Project description:The root-colonizing fungal endophyte Serendipita indica, formerly known as Piriformospora indica, is well known to promote plant biomass production and stress tolerance of its host plants. Co-cultivation of Arabidopsis thaliana seedlings with the fungus triggers a substantial induction of the growth of the root system. However, the molecular mechanisms by which the fungus promotes plant growth over an extended period of time is still unclear. We here report the comparative analysis of the effect of a mock- and S. indica-infection on wild-type Arabidopsis plants (Col-0) after 2 and 10 days of co-cultivation. Our data provide evidence for the induction of a number of genes that are consistingly induced during the plant–fungus interaction.
Project description:The root-colonizing fungal endophyte Serendipita indica, formerly known as Piriformospora indica, is well known to promote plant biomass production and stress tolerance of its host plants. Moreover, previous studies highlighted an important impact of the fungus on auxin homeostasis during the infection of Arabidopsis thaliana plants. Auxin is a key determinant of plant growth, including the growth of the root system. Auxin overproducing mutants, like for instance YUC9oe (Hentrich et al., 2013 Plant J.), show a pronounced root phenotype that can be restored by the co-cultivation with S. indica. We here report the comparative analysis of the effect of a mock- and S. indica-infection on both wild-type Arabidopsis plants (Col-0) and YUC9 overexpressing mutants. Our data provide evidence for the induction of GRETCHEN HAGEN 3 (GH3) genes that are involved in conjugating active free indole-3-acetic acid with amino acids. The fungus triggered induction GH3s is suggested to be involved in affecting the cellular auxin homeostasis.
Project description:Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant per-formance, growth and resistance/tolerance against abiotic and biotic stress. We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the gene expression pattern indicates a shift from defense to mutualistic interaction. We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the downregulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance.
Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease. The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana, and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/P. parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy. The present project aims at analyzing the compatible interaction between A. thaliana roots and P. parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom-designed P. parasitica biochip will enable analyzing of P. parasitica gene expression during the same stages.
Project description:Piriformospora indica is a root-colonizing fungus, which interacts with a variety of plants including Arabidopsis thaliana. This interaction has been considered as mutualistic, as it leads to an increased mycelia dry weight and increased shoot fresh weight, respectively. So far, only indolic glucosinolates and phytohormones have been identified as major key players. In a comprehensive non-targeted metabolite profiling study by means of UPLC/ESI-QTOFMS and GC/EI-QMS we analyzed Arabidopsis thaliana’s roots, root exudates, and leaves of inoculated and non-inoculated plants and identified further biomarkers. Among them, the concentration of nucleosides, dipeptides, oligolignols, and glucosinolate degradation products was affected in the exudates. In the root profiles, nearly all metabolite levels increased upon co-cultivation, namely those of carbohydrates, organic acids, amino acids, glucosinolates, oligolignols, and flavonoids. In the leaf profiles, we detected by far less significant changes. We only observed an increased concentration in organic acids, carbohydrates, ascorbate, glucosinolates and hydroxycinnamic acids, and a decreased concentration in nitrogen-rich amino acids in inoculated plants.
Project description:Piriformospora indica, an endophytic fungus of Sebacinales, colonizes the roots of many plant species including Arabidopsis thaliana. The symbiotic interaction promotes plant per-formance, growth and resistance/tolerance against abiotic and biotic stress. We demonstrate that exudated compounds from the fungus activate stress and defense responses in the Arabidopsis roots and shoots before the two partners are in physical contact. They induce stomata closure, stimulate reactive oxygen species (ROS) production, stress-related phytohormone accumulation and activate defense and stress genes in the roots and/or shoots. Once a physical contact is established, the stomata re-open, ROS and phytohormone levels decline, and the gene expression pattern indicates a shift from defense to mutualistic interaction. We propose that exudated compounds from P. indica induce stress and defense responses in the host. Root colonization results in the downregulation of defense responses and the activation of genes involved in promoting plant growth, metabolism and performance. Twelve day-old (48 h cold treatment and 10 days of illumination) Arabidopsis seedlings of equal sizes were selected for co-cultivation experiments. They were transferred to PNM plates with a nylone membrane on the top (Johnson et al. 2011) and exposed to a fungal plug 5 mm in diameter or a KM plug of the same size without fungal hyphae (control). The plugs were placed 3 cm away from the closest root part . The light intensity (80 ± 5 μmol m-2 sec-1) was checked every third day to ensure that both P. indica- and mock-treated seedlings receive equal amounts of light.
Project description:Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to particular physiological characteristics, no treatments against diseases caused by oomycetes are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. The present project is focused on the molecular mechanisms that underlie the compatible plant-oomycete interaction and plant disease. The laboratory developed a novel interaction system involving the model plant, Arabidopsis thaliana, and Phytophthora parasitica, a soil-borne pathogen infecting a wide host range, thus representing the majority of Phytophthora species. A characteristic feature of the compatible Arabidopsis/P. parasitica interaction is an extended biotrophic phase, before infection becomes necrotrophic. Because the initial biotrophic phase is extremely short on natural (e.g. solanaceous) hosts, the Arabidopsis system provides the opportunity to analyze, for both interaction partners, the molecular events that determine the initiation of infection and the switch to necrotrophy. The present project aims at analyzing the compatible interaction between A. thaliana roots and P. parasitica. The Affymetrix A. thaliana full genome chip will be used to characterize modulations of the transcriptome occurring over a period of 24h from the onset of plant root infection to the beginning of necrotrophy. Parallel to this study, a custom-designed P. parasitica biochip will enable analyzing of P. parasitica gene expression during the same stages. 10 samples were used in this experiment.
Project description:Plants interact with a wide variety of fungi in a mutualistic, parasitic or neutral way. The associations formed depend on the exchange of nutrients and signalling molecules between the partners. The latter include a diverse set of protein classes, of which some have been demonstrated to be functionally implicated in defence, nutrient uptake and establishing a symbiotic relationship. Here, we have analysed the secretomes of the mutualistic, root-endophytic fungus Piriformospora indica and Arabidopsis thaliana when cultivated alone or in a co-culture. More than one hundred proteins were identified as differentially secreted, including proteins associated with growth, development, abiotic and biotic stress response and mucilage. One protein found in the co-culture is PLAT1 (Polycystin, Lipoxygenase, Alpha-toxin and Triacylglycerol lipases). PLAT1 has not been associated with plant-fungal-interaction before and is known to play a role in abiotic stress responses. It co-localizes with Brassicaceae-specific endoplasmic reticulum bodies (ER bodies), which are involved in the formation of the defence compound scopolin. We observed degraded ER bodies in P. indica infected Arabidopsis roots and plat1 mutants were stronger colonised than wild tyype (WT) plants. Furthermore, PLAT1 RNA (ribonucleic acid) and scopolin levels were detected to be regulated by the fungus in a stage-specific manner.
Project description:Broad-host root endophytes establish long-term interactions with a large variety of plants, thereby playing a significant role in natural and managed ecosystems and in evolution of land plants. To exploit plants as living substrates and to establish a compatible interaction with morphologically and biochemically extremely different hosts, endophytes must respond and adapt to different plant signals and host metabolic states. Here we identified host-adapted colonization strategies and host-specific effector candidates of the mutualistic root endophyte Piriformospora indica by a global investigation of fungal transcriptional responses to barley and Arabidopsis at different symbiotic stages. Additionally we examined the role played by nitrogen in these two diverse associations. Cytological studies and colonization analyses of a barley mutant and fungal RNAi strains show that distinct physiological and metabolic signals regulate host-specific lifestyle in P. indica. This is the foundation for exploring how distinct fungal and host symbiosis determinants modulate biotrophy in one host and saprotrophy in another host and, ultimately, gives hints into the mechanisms underlying host adaptation in root symbioses. Arabidopsis and barley roots were inoculated with Piriformospora indica and grown for 14 days. Additionally P. indica was grown on 1/10 PNM medium alone. Samples were taken 3 and 14 dpi (Arabidopsis), 14 dpi (barley) and 3dpi (1/10 PNM). Each experiment was performed in three independent biological repetitions. Piriformospora indica gene expression examined only.