Nicholas Talbot | University of Exeter (original) (raw)

Papers by Nicholas Talbot

Nature, Jan 23, 2006

To cause diseases in plants, pathogenic microorganisms have evolved mechanisms to deliver protein... more To cause diseases in plants, pathogenic microorganisms have evolved mechanisms to deliver proteins directly into plant cells, where they suppress plant defences and facilitate tissue invasion. How plant pathogenic fungi, which cause many of the world's most serious plant diseases, deliver proteins during plant infection is currently unknown. Here we report the characterization of a P-type ATPase-encoding gene, MgAPT2, in the economically important rice blast pathogen Magnaporthe grisea, which is required for exocytosis during plant infection. Targeted gene replacement showed that MgAPT2 is required for both foliar and root infection by the fungus, and for the rapid induction of host defence responses in an incompatible reaction. DeltaMgapt2 mutants are impaired in the secretion of a range of extracellular enzymes and accumulate abnormal Golgi-like cisternae. However, the loss of MgAPT2 does not significantly affect hyphal growth or sporulation, indicating that the establishment ...

Nature protocols, 2008

Interactions between plants and compatible fungal pathogens are spatially and temporally dynamic,... more Interactions between plants and compatible fungal pathogens are spatially and temporally dynamic, posing a major challenge for sampling and data analysis. A protocol is described for the infection of the model grass species Brachypodium distachyon with Magnaporthe grisea (rice blast), together with modifications to extend the use to rice and barley. We outline a method for the preparation of long-term stocks of virulent fungal pathogens and for the generation of fungal inoculants for challenge of host plants. Host plant growth, pathogen inoculation and plant sampling protocols are presented together with methods for assessing the efficiency of both infection and sampling procedures. Included in the anticipated results is a description of the use of metabolite fingerprinting and multivariate data analysis to assess disease synchrony and validate system reproducibility between experiments. The design concepts will have value in any studies using biological systems that contain dynamic...

Protoplasma, 2001

Summary Histochemical and ultrastructural studies were carried out on a wild-type strain (Guyll)... more Summary Histochemical and ultrastructural studies were carried out on a wild-type strain (Guyll) and a melanin-deficient mutant(büβ) of the rice-blast pathogen,Magnaporthe grisea (=Pyricularia oryzae), in order to investigate the destination of lipid storage reserves during appressorium development. Lipid droplets were abundant in conidia and were mobilised upon germination, accumulating in the appressorial hook which developed at the tip of each germ

Science, 2006

Rice blast is caused by the fungus Magnaporthe grisea, which elaborates specialized infection cel... more Rice blast is caused by the fungus Magnaporthe grisea, which elaborates specialized infection cells called appressoria to penetrate the tough outer cuticle of the rice plant Oryza sativa. We found that the formation of an appressorium required, sequentially, the completion of mitosis, nuclear migration, and death of the conidium (fungal spore) from which the infection originated. Genetic intervention during mitosis

Nature Communications, 2014

To cause plant disease, pathogenic fungi can secrete effector proteins into plant cells to suppre... more To cause plant disease, pathogenic fungi can secrete effector proteins into plant cells to suppress plant immunity and facilitate fungal infection. Most fungal pathogens infect plants using very long strand-like cells, called hyphae, that secrete effectors from their tips into host tissue. How fungi undergo long-distance cell signalling to regulate effector production during infection is not known. Here we show that long-distance retrograde motility of early endosomes (EEs) is necessary to trigger transcription of effector-encoding genes during plant infection by the pathogenic fungus Ustilago maydis. We demonstrate that motor-dependent retrograde EE motility is necessary for regulation of effector production and secretion during host cell invasion. We further show that retrograde signalling involves the mitogen-activated kinase Crk1 that travels on EEs and participates in control of effector production. Fungal pathogens therefore undergo long-range signalling to orchestrate host invasion. Plant Cmu1 cytoplasmic GFP EEs (paGFP-Rab5a) Cell wall Nucleus (H4) Figure 1 | Endosomes travel from the invading hyphal tip to the nucleus. (a) Lectin-stained hyphal cells (green) colonizing a leaf at 2 d.p.i. Plant cell walls were stained using propidium iodide (red). Scale bars, 20 mm (left panel) and 10 mm (right panel). (b) Invasion of hyphal cells, expressing a nuclear RFP (nucleus; appearing yellow) and cytoplasmic GFP (green), at 1 d.p.i. Dotted line indicates plant surface. Chloroplasts visualized by their auto-fluorescence (asterisks, red). Arrow head points towards invading hyphal tip. Scale bar, 10 mm. See Supplementary Movie 1. (c) Secretion of effector protein Cmu1-mCherry (red) during early fungal invasion (fungus in green). Right panels reveal Cmu1-mCherry at the fungus-plant interface. Scale bars, 2 mm. See Supplementary Movie 2. (d) Image and kymograph show retrograde motility of photo-activated paGFP-Rab5a-labelled EEs (green) towards subapical nucleus (red, labelled with histone4-mCherry) in an invading fungal cell. The fungal cell wall was stained with Calcofluor White (blue). Point of photo-activation indicated by open arrowhead. Solid arrows in lower panel indicate long range motility. Scale bars, 10 mm (upper panel), 3 s (vertical, lower panel) and 5 mm (horizontal, lower panel). (e) Retrograde run-length of photo-activated EEs in invading hyphae (1 d.p.i.). Mean position of nucleus is indicated in red; 95% confidence intervals (CIs) indicated by green dotted line. Sample size from 43 experiments is shown.

Comparative and Functional Genomics, 2003

Fungal phytopathogens continue to cause major economic impact, either directly, through crop loss... more Fungal phytopathogens continue to cause major economic impact, either directly, through crop losses, or due to the costs of fungicide application. Attempts to understand these organisms are hampered by a lack of fungal genome sequence data. A need exists, however, to develop specific bioinformatics tools to collate and analyse the sequence data that currently is available. A web-accessible gene discovery database (http://cogeme.ex.ac.uk/biosynthesis.html) was developed as a demonstration tool for the analysis of metabolic and signal transduction pathways in pathogenic fungi using incomplete gene inventories. Using Bayesian probability to analyse the currently available gene information from pathogenic fungi, we provide evidence that the obligate pathogen Blumeria graminis possesses all amino acid biosynthetic pathways found in free-living fungi, such as Saccharomyces cerevisiae. Phylogenetic analysis was also used to deduce a gene history of succinate-semialdehyde dehydrogenase, an enzyme in the glutamate and lysine biosynthesis pathways. The database provides a tool and methodology to researchers to direct experimentation towards predicting pathway conservation in pathogenic microorganisms.

Molecular Microbiology, 2006

Magnaporthe grisea, the causal agent of rice blast disease, invades plant tissue due to the actio... more Magnaporthe grisea, the causal agent of rice blast disease, invades plant tissue due to the action of specialized infection structures called appressoria, which are used to breach the leaf cuticle and allow development of intracellular, infectious hyphae. In this report we demonstrate that peroxisomal carnitine acetyl transferase (CAT) activity is necessary for appressorium function, and in particular, for the elaboration of primary penetration hyphae. The major CAT activity in M. grisea is encoded by the PTH2 gene, which shows elevated expression in response to acetate and lipid, and is regulated by the cyclic AMP response pathway. Furthermore, a Pth2-GFP fusion protein colocalizes with a peroxisomal marker protein. Targeted deletion of PTH2, generated mutants that were completely non-pathogenic, lacked CAT activity and were unable to utilize a range of lipid substrates. The impairment of appressorium function in Dpth2 was associated with a delay in lipid reserve mobilization from germ tubes into developing infection cells, and abnormal chitin distribution in infection structures. Addition of glucose to Dpth2 mutants partially restored the ability to cause rice blast disease and lipid reserve mobilization. Taken together, our findings provide evidence that Pth2 plays a role in the generation of acetyl CoA pools necessary for appressorium function and rapid elaboration of penetration hyphae during host infection.

Plos One, 2014

LIM domain proteins contain contiguous double-zinc finger domains and play important roles in cyt... more LIM domain proteins contain contiguous double-zinc finger domains and play important roles in cytoskeletal re-organisation and organ development in multi-cellular eukaryotes. Here, we report the characterization of four genes encoding LIM proteins in the rice blast fungus Magnaporthe oryzae. Targeted gene replacement of either the paxillin-encoding gene, PAX1, or LRG1 resulted in a significant reduction in hyphal growth and loss of pathogenicity, while deletion of RGA1 caused defects in conidiogenesis and appressorium development. A fourth LIM domain gene, LDP1, was not required for infection-associated development by M. oryzae. Live cell imaging revealed that Lrg1-GFP and Rga1-GFP both localize to septal pores, while Pax1-GFP is present in the cytoplasm. To explore the function of individual LIM domains, we carried out systematic deletion of each LIM domain, which revealed the importance of the Lrg1-LIM2 and Lrg1-RhoGAP domains for Lrg1 function and overlapping functions of the three LIM domains of Pax1. Interestingly, deletion of either PAX1 or LRG1 led to decreased sensitivity to cell wall-perturbing agents, such as Congo Red and SDS (sodium dodecyl sulfate). qRT-PCR analysis demonstrated the importance of both Lrg1 and Pax1 to regulation of genes associated with cell wall biogenesis. When considered together, our results indicate that LIM domain proteins are key regulators of infection-associated morphogenesis by the rice blast fungus.

Fungal Genetics and Biology, 2014

Fungi have the capacity to cause devastating diseases of both plants and animals, causing signifi... more Fungi have the capacity to cause devastating diseases of both plants and animals, causing significant harvest losses that threaten food security and human mycoses with high mortality rates. As a consequence, there is a critical need to promote development of new antifungal drugs, which requires a comprehensive molecular knowledge of fungal pathogenesis. In this review, we critically evaluate current knowledge of seven fungal organisms used as major research models for fungal pathogenesis. These include pathogens of both animals and plants; Ashbya gossypii, Aspergillus fumigatus, Candida albicans, Fusarium oxysporum, Magnaporthe oryzae, Ustilago maydis and Zymoseptoria tritici. We present key insights into the virulence mechanisms deployed by each species and a comparative overview of key insights obtained from genomic analysis. We then consider current trends and future challenges associated with the study of fungal pathogenicity.

Applied Mycology and Biotechnology, 2004

... In 344 Martin J. Gilbert, Darren M. Soanes and Nicholas J Talbot this method, linearized plas... more ... In 344 Martin J. Gilbert, Darren M. Soanes and Nicholas J Talbot this method, linearized plasmid DNA is transformed into the organism of choice in the presence of a restriction enzyme, which generates compatible or incompatible ends. ... 2000; Mikosch et al. 2001; Mullins et al. ...

Fungal Biology Reviews, 2011

Lateral gene transfer Osmotrophy Phagotrophy Phylogeny Supernumerary chromosomes a b s t r a c t ... more Lateral gene transfer Osmotrophy Phagotrophy Phylogeny Supernumerary chromosomes a b s t r a c t A growing body of data suggests that fungi have gained genes by horizontal gene transfer (HGT). This is an exciting result because fungi at first glance represent the most recalcitrant of all organisms to gene transfer, possessing robust cell walls and having lost phagotrophic capacities because they feed exclusively by osmotrophy. Nonetheless, a number of mechanisms have been implicated in gene transfer including: anastomosis of cellular structures, conjugation-like transfer between bacteria and yeasts, and exchange of supernumerary chromosomes. Despite absence of clearly identified mechanisms driving gene transfer in fungi,

PLoS ONE, 2014

The rice blast fungus Magnaporthe oryzae causes plant disease via specialised infection structure... more The rice blast fungus Magnaporthe oryzae causes plant disease via specialised infection structures called appressoria. These dome-shaped cells are able to generate enormous internal pressure, which enables penetration of rice tissue by invasive hyphae. Previous studies have shown that mobilisation of lipid bodies and subsequent lipid metabolism are essential prerequisites for successful appressorium-mediated plant infection, which requires autophagic recycling of the contents of germinated spores and germ tubes to the developing appressorium. Here, we set out to identify putative regulators of lipid metabolism in the rice blast fungus. We report the identification of FAR1 and FAR2, which encode highly conserved members of the Zn2-Cys6 family of transcriptional regulators. We generated Dfar1, Dfar2 and Dfar1Dfar2 double mutants in M. oryzae and show that these deletion mutants are deficient in growth on long chain fatty acids. In addition, Dfar2 mutants are also unable to grow on acetate and short chain fatty acids. FAR1 and FAR2 are necessary for differential expression of genes involved in fatty acid b-oxidation, acetyl-CoA translocation, peroxisomal biogenesis, and the glyoxylate cycle in response to the presence of lipids. Furthermore, FAR2 is necessary for expression of genes associated with acetyl-CoA synthesis. Interestingly, Dfar1, Dfar2 and Dfar1Dfar2 mutants show no observable delay or reduction in lipid body mobilisation during plant infection, suggesting that these transcriptional regulators control lipid substrate utilization by the fungus but not the mobilisation of intracellular lipid reserves during infection-related morphogenesis. Citation: bin Yusof MT, Kershaw MJ, Soanes DM, Talbot NJ (2014) FAR1 and FAR2 Regulate the Expression of Genes Associated with Lipid Metabolism in the Rice Blast Fungus Magnaporthe oryzae. PLoS ONE 9(6): e99760.

by Kim Plummer, Darren Soanes, Muriel Viaud, Linda Kohn, Marc-henri Lebrun, Jeffrey Rollins, Nicholas Talbot, Oded Yarden, Luis Aguirrezabal Christine Granier, Sabine Fillinger, Emmanuel Quévillon, Baptiste Brault, Ulrich Güldener, and Pascale Cotton

PLoS Genetics, 2011

Sclerotinia sclerotiorum and Botrytis cinerea are closely related necrotrophic plant pathogenic f... more Sclerotinia sclerotiorum and Botrytis cinerea are closely related necrotrophic plant pathogenic fungi notable for their wide host ranges and environmental persistence. These attributes have made these species models for understanding the complexity of necrotrophic, broad host-range pathogenicity. Despite their similarities, the two species differ in mating behaviour and the ability to produce asexual spores. We have sequenced the genomes of one strain of S. sclerotiorum and two strains of B. cinerea. The comparative analysis of these genomes relative to one another and to other sequenced fungal genomes is provided here. Their 38-39 Mb genomes include 11,860-14,270 predicted genes, which share 83% amino acid identity on average between the two species. We have mapped the S. sclerotiorum assembly to 16 chromosomes and found large-scale co-linearity with the B. cinerea genomes. Seven percent of the S. sclerotiorum genome comprises transposable elements compared to ,1% of B. cinerea. The arsenal of genes associated with necrotrophic processes is similar between the species, including genes involved in plant cell wall degradation and oxalic acid production. Analysis of secondary metabolism gene clusters revealed an expansion in number and diversity of B. cinerea-specific secondary metabolites relative to S. sclerotiorum. The potential diversity in secondary metabolism might be involved in adaptation to specific ecological niches. Comparative genome analysis revealed the basis of differing sexual mating compatibility systems between S. sclerotiorum and B. cinerea. The organization of the mating-type loci differs, and their structures provide evidence for the evolution of heterothallism from homothallism. These data shed light on the evolutionary and mechanistic bases of the genetically complex traits of necrotrophic pathogenicity and sexual mating. This resource should facilitate the functional studies designed to better understand what makes these fungi such successful and persistent pathogens of agronomic crops.

PLOS Genetics, 2011

Research in autophagy continues to accelerate, and as a result many new scientists are entering t... more Research in autophagy continues to accelerate, and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose. There are many useful and convenient methods that can be used

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since t... more In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have

Trends in Microbiology, 2008