Project description:As the phyllosphere is a resource-limited niche, microbes have evolved different survival strategies by collaborating or competing with other organisms. This leads to the establishment of network structures which are stabilised by so-called microbial hub organisms. An already identified hub in the Arabidopsis thaliana phyllosphere is the oomycete pathogen Albugo laibachii. From wild Arabidopsis plants with white rust symptoms we isolated the basidiomycete yeast Moesziomyces albugensis, which is closely related to plant pathogenic smut fungi. It suppresses the infection of A. laibachii in lab experiments and inhibits growth of several bacterial phyllosphere members. The transcriptomic response of M. albugensis to presence of A. laibachii and bacterial SynCom members was investigated by using RNA sequencing. Interestingly, several genes encoding secretory proteins, mostly glycoside hydrolases and peptidases, are particularly induced upon interaction with A. laibachii.
Project description:Plants are colonized by a variety of microorganisms, the plant microbiota. In the phyllosphere, the above-ground parts of plants, bacteria are the most abundant inhabitants. Most of these microorganisms are not pathogenic and the plant responses to commensals or to pathogen infection in the presence of commensals are not well understood. We report the Arabidopsis leaf transcriptome after 3 to 4 weeks of colonization by Methylobacterium extorquens PA1 and Sphingomonas melonis Fr1, representatives of two abundant genera in the phyllosphere, compared to axenic plants. In addition, we also sequenced the transcriptome of Arabidopsis 2 and 7 days after spray-infection with a low dose of P. syringae DC3000 and in combination with the commensals.
Project description:The microbiota plays a crucial role in protecting plants from pests and pathogens. The protection provided by the microbiota constitutes not just the plant’s first line of defense, but possibly its most potent one, as experimental disruptions to the microbiota cause plants to succumb to otherwise asymptomatic infections. To understand how microbial plant defense is deployed, we applied a complex and tractable plant-soil-microbiome microcosm. This system, consisting of Arabidopsis plants and a 150-member bacterial synthetic community, provides a platform for the discovery of novel bacterial plant-beneficial traits, under a realistically complex microbial community context. To identify which components of the plant microbiota are critical for plant defense, we deconstructed this microcosm top-down, removing different microbial groups from the community to examine their protective effect on the plant when challenged with the leaf pathogen Pseudomonas syringae. This process of community deconstruction revealed a critical role for the genus Bacillus in protecting the plant from infection. Using plant RNA-seq and bacterial co-culturing experiments, we demonstrated that Bacillus-provided plant protection is independent of plant immune system activation. We also show that the level of plant protection is strongly dependent on the diversity of the protective inoculum. We show that deconstructing the microbiome top-down is a powerful tool for identifying and prioritizing microbial taxa with specific functions within it.
Project description:RNASeq of roots from two genotypes of Arabidopsis thaliana plants, Col-0 and myb36-2 grown axenically or with a 41 member bacterial Synthetic Community (SynCom) to explore the interaction between the root diffusion barriers and the root microbiome.
Project description:Arthrobacter chlorophenolicus A6 is a 4-chlorophenol degrading soil bacterium with high phyllosphere colonization capacity. Till now the genetic basis for the phyllosphere competency of Arthrobacter or other pollutant-degrading bacteria is uncertain. We investigated global gene expression profile of A. chlorophenolicus grown in the phyllosphere of common bean (Phaseolus vulgaris) compared to growth on agar surfaces.
Project description:Arthrobacter chlorophenolicus A6 is a 4-chlorophenol degrading soil bacterium with high phyllosphere colonization capacity. Till now the genetic basis for the phyllosphere competency of Arthrobacter or other pollutant-degrading bacteria is uncertain. We investigated global gene expression profile of A. chlorophenolicus grown in the phyllosphere of common bean (Phaseolus vulgaris) compared to growth on agar surfaces. We designed transcriptome arrays and investigated which genes had different transcript levels in the phyllosphere of common bean (Phaseolus vulgaris) as compared to agar surfaces. Since water availability is considered an important factor in phyllosphere survival and activity, we included both high and low relative humidity treatments for the phyllosphere-grown cells. In addition, we determined the expression profile under pollutant exposure by the inclusion of two agar surface treatments, i.e. with and without 4-chlorophenol.