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.
Project description:MicroRNAs (miRNAs) are small non-coding RNAs that function as post-transcriptional regulators of gene expression in eukaryotes. In rice, miR7695 targets an alternatively spliced transcript of natural resistance-associated macrophage protein 6 (OsNramp6) encoding an iron transporter whose expression is regulated by infection with the rice blast fungus Magnaporthe oryzae. Rice plants grown under high iron supply showed blast resistance, which supports that iron is a factor in controlling blast resistance by still unknown mechanisms. Here, iron accumulated near M. oryzae appressoria, the sites of pathogen entry, and in cells surrounding infected regions of the rice leaf. Activation-tagged MIR7695 rice plants (MIR7695-Ac) exhibited enhanced resistance to M. oryzae infection. RNA-seq analysis revealed that blast resistance in MIR7695-Ac plants was associated with strong induction of defense-related genes, including pathogenesis-related and diterpenoid biosynthetic genes. Levels of phytoalexins during pathogen infection were higher in MIR7695-Ac than wild-type plants. Early phytoalexin biosynthetic genes, OsCPS2 and OsCSP4, were highly upregulated in rice plants grown under high iron supply. Our data indicate that miR7695 positively regulates rice immunity while establishing links between defense and iron signaling in rice. MiR7695-mediated regulation of OsNramp6 has great potential for the development of strategies to control rice blast disease.
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:Magnaporthe oryzae (rice blast) and the root-knot nematode Meloidogyne graminicola are causing two of the most important pathogenic diseases jeopardizing rice production. Here, we show that root-knot nematode infestation on rice roots leads to important above-ground changes in plant immunity gene expression, which is correlated with significantly enhanced susceptibility to blast disease.