Project description:Transgenic expression of a double-stranded RNA in plants can induce silencing of homologous mRNAs in fungal pathogens. Although such host-induced gene silencing is well documented, the molecular mechanisms by which RNAs can move from the cytoplasm of plant cells across the plasma membrane of both the host cell and fungal cell are poorly understood. Indirect evidence suggests that this RNA transfer may occur at a very early stage of the infection process, prior to breach of the host cell wall, suggesting that silencing RNAs might be secreted onto leaf surfaces. To assess whether Arabidopsis plants possess a mechanism for secreting RNA onto leaf surfaces, we developed a protocol for isolating leaf surface RNA separately from intercellular (apoplastic) RNA. This protocol yielded abundant leaf surface RNA that displayed an RNA banding pattern distinct from apoplastic RNA, suggesting that it may be secreted directly onto the leaf surface rather than exuded through stomata or hydathodes. Notably, this RNA was not associated with either extracellular vesicles or protein complexes; however, RNA species longer than 100 nucleotides could be pelleted by ultracentrifugation. Furthermore, pelleting was inhibited by the divalent cation chelator EGTA, suggesting that these RNAs may form condensates on the leaf surface. These leaf surface RNAs are derived almost exclusively from Arabidopsis, but come from diverse genomic sources, including rRNA, tRNA, mRNA, intergenic RNA, microRNAs, and small interfering RNAs, with tRNAs especially enriched. We speculate that endogenous leaf surface RNA plays an important role in the assembly of distinct microbial communities on leaf surfaces.
Project description:Conidial germination marks the beginning of the fungal life cycle, and understanding the genes associated with conidial germination provides insights into fungal pathogenicity and host interactions. Here, we use comparative transcriptomics to demonstrate the transcriptional similarities and differences during conidial germination and initial colony establishment in a plant pathogenic and an endophytic fungus, Fusarium graminearum and M. anisopliae, respectively. We compared the transcriptomes of F. graminearum and M. anisopliae across four stages of conidial germination: fresh conidia, polar growth, hyphal extension, and either first hyphal branching (on medium) or appressorium formation (on barley). F. graminearum exhibited a higher upregulation of CAZyme, specialized metabolite and effector genes compared to M. anisopliae during interaction with the host, particularly in the appressorium stage, reflecting its pathogenic nature. The appressorium structures formed when M. anisopliae conidia germinated on the host. The transcriptome analysis revealed that the fungus produced reduced transcript levels of CAZyme and specialized metabolite genes reflecting a less aggressive host penetration approach. The candidate genes associated with IAA synthesis were upregulated in M. anisopliae during the appressorium stage, supporting its endophytic lifestyle and suggests that the fungus uses a phytohormone based strategy to interact with plant hosts. Collectively, our findings expand the transcriptome resources and provide valuable insights into the gene networks involved in conidial germination and initiation of infection in pathogenic versus endophytic fungus.
2024-11-05 | GSE277627 | GEO
Project description:Fungal Microbiome of Medicinal Plants
Project description:Conidial germination marks the beginning of the fungal life cycle, and understanding the genes associated with conidial germination provides insights into fungal pathogenicity and host interactions. Here, we use comparative transcriptomics to demonstrate the transcriptional similarities and differences during conidial germination and initial colony establishment in a plant pathogenic and an endophytic fungus, Fusarium graminearum and M. anisopliae, respectively. We compared the transcriptomes of F. graminearum and M. anisopliae across four stages of conidial germination: fresh conidia, polar growth, hyphal extension, and either first hyphal branching (on medium) or appressorium formation (on barley). F. graminearum exhibited a higher upregulation of CAZyme, specialized metabolite and effector genes compared to M. anisopliae during interaction with the host, particularly in the appressorium stage, reflecting its pathogenic nature. The appressorium structures formed when M. anisopliae conidia germinated on the host. The transcriptome analysis revealed that the fungus produced reduced transcript levels of CAZyme and specialized metabolite genes reflecting a less aggressive host penetration approach. The candidate genes associated with IAA synthesis were upregulated in M. anisopliae during the appressorium stage, supporting its endophytic lifestyle and suggests that the fungus uses a phytohormone based strategy to interact with plant hosts. Collectively, our findings expand the transcriptome resources and provide valuable insights into the gene networks involved in conidial germination and initiation of infection in pathogenic versus endophytic fungus.