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The forest pathogen, Heterobasidion irregulare, is a serious threat to conifers in North America including Minnesota. Fungi native to Minnesota were isolated and tested in laboratory and field assays to evaluate their antagonism towards H. irregulare. One management strategy for plant pathogens, and especially H. irregulare, is to use fungi as biological control agents. A successful biological control agent used to manage root rot disease caused by H. irregulare is the fungus Phlebiopsis gigantea. The goal of this research was to screen different native fungi, including P. gigantea, against H. irregulare and examine and quantify their interactions in vitro and ex vitro. A set of four different antagonism assays were conducted. These assays served as a screening process involving both the laboratory and the field. Interactions were first examined with dual inoculation studies on media and wood discs of red pine (Pinus resinosa). These assays demonstrated strong inhibition and limited growth of H. irregulare by select fungi, including Phanerochaete livescens and P. gigantea. Another assay involved using soil microcosms and wood wedges of red pine. This allowed for a different examination, as wood wedges were inoculated with a candidate antagonistic fungus and placed in soil microcosms with H. irregulare. The opposite interaction was also examined with wedges inoculated with H. irregulare and then placed in soil microcosms containing different candidate fungi. In the field, large wood discs were placed around stumps and inoculated with candidate fungi in a red pine plantation infected with H. irregulare. Certain fungi performed well in different assays, but across all assays, P. gigantea performed the best. The antagonism of P. gigantea was most noticeable on wood discs and wood wedges used in vitro, as H. irregulare was not able to be reisolated from these substrates. Overall, these results provide more information on the fungi that appear to be acting as antagonists in forests to prevent H. irregulare from colonizing and provide new information on potential candidate fungi that could be used as a new biological control agent. [ABSTRACT FROM AUTHOR]

Brown-rot fungi lack many enzymes associated with complete wood degradation, such as lignin-attacking peroxidases, and have developed alternative mechanisms for rapid wood breakdown. To identify the effects of culture conditions and wood substrates on gene expression, we grew Fibroporia radiculosa in submerged cultures containing Wiley milled wood (5 days) and solid wood wafers (30 days), using aspen, pine, and spruce as a substrate. The comparative analysis revealed that wood species had a limited effect on the transcriptome: <3% of genes were differentially expressed between different wood species substrates. The comparison between gene expression during growth on milled wood and wood wafer conditions, however, indicated that the genes encoding plant cell wall-degrading enzymes, such as glycoside hydrolases and peptidases, were activated during growth on wood wafers, confirming previous reports. On the other hand, it was shown for the first time that the genes encoding Fenton chemistry enzymes, such as hydroquinone biosynthesis enzymes and oxidoreductases, were activated during submerged growth on ground wood. This illustrates the diversity of wood-decay reactions encoded in fungi and activated at different stages of this process. [ABSTRACT FROM AUTHOR]

Fungi are probably the most diverse group of eukaryotic organisms in the Antarctic continent and nearby archipelagos, and they dominate communities in either mild or harsh habitats. However, our knowledge of their global distribution ranges and the temporal origins of their Antarctic populations is rather limited or almost absent, especially for species that do not lichenize. We focused for the first time on elucidating the taxonomic identity and phylogenetic relationships of several Antarctic collections of the deadly fungal Basidiomycota genus Galerina. By using molecular sequence data from the universal fungal barcode and a dataset encompassing 178 specimens, the inferred phylogeny showed that the Antarctic specimens corresponded with the sub-cosmopolitan species Galerina marginata , Galerina badipes and Galerina fallax , and their most closely related intraspecific genetic lineages were from northern Europe and North America. We found that these species probably host Antarctic-endemic intraspecific lineages. Furthermore, our dating analyses indicated that their Antarctic populations originated in the Pleistocene, a temporal frame that agrees with that proposed for the Antarctic colonization of plants such as the grass Deschampsia antarctica , mosses and some amphitropical lichens. Altogether, these findings converge on the same temporal scenario for the assembly of the most conspicuous terrestrial Antarctic plant and fungal communities. [ABSTRACT FROM AUTHOR]

The emerald ash borer is causing dramatic losses following its introduction into North America, with hundreds of millions of ash trees killed. Attacked trees lose wood integrity rapidly after infestation and are prone to failure. The aim of this study was to investigate the wood degrading potential of Basidiomycota fungi previously found associated with EAB galleries. Laboratory soil and agar microcosm experiments showed that many of the white-rot fungi isolated were aggressive wood degraders. Trametes versicolor, Phlebia radiata and Phlebia acerina were among the top decomposers from the 13 tested fungi, resulting in as much as 70%, 72% and 64% weight loss, respectively, after 6 months of incubation. Micromorphological observations documented the significant wood cell wall degradation that had taken place. The decay capacity of these fungi confirms their contributing role to the loss of wood integrity in ash trees after EAB attack. [ABSTRACT FROM AUTHOR]

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Laurel wilt, caused by the fungus Raffaelea lauricola, has caused widespread mortality to Persea borbonia across the southeastern United States. The invasive ambrosia beetle vector of the pathogen, Xyleborus glabratus, attacks and infects trees, leaving only P. borbonia seedlings, saplings, and stump sprouts in heavily affected areas. To facilitate mitigation of this ecological damage, we initiated a screening program for laurel wilt disease resistance. We established circular field plots (0.08 hectare) in six significantly impacted sites, measured laurel wilt epidemiological characteristics, and selected 61 survivor P. borbonia ortets (≥7.5 cm diameter at breast height [DBH]) for vegetative propagation, screening, and monitoring. Disease incidence in the plots ranged from 50% to 87% of P. borbonia stems thicker than 2.5 cm DBH and ortet survival per site ranged from 0% to 70% a decade after initial selection. Clonal ramets from 38 survivor ortets were out planted and screened for resistance to R. lauricola in a series of field inoculation trials. Results indicate variable levels of host susceptibility and suggest rare individuals exist with tolerance to R. lauricola. Scanning electron microscopy imaging of xylem samples from three infected P. borbonia clones suggests that reduced tylose production and granular deposition in xylem lumina are associated with increased resistance to R. lauricola. Results from this study will aid in the selection of disease‐resistant P. borbonia germplasm for restoration plantings in affected sites and provide new insights into the host–pathogen interaction of this deadly vascular disease. [ABSTRACT FROM AUTHOR]

Raffaelea lauricola causes laurel wilt of avocado, Persea americana. Host X pathogen interactions were examined with light and scanning electron microscopy. The susceptible avocado cultivar 'Simmonds' was inoculated and examined 5 cm above the inoculation site 3, 7, 14, 21, and 42 days after inoculation (dai). No external symptoms were observed at 3 and 7 dai, and there were no anatomical differences when compared with the mock-inoculated plants. By 14 dai, external symptoms were present and dark discoloration had developed in sapwood. Tylose development increased significantly by 14 dai, and was positivity correlated with disease severity (P < 0.05). By 14 dai, gels formed in xylem vessels, fibers, and adjacent parenchyma cells; they were associated with xylem blockage and composed of phenols, pectin, and lipids, as suggested by, respectively, toluidine blue O, ruthenium red, and Sudan III stains. With a chitin-specific stain, fluorescein-conjugated wheat germ agglutinin, infrequent mycelia, and conidia of R. lauricola were visualized within xylem lumena and fibers, regardless of sample date. Understanding how avocado responds to the presence of this pathogen could assist the development of laurel wilt-resistant avocado genotypes and inform efforts to manage this disease with other measures. Key words: avocado, laurel wilt, Raffaelea lauricola, Xyleborus glabratus, ambrosia beetle. Le Raffaelea lauricola cause la fletrissure du laurier chez l'avocat. Les auteurs ont examine les interactions hote x pathogene a l'aide de la microscopie photonique et electronique par balayage. Ils ont inocule le cultivar d'avocat 'Simmonds' susceptible, et ont examine la partie situee a 5 cm au dessus du site d'inoculation, 3, 7, 14, 21, et 42 jours apres l'inoculation (jai) On n'observe aucun symptome aux jai 3 et 7, et il n'y a pas de differences anatomiques lorsque que l'on compare avec les plants inocules a blanc. Vers le jai 14, on observe des symptomes externes montrant une decoloration foncee se developpant dans l'aubier. Le developpement des thylles augmente significativement vers le jai 14 et montre une correlation avec la severite de la maladie (P < 0,05). Vers le jai 14, des gels se forment dans les vaisseaux du xyleme, les fibres et les cellules de parenchymes adjacentes; ils sont associes au blocage du xyleme et sont composes de phenols, pectine et lipides, tel que suggere par les colorations au bleu de toluidine O, au rouge de ruthenium, et au Soudan III. Independamment de la date d'echantillonnage, on observe a l'aide d'un colorant specifique a la chitine, une fluoresceine conjuguee al'agglutinine du germe de ble, une presence peu frequente de myceliums et de conidies du R. lauricola dans les lumens du xyleme et des fibres. Une meilleure comprehension des reactions de l'avocat a la presence de ce champignon pathogene pourrait aider a developper des genotypes d'avocat resistants a cette fletrissure et orienter les efforts d'amenagement de la maladie vers d'autres directions. Mots-cles : avocat, fletrissure du laurier, Raffaelea lauricola, Xyleborus glabratus, scolyte du bois. [Traduit par la Redaction], Introduction Laurel wilt affects American members of the Lauraceae plant family, including the important fruit crop avocado (Persea americana Mill.) and native trees in the southeastern USA, such as redbay [...]

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. [ABSTRACT FROM AUTHOR]

Bark beetles, fossil wood, Upper Cretaceous, wood-colonizing fungi, Araucariaceae, Ascomycota Here we describe a fungus colonizing wood of the extinct conifer I Agathoxylon i Hartig from the Upper Cretaceous Mzamba Formation of Pondoland (South Africa), and we draw comparisons with a blue stain fungus colonizing the wood of extant I Pinus strobus i . Keywords: Araucariaceae; Ascomycota; bark beetles; fossil wood; Upper Cretaceous; wood-colonizing fungi EN Araucariaceae Ascomycota bark beetles fossil wood Upper Cretaceous wood-colonizing fungi 1032 1037 6 01/10/22 20220201 NES 220201 Introduction Fossil fungi are frequently observed in association with fossil plants in a geological record that dates back over 400 Myr to the beginning of the Devonian Period (e.g. Strullu-Derrien I et al i ., 2014, 2018; Taylor I et al i ., 2015; Krings I et al i ., 2018; Krings & Harper, 2019). In most modern trees, two types of wood can be recognized: sapwood is the outer, pale-coloured wood, and heartwood the inner, mostly darker wood (Githiomi & Dougal, 2012). [Extracted from the article]

Yasuní National Park in Ecuador is one of the most biodiverse places on earth. The fungi in this tropical rainforest are also diverse but have received little research attention. This research paper focuses on an important group of fungi in the family Polyporaceae and examines the genera Polyporus, Atroporus, and Neodictyopus that form aerial melanized cord-like structures called rhizomorphs. Phylogenetic analyses, macro and micromorphological descriptions of basidiomata and rhizomorphs, as well as cultural characterization were completed to better understand these ecologically important fungi. Here we describe four new species: Atroporus yasuniensis, Atroporus tagaeri, Neodictyopus sylvaticus, and Polyporus taromenane, and a new variety Polyporus leprieurii var. yasuniensis. The information presented in this study adds important new knowledge about the unusual rhizomorph producing fungi found in Yasuní National Park, Ecuador and other tropical rainforests. [ABSTRACT FROM AUTHOR]

The indigenous people of the United States and Canada long have used forest fungi for food, tinder, medicine, paint, and many other cultural uses. New information about historical uses of fungi continues to be discovered from museums as accessions of fungi and objects made from fungi collected over the last 150+ years are examined and identified. Two textiles thought to be made from fungal mats are located in the Hood Museum of Art, Dartmouth College, and the Oakland Museum of California. Scanning electron microscopy and DNA sequencing were used to attempt to identify the fungus that produced the mats. Although DNA sequencing failed to yield a taxonomic identification, microscopy and characteristics of the mycelial mats suggest that the mats were produced by Laricifomes officinalis. This first report of fungal mats used for textile by indigenous people of North America will help to alert museum curators and conservators as well as mycological researchers to their existence and hopefully lead to more items being discovered that have been made from fungal fabric. [ABSTRACT FROM AUTHOR]

Historic wooden structures in Polar Regions are being adversely affected by decay fungi and a warming climate will likely accelerate degradation. Fort Conger and the Peary Huts at Lady Franklin Bay in northern Ellesmere Island are important international heritage sites associated with early exploration in the High Arctic. Fort Conger, built by Adolphus Greely and expedition members during the First International Polar Year in 1881, was dismantled and used by Robert Peary and his expedition crew in the early 1900's to build several smaller shelters. These historic structures remain at the site but are deteriorating. This investigation examines the fungi associated with wood decay in the historic woods. Soft rot was observed in all 125 wood samples obtained from the site. The major taxa found associated with the decayed wood were Coniochaeta (18%), Phoma (13%) Cadophora (12%), Graphium (9%), and Penicillium (9%) as well as many other Ascomycota that are known to cause soft rot in wood. Micromorphological observations using scanning electron microscopy of historic wooden timbers that were in ground contact revealed advanced stages of type I soft rot. No wood destroying Basidiomycota were found. Identification of the fungi associated with decay in these historic woods is a first step to better understand the unusual decomposition processes underway in this extreme environment and will aid future research to help control decay and preserve this important cultural heritage. [ABSTRACT FROM AUTHOR]

Traditional screening of American elm (Ulmus americana) for resistance to Dutch elm disease (DED) often requires many years between initial propagation of trees and inoculation of older trees in the field. Previously published studies have found an association between smaller vessel diameters and increased resistance to DED, but further validation was needed to determine whether it could provide a rapid screening method to identify candidate trees for further testing. This investigation examined xylem characteristics in main stems of three‐year‐old trees for five cultivars and two wild‐type seedling populations of U. americana with varying levels of resistance to DED. Cultivars with low disease severity ratings tended to have smaller vessel diameters and higher vessel densities than cultivars with high disease severity ratings. Xylem characteristics were also assessed in branches and main stems of larger plant material. Data suggest that the use of main stems is preferential to branches when evaluating large trees, as main stems provided more resolution in differentiating between the genotypes. Results from this study indicate that there is potential for the use of xylem characteristics, such as vessel diameter and vessel density, for selecting trees with putative resistance. However, caution should be used due to the potential effects of the environment, such as the effect of water availability and its impacts on xylem development. [ABSTRACT FROM AUTHOR]

Mines and caves are unusual ecosystems containing unique fungi and are greatly understudied compared to other environments. The Soudan Mine in Tower, MN, an iron ore mine that closed in 1963 after operating for 80 years, was sampled to explore fungal diversity and to investigate taxa that tolerate heavy metals for potential bioprocessing technologies or as sources of bioactive molecules for drug discovery and possible biocontrol for white-nose syndrome (WNS) of bats. The mine is 714 m deep, has 18 levels and contains large quantities of wooden timbers, in contrast to many other oligotrophic subterranean environments. Fungi were cultured from samples and the ITS region was sequenced for identification and phylogenetic analysis. Results show Ascomycota are the dominant fungi followed by Basidiomycota and Mucoromycota. Out of 164 identified taxa, 108 belong to the Ascomycota and 26 and 31 to Basidiomycota and Mucoromycota, respectively. There are also 46 taxa that do not match (<97% BLAST GenBank identity) sequenced fungal species. Examples of the most commonly isolated Ascomycota include Scytalidium sp., Mariannaea comptospora, Hypocrea pachybasidioides, Oidiodendron griseum and Pochonia bulbillosa; Basidiomycota include Postia sp., Sistotrema brinkmannii, Calocera sp., Amylocorticiellum sp.; Mucoromycota include Mortierella parvispora, M. gamsii, M. hyaline, M. basiparvispora and Mortierella sp. Unusual growth forms were also found including large quantities of black rhizomorphs of Armillaria sinapina and white mycelial cords of Postia sp. mycelium, as well as Pseudogymnoascus species growing over large areas of mine walls and ceiling. The mine environment is a relatively extreme environment for fungi, with the presence of high levels of heavy metals, complete darkness and poor nutrient availability. Several genera are similar to those isolated in other extreme environments but phylogenetic analyses show differences in species between these environments. Results indicate this subterranean environment hosts a wide diversity of fungi, many of them not found in above ground environments. [ABSTRACT FROM AUTHOR]