Project description:Lipids play crucial roles in plant-microbe interactions, functioning as structural components, signaling molecules, and microbe-associated molecular patterns (MAMPs); however, the mechanisms underlying lipid perception and signaling pathways in plants remain largely unknown. This study investigates the immune responses triggered in Hordeum vulgare (barley) by lipid extracts from the root endophytic fungus Serendipita indica. We compare these responses to those elicited by the carbohydrate MAMP chitohexaose and the fungal sterol lipid ergosterol, a 5,7-diene oxysterol recognized as a MAMP in plants. Our results demonstrate that S. indica lipid extract induces hallmarks of pattern-triggered immunity (PTI) in barley. Ergosterol was identified as the main immunogenic component and was detected in the apoplastic fluid of S. indica-colonized barley roots. Using a multi-omics approach combining transcriptomics, phosphoproteomics, and metabolomics, our data provide evidence for the activation of phosphatidylinositol phosphate (PIP) signaling and diterpene biosynthesis upon exposure to fungal lipids. Furthermore, we show that phosphatidic acid (PA) enhances lipid-mediated apoplastic reactive oxygen species (ROS) production in barley. These findings indicate that plant lipids mediate immune responses to fungal lipids in barley, advancing our understanding of lipid perception and signaling in plant-microbe interactions.
Project description:Lipids play crucial roles in plant-microbe interactions, functioning as structural components, signaling molecules, and microbe-associated molecular patterns (MAMPs). However, the mechanisms underlying lipid perception and signaling in plants remain largely unknown. Here, we investigate the immune responses activated in barley (Hordeum vulgare L.) by lipid extracts from the beneficial root endophytic fungus Serendipita indica and compare them to responses elicited by chitohexaose and the fungal sterol ergosterol. We demonstrate that S. indica lipid extract induces hallmarks of pattern-triggered immunity (PTI) in barley. Ergosterol emerged as the primary immunogenic component and was detected in the apoplastic fluid of S. indica-colonized barley roots. Notably, S. indica colonization suppresses the ergosterol-induced burst of reactive oxygen species (ROS) in barley. By employing a multi-omics approach, which integrates transcriptomics, phosphoproteomics, and metabolomics, we provide evidence for the phosphorylation of phosphatidylinositol phosphate (PIP) metabolic enzymes and activation of diterpene biosynthesis upon exposure to fungal lipids. Furthermore, we show that phosphatidic acid (PA) enhances lipid-mediated apoplastic ROS production in barley. These findings indicate that plant lipids facilitate immune responses to fungal lipids in barley, providing new insights into lipid-based signaling mechanisms in plant-microbe interactions.
Project description:The recent release of a large number of genomes from ectomycorrhizal, orchid mycorrhizal and root endophytic fungi have provided deep insight into fungal lifestyle-associated genomic adaptation. Comparative analyses of symbiotic fungal taxa showed that similar outcomes of interactions in distant related root symbioses are examples of convergent evolution. The order Sebacinales represents a sister group to the Agaricomycetes (Basidiomycota) that is comprised of ectomycorrhizal, ericoid-, orchid- mycorrhizal, root endophytic fungi and saprotrophs (Oberwinkler et al., 2013). Sebacinoid taxa are widely distributed from arctic to temperate to tropical ecosystems and are among the most common and species-rich groups of ECM, OM and endophytic fungi (Tedersoo et al., 2012, Tedersoo et al., 2010, Oberwinkler et al., 2013). The root endophyte Piriformospora indica and the orchid mycorrhizal fungus S. vermifera (MAFF 305830) are non-obligate root symbionts which were shown to be able to interact with many different experimental hosts, including the non-mycorrhizal plant Arabidopsis thaliana. These two fungi display similar colonization strategies in barley and in Arabidopsis and the ability to establish beneficial interactions with different hosts (Deshmukh et al., 2006). Colonization of the roots by P. indica and S. vermifera results in enhanced seed germination and biomass production as well as increased resistance against biotic and abiotic stresses in its experimental hosts, including various members of the Brassicaceae family, barley, Nicotiana attenuata and switchgrass (Ghimire, 2011, Ghimire et al., 2009, Ghimire et al., 2011, Waller et al., 2008, Barazani et al., 2007, Deshmukh et al., 2006). Microarray experiments were performed to identify and characterize conserved sebacinoid genes as key determinants in the Sebacinales symbioses.
Project description:Potato (Solanum tuberosum, variety Princ) and barley (Hordeum vulgare, variety Sebastian) plants were cultivated in a controlled environment. Plants were grown in Potgrond H soil (Klasmann-Deilmann GmbH, Germany) under a 12-hour photoperiod with a constant temperature of 21 °C and a photon flux density of 100 μmol m⁻² s⁻¹. Potato tubers were used as starting material, while barley plants were grown from surface-sterilized seeds. After six weeks of cultivation for potato and three weeks for barley, the sap proteome was collected by cutting the stems 10–20 mm above the soil surface. Root exudates were sampled into three fractions over a two-hour period: F1 (15 min), F2 (75 min), and F3 (135 min). Each experiment included at least three independent biological replicates. A subset of plants was pre-incubated with flg22, a conserved peptide sequence derived from bacterial flagellin (QRLSTGSRINSAKDDAAGLQIA, >95% purity; ProteoGenix, France). Flg22 solution (1 μM flg22, 0.025% v/v Silwet L-77) was applied by spraying the leaves and pouring the solution under the pot. Potato plants received 30 ml and 200 ml of the solution for spraying and watering, respectively. Due to their smaller size, barley plants were treated with half the solution volume. Mock-treated plants received a solution containing only 0.025% Silwet L-77. After 24 hours, plants were cut, and the third fraction of the sap (75-135 min) was collected. Root and shoot tissues were collected in liquid nitrogen, the sap was collected as described above. Each experiment included at least three independent biological replicates.