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The genus Elsinoe contains many aggressive pathogens of a wide range of plants, many of which are economically important. These fungal pathogens cause serious scab diseases affecting various plant parts, impacting plant vigour, yield and market value. While studies on Elsinoe species have predominantly focused on their taxonomy, there is a conspicuous gap in knowledge of these fungi from a plant pathology perspective. In this review, we draw together and critically evaluate the existing, but rather fragmented, research on the taxonomic status, phylogenetic relationships, host range, as well as the biology and epidemiology of Elsinoe species. Our aim is primarily to augment the existing understanding of the global significance of Elsinoe species, and furthermore, to shed light on the escalating prominence of scab diseases caused by species in a fungal genus that has been known for over 100 years but remains relatively poorly understood and somewhat enigmatic. [ABSTRACT FROM AUTHOR]

Two outbreaks of coffee wilt disease have devastated African coffee production. A PLOS Biology study suggests that horizontal gene transfer via large Starship transposons between 2 fungal species played a key role in the repeated emergence of the disease. Two outbreaks of coffee wilt disease have devastated African coffee production. A PLOS Biology study suggests that horizontal gene transfer via Starships between two fungal strains played a key role in the repeated emergence of the disease. [ABSTRACT FROM AUTHOR]

Canary Island date palm, Phoenix canariensis, is a popular ornamental species commonly planted in urban areas worldwide, including South Africa. In November 2023, symptoms typical of Fusarium wilt were detected on ornamental palms at the Waterfront in Cape Town, Western Cape Province, South Africa. Samples were collected from three wilting palms with one‐sided frond death and pink sporulation on the bark. Isolations to culture media yielded two fungal species, which were confirmed based on DNA sequence data as Fusarium oxysporum f.sp. canariensis (Foc) and Nalanthamala vermoesenii. Fusarium wilt, caused by Foc, is among the most serious diseases of these palms. There is no effective treatment for this vascular wilt disease and infected palms inevitably die. Pink rot, caused by N. vermoesenii, is commonly found as a secondary infection associated with Fusarium wilt in P. canariensis. This is the first detection of the Fusarium wilt and pink rot pathogens in South Africa. [ABSTRACT FROM AUTHOR]

Ralstonia solanacearum and R. pseudosolanacearum are well-known bacterial plant pathogens that cause significant losses to both ornamental and agricultural plants. It has been suggested that they are not the primary cause of bacterial wilt in Eucalyptus species, but rather are opportunistic, taking advantage of trees predisposed to infection by abiotic and biotic factors. To test this hypothesis, the bacterial community within the vascular tissue of asymptomatic Eucalyptus grandis x E. urophylla trees, and those displaying varying stages of infection in China and Indonesia were compared using 16S rRNA profiling. Asymptomatic trees growing in areas where bacterial infections had never previously been reported to occur were included as controls. Ralstonia species were found within the vascular tissue of both asymptomatic and symptomatic trees, in high abundance. In the control samples, bacterial diversity within the vascular tissue was high with a low abundance of Ralstonia species. The presence of Ralstonia species in asymptomatic and control samples supports the hypothesis that these species are latent and/or opportunistic pathogens in E. grandis x E. urophylla trees. [ABSTRACT FROM AUTHOR]

Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are small wood-boring insects that live in an obligate symbiosis with fungi, which serve as their primary food source. Beetles residing in the genus Euwallacea have evolved a unique association with a clade of Fusarium that falls within the aptly named Ambrosia Fusarium Clade (AFC). The discovery of the invasive polyphagous shot hole borer, E. fornicatus, in South Africa, has heightened awareness of ambrosia beetles and their symbionts in the country. In this study, we investigated the Fusarium symbionts of three species of Euwallacea in South Africa, with a specific focus on those associated with E. xanthopus. Isolations of Fusarium strains from both living and dissected beetles yielded nearly 100 isolates. Using multigene phylogenetic analyses, these isolates were identified as six different Fusarium species. Fusarium hypothenemi and F. euwallaceae have previously been reported from South Africa. Fusarium pseudensiforme and Fusarium AF-6 are new records for the country. The remaining two species are new to science and are described here as F. rufum sp. nov. and F. floriferum sp. nov. Targeted fungal isolation from specific beetle body parts revealed that the AFC species collected were typically associated with the dissected beetle heads and helped us identify the likely nutritional symbiont of E. xanthopus. This study highlights the understudied diversity of fungal associates of ambrosia beetles present in South Africa. [ABSTRACT FROM AUTHOR]

Elsinoë species are phytopathogenic fungi that cause serious scab diseases on economically important plants. The disease symptoms arise from the effects of a group of phytotoxins known as elsinochromes, produced via a type-I polyketide synthase (PKS) biosynthetic pathway. The elsinochrome gene cluster was first annotated in Elsinoë fawcettii where the main type-I PKS gene was characterized as EfPKS1. A later study showed that this gene and the associated cluster had not been correctly annotated, and that EfPKS1 was actually the anchor gene of the melanin biosynthetic pathway. A new type-I PKS gene EfETB1 associated with elsinochrome production was also identified. The aim of this study was to identify all type-I PKS genes in the genomes of seven Elsinoë species with the goal of independently verifying the PKS containing clusters for both melanin and elsinochrome production. A total of six type-I PKS classes were identified, although there was variation between the species in the number and type of classes present. Genes similar to the E. fawcettii EfPKS1 and EfETB1 type-I PKS genes were associated with melanin and elsinochrome production respectively in all species. The complete melanin and elsinochrome PKS containing clusters were subsequently annotated in all the species with high levels of synteny across Elsinoë species. This study provides a genus-level overview of type-I PKS distribution in Elsinoë species, including an additional line of support for the annotation of the melanin and elsinochrome PKS containing clusters in these important plant pathogens. [ABSTRACT FROM AUTHOR]

Sporotrichosis is a disease that arises from a fungal infection caused by members of the Ascomycete genus Sporothrix. The disease has a unique history in South Africa, due to an association with gold mines, where large numbers of mine workers were infected in the 1930s and 1940s. This was likely driven by hot humid conditions and timber supports used in these mine shafts. Furthermore, the disease is the most common subcutaneous fungal infection amongst the general population in South Africa, and the large number of immunocompromised individuals increases the public health risk in the country. Sporothrix is a genus in the Ophiostomatales, a fungal order primarily associated with environmental habitats. Unsurprisingly, sporotrichosis therefore has a documented history of sapronotic transmission from contaminated plant material. This review provides insights into the understanding of sporotrichosis and Sporothrix species, with a particular emphasis on the South African situation. We highlight knowledge gaps, particularly regarding the ecological factors influencing the occurrence and distribution of these species, which in turn affect the patterns of sporotrichosis. We also emphasise a need for ongoing proactive research and surveillance to prevent future outbreaks of sporotrichosis, an emerging disease with growing health implications worldwide. [ABSTRACT FROM AUTHOR]

The Namib Desert (Namibia) is home to fairy circles which are barren, circular to almost-circular patches of land surrounded by grasses. During a survey of the fungi associated with the most common grass species, Stipagrostis ciliata (Poaceae), and its rhizospheric soils associated with these fairy circles, Curvularia was commonly isolated (80 strains). Curvularia is a cosmopolitan fungal genus that occurs in diverse geographical locations and on a wide range of substrates, but particularly on foliar plants. Curvularia strains were identified based on multilocus sequence comparisons of their internal transcribed spacer rDNA region (ITS), and the partial gene regions of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and translation elongation factor 1-alpha (TEF1). The strains belonged to 13 species, including the discovery of five novel Curvularia species. The aim of this paper was to report on the identified species and to formally describe and name the new species as C. deserticola, C. gobabebensis, C. maraisii, C. namibensis, and C. stipagrostidicola. [ABSTRACT FROM AUTHOR]

Fungi in the Cryphonectriaceae are important canker pathogens of woody shrubs and trees in the Melastomataceae and Myrtaceae (Myrtales). During 2021 disease surveys in KwaZulu‐Natal (South Africa) plantations, a serious stem canker disease was discovered on species of Eucalyptus and Corymbia. The cankers had structures on their surfaces typical of fungi in the Cryphonectriaceae. The aims of the study were to identify the fungus associated with the disease and to test its pathogenicity. Morphological characteristics of both sexual and asexual structures and phylogenetic analyses based on partial sequences of the conserved nuclear large subunit (LSU) ribosomal DNA, the internal transcribed spacer (ITS) regions including the 5.8S gene of the ribosomal DNA operon, and two β‐tubulin (BT1/BT2) regions were used for identification purposes. Phylogenetic analyses of the sequence data and morphological characteristics supported the establishment of a new genus in the Cryphonectriaceae, for which the name Xanthoporthe myrticola gen. et sp. nov. is provided. Pathogenicity trials showed that isolates were pathogenic on tested Eucalyptus grandis and hybrids as well as Corymbia henryi. The results suggest that this is an emerging pathogen that could influence the sustainability of plantation forestry in South Africa. [ABSTRACT FROM AUTHOR]

Eucalyptus scab and shoot malformation is an emerging disease and a serious threat to the global plantation forestry industry. The disease appeared in North Sumatra (Indonesia) in the early 2010s and the causal agent was recently described as a novel species, Elsinoe necatrix. Nothing is known regarding its possible origin or why it emerged rapidly to cause a serious local epidemic. To investigate its population biology, we developed 15 polymorphic microsatellite markers as well as mating‐type markers using genome sequences for two E. necatrix isolates. Isolates of the pathogen were collected from different host varieties at four locations in the Lake Toba region of North Sumatra and characterized using these markers. A high level of genotypic diversity was observed for all populations with little to no genetic differentiation between sampling areas. Discriminant analysis of principal components, genotype networks and analysis of molecular variance all showed a lack of population structure and a high level of gene flow among sampling regions. Mating‐type ratios and linkage disequilibrium analyses suggest that sexual recombination is likely to be occurring, although a sexual state has not been found for the pathogen. The results of this study highlight the fact that new genotypes of E. necatrix, probably arising from cryptic sexual recombination, will challenge efforts to manage the disease, and that breeding and selection for tolerance will require substantial host genetic diversity. [ABSTRACT FROM AUTHOR]

A root disease in plantations of Pinus radiata and Pinus pinaster, where trees died in distinct patches, was present in the Western Cape province of South Africa during the 1970s and 1980s. Phytophthora cinnamomi was initially believed to be the cause, but the disease was later ascribed to the insect-associated fungus Leptographium serpens, a fungal species residing in the Ophiostomatales. Doubt regarding the cause of the disease was raised in a later study due to the fact that most Leptographium spp., particularly those that colonise ray parenchyma tissues, which is the case for L. serpens, are not typically primary disease agents. In this study, cultures of an unidentified sterile fungus collected from the dying trees were revived and identified using DNA sequencing methods, which were not available when the disease was first studied. These cultures were identified as the pyrophillic pathogen Rhizina undulata, well-known to cause patch death of conifers in South Africa and elsewhere in the world. While the patches of dying trees no longer exist and the disease cannot be newly studied, it is most likely that the tree death originally thought to be caused by L. serpens was due primarily to R. undulata. The study provides a vivid example of the value of preserving cultures of fungi for later study and the power of modern techniques to identify fungal pathogens. [ABSTRACT FROM AUTHOR]

Aim: Spreading infectious diseases associated with introduced pathogens can have devastating effects on native biota and human livelihoods. We analyse the global distribution of 100 major alien fungal and oomycete pathogens with substantial socio‐economic and environmental impacts and examine their taxonomy, ecological characteristics, temporal accumulation trajectories, regional hot‐ and coldspots of taxon richness and taxon flows between continents. Location: Global. Taxon: Alien/cryptogenic fungi and fungus‐like oomycetes, pathogenic to plants or animals. Methods: To identify over/underrepresented classes and phyla, we performed Chi2 tests of independence. To describe spatial patterns, we calculated the region‐wise richness and identified hot‐ and coldspots, defined as residuals after correcting taxon richness for region area and sampling effort via a quasi‐Poisson regression. We examined the relationship with environmental and socio‐economic drivers with a multiple linear regression and evaluated a potential island effect. Regional first records were pooled over 20‐year periods, and for global flows the links between the native range to the alien regions were mapped. Results: Peronosporomycetes (Oomycota) were overrepresented among taxa and regional taxon richness was positively correlated with area and sampling effort. While no island effect was found, likely due to host limitations, hotspots were correlated with human modification of terrestrial land, per capita gross domestic product, temperate and tropical forest biomes, and orobiomes. Regional first records have increased steeply in recent decades. While Europe and Northern America were major recipients, about half of the taxa originate from Asia. Main Conclusions: We highlight the putative importance of anthropogenic drivers, such as land use providing a conducive environment, contact opportunities and susceptible hosts, as well as economic wealth likely increasing colonisation pressure. While most taxa were associated with socio‐economic impacts, possibly partly due to a bias in research focus, about a third show substantial impacts to both socio‐economy and the environment, underscoring the importance of maintaining a wholescale perspective across natural and managed systems. [ABSTRACT FROM AUTHOR]

Australian Acacia species are among the most important trees planted for wood and pulp production in several African countries, including Ethiopia. In 2020, symptoms of a serious shoot and leaf rust disease were observed on black wattle (Acacia mearnsii De Wild.) trees across the three main wattle growing regions of Ethiopia. The aim of this study was to describe the disease and identify its causal agent based on morphological characteristics as well as DNA sequence data for the ITS and LSU regions of ribosomal DNA. Here we report for the first time, the presence of the wattle rust pathogen, Uromycladium acaciae, in Ethiopia. [ABSTRACT FROM AUTHOR]

A serious new disease of Eucalyptus was detected in South African plantations of these trees during the summer of 2021/2022. The first symptoms are minute dark spots on young leaves, petioles and shoots, becoming scab-like as the spots age. On highly susceptible Eucalyptus genotypes, leaves and shoots can become malformed leading to a 'feathering' appearance in the tree canopies and in the case of heavy infections, leaf and shoot death occur. Isolations made directly from developing scabs resulted in slow-growing cultures. These were identified, based on phylogenetic analyses of DNA sequence data for the ITS, LSU, TEF1 and RPB2 regions, as a novel species of Elsinoe (Elsinoaceae, Myriangiales), described here as E. masingae. Inoculations of an Eucalyptus grandis  ×  Eucalyptus nitens hybrid variety produced the same symptoms as those observed under natural conditions and the pathogen could be re-isolated from the emerging lesions. Elsinoe masingae is closely related to, but clearly distinct from, the recently described Elsinoe necatrix that causes a serious scab and shoot malformation disease on Eucalyptus in Indonesia. Field surveys revealed significant variation in the susceptibility of different Eucalyptus genotypes, with the most severely affected genotypes including an E. grandis  ×  nitens and an E. grandis  ×  urophylla hybrid variety and E. grandis. The disease has also been observed on Eucalyptus amplifolia and on Eucalyptus dunnii , which had mild infections. The observed variation in susceptibility of Eucalyptus planting stock should provide opportunities to avoid serious damage because of scab caused by E. masingae in the future. [ABSTRACT FROM AUTHOR]

Several economically important pathogens, including species of Chrysoporthe, pose a threat to the rapidly expanding eucalypt plantation industry in Southeast Asia. During 2019 disease surveys in Riau and Kalimantan (Indonesia), cankers were observed on eucalypt trees and a collection of fungal isolates was obtained from them. The aim of this study was to confirm the identity of the isolates and to evaluate their relative pathogenicity on different eucalypt clones. Using the DNA sequence data based on the internal transcribed spacer (ITS) region of the ribosomal DNA and two regions of the β-tubulin gene (TUB1 and TUB2), 31 fungal isolates were identified as C. deuterocubensis. Pathogenicity trials showed that C. deuterocubensis isolates differed in their pathogenicity and that different eucalypt genotypes differed in their susceptibility to the pathogen. These results will provide valuable information to reduce the threat of stem canker to future eucalypt plantation development. [ABSTRACT FROM AUTHOR]

Acacia crassicarpa is a tropical tree species native to Australia, West Papua and Papua New Guinea, which has been widely used to establish plantations in the lowland humid tropics of Sumatra and Kalimantan. These trees, able to grow on sites having relatively poor nutrition, have been relatively free of serious disease problems. A rust disease infecting the phyllodes of A. crassicarpa has recently been encountered in plantations in various areas of Indonesia and Malaysia where they are not native. In this study, the rust was collected and identified as Endoraecium violae‐faustiae using DNA sequence analysis based on the internal transcribed spacer (ITS) region of the rDNA. This is the first record of the rust outside its native range. Damage at present appears to be relatively mild but the pathogen could become important in the future. [ABSTRACT FROM AUTHOR]

The Proteaceae, a diverse family of woody flowering plants in the Southern Hemisphere, contains many species known to be susceptible to Phytophthora cinnamomi, both in the natural environment and in cut-flower orchards. Very little is known about the prevalence of P. cinnamomi and other oomycetes across these landscapes. To address this knowledge gap, we used a double ITS1 and RPS10 gene metabarcoding approach and traditional isolation protocols to investigate oomycetes in orchards and natural stands of Proteaceae across South Africa, South Africa (eastern and western), Australia, and Europe. The RPS10 primers amplified more samples, including various Pythium species, while the ITS primers detected more Phytophthora phylotypes. Both datasets showed that geographic regions influenced oomycete species richness and community composition, while they did not show any variation between orchards and natural vegetation. RPS10 metabarcoding detected the largest number of species and provided greater statistical confidence than ITS1 when considering oomycete species composition. Metabarcoding also showed that orchards had a higher abundance of P. cinnamomi compared to native stands, although this was not found when isolating through baiting of roots and rhizosphere soil. Direct isolation and metabarcoding are complementary, with metabarcoding serving as an early detection tool. However, it cannot distinguish living viable propagules from residual DNA of dead propagules, limiting its use for diagnostic purposes related to Phytophthora management and control. These results, along with those of other recent studies, show that metabarcoding offers an effective tool to describe the dynamics of soil oomycetes in different ecosystems. [ABSTRACT FROM AUTHOR]

The Leotiomycetes is a hugely diverse group of fungi, accommodating a wide variety of important plant and animal pathogens, ericoid mycorrhizal fungi, as well as producers of antibiotics. Despite their importance, the genetics of these fungi remain relatively understudied, particularly as they don't include model taxa. For example, sexual reproduction and the genetic mechanisms that underly this process are poorly understood in the Leotiomycetes. We exploited publicly available genomic and transcriptomic resources to identify genes of the mating-type locus and pheromone response pathway in an effort to characterize the mating strategies and behaviors of 124 Leotiomycete species. Our analyses identified a putative a-factor mating pheromone in these species. This significant finding represents the first identification of this gene in Pezizomycotina species outside of the Sordariomycetes. A unique mating strategy was also discovered in Lachnellula species that appear to have lost the need for the primary MAT1-1-1 protein. Ancestral state reconstruction enabled the identification of numerous transitions between homothallism and heterothallism in the Leotiomycetes and suggests a heterothallic ancestor for this group. This comprehensive catalog of mating-related genes from such a large group of fungi provides a rich resource from which in-depth, functional studies can be conducted in these economically and ecologically important species. [ABSTRACT FROM AUTHOR]

Species of Corymbia are increasingly being tested for plantation establishment in South Africa. During disease surveys in KwaZulu-Natal plantations in 2020, a serious canker disease was found on Corymbia henryi. The cankers were seemingly caused by a fungus belonging to the family Cryphonectriaceae. The aims of the study were to identify the fungus causing the disease, to test its pathogenicity and to determine the genetic diversity of a population of isolates from infected trees. Phylogenetic analyses using sequence data for the internal transcribed spacer, β-tubulin 1 and β-tubulin 2 gene regions showed that the causal agent of the cankers was Chrysoporthe austroafricana. This is the first record of C. austroafricana causing cankers on a Corymbia species. A pathogenicity trial demonstrated that the fungus could infect C. henryi and cause cankers. Fifteen isolates of C. austroafricana were subjected to population genetic analyses using microsatellite markers. Eleven multilocus genotypes (MLGs) were detected. Mating-type distribution was approximately equal (MAT1-1:MAT1-2 = 8:7). The results indicate that a wide diversity of genotypes of C. austroafricana have undergone a host shift to infect C. henryi. This is a similar situation to that observed for Eucalyptus in South Africa and suggests that research efforts will be required to reduce the risk of Cryphonectria canker limiting afforestation using Corymbia species in the future. [ABSTRACT FROM AUTHOR]

The Eucalyptus plantation industry in Indonesia has expanded rapidly during the last few decades. During routine nursery disease surveys, symptoms of a leaf and shoot blight disease were detected on Eucalyptus mother plants. Isolates were obtained from symptomatic tissues and identified using DNA sequence analyses. Phylogenetic analyses showed that the isolates were those of Quambalaria eucalypti. Pathogenicity tests were conducted with isolates of Q. eucalypti on clones of E. pellita and E. grandis × E. pellita hybrids. These resulted in symptoms similar to those observed on naturally infected plants. Eucalyptus genotypes tested showed variation in their susceptibility, highlighting the potential to select and breed for resistance and thus to manage future outbreaks of the disease. This is the first report of the pathogen in Indonesia as well as in Southeast Asia. [ABSTRACT FROM AUTHOR]

Society is confronted by interconnected threats to ecological sustainability. Among these is the devastation of forests by destructive non-native pathogens and insects introduced through global trade, leading to the loss of critical ecosystem services and a global forest health crisis. We argue that the forest health crisis is a public-good social dilemma and propose a response framework that incorporates principles of collective action. This framework enables scientists to better engage policymakers and empowers the public to advocate for proactive biosecurity and forest health management. Collective action in forest health features broadly inclusive stakeholder engagement to build trust and set goals; accountability for destructive pest introductions; pooled support for weakest-link partners; and inclusion of intrinsic and nonmarket values of forest ecosystems in risk assessment. We provide short-term and longer-term measures that incorporate the above principles to shift the societal and ecological forest health paradigm to a more resilient state. [ABSTRACT FROM AUTHOR]

Araucaria araucana is an ancient conifer, native to the mountain ranges in Chile and Argentina. These trees host a large number of organisms, mainly insects, strongly or even exclusively associated with them. The recent emergence of a novel canker disease on A. araucana has emphasised the importance of fungi associated with these iconic trees and has resulted in the discovery of various new species. In this study, we considered the identity of an unknown calicioid fungus consistently found on resin on the branches of A. araucana. Preliminary phylogenetic analyses placed isolates in the recently described sub-class Cryptocaliciomycetidae, closest to Cryptocalicium blascoi. However, the morphology of the ascomata and its occurrence in a unique niche suggested that the closest relative could be Resinogalea humboldtensis (Bruceomycetaceae, incertae sedis), a fungus with similar sporing structures found on resin of Araucaria humboldtensis in New Caledonia. There are no living cultures or sequence data available for either R. humboldtensis or its supposed closest relative, Bruceomyces castoris, precluding sequence-based comparisons. Morphological comparisons of the sporing structures on A. araucana confirmed that the ascomatal morphology of our unknown calicioid fungus and R. humboldtensis are almost identical and resemble each other more so than B. castoris or Cr. blascoi. A phylogenetic analysis based on the small subunit (SSU), internal transcribed spacer (ITS) and large subunit (LSU) rDNA regions resolved our strains into two clades with Cr. blascoi as its closest relative. Further analyses applying the Genealogical Concordance Phylogenetic Species Recognition (GCPSR) based on ITS, mini chromosome maintenance protein complex (MCM7), RNA polymerase II second largest subunit (RPB2) and translation elongation factor 1-alpha (TEF) gene regions, confirmed that strains represent two new species. Based on our morphological observations and phylogenetic analyses, we introduce two new Resinogalea species, R. araucana and R. tapulicola, and reclassify the genus in the subclass Cryptocaliciomycetidae. [ABSTRACT FROM AUTHOR]

Calonectria leaf blight (CLB) is one of the most important diseases of Eucalyptus trees grown in plantations. This disease poses a serious threat to the sustainability of Eucalyptus plantations in southern China. To better understand the causal agents of CLB, we collected samples of diseased leaves and soil from Eucalyptus plantations from nine regions in Guangdong Province where the disease has become a serious problem. A total of 606 Calonectria isolates were purified from the samples, with 399 and 207 originating from diseased leaves and soils, respectively. Phylogenetic analyses utilizing six gene regions resolved 303 isolates in the C. kyotensis species complex and an equal number of isolates in the C. reteaudii species complex. These two complexes were represented by ten known Calonectria species, including C. aconidialis (12.0%), C. curvispora (0.3%), C. hongkongensis (24.8%), C. ilicicola (0.9%), and C. kyotensis (12.0%) in the C. kyotensis species complex, and C. crousiana (1.0%), C. Guangdongensis (0.3%), C. pseudoreteaudii (40.7%), C. queenslandica (7.3%), and C. reteaudii (0.7%) in the C. reteaudii species complex. Pathogenicity tests showed that all species were capable of causing disease on two tested Eucalyptus genotypes, albeit at varying degrees of aggressiveness. Most isolates (98.3%) in the C. reteaudii species complex were from the diseased leaves, indicating that species in this complex are the main causal agents of CLB outbreak. In addition, a significant number of the C. kyotensis species complex isolates (66.7%) from the soil samples could also cause the disease on Eucalyptus leaves. [ABSTRACT FROM AUTHOR]

Background: Huntiella resides in the Ceratocystidaceae, a family of fungi that accommodates important plant pathogens and insect-associated saprotrophs. Species in the genus have either heterothallic or unisexual (a form of homothallism) mating systems, providing an opportunity to investigate the genetic mechanisms that enable transitions between reproductive strategies in related species. Two newly sequenced Huntiella genomes are introduced in this study and comparative genomics and transcriptomics tools are used to investigate the differences between heterothallism and unisexuality across the genus. Results: Heterothallic species harbored up to seven copies of the a-factor pheromone, each of which possessed numerous mature peptide repeats. In comparison, unisexual Huntiella species had only two or three copies of this gene, each with fewer repeats. Similarly, while the heterothallic species expressed up to 12 copies of the mature α-factor pheromone, unisexual species had up to six copies. These significant differences imply that unisexual Huntiella species do not rely on a mating partner recognition system in the same way that heterothallic fungi do. Conclusion: While it is suspected that mating type-independent pheromone expression is the mechanism allowing for unisexual reproduction in Huntiella species, our results suggest that the transition to unisexuality may also have been associated with changes in the genes governing the pheromone pathway. While these results are specifically related to Huntiella, they provide clues leading to a better understanding of sexual reproduction and the fluidity of mating strategies in fungi more broadly. [ABSTRACT FROM AUTHOR]

Graphium species form a well-supported monophyletic lineage within the Microascales (Ascomycota). Members of this genus can be found in association with bark beetles, as well as on tree wounds and in soils. During surveys of bark and ambrosia beetle–associated fungi and cavities made by woodpeckers on hardwood trees in Poland, many isolates with an affinity to Graphium were recovered. They were identified based on their morphological characters and sequence data for the internal transcribed spacer (ITS), 28S rDNA, β-tubulin (TUB2), and translation elongation factor 1-α (TEF1) gene regions. The results revealed five new species, described here as G. brachiatum, G. longistipitatum, G. polonicum, G. radicatum, and G. trypophloei. [ABSTRACT FROM AUTHOR]

Austropuccinia psidii, the causal agent of myrtle rust, has emerged as a significant threat to Myrtaceae in planted and natural woody ecosystems. The first detection of A. puccinia in South Africa was from severely infected ornamental Myrtus communis. This raised concern that M. communis, the sole Myrtaceae species native to Europe and an important component of vegetation in Mediterranean regions, could be threatened by the rust. In light of the potential threat to this unique species, seed was collected from 12 Italian provenances of M. communis, including mainland and island (Sardinia and Sicily) populations. We assessed the susceptibility of these provenances to both the pandemic and South African strains of A. psidii. In Colombia, where the pandemic strain of A. psidii is native, seedlings rapidly became infected by natural inoculum. In South Africa, a preliminary screening of seedlings by artificial inoculation with a single-uredinium isolate produced high levels of disease. Finally, plants of each of the 12 provenances were planted and monitored in Florence, Italy. To date, these showed no signs of disease, but will continue to be monitored. This study highlights the significant threat that both the pandemic and South African strains of A. puccinia pose to M. communis in Europe. [ABSTRACT FROM AUTHOR]

Eucalyptus nitens is a cold-tolerant eucalypt that is native to Eastern Australia. Pure E. nitens as well as its hybrids, such as Eucalyptus grandis × Eucalyptus nitens, is propagated commercially in various regions of the southern hemisphere, including South Africa. In a plantation environment, E. nitens is susceptible to a variety of native and invasive pathogens, including Phytophthora alticola and P. cinnamomi. Recently, there have been increasing reports of root and collar rot in E. nitens in South Africa. The severity of this disease was substantially lower among interspecific hybrids of E. grandis × E. nitens compared to purebred E. nitens. In South Africa, the susceptibility of commercially propagated provenances of pure E. nitens and varieties of hybrid E. grandis × E. nitens to Phytophthora species is unknown. Therefore, we conducted greenhouse trials to evaluate the pathogenicity of P. alticola and P. cinnamomi to two families of pure E. nitens, one self-fertilized and the other outcrossed, as well as a single clonal variety of the most widely planted interspecific hybrid, E. grandis × E. nitens. The outcomes from these trials revealed that both self-fertilized and outcrossed families of E. nitens were highly susceptible to the tested Phytophthora species. The severity of root rot was greatest among plants inoculated with P. cinnamomi. The tested interspecific hybrid was tolerant to both Phytophthora species and developed new lateral and fine roots to offset the effects of root rot. [ABSTRACT FROM AUTHOR]

Diseases increasingly threaten the rapidly expanding eucalypt plantation industry of Indonesia. Of these, leaf blight caused by Calonectria spp. is considered amongst the more important problems, causing losses both in production nurseries and plantations. Using DNA sequence data based on the translation elongation factor 1-alpha, β-tubulin, calmodulin, and histone H3 gene regions, 163 isolates of Calonectria spp. obtained from diseased eucalypt seedlings in nurseries and infected leaves in plantations were identified as Calonectria acicola, C. hawksworthii, C. lombardiana, C. multiseptata, C. pseudoreteaudii and C. reteaudii. Of these, C. lombardiana was by far the most commonly isolated and accounted for approximately 84% of the isolates. Given the predominance of this fungus, it is interesting that it has not previously been reported from Indonesia. This is also the first report of C. pseudoreteaudii and C. acicola from the country. All six species of Calonectria were found to be pathogenic to eucalypts in artificial inoculation studies. Calonectria lombardiana was generally the most pathogenic species and eucalypt genotypes displayed different levels of susceptibility, providing confidence that disease caused by this fungus can be reduced by selecting disease-tolerant planting stock. [ABSTRACT FROM AUTHOR]

Simple Summary: The accidental introduction of the ambrosia beetle Euwallacea fornicatus and its fungal symbiont, Fusarium euwallaceae, into Israel, the United States and South Africa has had a devastating impact on many economically and ornamentally important tree species. Currently, there is no effective control measure in place to control this beetle pest and its symbiont. As a first step towards controlling this beetle in South Africa, this study investigated the efficacy of commercialized entomopathogenic products against the beetle. Results showed that although effective under lab conditions, currently recommended field application methods of these products to the outer bark of trees have limited effects on beetle survival and reproduction. The invasive ambrosia beetle, Euwallacea fornicatus, was first reported in South Africa in 2018. The beetle has now spread to eight provinces of the country and has had a devastating impact on both native and non-native tree species. This is especially true for trees located in urban and peri-urban environments. Recent predictions are that the South African E. fornicatus invasion will cost an estimated ZAR 275 billion (approx. USD 16 billion) if it continues to spread uncontrollably, justifying an urgent need for its effective management in the country. One option is biological control, which is preferred over the use of chemicals due to its lower environmental impact. We tested two broad-spectrum fungal entomopathogenic agents, Eco-Bb® and Bio-Insek, which are commercially available in South Africa, for efficacy against E. fornicatus. Initial laboratory assays yielded promising results. However, beetle infestation trials using treated pieces of woody castor bean stems showed little effect on beetle survival and reproduction. [ABSTRACT FROM AUTHOR]

Nonnative insects and pathogens pose major threats to forest ecosystems worldwide, greatly diminishing the ecosystem services trees provide. Given the high global diversity of arthropod and microbial species, their often unknown biological features or even identities, and their ease of accidental transport, there is an urgent need to better forecast the most likely species to cause damage. Several risk assessment approaches have been proposed or implemented to guide preventative measures. However, the underlying assumptions of each approach have rarely been explicitly identified or critically evaluated. We propose that evaluating the implicit assumptions, optimal usages, and advantages and limitations of each approach could help improve their combined utility. We consider four general categories: using prior pest status in native and previously invaded regions; evaluating statistical patterns of traits and gene sequences associated with a high impact; sentinel and other plantings to expose trees to insects and pathogens in native, nonnative, or experimental settings; and laboratory assays using detached plant parts or seedlings under controlled conditions. We evaluate how and under what conditions the assumptions of each approach are best met and propose methods for integrating multiple approaches to improve our forecasting ability and prevent losses from invasive pests. [ABSTRACT FROM AUTHOR]

Background: Sorocephalus imbricatus (Thunb.) R.Br. is a range-restricted species endemic to the Cape Floristic Region (CFR), South Africa. It is currently classified as Critically Endangered in accordance with the IUCN criteria. Like many other species endemic to the CFR, S. imbricatus is subjected to several major threats including habitat loss, habitat degradation and the impacts of invasive alien species. Sorocephalus imbricatus was recently identified as a species requiring improved representation in ex-situ collections. During field work undertaken to collect germplasm for this purpose, a concerning number of dead and dying plants were observed. Objectives: To determine the cause of rapid death of individuals in a remnant subpopulation of S. imbricatus. Method: A field visit to a subpopulation of the only extant population, Elandskloof, was conducted to examine the symptoms associated with S. imbricatus mortality, and to collect samples for isolation and identification of putative pathogens. Results: Dead and dying plants showed clear symptoms of root and collar rot, with Phytophthora cinnamomi Rands recovered from all samples. The collections highlighted the severe impact of P. cinnamomi on S. imbricatus, with the size of the subpopulation being reduced from 62 to 37 individuals (a 40% reduction) between October 2021 and May 2022. Conclusion: This study describes, for the first time, rapid mortality of the Critically Endangered Proteaceae species, S. imbricatus, likely caused by the invasive pathogen P. cinnamomi. This concerning discovery highlights the urgent need for greater recognition of the threat P. cinnamomi poses not only to S. imbricatus, but to the broader floristic diversity of the CFR. Importantly, it illustrates a need for a substantial body of work to be undertaken to address a significant lack of knowledge regarding the relative threat that P. cinnamomi poses to species of the CFR. [ABSTRACT FROM AUTHOR]

Pitch canker on plantation‐grown Pinus species, caused by the fungal pathogen Fusarium circinatum, first appeared in the western and southern Cape regions of South Africa. However, outbreaks have subsequently been reported from the major plantation growing regions of KwaZulu‐Natal and Limpopo in the eastern, summer rainfall regions of the country. It is more than 10 years since the last detailed population genetics studies on F. circinatum in the region were conducted. To shed light on the population biology of F. circinatum in this region of South Africa, we used microsatellite markers and mating‐type assays to study a collection of 296 isolates from different nurseries and plantation sites. Our results showed that populations in the region are highly diverse, but strongly interconnected, with various genotypes shared across nursery and plantation collection sites. In contrast to nursery populations, those associated with pitch canker outbreaks were characterized by the presence of relatively small numbers of dominant genotypes that were generally widespread across the region. Opposite mating‐type individuals occurred in most of the isolate collections, but multilocus linkage disequilibrium analyses pointed towards clonality being the main reproductive mode of F. circinatum in the region. Most of the pathogen's genetic variation could probably have resulted from multiple different introductions into the country and more specifically, into the summer rainfall region. Because the spread and establishment of invasive pathogens are typically driven by aggressive clones, the results of this study provide important considerations for current and future Pinus disease management strategies. [ABSTRACT FROM AUTHOR]

Cypress canker is a branch and stem canker disease of Cupressaceae trees, particularly those in the genera Cupressus and Hesperocyparis. These trees have been planted in many parts of the world as ornamentals and the Seiridium species that cause the disease, consequently, also have an almost global distribution. The taxonomy of Seiridium species causing cypress canker has recently been revised and numerous species are now believed to cause the disease. This study describes, for the first time, cypress canker on the native South African Cupressaceae tree, Widdringtonia nodiflora. The aim was to identify the causal agent and confirm its pathogenicity. Phylogenetic analyses of sequence data for four regions identified the fungus as Seiridium neocupressi, a species previously known only from Australia, New Zealand and Italy. Field inoculations of W. nodiflora branches resulted in distinct cankers within 6 weeks and the fungus could be reisolated from the treated trees. Cypress canker has been known in South Africa for many decades, where it causes a serious disease on nonnative species of Cupressus, but it has never been found on native Cupressaceae. The newly discovered disease caused by a probable alien pathogen is of particular concern because only three species of Widdringtonia occur in South Africa and are important components of the native flora. The two other species, W. wallichii and W. schwartzii, occur in small endemic and threatened populations. The origin of S. neocupressi in South Africa and the relative susceptibility of the three Widdringtonia species, consequently, requires urgent attention. [ABSTRACT FROM AUTHOR]

Eucalyptus spp. are widely planted in Colombia as an important component of a growing paper and pulp industry. Leaf and shoot blight caused by Calonectria spp. was one of the first disease problems to emerge in these plantations. A survey of Eucalyptus plantations in four forestry regions of Colombia during 2016 resulted in a large number of Calonectria isolates from soil samples collected in the understories of trees having symptoms of Calonectria leaf and shoot blight. The aim of this study was to identify and resolve the phylogenetic relationships for these isolates using DNA sequence comparisons of six gene regions as well as morphological characters. From a collection of 107 isolates, seven Calonectria species residing in three species complexes were identified. Two of these represented undescribed species, namely C. exiguispora sp. nov. and C. guahibo sp. nov. Calonectria parvispora and C. spathulata were the most commonly isolated species, each of which accounted for approximately 30% of the isolates. The results suggest that Colombia has a wide diversity of Calonectria spp. and that these could challenge Eucalyptus plantation forestry in the future. [ABSTRACT FROM AUTHOR]

To meet the growing demand for wood and pulp products, Eucalyptus plantations have expanded rapidly during the past two decades, becoming an integral part of the southern China landscape. Leaf blight caused by various Calonectria spp., is a serious threat to these plantations. In order to explore the diversity and distribution of Calonectria spp. in Fujian Province soils, samples were collected in Eucalyptus plantations and adjacent plantings of Cunninghamia lanceolata, Phyllostachys heterocycle and Pinus massoniana as well as in natural forests. Three hundred and fifty-three Calonectria isolates were recovered from soil samples and they were identified based on a comparison of multilocus DNA sequence data for the act (actin), cmdA (calmodulin), his3 (histone H3), rpb2 (the second largest subunit of RNA polymerase), tef1 (translation elongation factor 1-alpha) and tub2 (β-tubulin) gene regions, as well as morphological characteristics. Six known taxa including Calonectria aconidialis, Ca. hongkongensis, Ca. ilicicola, Ca. kyotensis, Ca. pacifica, Ca. pseudoreteaudii and one novel species described here as Ca. minensis sp. nov. were identified. Of these, Ca. aconidialis and Ca. kyotensis were the most prevalent species, and found in eight and seven sites, and four and five forest types, respectively. Calonectria spp. were most abundant in soils from Eucalyptus stands, followed by P. heterocycle and natural forests. Relatively few species were found in the soils associated with Cunninghamia lanceolata and Pinus massoniana. The abundance of known Calonectria spp. suggests that these fungi have been relatively well sampled in Fujian. The results are also consistent with the fact that most Calonectria diseases are found on Angiosperm as opposed to Gymnosperm plants. [ABSTRACT FROM AUTHOR]

Chrysoporthe deuterocubensis is the causal agent of a serious canker disease of Eucalyptus spp. in tropical and sub‐tropical areas of Asia. Where the disease occurs, Eucalyptus spp. are non‐native and the native hosts of the pathogen have not been conclusively determined. The chance discovery of C. deuterocubensis on native Melastoma malabathricum growing in the understory of Eucalyptus trees in Indonesia raised the possibility that this woody shrub could be a native host of C. deuterocubensis, which would then have undergone a host jump to Eucalyptus. Four populations of C. deuterocubensis were collected from cankers on Eucalyptus and Melastoma trees in Indonesia and Malaysia. These were subjected to population genetic analyses using microsatellite markers. The genetic diversity for isolates in all four populations was relatively low (H¯ = 0.166–0.316) and unlikely to represent a native source. The maximum percentage of genotypic diversity was high for all four populations (Gmax = 60.0–71.5%) irrespective of the host. Structure analyses and haplotype networks showed no structure related to the host plant species. Overall, the results failed to provide evidence that the indigenous M. malabathricum is the native host or origin of C. deuterocubensis infections on the Eucalyptus trees studied. [ABSTRACT FROM AUTHOR]

The genus Calonectria includes many aggressive plant pathogens causing diseases on various agricultural crops as well as forestry and ornamental tree species. Some species have been accidentally introduced into new environments via international trade of putatively asymptomatic plant germplasm or contaminated soil, resulting in significant economic losses. This review provides an overview of the taxonomy, population biology, and pathology of Calonectria species, specifically emerging from contemporary studies that have relied on DNA‐based technologies. The growing importance of genomics in future research is highlighted. A life cycle is proposed for Calonectria species, aimed at improving our ability to manage diseases caused by these pathogens. [ABSTRACT FROM AUTHOR]

During a routine survey conducted in July 2021, several dead and dying Ulmus macrocarpa trees were observed in an urban forest located in the Gyeonggi Province of South Korea. The trees had symptoms of wilt with yellowing and browning of leaves, and, in most cases, the trunks of dying trees were infested by bark beetles. Isolations were made from small pieces of wood taken from dying trees, and beetles were collected from the infested stems. Fungal isolates and the beetles were identified using DNA sequence-based phylogenies and morphology, respectively. The results revealed that the fungus was Ophiostoma novo-ulmi, the causal agent of Dutch elm disease, and the associated bark beetle was Scolytus jacobsoni. This study provides the first record of Dutch elm disease in South Korea and suggests that a nationwide survey for the disease should be undertaken. [ABSTRACT FROM AUTHOR]

Quambalaria are fungal pathogens of Corymbia, Eucalyptus and related genera of Myrtaceae. They are smut fungi (Ustilaginomycota) described from structures that resemble conidia and conidiophores. Whether these spore forms have asexual or sexual roles in life cycles of Quambalaria is unknown. An epidemic of Q. pitereka destroyed plantations of Corymbia in New South Wales and Queensland (Australia) in 2008. We sampled 177 individuals from three plantations of C. variegata and used AFLPs to test hypotheses that the epidemic was spread by asexual reproduction and dominated by a single genotype. There was high genotypic diversity across ≥600 AFLP loci in the pathogen populations at each plantation, and evidence of sexual reproduction based on neighbour-net analyses and rejection of linkage disequilibrium. The populations were not structured by host or location. Our data did not support a hypothesis of asexual reproduction but instead that Q. pitereka spreads exclusively by sexual reproduction, similar to life cycles of other smut fungi. Epidemics were exacerbated by monocultures of Corymbia established from seed collected from a single provenance. This study showcases an example of an endemic pathogen, Q. pitereka, with a strictly outbreeding life cycle that has caused epidemics when susceptible hosts were planted in large monoculture plantations. [ABSTRACT FROM AUTHOR]

Eucalypt plantations in South Africa make up an important part of the local forestry industry. Recently, one-year-old nursery plants of a Eucalyptus grandis × Eucalyptus urophylla variety displayed symptoms of leaf and shoot anthracnose disease. Samples were collected from these plants and isolations were made from the disease symptoms. Isolates were identified based on their morphological characteristics and DNA sequence data for eight gene regions. Phylogenetic analyses led to the isolates being identified as Colletotrichum theobromicola and the reduction of Colletotrichum pseudotheobromicola to synonymy with the former species. Pathogenicity trials with isolates of C. theobromicola were conducted on clones of E. grandis and hybrids of E. grandis × E. urophylla and E. grandis × Eucalyptus camaldulensis. Resulting symptoms were similar to those found on naturally infected plants and the fungus was re-isolated from the infections. Colletotrichum theobromicola is known to cause anthracnose on various plants including eucalypts in Brazil, but this is the first record of the pathogen in South Africa. [ABSTRACT FROM AUTHOR]

The Botryosphaeriaceae is an important and diverse family of latent fungal pathogens of woody plants, including Eucalyptus. These fungi live within infected plant tissues for extended periods without causing symptoms, but emerge to cause severe disease when their hosts are subjected to stress. In this study, we compared the diversity of the Botryosphaeriaceae in samples from nine different Eucalyptus clones growing in North and Central Sumatra, Indonesia, having distinct climates. Samples were taken from asymptomatic trees as well as those damaged by a sucking insect (Helopeltis sp.: Miridae), a stem boring moth (Polyphagozerra coffeae: Cossidae) and a Eucalyptus scab and shoot malformation fungal disease caused by Elsinoe necatrix. In total, 215 Botryosphaeriaceae isolates were obtained from which 13 species were identified based on rDNA‐ITS, TEF‐1α, β‐tubulin and rpb2 sequence data. These species included seven Lasiodiplodia species, four Neofusicoccum species as well as Endomelanconiopsis endophytica and Cophinforma atrovirens. A new species of Lasiodiplodia arose from collections and for which the name L. riauensis is provided. Two species, L. theobromae and L. brasiliensis, were found in both climatic zones, whereas other species were specific to the areas from which they were collected. No correlation was found between the Botryosphaeriaceae species diversity and damage to trees caused by insects or E. necatrix disease. [ABSTRACT FROM AUTHOR]

Syzygium cordatum (Myrtacease) is one of the most common encountered and widely distributed tree species indigenous to South Africa. This tree is often affected by a malformation disease characterized by grossly misshapen inflorescences that do not bear fruit. Because such symptoms have previously been attributed to Fusarium species in other plants, the aim of this study was to determine the diversity of Fusarium species associated with S. cordatum inflorescences. Healthy and malformed S. cordatum inflorescences were collected from Gauteng, Mpumalanga, Western Cape, and KwaZulu-Natal. A total of 118 Fusarium isolates were obtained from healthy (19) and malformed (99) inflorescences and identified using the translation elongation factor 1 alpha (TEF1α) gene region. The results revealed that 39 isolates belonged to the Fusarium fujikuroi species complex (FFSC), 45 isolates to the Fusarium oxysporum species complex (FOSC), 33 to the Fusarium incarnatum-equiseti species complex (FIESC) and one isolate resided in the Fusarium chlamydosporum species complex (FCSC). Phylogenetic analysis separated these isolates into 15 species, of which five (two in the FFSC, three in the FIESC) are new to science. No obvious patterns were found with respect to species recovered in different geographic areas sampled. However, FFSC species, were all recovered only from malformed inflorescences. [ABSTRACT FROM AUTHOR]

The genus Calonectria accommodates many important pathogens of agricultural, horticultural and forestry crops, including Eucalyptus. During 2017 surveys of Eucalyptus diseases in Sabah, Malaysia, typical symptoms of Calonectria leaf blight were observed. A large number of Calonectria isolates were collected from diseased leaves and soils associated with symptomatic trees. The aim of this study was to identify and resolve the phylogenetic relationships between these isolates using morphological characters and DNA sequence comparisons for six gene regions. From a collection of 73 isolates, eight species residing in three species complexes were identified. Amongst these, four undescribed species were characterized and are named here as Ca. borneana, Ca. ladang, Ca. pseudomalesiana and Ca. tanah. Results of this study support the view that planted Eucalyptus in tropical and subtropical areas of the world represent niches remarkably rich in Calonectria spp. This also has implications for the management of diseases on these important trees. [ABSTRACT FROM AUTHOR]

Teratosphaeria destructans is one of the most aggressive foliar pathogens of Eucalyptus. The biological factors underpinning T. destructans infections, which include shoot and leaf blight on young trees, have never been interrogated. Thus, the means by which the pathogen modifies its host environment to overcome host defences remain unknown. By applying transcriptome sequencing, the aim of this study was to compare gene expression in a South African isolate of T. destructans grown on nitrogen-deficient and complete media. This made it possible to identify upregulated genes in a nitrogen-starved environment, often linked to the pathogenicity of the fungus. The results support the hypothesis that nitrogen starvation in T. destructans likely mirrors an in planta genetic response. This is because 45% of genes that were highly upregulated under nitrogen starvation have previously been reported to be associated with infection in other pathogen systems. These included several CAZymes, fungal effector proteins, peptidases, kinases, toxins, lipases and proteins associated with detoxification of toxic compounds. Twenty-five secondary metabolites were identified and expressed in both nitrogen-deficient and complete conditions. Additionally, the most highly expressed genes in both growth conditions had pathogenicity-related functions. This study highlights the large number of expressed genes associated with pathogenicity and overcoming plant defences. As such, the generated baseline knowledge regarding pathogenicity and aggressiveness in T. destructans is a valuable reference for future in planta work. [ABSTRACT FROM AUTHOR]

The Ophiostomatales (Ascomycota) accommodates more than 300 species characterized by similar morphological adaptations to arthropod dispersal. Most species in this order are wood-inhabiting fungi associated with bark or ambrosia beetles. However, a smaller group of species occur in other niches such as in soil and Protea infructescences. Recent surveys of Termitomyces fungus gardens (fungus combs) of fungus-growing termites led to the discovery of characteristic ophiostomatalean-like fruiting structures. In this study, these ophiostomatalean-like fungi were identified using morphological characteristics, conventional molecular markers, and whole genome sequencing. In addition, the influence of the extracts derived from various parts of Termitomyces combs on the growth of these fungi in culture was considered. Based on phylogenomic analyses, two new genera (Intubia and Chrysosphaeria) were introduced to accommodate these ophiostomatalean species. Phylogenetic analyses revealed that the isolates resided in three well-supported lineages, and these were described as three new species (Intubia macrotermitinarum, I. oerlemansii, and Chrysosphaeria jan-nelii). Culture-based studies showed that these species do not depend on the Termitomyces comb material for growth. [ABSTRACT FROM AUTHOR]

Aims: Understanding the contributions of abiotic and biotic conditions to soil microbial diversity, structure, and function, remains a central focus in soil biology and biogeochemistry. Here we aim to determine how geography and host plant identity influence these different components of rhizosphere bacterial communities and endosymbionts associated with Acacia heterophylla on Réunion island (Mascarene archipelago, Indian Ocean) and A. koa in the Hawaiian Islands (Hawaiian archipelago, Pacific Ocean). These two tree species are remarkable: they are each other's closest living relatives despite their habitats being more than 16 000 km apart. Methods: Using 16S rRNA amplicon next-generation sequencing data we show that the structure of rhizosphere communities of these two acacias is largely driven by dispersal limitation between sites and local soil chemical conditions within sites. Results: Despite high taxonomic turnover in soils collected from different sites, we found their predicted functions to be largely similar, suggestive of functional redundancy. We also identify a core of rhizosphere taxa associated with both Acacia species in both archipelagos, which included potential nitrogen-fixing mutualists. Isolation and characterisation of rhizobia from root nodules of both acacias further supported strong selection by these plants for the same Bradyrhizobium endosymbionts. Conclusions: Overall, our data suggest that phylogenetically-closely related plants may show remarkably similar selectivity for bacterial mutualists over vast geographic distances. [ABSTRACT FROM AUTHOR]

The diverse bacterial communities in and around plants provide important benefits, such as protection against pathogens and cycling of essential minerals through decomposition of moribund plant biomass. Biodiverse fynbos landscapes generally have limited deadwood habitats due to the absence of large trees and frequent fire. In this study, we determined the effect of a fire disturbance on the bacterial communities in a fynbos landscape dominated by the shrub Protea repens using 16S ribosomal RNA amplicon sequencing. The bacterial community composition in newly formed fruiting structures (infructescences) and soil at a recently burnt site was different from that in an unburnt site. Bacteria inhabiting P. repens infructescences were similar to well-known taxa from decomposing wood and litter. This suggests a putative role for these aboveground plant structures as reservoirs for postfire decomposer bacteria. The results imply that inordinately frequent fires, which are commonplace in the Anthropocene, are a significant disturbance to bacterial communities and could affect the diversity of potentially important microbes from these landscapes. [ABSTRACT FROM AUTHOR]