Genetic diversification of the chestnut blight fungus Cryphonectria parasitica and its associated hypovirus in Germany

Molecular genetic variability of Cryphonectria hypovirus 1 associated with Cryphonectria parasitica in South Tyrol (northern Italy)

Cryphonectria hypovirus 1 (CHV-1) has been widely studied and used as a biocontrol agent because of its ability to infect the chestnut blight fungus, Cryphonectria parasitica, and to reduce its virulence. Knowledge about the hypovirus, its presence, and diversity is completely lacking in South Tyrol (northern Italy), which may obstruct biocontrol measures for chestnut blight based on CHV-1. This work aimed to study the occurrence of CHV-1 infecting C. parasitica in South Tyrol and to perform a genetic characterization of the hypovirus. In South Tyrol, CHV-1 was found to occur in 29.2% of the fungal isolates investigated, varying in frequency between different regions and chestnut stands. Twenty-three haplotypes based on partial cDNA (complementary DNA) sequences of open reading frame (ORF)-A and 30 haplotypes based on partial cDNA sequences of ORF-B were identified among 47 and 56 hypovirulent fungal isolates, respectively. Phylogenetic analysis showed that all the haplotypes belonged to the Italian subtype of CHV-1 and that they were closely related to the populations of Italy, Switzerland, Croatia and Slovenia. Evidence of recombination was not found in the sequences and point mutations were the main source of diversity. Overall, this study indicated that the prevalence of CHV-1 in South Tyrol is low compared to many other central and western European populations and determined a need to actively impose biocontrol measures. Using sequence analysis, we identified some variants of interest of CHV-1 that should be studied in detail for their potential use in biocontrol.

Spanish ecological battleground: population structure of two invasive fungi, Cryphonectria parasitica and Fusarium circinatum

Introduction

Invasive fungi distributed worldwide through globalization have caused devastating diseases in different forests, causing economic and ecologic disturbances. Two such invasive species are Cryphonectria parasitica and Fusarium circinatum, which were introduced to Europe from North America, separated temporally: C. parasitica was introduced about nine decades ago, whereas F. circinatum was introduced around two decades ago. As C. parasitica had a longer time to undergo genetic changes, we hypothesized that it has higher genetic diversity than the recently introduced F. circinatum in Spain. In addition, we studied the genetic characterization of both fungi present in similar ecological conditions in Northern Spain with the aim of providing data for biocontrol measures.

Methods

Molecular genetic markers were used to test these hypotheses, including mating type and DNA sequencing of internal transcribed spacer (ITS) regions. In addition, we used vegetative compatibility (VC) type markers in C. parasitica as the information about VC type is essential to apply biocontrol against the fungus.

Results and discussion

All the isolates of C. parasitica from the studied area belonged to only one VC type (EU-1) and one mating type (MAT-2). However, three distinct haplotypes of C. parasitica were identified through ITS sequencing, showing that multiple introductions might have happened to Cantabria. Among F. circinatum, no diversity was observed in ITS and MAT loci in the studied area but isolates from other Spanish regions showed the presence of both mating types. Overall, C. parasitica had higher genetic diversity than F. circinatum, despite both organisms appearing to reproduce clonally. This study helped understand the invasion patterns of C. parasitica and F. circinatum in northern Spain and will be useful in applying biocontrol measures against both pathogens.

Bark-inhabiting fungal communities of European chestnut undergo substantial alteration by canker formation following chestnut blight infection

Background

Chestnut forests are severely threatened by chestnut blight caused by the fungal pathogen Cryphonectria parasitica and the infected trees exhibit bark canker in the later stage of the disease. European chestnut (Castanea sativa) is further infected by Gnomoniopsis smithogilvyi, another canker-causing fungal pathogen. We explored whether and how chestnut blight is reflected in bark-inhabiting fungal communities of European chestnut and also assessed the co-occurrence of C. parasitica and G. smithogilvyi.

Materials and methods

We initially investigated the fungal communities of European chestnut bark tissues and further monitored changes in these fungal communities with regard to disease progression from infection to canker formation by analyzing bark samples from asymptomatic trees, asymptomatic trees with latent C. parasitica infection, and infected trees with canker tissues, using amplicon sequencing of the ITS2 region of rDNA.

Results

The results showed that fungal community composition and diversity differed between the sample types. The fungal community composition was substantially reshaped by canker formation, whereas latent C. parasitica infection and more specifically pre-canker infection period per se had a weak effect. Fungal communities of canker samples was less diverse and more dissimilar to those of other sample types. C. parasitica dominated the mycobiome of canker samples, whereas G. smithogilvyi was found in only 9% of canker samples at very low abundances. However, G. smithogilvyi was a dominant fungus in the bark of healthy plants.

Conclusion

This study highlights that canker formation is the principal driver of decreasing diversity and altered composition of the mycobiome in bark tissues of European chestnut infected by C. parasitica infection. It additionally emphasizes the scarce co-occurrence of C. parasitica and G. smithogilvyi on European chestnut.

Canker Development and Biocontrol Potential of CHV-1 Infected English Isolates of Cryphonectria parasitica Is Dependent on the Virus Concentration and the Compatibility of the Fungal Inoculums

Biological control of Cryphonectria parasitica fungus, causal agent of chestnut blight, by virus infection (hypovirulence) has been shown to be an effective control strategy against chestnut blight in Europe and some parts of North America. The most studied mycovirus is the Cryphonectria hypovirus 1 (CHV-1) type species of the Hypoviridae family. To efficiently provide biocontrol, the virus must be able to induce hypovirulence in its fungal host in chestnut trees. Here, two different CHV-1 subtype I virus strains (E-5 and L-18), gained by transmissions, were tested for their hypovirulence induction, biocontrol potential, and transmission between vegetatively compatible (VCG) and incompatible fungal isolate groups in sweet chestnut seedlings and branches. Both strains of CHV-1 showed great biocontrol potential and could protect trees by efficiently transmitting CHV-1 by hyphal anastomosis between fungal isolates of the same VCG and converting virulent to hypovirulent cankers. The hypovirulent effect was positively correlated with the virus concentration, tested by four different reverse-transcription PCRs, two end-point and two real-time methods, one of which represents a newly developed real-time PCR for the detection and quantification of CHV-1.

Filling the Gap in Southern Europe—Diversity of Cryphonectria parasitica and Associated Mycovirus (Cryphonectria hypovirus 1) in Montenegro

Cryphonectria parasitica is an invasive fungal pathogen that causes blight disease on chestnut trees. Its destructive effect can be controlled with naturally occurring mycovirus Cryphonectria hypovirus 1 (CHV1). To date, the spread of C. parasitica and CHV1 in Europe is fairly well documented, but there are still several unexplored regions. Thus, we sampled blight cankers from four sweet chestnut populations in Bay of Kotor and Lake Skadar regions in Montenegro. We determined vegetative compatibility (vc) type and mating-type diversity using molecular vic and MAT1 genotyping, as well as confirming the presence of CHV1 by RT-PCR. We identified 11 vc types, with EU-12 being the dominant one represented by 58.2% of all fungal isolates. The Shannon diversity index ranged from 0.93 to 1.47. Both mating types of C. parasitica were found in all four populations. The prevalence of CHV1 ranged from 15% to 40%. All CHV1 isolates belonged to Italian subtype I of CHV1 and were closely related, with relatively recent common ancestors. Our results indicate a longer presence of C. parasitica and CHV1 in Montenegro than previously thought. Natural biocontrol with CHV1 seems to be well established. However, it has the potential for deterioration; thus, close monitoring is required.

Microsatellite Analysis Revealing High Genetic Diversity of the Chestnut Blight Fungus in South Tyrol (Northern Italy)

Cryphonectria parasitica, which causes chestnut blight, is one of the most important pathogens of forest trees. In Europe, mycovirus-mediated biocontrol is the most efficient method to control the disease but can be impeded by the lack of information about the population structure of the fungus within a region. In particular, sexual reproduction and the new introduction of the pathogen can complicate biocontrol strategies. For this reason, this study aimed to determine the population structure of C. parasitica, which causes chestnut blight, in the northern Italian region of South Tyrol, using eleven multilocus microsatellite markers. Fifty-one haplotypes were found across South Tyrol, belonging to three divergent clusters. Recombinant genotypes demonstrated that sexual reproduction occurs across the different clusters. The most dominant genotypes in the region were also the most dominant in neighboring areas, such as Switzerland, northern Italy and France. All of the clusters from South Tyrol were related to the Italian genotype pool and are thought to have been introduced from northern Italian and other European populations due to naturally occurring gene flow or human-mediated introduction. At least three separate introduction events of C. parasitica might have happened in South Tyrol that could be separated by time. This study demonstrated a high genetic diversity of C. parasitica in South Tyrol and helped to shed light on the sexual reproduction and introduction events in the local populations.

The Use of qPCR to Detect Cryphonectria parasitica in Plants

Cryphonectria parasitica is a fungal pathogen that causes lethal bark necrosis in chestnut. A duplex qPCR allowing detection of the pathogen and its host, Castanea sativa, is described. The method can be used for early detection of the pathogen in chestnut bark tissues with an internal control of false-negative results caused by PCR inhibitors and/or DNA extraction failure. A positive amplification control of qPCR that allows detection of any deviation from a normal qPCR run based on a control chart is also described. As C. parasitica is a regulated pathogen in Europe, the protocol also provides information on the way to collect and handle bark samples to fulfil biosecurity rules.

Microsatellite Genotyping in the Chestnut Blight Fungus Cryphonectria parasitica

This chapter describes the use of polymorphic microsatellite (simple sequence repeats, SSR) markers for genotyping isolates of Cryphonectria parasitica, the causal agent of chestnut blight. The SSR presented are particularly useful to characterize the genetic population structure of this invasive fungal pathogen, including invasion history (e.g., possible source population, introduced genotypes) and reproduction mode (sexual vs. asexual). Microsatellite markers can also be used to track fungal strains in laboratory and field experiments.

Temporal and Spatial Genetic Population Structure of Cryphonectria parasitica and Its Associated Hypovirus Across an Invasive Range of Chestnut Blight in Europe

Chestnut blight has spread throughout Europe since the introduction of its causal agent, Cryphonectria parasitica, >70 years ago. In our study, we analyzed the diversity of vegetative compatibility (vc) and microsatellite genotypes of C. parasitica, as well as sequence diversity of Cryphonectria hypovirus 1 (CHV1) in six populations from Switzerland, Croatia, and North Macedonia. Resampling of local populations that were already investigated more than a decade ago allowed us to analyze the spatial and temporal population structure across an invasive range of the pathogen in Europe. Regardless of which genetic marker was used, the >60-year-old Swiss and Croatian populations had high population diversity, whereas more recent North Macedonian populations were mostly clonal. These diversity differences between the investigated populations remained stable over time. A high diversity of CHV1 was observed in all three countries, with North Macedonian strains forming a separate cluster from strains obtained in other countries. No correlation between vc diversity and CHV1 prevalence was observed, suggesting a well-established and maintained natural hypovirulence in all countries, further corroborated by an observed increase in genetic diversity of Croatian C. parasitica populations over time, without collapse of CHV1 prevalence.

Hypovirulent effect of the Cryphonectria hypovirus 1 in British isolates of Cryphonectria parasitica

BACKGROUND

Chestnut blight, caused by Cryphonectria parasitica, is controlled in many European countries by the naturally occurring mycovirus Cryphonectria hypovirus 1 (CHV-1). During surveys of recently identified chestnut blight outbreak in England, CHV-1 was detected in several individuals of the pathogen isolated from affected trees. We investigated two of these CHV-1-infected isolates (L-6 and Db-1) as potential biocontrol agents for deployment in the UK comparing their virulence against virus-free (M1275) and hypovirulent (M784) European isolates by inoculating sweet chestnut seedlings.

RESULTS

Both the European CHV-1 M784 hypovirulent isolate and UK L-6 isolate formed significantly smaller lesions in sweet chestnut seedling bark than the other three isolates (Db-1, and virulent isolates FTC121 and M1275). The highest virus concentration was detected in isolate M784, followed by L-6, with the lowest concentration in isolate Db-1. White colony colouration indicative of hypovirulence was common in colonies re-isolated from smaller lesions, and the same isolates also tended to be slower growing in culture, have a higher virus concentration, and caused less epicormic growth and fewer stromata to be present in plants. L-6 and Db-1 virus sequences, respectively, matched the virus haplotype E-5 detected previously in Switzerland and a mutation of the same subtype I haplotype.

CONCLUSION

Isolate L-6 could potentially act as biocontrol for chestnut blight outbreaks in the UK but further laboratory and field experiments are needed. © 2019 Crown copyright. Pest Management Science © 2019 Society of Chemical Industry.

Genetic Diversity of Cryphonectria hypovirus 1, a Biocontrol Agent of Chestnut Blight, in Croatia and Slovenia

Transmissible hypovirulence associated with Cryphonectria hypovirus 1 (CHV1) has been used for biological control of chestnut blight, devastating disease of chestnut caused by the fungus Cryphonectria parasitica. The main aims of this study were to provide molecular characterization of CHV1 from Croatia and Slovenia and to reveal its genetic variability, phylogeny, and diversification of populations. Fifty-one CHV1 haplotypes were detected among 54 partially sequenced CHV1 isolates, all belonging to Italian subtype (I). Diversity was mainly generated by point mutations while evidence of recombination was not found. The level of conservation over analyzed parts of ORF-A proteins p29 and p40 varied, but functional sites were highly conserved. Phylogenetic analysis revealed close relatedness and intermixing of Croatian and Slovenian CHV1 populations. Our CHV1 isolates were also related to Swiss and Bosnian hypoviruses supporting previously suggested course of CHV1 invasion in Europe. Overall, this study indicates that phylogeny of CHV1 subtype I in Europe is complex and characterized with frequent point mutations resulting in many closely related variants of the virus. Possible association between variations within CHV1 ORF-A and growth of the hypovirulent fungal isolates is tested and presented.

Genetic and Phenotypic Characterization of Cryphonectria hypovirus 1 from Eurasian Georgia

Cryphonectria hypovirus 1 (CHV-1) infects the chestnut blight fungus Cryphonectria parasitica and acts as a biological control agent against this harmful tree disease. In this study, we screened the recently characterized C. parasitica population in Eurasian Georgia for the presence of CHV-1. We found 62 CHV-1 infected C. parasitica isolates (9.3%) among a total of 664 isolates sampled in 14 locations across Georgia. The prevalence of CHV-1 at the different locations ranged from 0% in the eastern part of the country to 29% in the western part. Sequencing of two specific regions of the viral genome one each in ORFA and ORFB revealed a unique CHV-1 subtype in Georgia. This subtype has a recombinant pattern combining the ORFA region from the subtype F2 and the ORFB region from subtype D. All 62 viral strains belonged to this Georgian CHV-1 subtype (subtype G). The CHV-1 subtype G strongly reduced the parasitic growth of C. parasitica isolates from Georgia, with a more severe effect on the European genepool compared to the Georgian genepool. The CHV-1 subtype detected in Georgia provides a valuable candidate for biological control applications in the Caucasus region.

Changes in Cryphonectria parasitica Populations Affect Natural Biological Control of Chestnut Blight

Invasive species, especially plant pathogens, have a potential to completely eradicate native plant species and remodel landscapes. Tripartite interactions among sweet chestnut (Castanea sativa), chestnut blight-causing invasive fungus Cryphonectria parasitica, and hyperparasitic virus Cryphonectria hypovirus 1 (CHV1) were studied in two populations. The number of different vegetative compatibility (vc) types of C. parasitica more than doubled over the 10 years, while the hypovirulence incidence dropped in one population and slightly increased in the other one. Over the course of our 3-year monitoring experiment, the prevalence of hypovirulent isolates obtained from monitored cankers increased slowly (i.e., more hypovirulent isolates were being obtained from the same cankers over time). Within studied cankers, considerable changes in vc type and CHV1 presence were observed, indicating a highly dynamic system in which virulent and hypovirulent mycelia, sometimes of discordant vc types, often appeared together. The increase in hypovirulence prevalence did not have any observable curative effect on the cankers and, occasionally, reactivation of healed cankers by new, virulent C. parasitica isolates was observed. Both short- and long-term observations and revalidation of the infected plant populations are necessary to accurately estimate disease progress and formulate an adequate disease management strategy.

Cryphonectria parasitica, the causal agent of chestnut blight: invasion history, population biology and disease control

Chestnut blight, caused by Cryphonectria parasitica, is a devastating disease infecting American and European chestnut trees. The pathogen is native to East Asia and was spread to other continents via infected chestnut plants. This review summarizes the current state of research on this pathogen with a special emphasis on its interaction with a hyperparasitic mycovirus that acts as a biological control agent of chestnut blight.

TAXONOMY

Cryphonectria parasitica (Murr.) Barr. is a Sordariomycete (ascomycete) fungus in the family Cryphonectriaceae (Order Diaporthales). Closely related species that can also be found on chestnut include Cryphonectria radicalis, Cryphonectria naterciae and Cryphonectria japonica.

HOST RANGE

Major hosts are species in the genus Castanea (Family Fagaceae), particularly the American chestnut (C. dentata), the European chestnut (C. sativa), the Chinese chestnut (C. mollissima) and the Japanese chestnut (C. crenata). Minor incidental hosts include oaks (Quercus spp.), maples (Acer spp.), European hornbeam (Carpinus betulus) and American chinkapin (Castanea pumila).

DISEASE SYMPTOMS

Cryphonectria parasitica causes perennial necrotic lesions (so-called cankers) on the bark of stems and branches of susceptible host trees, eventually leading to wilting of the plant part distal to the infection. Chestnut blight cankers are characterized by the presence of mycelial fans and fruiting bodies of the pathogen. Below the canker the tree may react by producing epicormic shoots. Non-lethal, superficial or callusing cankers on susceptible host trees are usually associated with mycovirus-induced hypovirulence.

DISEASE CONTROL

After the introduction of C. parasitica into a new area, eradication efforts by cutting and burning the infected plants/trees have mostly failed. In Europe, the mycovirus Cryphonectria hypovirus 1 (CHV-1) acts as a successful biological control agent of chestnut blight by causing so-called hypovirulence. CHV-1 infects C. parasitica and reduces its parasitic growth and sporulation capacity. Individual cankers can be therapeutically treated with hypovirus-infected C. parasitica strains. The hypovirus may subsequently spread to untreated cankers and become established in the C. parasitica population. Hypovirulence is present in many chestnut-growing regions of Europe, either resulting naturally or after biological control treatments. In North America, disease management of chestnut blight is mainly focused on breeding with the goal to backcross the Chinese chestnut's blight resistance into the American chestnut genome.

Biological control of chestnut blight in Croatia: an interaction between host sweet chestnut, its pathogen Cryphonectria parasitica and the biocontrol agent Cryphonectria hypovirus 1

BACKGROUND

Chestnut blight, caused by the fungus Cryphonectria parasitica, is a severe chestnut disease that can be controlled with naturally occurring hypoviruses in many areas of Europe. The aim of this research was to measure the effect of different Cryphonectria hypovirus 1 (CHV1) strains on the growth of the fungal host and select strains that could potentially be used for human-mediated biocontrol in forests and orchards, and to investigate whether and how chestnut-fungus-virus interactions affect the development and growth of the lesion area on cut stems.

RESULTS

Two Croatian CHV1 strains (CR23 and M56/1) were selected as potential biocontrol agents. The sequencing of CHV1/ORF-A showed that both of these virus strains belonged to the Italian subtype of CHV1. In vitro transfection of selected virus strains from hypovirulent to genetically diverse virus-free fungal isolates and subsequent inoculation of all virus/fungus combinations on stems of genetically diverse sweet chestnut trees revealed that Croatian virus strain CR23 had an equally hypovirulent effect on the host as the strong French strain CHV1-EP713, while M56/1 had a weaker effect. Furthermore, it was shown that in some cases the same hypovirus/fungus combinations induced various degrees of canker development on different chestnut genotypes.

CONCLUSION

Some CHV1 strains belonging to the Italian subtype have similar hypovirulent effects on C. parasitica to those belonging to the French subtype. Furthermore, chestnut susceptibility and recovery could be influenced by the response of chestnut trees to particular hypovirulent C. parasitica isolates, and virus-fungus-chestnut interactions could have significant implications for the success of chestnut blight biocontrol. © 2016 Society of Chemical Industry.

Investigation on the partial resistance of Cpkk2 knock out strain of Cryphonectria parasitica to Cryphonectria hypovirus 1 infection in presence of Geneticin and Geneticin resistance gene

We have recently characterized the central components of the three MAP kinase cascades present in Cryphonectria parasitica : the MEK genes cpkk1, cpkk2 and cpkk3. When we attempted to infect through anastomosis the three knock out strains with Cryphonectria hypovirus 1 (CHV1), only the deletion strain of Cpkk2, the yeast Ste7 homologue, involved in mating and filamentous growth, could not be infected. We then proceeded to attempt virus infection through transformation of Δcpkk2 protoplasts using an infectious cDNA clone able to establish virus infection through transformation. In this case, a very limited number of strains could be recovered as stable transformants compared to the efficiency of control transformations with plasmid carrying only the antibiotic marker. Furthermore, transformants carrying actively replicating virus could be isolated only if the selection marker Geneticin was used during the very initial selection process, and not maintained throughout the growth of the colonies. Moreover, Δcpkk2 isolates that maintained the virus lost Geneticin resistance. We therefore unveiled a specific negative interaction among virus infection, presence of Geneticin in the growth media, and lack of Cpkk2 MEK in the fungal host.

Engineering super mycovirus donor strains of chestnut blight fungus by systematic disruption of multilocus vic genes

Transmission of mycoviruses that attenuate virulence (hypovirulence) of pathogenic fungi is restricted by allorecognition systems operating in their fungal hosts. We report the use of systematic molecular gene disruption and classical genetics for engineering fungal hosts with superior virus transmission capabilities. Four of five diallelic virus-restricting allorecognition [vegetative incompatibility (vic)] loci were disrupted in the chestnut blight fungus Cryphonectria parasitica using an adapted Cre-loxP recombination system that allowed excision and recycling of selectable marker genes (SMGs). SMG-free, quadruple vic mutant strains representing both allelic backgrounds of the remaining vic locus were then produced through mating. In combination, these super donor strains were able to transmit hypoviruses to strains that were heteroallelic at one or all of the virus-restricting vic loci. These results demonstrate the feasibility of modulating allorecognition to engineer pathogenic fungi for more efficient transmission of virulence-attenuating mycoviruses and enhanced biological control potential.

Multilocus PCR Assays Elucidate Vegetative Incompatibility Gene Profiles of Cryphonectria parasitica in the United States

Chestnut blight is a devastating disease of Castanea spp. Mycoviruses that reduce virulence (hypovirulence) of the causative agent, Cryphonectria parasitica, can be used to manage chestnut blight. However, vegetative incompatibility (vic) barriers that restrict anastomosis-mediated virus transmission hamper hypovirulence efficacy. In order to effectively determine the vegetative incompatibility genetic structure of C. parasitica field populations, we have designed PCR primer sets that selectively amplify and distinguish alleles for each of the six known diallelic C. parasitica vic genetic loci. PCR assay results were validated using a panel of 64 European tester strains with genetically determined vic genotypes. Analysis of 116 C. parasitica isolates collected from five locations in the eastern United States revealed 39 unique vic genotypes and generally good agreement between PCR and tester strain coculturing assays in terms of vic diversity and genotyping. However, incongruences were observed for isolates from multiple locations and suggested that the coculturing assay can overestimate diversity at the six known vic loci. The availability of molecular tools for rapid and precise vic genotyping significantly improves the ability to predict and evaluate the efficacy of hypovirulence and related management strategies.

Forest health in a changing world

Forest pathology, the science of forest health and tree diseases, is operating in a rapidly developing environment. Most importantly, global trade and climate change are increasing the threat to forest ecosystems posed by new diseases. Various studies relevant to forest pathology in a changing world are accumulating, thus making it necessary to provide an update of recent literature. In this contribution, we summarize research at the interface between forest pathology and landscape ecology, biogeography, global change science and research on tree endophytes. Regional outbreaks of tree diseases are requiring interdisciplinary collaboration, e.g. between forest pathologists and landscape ecologists. When tree pathogens are widely distributed, the factors determining their broad-scale distribution can be studied using a biogeographic approach. Global change, the combination of climate and land use change, increased pollution, trade and urbanization, as well as invasive species, will influence the effects of forest disturbances such as wildfires, droughts, storms, diseases and insect outbreaks, thus affecting the health and resilience of forest ecosystems worldwide. Tree endophytes can contribute to biological control of infectious diseases, enhance tolerance to environmental stress or behave as opportunistic weak pathogens potentially competing with more harmful ones. New molecular techniques are available for studying the complete tree endobiome under the influence of global change stressors from the landscape to the intercontinental level. Given that exotic tree diseases have both ecologic and economic consequences, we call for increased interdisciplinary collaboration in the coming decades between forest pathologists and researchers studying endophytes with tree geneticists, evolutionary and landscape ecologists, biogeographers, conservation biologists and global change scientists and outline interdisciplinary research gaps.