Project description:The identification of processes activated by specific microbes during microbiota colonization of plant roots has been hampered by technical constraints in metatranscriptomics. These include lack of reference genomes, high representation of host or microbial rRNA sequences in datasets, or difficulty to experimentally validate gene functions. Here, we recolonized germ-free Arabidopsis thaliana with a synthetic, yet representative root microbiota comprising 106 genome-sequenced bacterial and fungal isolates. We used multi-kingdom rRNA depletion, deep RNA-sequencing and read mapping against reference microbial genomes to analyse the in-planta metatranscriptome of abundant colonizers. We identified over 3,000 microbial genes that were differentially regulated at the soil-root interface. Translation and energy production processes were consistently activated in planta, and their induction correlated with bacterial strains’ abundance in roots. Finally, we used targeted mutagenesis to show that several genes consistently induced by multiple bacteria are required for root colonization in one of the abundant bacterial strains (a genetically tractable Rhodanobacter). Our results indicate that microbiota members activate strain-specific processes but also common gene sets to colonize plant roots.
Project description:Interactions between plants and each neighboring microbial species are fundamental building blocks that collectively determine the structure and function of the plant microbiota, but the molecular basis of such interactions is poorly characterized. Here, we monocolonized Arabidopsis leaves with nine plant-associated bacteria from all major phyla of the plant microbiota and profiled co-transcriptomes of plants and bacteria. These strains elicited quantitatively different plant transcriptional responses including typical pattern-triggered immunity responses. Genes of non-pathogenic bacteria involved in general metabolism and energy production were commonly suppressed in planta in contrast to a virulent pathogen. Various nutrient acquisition pathways that are frequently encoded in the genomes of plant-associated bacteria were induced in planta in a strain-specific manner, shedding light on bacterial adaptation to the plant environment and identifying a potential driving force of niche separation. Integrative analyses of plant and bacterial transcriptomes suggested that the transcriptional reprogramming of plants is largely uncoupled from that of bacteria at an early stage of interactions. This study provides insights into how plants discriminate among bacterial strains and sets the foundation for in-depth mechanistic dissection of plant-microbiota interactions.
Project description:Plants are naturally associated with diverse microbial communities, which play significant roles in plant performance, such as growth promotion or fending off pathogens. The roots of Alkanna tinctoria L. are rich in naphthoquinones, particularly the medicinally used chiral compounds alkannin, shikonin and their derivatives. Former studies already have shown that microorganisms may modulate plant metabolism. To further investigate the potential interaction between A. tinctoria and associated microorganisms we performed a greenhouse experiment, in which A. tinctoria plants were grown in the presence of three distinct soil microbiomes. At four defined plant developmental stages we made an in-depth assessment of bacterial and fungal root-associated microbiomes as well as all primary and secondary metabolites. Our results showed that the plant developmental stage was the most important driver influencing the plant metabolite content, revealing peak contents of alkannin/shikonin at the fruiting stage. In contrast, the soil microbiome had the biggest impact on the plant root microbiome. Correlation analyses performed on the measured metabolite content and the abundance of individual bacterial and fungal taxa suggested a dynamic, at times positive or negative relationship between root-associated microorganisms and root metabolism. In particular, the bacterial Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium group and the fungal species Penicillium jensenii were found to be positively correlated with higher content of alkannins.
Project description:Microarray experiments were used to build a profile of candidate stigma genes that facilitate early pollination events. Of over 24,000 genes probed, we identified 11,403 genes expressed in stigma tissue, 317 of these that are stigma specific (not expressed in control tissues). To appear in Sexual Plant Reproduction, Swanson, Clark, and Preuss, "Expression Profiling of Arabidopsis Stigma Tissue Identifies Stigma-Specific Genes." Experiment Overall Design: Expression profiles of stigma, ovary and seedling tissues were studied and contrasted. Four samples each of seedling and ovary were used; and three stigma samples.
Project description:In many plant species, flower stigma secretions are important in early stages of sexual reproduction. Previous chemical analysis and proteomic characterization of these exudates provided insights into their biological function. Nevertheless, the presence of nucleic acids in the stigma exudates has not been previously reported. Here we studied the stigma exudates of Pyrus communis, Pyrus pyrifolia and Pyrus syriaca, and showed them to harbor extracellular RNAs of various sizes. RNA sequencing revealed, for the first time, the presence of known Rosaceae mature micro-RNAs (miRs), also abundant in the stigma source tissue. Predicted targets of the exudate miRs in the Arabidopsis thaliana genome include genes involved in various biological processes. Several of these genes are pollen transcribed, suggesting possible involvement of exudate miRs in transcriptional regulation of the pollen. Moreover, extracellular miRs can potentially act across kingdoms and target genes of stigma interacting organisms/microorganisms, thus opening novel applicative avenues in HortSciences.
Project description:Background: The parasitic mite Sarcoptes scabiei is an economically highly significant parasite of the skin of humans and animals worldwide. This mite causes a neglected tropical disease (NTD), called scabies - one of the commonest dermatological problems globally, resulting in major morbidity, disability, stigma and poverty. In hyperendemic situations, scabies is often associated with secondary opportunistic bacterial infections/diseases - a major concern in children. Although some stages of this mite can be treated with drugs, resistance against some drugs is emerging, and there is no vaccine available against scabies. Here, we report molecular resources (including a high-quality genome as well as transcriptomic and proteomic data sets) for S. scabiei to aid basic and applied research of this and related mites.
Project description:The parasitic lifestyle of parasitic plants relies on the development of a haustorium, a specific infectious organ required for attachment to host roots. While haustorium development is initiated upon chemodetection of host-derived molecules in hemiparasitic plants, the induction of haustorium formation remains largely misunderstood in holoparasitic species such as Phelipanche ramosa. This work demonstrates that the root exudates of the host plant Brassica napus contain allelochemicals displaying a haustorium-inducing activity on P. ramosa germinating seeds which increases the parasite aggressiveness. A de novo assembled P. ramosa transcriptome and a microarray approach during early haustorium formation upon treatment with B. napus root exudates allowed the identification of differentially expressed genes involved in hormone signaling. Bioassays using exogenous cytokinins and the specific cytokinin receptor inhibitor PI55 showed that cytokinins induced haustorium formation and increased parasite aggressiveness. Root exudates triggered the expression of cytokinin responsive genes during early haustorium development in germinated seeds and bio-guided UPLC-MS analysis showed that these exudates contain a cytokinin with dihydrozeatin characteristics. These results suggest that cytokinins constitutively exudated from host roots play a major role in haustorium formation and aggressiveness in P. ramosa.
2017-05-27 | GSE99377 | GEO
Project description:Mulberry Fruit-Associated Bacterial and Fungal Microbiota