scholarly journals VelA and LaeA are key regulators of the Epichloë festucae transcriptomic response during symbiosis with perennial ryegrass

2019 ◽  
Author(s):  
M. Rahnama ◽  
P. Maclean ◽  
D.J. Fleetwood ◽  
R.D. Johnson
Keyword(s):  
Cell Wall ◽  
Secondary Metabolism ◽  
Perennial Ryegrass ◽  
Comparative Transcriptomics ◽  
Global Regulator ◽  
Symbiotic Interaction ◽  
Fungal Cell ◽  
Transcriptomic Response ◽  
Epichloë Festucae ◽  
The Impact

AbstractVelA (or VeA) is a key global regulator in fungal secondary metabolism and development which we previously showed is required during the symbiotic interaction of Epichloë festucae with perennial ryegrass. In this study, comparative transcriptomics analyses of ΔvelA mutant compared to wild type E. festucae, under three different conditions (in culture, infected seedlings and infected mature plants) were performed to investigate the impact VelA on the E. festucae transcriptome. These comparative transcriptomics studies showed that VelA regulates the expression of genes encoding proteins involved in membrane transport, fungal cell wall biosynthesis, host cell wall degradation and secondary metabolism, along with a number of small secreted proteins and a large number of proteins with no predictable functions. In addition, these results were compared with previous transcriptomics experiments studying the impact of LaeA, another key global regulator of secondary metabolism and development that we have shown is important for the E. festucae- perennial ryegrass interaction. The results showed that although VelA and LaeA regulate a sub-set of E. festucae genes in a similar manner, they also regulated many other genes independently of each other suggesting specialised roles.

scholarly journals VelA and LaeA are Key Regulators of Epichloë festucae Transcriptomic Response during Symbiosis with Perennial Ryegrass

2019 ◽  
Vol 8 (1) ◽  
pp. 33 ◽  
Author(s):  
Mostafa Rahnama ◽  
Paul Maclean ◽  
Damien J. Fleetwood ◽  
Richard D. Johnson
Keyword(s):  
Cell Wall ◽  
Secondary Metabolism ◽  
Perennial Ryegrass ◽  
Global Regulator ◽  
Symbiotic Interaction ◽  
Fungal Cell ◽  
Transcriptomic Response ◽  
Epichloë Festucae ◽  
Genes Encoding ◽  
The Impact

VelA (or VeA) is a key global regulator in fungal secondary metabolism and development which we previously showed is required during the symbiotic interaction of Epichloë festucae with perennial ryegrass. In this study, comparative transcriptomic analyses of ∆velA mutant compared to wild-type E. festucae, under three different conditions (in culture, infected seedlings, and infected mature plants), were performed to investigate the impact of VelA on E. festucae transcriptome. These comparative transcriptomic studies showed that VelA regulates the expression of genes encoding proteins involved in membrane transport, fungal cell wall biosynthesis, host cell wall degradation, and secondary metabolism, along with a number of small secreted proteins and a large number of proteins with no predictable functions. In addition, these results were compared with previous transcriptomic experiments that studied the impact of LaeA, another key global regulator of secondary metabolism and development that we have shown is important for E. festucae–perennial ryegrass interaction. The results showed that although VelA and LaeA regulate a subset of E. festucae genes in a similar manner, they also regulated many other genes independently of each other suggesting specialised roles.

scholarly journals TheAspergillus flavus rtfAGene Regulates Plant and Animal Pathogenesis and Secondary Metabolism

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Jessica M. Lohmar ◽  
Olivier Puel ◽  
Jeffrey W. Cary ◽  
Ana M. Calvo
Keyword(s):  
Oxidative Stress ◽  
Cell Wall ◽  
Secondary Metabolism ◽  
Elongation Factor ◽  
Host Tissue ◽  
Infection Model ◽  
Global Regulator ◽  
Pol Ii ◽  
Content Type ◽  
Transcription Elongation Factor

ABSTRACTAspergillus flavusis an opportunistic fungal plant and human pathogen and a producer of mycotoxins, including aflatoxin B1(AFB1). As part of our ongoing studies to elucidate the biological functions of theA. flavusrtfAgene, we examined its role in the pathogenicity of both plant and animal model systems.rtfAencodes a putative RNA polymerase II (Pol II) transcription elongation factor previously characterized inSaccharomyces cerevisiae,Aspergillus nidulans, andAspergillus fumigatus, where it was shown to regulate several important cellular processes, including morphogenesis and secondary metabolism. In addition, an initial study inA. flavusindicated thatrtfAalso influences development and production of AFB1; however, its effect on virulence is unknown. The current study reveals that thertfAgene is indispensable for normal pathogenicity in plants when using peanut seed as an infection model, as well as in animals, as shown in theGalleria mellonellainfection model. Interestingly,rtfApositively regulates several processes known to be necessary for successful fungal invasion and colonization of host tissue, such as adhesion to surfaces, protease and lipase activity, cell wall composition and integrity, and tolerance to oxidative stress. In addition, metabolomic analysis revealed thatA. flavusrtfAaffects the production of several secondary metabolites, including AFB1, aflatrem, leporins, aspirochlorine, ditryptophenaline, and aflavinines, supporting a role ofrtfAas a global regulator of secondary metabolism. Heterologous complementation of anA. flavusrtfAdeletion strain withrtfAhomologs fromA. nidulansorS. cerevisiaefully rescued the wild-type phenotype, indicating that thesertfAhomologs are functionally conserved among these three species.IMPORTANCEIn this study, the epigenetic global regulatorrtfA, which encodes a putative RNA-Pol II transcription elongation factor-like protein, was characterized in the mycotoxigenic and opportunistic pathogenA. flavus. Specifically, its involvement inA. flavuspathogenesis in plant and animal models was studied. Here, we show thatrtfApositively regulatesA. flavusvirulence in both models. Furthermore,rtfA-dependent effects on factors necessary for successful invasion and colonization of host tissue byA. flavuswere also assessed. Our study indicates thatrtfAplays a role inA. flavusadherence to surfaces, hydrolytic activity, normal cell wall formation, and response to oxidative stress. This study also revealed a profound effect ofrtfAon the metabolome ofA. flavus, including the production of potent mycotoxins.

scholarly journals Chitin Deacetylases are Required for Epichloë festucae Endophytic Cell Wall Remodelling During Establishment of a Mutualistic Symbiotic Interaction with Lolium perenne

2021 ◽  
Author(s):  
Nazanin Noorifar ◽  
Matthew Savoian ◽  
Arvina Ram ◽  
Yonathan Lukito ◽  
Berit Hassing ◽  
...  
Keyword(s):  
Cell Wall ◽  
Lolium Perenne ◽  
Molecular Probes ◽  
Symbiotic Association ◽  
In Planta ◽  
Intercellular Spaces ◽  
Free Living ◽  
Chitin Deacetylase ◽  
Symbiotic Interaction ◽  
Epichloë Festucae

Epichloë festucae forms a mutualistic symbiotic association with Lolium perenne. This biotrophic fungus systemically colonizes the intercellular spaces of aerial tissues to form an endophytic hyphal network, and also grows as an epiphyte. However, little is known about the cell wall remodelling mechanisms required to avoid host defence and maintain intercalary growth within the host. Here we use a suite of molecular probes to show that the E. festucae cell wall is remodelled by conversion of chitin to chitosan during infection of L. perenne seedlings as the hyphae switch from free-living to endophytic growth. When hyphae transition from endophytic to epiphytic growth the cell wall is remodelled from predominantly chitosan to chitin. This conversion from chitin to chitosan is catalysed by chitin deacetylase. The genome of E. festucae encodes three putative chitin deacetylases, two of which (cdaA and cdaB) are expressed in planta. Deletion of either of these genes results in disruption of fungal intercalary growth in the intercellular spaces of plants infected with these mutants. These results establish that these two genes are required for maintenance of the mutualistic symbiotic interaction between E. festucae and L. perenne.

scholarly journals The Fungal Cell-Wall Integrity MAPK Cascade Is Crucial for Hyphal Network Formation and Maintenance of Restrictive Growth of Epichloë festucae in Symbiosis With Lolium perenne

2015 ◽  
Vol 28 (1) ◽  
pp. 69-85 ◽  
Author(s):  
Yvonne Becker ◽  
Carla J. Eaton ◽  
Emma Brasell ◽  
Kimberley J. May ◽  
Matthias Becker ◽  
...  
Keyword(s):  
Cell Wall ◽  
Lolium Perenne ◽  
Network Formation ◽  
Mapk Pathway ◽  
Cell Wall Integrity ◽  
Mitogen Activated Protein Kinase ◽  
Vascular Bundles ◽  
Intercellular Spaces ◽  
Symbiotic Interaction ◽  
Epichloë Festucae

Epichloë festucae is a mutualistic symbiont that systemically colonizes the intercellular spaces of Lolium perenne leaves to form a highly structured and interconnected hyphal network. In an Agrobacterium tumefaciens T-DNA forward genetic screen, we identified a mutant TM1066 that had a severe host interaction phenotype, causing stunting and premature senescence of the host. Molecular analysis revealed that the mutation responsible for this phenotype was in the cell-wall integrity (CWI) mitogen-activated protein kinase kinase (MAPKK), mkkA. Mutants generated by targeted deletion of the mkkA or the downstream mpkA kinase recapitulated the phenotypes observed for TM1066. Both mutants were defective in hyphal cell–cell fusion, formed intrahyphal hyphae, had enhanced conidiation, and showed microcyclic conidiation. Transmission electron microscopy and confocal microscopy analysis of leaf tissue showed that mutant hyphae were more abundant than the wild type in the intercellular spaces and colonized the vascular bundles. Hyphal branches failed to fuse but, instead, grew past one another to form bundles of convoluted hyphae. Mutant hyphae showed increased fluorescence with AF488-WGA, indicative of increased accessibility of chitin, a hypothesis supported by changes in the cell-wall ultrastructure. These results show that the CWI MAPK pathway is a key signaling pathway for controlling the mutualistic symbiotic interaction between E. festucae and L. perenne.

scholarly journals Collembola interact with mycorrhizal fungi in modifying oak morphology, C and N incorporation and transcriptomics

2019 ◽  
Vol 6 (3) ◽  
pp. 181869 ◽  
Author(s):  
Marcel Graf ◽  
Markus Bönn ◽  
Lasse Feldhahn ◽  
Florence Kurth ◽  
Thorsten E. E. Grams ◽  
...  
Keyword(s):  
Gene Expression ◽  
Resource Allocation ◽  
Secondary Metabolism ◽  
Plant Defence ◽  
Plant Morphology ◽  
Pedunculate Oak ◽  
Pulse Labelling ◽  
Transcriptomic Response ◽  
The Impact ◽  
Go Terms

Soil detritivores such as Collembola impact plant growth, tissue nutrient concentration and gene expression. Using a model system with pedunculate oak ( Quercus robur ) microcuttings that display a typical endogenous rhythmic growth with alternating shoot (SF) and root flushes (RF), we investigated the transcriptomic response of oak with and without mycorrhiza ( Piloderma croceum ) to the presence of Collembola ( Protaphorura armata ), and linked it to changes in resource allocation by pulse labelling the plants with 13 C and 15 N. Collembola impacted Gene Ontology (GO) terms as well as plant morphology and elemental ratios with the effects varying markedly with developmental phases. During SF Collembola increased GO terms related to primary growth and this was mirrored in increased 13 C and 15 N excess in aboveground plant compartments. During RF, Collembola increased GO terms related to plant secondary metabolism and physical fortification. Further, Collembola presence resulted in an increase in plant defence-related GO terms suggesting that Collembola in the rhizosphere prime oak shoots against the attack by fungi or herbivores. Notably, the impact of Collembola on growth, resource allocation and oak gene expression was modified by presence of P. croceum . The results indicate that oaks clearly react to the presence of Collembola in the rhizosphere and respond in a complex way by changing the expression of genes of both primary and secondary metabolism, and this resulted in concomitant changes in plant morphology and physiology.

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