Project description:Plants and rhizosphere microbes rely closely on each other, with plants supplying carbon to bacteria in root exudates, and bacteria mobilizing soil-bound phosphate for plant nutrition. When the phosphate supply becomes limiting for plant growth, the composition of root exudation changes, affecting rhizosphere microbial communities and microbially-mediated nutrient fluxes. To evaluate how plant phosphate deprivation affects rhizosphere bacteria, Lolium perenne seedlings were root-inoculated with Pseudomonas aeruginosa 7NR, and grown in axenic microcosms under different phosphate regimes (330 uM vs 3-6 uM phosphate). The effect of biological nutrient limitation was examined by DNA microarray studies of rhizobacterial gene expression.
Project description:Root exudates contain specialised metabolites that affect the plant’s root microbiome. How host-specific microbes cope with these bioactive compounds, and how this ability shapes root microbiomes, remains largely unknown. We investigated how maize root bacteria metabolise benzoxazinoids, the main specialised metabolites of maize. Diverse and abundant bacteria metabolised the major compound in the maize rhizosphere MBOA and formed AMPO. AMPO forming bacteria are enriched in the rhizosphere of benzoxazinoid-producing maize and can use MBOA as carbon source. We identified a novel gene cluster associated with AMPO formation in microbacteria. The first gene in this cluster, bxdA encodes a lactonase that converts MBOA to AMPO in vitro. A deletion mutant of the homologous bxdA genes in the genus Sphingobium, does not form AMPO nor is it able to use MBOA as a carbon source. BxdA was identified in different genera of maize root bacteria. Here we show that plant-specialised metabolites select for metabolisation-competent root bacteria. BxdA represents a novel benzoxazinoid metabolisation gene whose carriers successfully colonize the maize rhizosphere and thereby shape the plant’s chemical environmental footprint
Project description:Bacillus amyloliquefaciens FZB42 is a representative organism for Gram positive soil bacteria associated with plant roots and beneficial to plant growth. It is of immense importance to understand mechanisms of this class of bacteria adapting to rhizosphere. In this work employing differential RNA sequencing (RNA-seq) and Northern blot, we systematically identified transcription start sites of mRNAs as well as non-coding regulatory RNAs in FZB42. The genes regulated at different growth phases and located in polycistronic operons were also identified. A set of genes were re-annotated. In addition, a sRNA named Bas01 was identified to be involved in Bacillus sporulation and biofilm formation. The result we obtained provides valuable data for investigation of Bacillus gene expression and molecular details of rhizobacterial interaction with host plants.
Project description:Bacillus amyloliquefaciens FZB42 is a representative organism for Gram positive soil bacteria associated with plant roots and beneficial to plant growth. It is of immense importance to understand mechanisms of this class of bacteria adapting to rhizosphere. In this work employing differential RNA sequencing (RNA-seq) and Northern blot, we systematically identified transcription start sites of mRNAs as well as non-coding regulatory RNAs in FZB42. The genes regulated at different growth phases and located in polycistronic operons were also identified. A set of genes were re-annotated. In addition, a sRNA named Bas01 was identified to be involved in Bacillus sporulation and biofilm formation. The result we obtained provides valuable data for investigation of Bacillus gene expression and molecular details of rhizobacterial interaction with host plants. Examination of transcriptome profile of rhizobacterium B. amyloliquefaciens FZB42 grown under six conditions.
Project description:ISR is the initiation of a beneficial association by certain fungi in the rhizosphere followed by the establishment of belowground-aboveground signaling communication may result in the induction of heightened host resistance to foliar and stem pathogens, as well as insect pests.
Project description:It has been performed a genome-wide analysis of gene expression of the root-colonizing bacterium Pseudomonas putida KT2440 in the rhizosphere of corn (Zea mays var. Girona. To identify reliable rhizosphere differentially expressed genes, rhizosphere populations of P. putida bacteria cells were compared with three alternative controls: i) planktonic cells growing exponentially in rich medium (LB), ii) planktonic cells in stationary phase in LB, and iii) sessile populations established in sand microcosms, under the same conditions used to grow inoculated corn plants.
Project description:This project is designed for whole transcriptome sequencing of bacteria isolated from Rhizosphere of Wheat Plant, which has its impact on overall plant growth.
Project description:Elevated atmospheric CO2 can influence the structure and function of rhizosphere microorganisms by altering root growth and the quality and quantity of compounds released into the rhizosphere via root exudation. In these studies we investigated the transcriptional responses of Bradyrhizobium japonicum cells growing in the rhizosphere of soybean plants exposed to elevated atmospheric CO2. The results of microarray analyses indicated that atmospheric elevated CO2 concentration indirectly influences on expression of large number of Bradyrhizobium genes through soybean roots. In addition, genes involved in C1 metabolism, denitrification and FixK2-associated genes, including those involved in nitrogen fixation, microanaerobic respiration, respiratory nitrite reductase, and heme biosynthesis, were significantly up-regulated under conditions of elevated CO2 in the rhizosphere, relative to plants and bacteria grown under ambient CO2 growth conditions. The expression profile of genes involved in lipochitinoligosaccharide Nod factor biosynthesis and negative transcriptional regulators of nodulation genes, nolA and nodD2, were also influenced by plant growth under conditions of elevated CO2. Taken together, results of these studies indicate that growth of soybeans under conditions of elevated atmospheric CO2 influences gene expressions in B. japonicum in the soybean rhizosphere, resulting in changes to carbon/nitrogen metabolism, respiration, and nodulation efficiency.