plants (chapter II), I provide novel insight into how environment, host-microbe and microbe-microbe interactions affect microbial community structure and plant health in nature. In the first chapter, I analyzed bacterial, fungal and oomycetal communities associated with Arabidopsis thaliana roots from seventeen natural populations across a European transect, for three consecutive years. By developing a fractionation protocol that distinguishes four microbial niches (Soil, Rhizosphere, Rhizoplane and Root), I dissected the relevance of host compartment, host species, biogeography, harvesting year, and soil characteristics on microbial communities’ distribution at a continental scale. I showed that bacterial, fungal and oomycetal communities are primarily shaped by different factors, including the host niche for bacteria, the site for fungi, and the year for oomycetes. Also, I identified an A.thaliana root-associated core microbiota, resilient across harvesting years and locations. Furthermore, reciprocal transplant experiments conducted in natural and controlled conditions uncovered the important role of climate as well as the climate-dependent host genotype effect on microbial communities’ distribution. In the second chapter, I utilized a gnotobiotic plant system for reconstituting multispecies synthetic microbial communities, which revealed the relevance of multi-kingdom microbe-microbe interactions for plant health and microbial communities’ assembly. In these experiments the bacterial microbiota is essential for plant survival and protection against detrimental activities of root-derived filamentous eukaryotes. Moreover, I revealed that microbial load only partially drives plant health and that disease protection of bacterial root commensals is a redundant trait needed to maintain microbial interkingdom balance for plant health. Finally, I investigated the dynamics of microbiota establishment and explored the importance of the host for microbiota establishment

New educational resources for pharmacy students

El objetivo del proyecto es la mejora de la enseñanza virtual a los alumnos del Grado en Farmacia mediante la realización de diversos recursos educativos abiertos virtuales, como vídeos o cuestionarios, que faciliten el aprendizaje.Depto. de Farmacia Galénica y Tecnología AlimentariaDepto. de Farmacología y ToxicologíaFac. de FarmaciaFac. de VeterinariaFALSEsubmitte