Phaeoacremonium Species Research Articles

Phaeoacremonium philippinense (Togniniales, Sordariomycetes), a novel freshwater fungus from the Philippines

An investigation of freshwater fungi in the Philippines resulted in the collection and isolation of a new species of Phaeoacremonium (Togniniaceae) from unidentified decayed submerged wood. The novel hyphomycetous species, Phaeoacremonium philippinense, shares the same morphology with other members of the genus, such as having short, usually unbranched conidiophores, the presence of three types of phialides, and oblong-ellipsoidal to oblong conidia. A multi-locus phylogenetic analysis of the combined ITS-tub2-act-tef1-α-LSU dataset placed P. philippinense as a sister taxon to P. thailandense and indicated a shared clade with P. sicilianum. Detailed descriptions and photographic illustrations of P. philippinense are provided.

Detection of Esca‐associated fungi in grapevine trunks using loop‐mediated isothermal amplification (LAMP) assays

AbstractEsca is a grapevine trunk disease (GTD) that is caused by filamentous fungi. It is responsible for considerable economic losses in viniculture on a global scale. Despite many unknown factors contributing to the development of symptoms in affected plants, Phaeoacremonium minimum (PMI), Phaeomoniella chlamydospora (PCH) and Fomitiporia mediterranea (FMED) are generally considered as the main causative fungal species. Early detection and specific identification of these pathogens therefore play an important role in disease control and evaluation of suitable countermeasures. In this study, loop‐mediated isothermal amplification (LAMP) assays were developed for each of the three pathogens. A genome‐based approach was applied for detection and selection of unique target DNA sequences. The designed primer sets showed overall good specificities, with some observed cross‐reactions towards closely related Phaeoacremonium species for the PMI primer set. The developed assays had detection limits of 100 pg (FMED, PMI) and 1 pg (PCH) per reaction (corresponding to 1460 [FMED]; 1950 [PMI]; 342 [PCH] genome copies per reaction). The application of the assays to field samples was demonstrated by testing individual infected grapevine trunks from two European viticultural regions using crude DNA obtained in a rapid sample preparation step. LAMP assay results matched those of PCR following a conventional DNA extraction protocol. The study showed that LAMP‐based rapid molecular detection of major Esca agents can serve as a useful tool for further research and surveillance of a highly devastating grapevine disease. The application of computer‐based whole genome comparison between target and non‐target species for the identification of unique target sequences as the basis for LAMP (or PCR) primer design was demonstrated to be a useful approach in species for which scarce sequence information is available. Moreover, the developed method for rapid DNA preparation from grapevine trunks may potentially be adapted to the DNA‐based detection also of other fungal species that cause grapevine trunk diseases.

Healthy Rootstock Cuttings are Essential for the International Nursery Industry

Rootstock cuttings infected with latent Grapevine Trunk Diseases (GTD’s) pathogens are a major problem for nurseries. These fungal pathogens include several species of the genera Phaeoacremonium, Phaeomoniella, Cadophora, Dactylonectria, Ilyonectria, Diaporthe and the family Botryosphaeriaceae. Infected rootstock cuttings can cause losses of up to 60 % during propagation and post planting, and can be a reservoir of disease in the vineyard. This article presents a protocol for sanitary production of rootstock cuttings and is a guide to improving health of the grafted vine, and the profitability of nurseries and vineyards.

Phaeohyphomycosis: A study from tertiary health care center in North India

Phaeohyphomycosis refers to infections caused by phaeoid/dematiaceous or darkly pigmented fungi. This study was undertaken to further increase our knowledge about the incidence of phaeohyphomycosis and its causative agents. The present study was conducted over a period of one and a half years (January 2018-June 2019) on specimens received from patients with varied clinical manifestations ranging from superficial infections, subcutaneous cysts, pneumonia, brain abscess to a disseminated infection. These specimens were processed in the Department of Microbiology for potassium hydroxide (KOH) examination and culture and in Pathology for cytology/histopathological examination (HPE). All specimens positive on direct examination for dark grey, brown or black fungi were included in the study. A total of 20 specimens were confirmed as phaeohyphomycosis. Most of the patients belonged to the age group of 41 to 50 years. Male: Female ratio was 2.3:1. Trauma was the most common risk factor. Spectra of the isolated fungal pathogens comprised of Bipolaris species, Exophiala species, Curvularia geniculata, Phialemonium species, Daldinia eschscholtzii, Hypoxylon anthochroum, Phaeoacremonium species, Leptosphaerulina australis, Medicopsis romeroi, Lasiodiplodia theobromae, Eutypella species, Chaetomium globosum, Alternaria species, Cladophialophora bantiana and 2 unidentified dematiaceous fungi. Recovery from phaeohyphomycosis was seen in 12 patients, 7 were lost to follow up and one patient succumbed to the illness. Infections caused by phaeoid fungi can no longer be viewed as rare. In fact, phaeohyphomycosis can have myriad of presentations spanning from mild cutaneous infections to fatal brain disease. Therefore, a high index of clinical suspicion is needed to diagnose such infections. The primary treatment modality remains surgical removal of the lesion in cutaneous or subcutaneous infections however disseminated disease with a guarded prognosis requires aggressive management.

P225 Subcutaneous phaeohyphomycosis by Phaeoacremonium species in a renal transplant recipient

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PMObjectivePhaeohyphomycosis refers to infections due to a large group of heterogenous organisms called ‘dematiaceous’ or ‘melanized’ fungi. The infection exhibits a wide spectrum of presentations such as deep local infections, pulmonary infection, cerebral infection, and disseminated disease, which are associated with high mortality. The incidence of phaeohyphomycosis among solid organ transplant recipients is 0.7%. Hereby, we report a case of phaeohyphomycosis in a post renal transplant patient who presented with a subcutaneous swelling over the right elbow region.MethodA detailed history was obtained from the patient after informed consent. The cystic fluid was subjected to microbiological including bacterial (Gram stain, culture on blood agar incubated at 37°C) and fungal investigations [Calcofluor potassium hydroxide (KOH) mount, culture on Sabouraud dextrose agar (SDA) incubated at 37°C and 25°C and brain heart infusion agar (BHI) incubated at 25°C]. The identification of isolate was done phenotypically by preparing lactophenol cotton blue (LCB) mount from slide culture and molecular technique using Sanger's sequencing.ResultA 61-year-old diabetic and post renal transplant (7 years) male presented with complaints of swelling over the right elbow region for 5 months duration. Swelling was insidious in onset, gradually progressive, painless, cystic, non-pulsatile, non-reducible, ∼9 × 7 cm in size, lobular in shape with irregular surface having normal overlying skin which minimally restricting the movement of the elbow. There was no history of trauma over the elbow region. Reddish purulent pus was received for mycological investigation. Calcofluor KOH mount demonstrated septate hyphae. Culture on SDA incubated at 37°C and 25°C grew cream-colored colonies, turning grayish beige to olive-brown and developed clusters of aerial hyphae with reverse tan to brown in color after 2 weeks of incubation. LCB mount showed hyaline to brownish hyphae, cylindrical phialides growing along the hyphae with slightly tapering towards the apex, hyaline, oblong, conidia, gathering in clusters at end of phialide. Phenotypically, the fungus was identified as Phaeoacremonium species and molecular identification and antifungal susceptibility are awaited. Patient was advised for surgical excision but he left against medical advice. Currently, he is not receiving any antifungals.ConclusionPhaeohyphomycosis is a rare and unique entity among fungal infections. Cutaneous phaeohyphomycosis predominantly occurs on the extremities with a localized solitary nodule or abscess. A high index of suspicion and the surgical approach including excision or debridement are mainly chosen.

First Report of Fusarium annulatum Associated with Young Vine Decline in California.

From 2018 to 2021 a decline was detected in young vineyards of both wine and table grape (Vitis vinifera L.) in seven counties across California (Kern, Monterey, Napa, Sonoma, Tulare, Yolo, and Yuba). Affected vines showed poor or no growth throughout the season, dieback, sap exudation and internal cankers around the graft union. Lack of feeder roots was detected, indicating weak root development. In some cases, graft failure was associated with the symptomatology in recently established vineyards (<3 years old). A prevalence from 5 to 50% was estimated in 10 vineyards. Affected vines (n=34) were collected by farm advisors and submitted to the laboratory. Symptomatic vines were surface disinfected with 70% ethanol for 1 minute and air dried under sterile conditions. Vascular discoloration around the graft union was observed and inspected by removing the bark using a sterile knife. Isolations were performed from the margin of lesions by placing five wood sections (1×1 mm) per vine onto potato dextrose agar acidified with 0.5 mL/L of 85% lactic acid (APDA) and incubated for 7 days at 25°C in the dark. Even though other fungi associated with young vine decline were isolated and identified as Phaeoacremonium, Ilyonectria, and Botryosphaeriaceae species, Fusarium colonies (Leslie and Summerell, 2006) were the most prevalent among all the symptomatic vines. Pure cultures were obtained by transferring single hyphal tips onto fresh PDA. After 5 days of incubation, colonies formed white aerial mycelium with orange to purple colors on the bottom. Colonies in Spezieller Nährstoffarmer agar (SNA) produced abundant microconidia that were hyaline and ovoid to elliptical, ranging from 5.4 to 10.6 (7.4) × 1.4 to 3.3 (2.4) µm in size (n=50). Straight and slightly curved macroconidia varied from 15.5 to 42.3 (23.7) × 2.6 to 5.0 (3.6) µm in size (n=50). Upon DNA extraction, the translation elongation factor 1α (tef1) and the RNA polymerase II second largest subunit (rpb2) partial gene regions were amplified and sequenced using the EF1/EF2, 5F2/7cR and 7cF/11aR pair primers, respectively (O'Donnell et al. 1998, O'Donnell et al. 2007, Liu et al. 1999). Consensus sequences were compared to the NCBI database using BLAST, showing over 99% similarity with the ex-type sequence of F. annulatum CBS 258.54 (MT010994 and MT010983). A maximum likelihood multi-locus phylogenetic analysis confirmed that all the Californian isolates cluster with F. annulatum strains. Sequences were deposited in GenBank (nos. OK888534 to OK888537). Two representative isolates (UCD9188 and UCD9416) were used for pathogenicity tests. One-year-old 'Chardonnay' vines were inoculated between the second and third node by removing a 5-mm diameter disk of the bark using a sterile cork borer and placing a 5-mm agar plug with actively growing mycelium. Five replicates per isolate including controls with sterile agar plugs were incubated under greenhouse conditions for 2 months. The experiment was performed twice. Symptoms expressed as vascular linear necrotic lesions that ranged from 25.6 to 62.8 mm and the same pathogen was recovered, thus fulfilling Koch's postulates. Fusarium annulatum Bugnic. is a morphologically and genetically diverse species that has been widely known as F. proliferatum and known to be pathogenic in more than 200 plant hosts (Yilmaz et al. 2021). Fusarium spp. have been previously reported to cause young vine decline in Australia and British Columbia, Canada (Highet and Nair, 1995; Úrbez-Torres et al. 2017). To the best of our knowledge, this is the first report of F. annulatum associated with young vine decline complex in California.

Grapevine trunk diseases of cold-hardy varieties grown in Northern Midwest vineyards coincide with canker fungi and winter injury.

Grapevine trunk diseases make up a disease complex associated with several vascular fungal pathogenic species. Surveys to characterize the composition of grapevine trunk diseases have been conducted for most major grape growing regions of the world. This study presents a similar survey characterizing the fungi associated with grapevine trunk diseases of cold-hardy interspecific hybrid grape varieties grown nearly exclusively in the atypical harsh winter climate of Northern Midwestern United states vineyards. From the 172 samples collected in 2019, 640 isolates obtained by culturing were identified by ITS sequencing and represent 420 sample-unique taxa. From the 420 representative taxa, opportunistic fungi of the order Diaporthales including species of Cytospora and Diaporthe were most frequently identified. Species of Phaeoacremonium, Paraconiothyrium, and Cadophora were also prevalent. In other milder Mediterranean growing climates, species of Xylariales and Botryosphaeriales are often frequently isolated but in this study they were isolated in small numbers. No Phaeomoniellales taxa were isolated. We discuss the possible compounding effects of winter injury, the pathogens isolated, and management strategies. Additionally, difficulties in researching and understanding the grapevine trunk disease complex are discussed.

Genome Resource of Colletotrichum spaethianum, the Causal Agent of Leaf Anthracnose in Polygonatum falcatum

Genome Resource of <i>Colletotrichum spaethianum</i>, the Causal Agent of Leaf Anthracnose in <i>Polygonatum falcatum</i>

Untargeted and Targeted LC-MS/MS Based Metabolomics Study on In Vitro Culture of Phaeoacremonium Species.

Grapevine (Vitis vinifera L.) can be affected by many different biotic agents, including tracheomycotic fungi such as Phaeomoniella chlamydospora and Phaeoacremonium minimum, which are the main causal agent of Esca and Petri diseases. Both fungi produce phytotoxic naphthalenone polyketides, namely scytalone and isosclerone, that are related to symptom development. The main objective of this study was to investigate the secondary metabolites produced by three Phaeoacremonium species and to assess their phytotoxicity by in vitro bioassay. To this aim, untargeted and targeted LC-MS/MS-based metabolomics were performed. High resolution mass spectrometer UHPLC-Orbitrap was used for the untargeted profiling and dereplication of secondary metabolites. A sensitive multi reaction monitoring (MRM) method for the absolute quantification of scytalone and isosclerone was developed on a UPLC-QTrap. Different isolates of P. italicum, P. alvesii and P. rubrigenum were grown in vitro and the culture filtrates and organic extracts were assayed for phytotoxicity. The toxic effects varied within and among fungal isolates. Isosclerone and scytalone were dereplicated by matching retention times and HRMS and MS/MS data with pure standards. The amount of scytalone and isosclerone differed within and among fungal species. To our best knowledge, this is the first study that applies an approach of LC-MS/MS-based metabolomics to investigate differences in the metabolic composition of organic extracts of Phaeoacremonium species culture filtrates.

Structure analysis of the ribosomal intergenic spacer region of Phaeoacremonium italicum as a study model

Increasing recognition of novel Phaeoacremonium species, and their recent taxonomic reassignment through phylogeny based on the β-tubulin and actin genes, have highlighted the presence of paraphyly, intraspecific variation, and incongruence of some Phaeoacremonium species. This study investigated the intergenic spacer rDNA regions of a representative collection of 31 Phaeoacremonium italicum strains, and compared their structures with those of the closest related species, Phaeoacremonium alvesii and Phaeoacremonium rubrigenum. These intergenic spacer sequences had five categories of repeat elements that were organised into distinct patterns. Morphological analyses of the P. italicum strains provided a more detailed description of P. italicum. The phylogenetic tree constructed using the intergenic spacer sequences compared with that obtained by combined analysis of β-tubulin and actin sequences indicated that the intergenic spacer rDNA region distinguished intraspecific and interspecific variations. Further molecular studies are required to determine whether intergenic spacer sequences can improve precision in defining Phaeoacremonium phylogeny, and prevent misidentification and the introduction of vague species boundaries for the genus.

Dissemination of esca-related pathogens in German vineyards: do arthropods play roles in vectoring spores?

Grapevine Trunk Diseases (GTDs) such as esca challenge viticulture. The main fungal agents of Petri disease or young esca, Phaeomoniella chlamydospora (Pch), diverse Phaeoacremonium species (Pm spp.) and Cadophora luteo-olivacea (Clo), are transmitted to pruning wounds of vines by rain splashes and air currents. Arthropod-mediated dispersal is another possibility for the pathogens to reach pruning wounds. The present study was the first to evaluate possible involvement of arthropods in the dissemination process of esca-related pathogens in German vineyards. Diversity of arthropods on grapevine trunks was determined in 2019 and 2020, using cardboard traps mounted on vine trunks. Captured arthropods were surveyed for the presence of esca-related pathogens on their exoskeletons by using a nested multiplex PCR. In total, 2099 arthropods were examined, of which 35% were positive for Phaeomoniella chlamydospora (Pch), 21% for Phaeoacremonium spp. (Pm), and 7% for Cadophora luteo-olivacea (Clo). Earwigs and spiders were the most prevalent trapped arthropods; Pch was detected on 27% of earwigs and 38% of spiders, Pm spp. on 17 and 19%, and Clo on 3 and 8% of these arthropods. In both years, arthropods carrying the pathogens were already present in April, and therefore within the presumed susceptibility phase of pruned vines. These results indicate involvement of arthropods in the dispersal of esca-related pathogens in German vineyards. Further research, particularly to determine the infection potential of insect-borne fungi, is needed to confirm transmission risk. These results underline the importance of protecting vine pruning wounds to prevent host invasion by GTD pathogens.

Cadophora sabaouae sp. nov. and Phaeoacremonium Species Associated with Petri Disease on Grapevine Propagation Material and Young Grapevines in Algeria.

A field survey conducted on asymptomatic grapevine propagation material from nurseries and symptomatic young grapevines throughout different regions of Algeria yielded a collection of 70 Phaeoacremonium-like isolates and three Cadophora-like isolates. Based on morphology and DNA sequence data of β-tubulin (tub2) and actin, five Phaeoacremonium species were identified including Phaeoacremonium minimum (22 isolates), Phaeoacremonium venezuelense (19 isolates), Phaeoacremonium parasiticum (17 isolates), Phaeoacremonium australiense (8 isolates), and Phaeoacremonium iranianum (4 isolates). The latter two species (P. australiense and P. iranianum) were reported for the first time in Algeria. Multilocus phylogenetic analyses (internal transcribed spacer, tub2, and translation elongation factor 1-α) and morphological features, allowed the description of the three isolates belonging to the genus Cadophora (WAMC34, WAMC117, and WAMC118) as a novel species, named Cadophora sabaouae sp. nov. Pathogenicity tests were conducted on grapevine cuttings cultivar Cardinal. All the identified species were pathogenic on grapevine cuttings.

Phaeoacremonium fusiformostromum sp. nov. and a new record of P. croatiense from China

Phaeoacremonium species are important pathogens with a worldwide distribution and diverse host and are commonly associated with brown wood streaking, dieback and Esca disease of plants and phaeohyphomycosis of humans. In this study, three sexual taxa, representing two Phaeoacremonium species, were collected from dead wood from Guangdong and Guizhou Provinces in China. Based on the morphological characters and phylogenetic analyses of a combined ACT and TUB2 sequence data, they are identified as Phaeoacremonium fusiformostromum sp. nov., and P. croatiense, which is a new record from China with its first sexual morph. Detailed descriptions and illustrations of these two species are provided, and an updated phylogenetic tree for all Phaeoacremonium species is also given.

Fungal communities of grapevine decline in the main grape-growing regions of Iran

Grapevine decline is a worldwide problem of viticulture, leading to significant yield loss in the grape-growing regions of Iran. Several species of fungal endophytes are known as the causal agents of the disease. Vines with internal and external symptoms were sampled from Qazvin, Lorestan, North Khorasan and Razavi Khorasan provinces, showing different climate regimes. Regarding geographical regions with their variable climatic background, the cultivars, and vineyard age, the dominant fungi were different. In Bojnord, Phaeomoniella chlamydospora and Phaeoacremonium minimum, the known causal agents of esca disease, were the most isolated fungi obtained from 27 and 24 symptomatic plants, respectively. The establishment of Phaeomoniella and Phaeoacremonium species in Takestan and Tajareh might be prevented by different environmental and biological factors. Fomitiporia mediterranea isolates, the white rot agent, were isolated from Takestan with 25–30 years old vineyards, and the average summer temperature, precipitation, and humidity were about 1 mm, 25 °C, 38% respectively. In jovein with 15 years old vineyards, the most important esca related fungi, Phaeomoniella, Phaeoacremonium, and Fomitiporia species, were isolated in the summer, obtained from 31, 23 and 18 symptomatic plants, respectively. This study gives some insights into the possible relationship between grapevine decline related fungi and, especially, environmental factors, which leads to a more diffused picture of esca and the related fungi communities, making it challenging to clearly separate the effects of other factors.

Dieback and decline pathogens of olive trees in South Africa.

Trunk disease fungal pathogens reduce olive production globally by causing cankers, dieback, and other decline-related symptoms on olive trees. Very few fungi have been reported in association with olive dieback and decline in South Africa. Many of the fungal species reported from symptomatic olive trees in other countries have broad host ranges and are known to occur on other woody host plants in the Western Cape province, the main olive production region of South Africa. This survey investigated the diversity of fungi and symptoms associated with olive dieback and decline in South Africa. Isolations were made from internal wood symptoms of 145 European and 42 wild olive trees sampled in 10 and 9 districts, respectively. A total of 99 taxa were identified among 440 fungal isolates using combinations of morphological and molecular techniques. A new species of Pseudophaeomoniella, P. globosa, had the highest incidence, being recovered from 42.8 % of European and 54.8 % of wild olive samples. This species was recovered from 9 of the 10 districts where European olive trees were sampled and from all districts where wild olive trees were sampled. Members of the Phaeomoniellales (mainly P. globosa) were the most prevalent fungi in five of the seven symptom types considered, the only exceptions being twig dieback, where members of the Botryosphaeriaceae were more common, and soft/white rot where only Basidiomycota were recovered. Several of the species identified are known as pathogens of olives or other woody crops either in South Africa or elsewhere in the world, including species of Neofusicoccum, Phaeoacremonium, and Pleurostoma richardsiae. However, 81 of the 99 taxa identified have not previously been recorded on olive trees and have unknown interactions with this host. These taxa include one new genus and several putative new species, of which four are formally described as Celerioriella umnquma sp. nov., Pseudophaeomoniella globosa sp. nov., Vredendaliella oleae gen. & sp. nov., and Xenocylindrosporium margaritarum sp. nov.

Phaeoacremonium species detected in fine needle aspiration: a rare case report

BackgroundFine needle aspiration cytology (FNAC) with rapid on-site evaluation has a great potential for the diagnosis of fungal lesions and other opportunistic infections. Fungal infections have been in increasing trend in the past two decades due to immunosuppression, travel, and environmental exposure. Human disease caused by Phaeoacremonium species is rare and was first reported in 1974 as subcutaneous tissue infection in a renal transplant recipient.Case presentationWe report a case of subcutaneous tissue swelling in a 67-year-old male, wherein FNAC was done with incidental detection of the fungus (Phaeoacremonium spp).ConclusionThere are very few reported cases of subcutaneous infection in humans by Phaeoacremonium spp. Clinical suspicion and FNAC can play an important role in early detection of the fungus, prevent spread, and facilitating early treatment.

A Survey of Trunk Disease Pathogens within Citrus Trees in Iran.

Citrus trees with cankers and dieback symptoms were observed in Bushehr (Bushehr province, Iran). Isolations were made from diseased cankers and branches. Recovered fungal isolates were identified using cultural and morphological characteristics, as well as comparisons of DNA sequence data of the nuclear ribosomal DNA-internal transcribed spacer region, translation elongation factor 1α, β-tubulin, and actin gene regions. Dothiorella viticola, Lasiodiplodia theobromae, Neoscytalidium hyalinum, Phaeoacremonium (P.) parasiticum, P. italicum, P. iranianum, P. rubrigenum, P. minimum, P. croatiense, P. fraxinopensylvanicum, Phaeoacremonium sp., Cadophora luteo-olivacea, Biscogniauxia (B.) mediterranea, Colletotrichum gloeosporioides, C. boninense, Peyronellaea (Pa.) pinodella, Stilbocrea (S.) walteri, and several isolates of Phoma, Pestalotiopsis, and Fusarium species were obtained from diseased trees. The pathogenicity tests were conducted by artificial inoculation of excised shoots of healthy acid lime trees (Citrus aurantifolia) under controlled conditions. Lasiodiplodia theobromae was the most virulent and caused the longest lesions within 40 days of inoculation. According to literature reviews, this is the first report of L. theobromae and N. hyalinum on citrus in Iran. Additionally, we report several Phaeoacremonium species, S. walteri, Pa. pinodella and C. luteo-olivacea on citrus trees for the first time in the world.

Mushroom forming fungi as possible reservoir hosts for Phaeoacremonium species: first occurrence of Phaeoacremonium fraxinopennsylvanicum on Flammulina velutipes s. lato

Members of the genus Phaeoacremonium are known to inhabit a wide spectrum of substrates and exhibit diverse lifestyles. Little information is available on fungicolous habits among Phaeoacremonium species. During surveys to Arasbaran forests in East Azerbaijan province, Iran, in 2016, several hyphomycete isolates morphologically resembling the genus Phaeoacremonium were recovered from the hymenium of Flammulina velutipes s. lato in different localities with no symptoms on the cap. The isolates were identified as Ph. fraxinopennsylvanicum based on a combination of morphological traits and phylogenetic analyses of β -tubulin gene sequence data. This is the first report on the occurrence of Ph. fraxinopennsylvanicum on F. velutipes worldwide; however, the pathogenic potential of Ph. fraxinopennsylvanicum on F. velutipes remains unclear. The data presented in the study reveal mushroom forming fungi as possible new reservoir hosts for Phaeoacremonium spp. Hence, extensive sampling from mushroom forming fungi is required to further explore fungicolous habit of Phaeoacremonium species.

Fungal pathogens associated with branch and trunk cankers of nut crops in Iran

Branch and trunk canker diseases have become prevalent on nut crops in Iran. During 2015 to 2018, extensive field surveys were conducted on 58 almond, 43 pistachio and 80 walnut orchards in Iran to study fungal pathogens associated with symptomatic trees. One hundred and fifty-six representative fungal isolates were selected and identified based on morphological characteristics and by phylogenetic comparison of DNA sequence data. Fungal species found were Collophorina hispanica, Pleurostoma richardsiae, nine species of Phaeoacremonium (namely P. angustius, P. cinereum, P. italicum, P. fraxinopennsylvanicum, P. minimum, P. parasiticum, P. scolyti, P. tuscanum and P. viticola), 11 species of Botryosphaeriaceae (namely Botryosphaeria dothidea, Diplodia gallae, D. mutila, D. seriata, Dothiorella plurivora, Do. sarmentorum, Do. viticola, Lasiodiplodia citricola, L. mahajangana, L. theobromae and Neofusicoccum parvum), four species of Diatrypaceae (namely Cryptosphaeria pullmanensis, Diatrype whitmanensis, Eutypella citricola and E. vitis) and two non-identified Eutypella spp. (Eutypella sp. 1 and Eutypella sp. 2). Some of these species represent new reports in Iran and/or are reported for the first time in their respective hosts. Pathogenicity tests demonstrated that most of these fungi were pathogenic to inoculated almond, pistachio and walnut shoots. Therefore, more importance should be given to fungal trunk pathogens in Iran, and specific management strategies should be included within the nut crops IPM management programs, with the aim of improving their sustainability.

Diversity Profiling of Grapevine Microbial Endosphere and Antagonistic Potential of Endophytic Pseudomonas Against Grapevine Trunk Diseases.

Grapevine trunk diseases (GTDs) are a serious problem of grapevines worldwide. The microbiota of the grapevine endosphere comprises prokaryotic and eukaryotic endophytes, which may form varied relationships with the host plant from symbiotic to pathogenic. To explore the interaction between grapevine endophytic bacteria and GTDs, the endomicrobiome associated with grapevine wood was characterized using next-generation Illumina sequencing. Wood samples were collected from grapevine trunks with and without external symptoms of GTD (cankers) from two vineyards in the Hunter Valley and Hilltops, NSW, Australia and metagenomic characterization of the endophytic community was conducted using the 16S rRNA gene (341F/806R) and ITS (1F/2R) sequences. Among the important GTD pathogens, Phaeomoniella, Phaeoacremonium, Diplodia and Cryptovalsa species were found to be abundant in both symptomatic and asymptomatic grapevines from both vineyards. Eutypa lata and Neofusicoccum parvum, two important GTD pathogens, were detected in low numbers in Hilltops and the Hunter Valley, respectively. Interestingly, Pseudomonas dominated the bacterial community in canker-free grapevine tissues in both locations, comprising 56–74% of the total bacterial population. In contrast, the Pseudomonas population in grapevines with cankers was significantly lower, representing 29 and 2% of the bacterial community in Hilltops and the Hunter Valley, respectively. The presence of Pseudomonas in healthy grapevine tissues indicates its ability to colonize and survive in the grapevine. The potential of Pseudomonas spp. as biocontrol agents against GTD pathogens was also explored. Dual culture tests with isolated fluorescent Pseudomonas against mycelial discs of nine Botryosphaeria dieback, three Eutypa dieback, and two Esca/Petri disease pathogens, revealed antagonistic activity for 10 Pseudomonas strains. These results suggest the potential of Pseudomonas species from grapevine wood to be used as biocontrol agents to manage certain GTD pathogens.