Welcome to IMC 2018 International Mycological Congress
Browsing Over 856 Presentations
Designer yeast strains for C1/3/5/6 biorefinery
- S. Han
Heterogeneous structure of lignin imparts plants with structural rigidity and also serves to protect cellulose and hemicellulose from degradation. Thus, prior to fermentative production of ethanol from the cellulose by yeast strains such as Saccharomyces cerevisiae and Pichia pastoris, the materials are degraded and hydrolyzed to release monomeric sugars. In this study, designer cellulosome was assembled in yeast Saccharomyces cerevisiae for utilizing of cellulose as the substrate. For utilizing of cellulose part in lignocellulosic biomass by simultaneous saccharification and fermentation, a recombinant scaffolding protein from Clostridium cellulovorans and a chimeric endoglucanase from Clostridium thermocellum were assembled as complex system. Compared to the results for single subunit, assembly of cellulosome-based enzyme complexes caused a noticeable increase in the level of enzyme activity. The resulting strain was able to ferment cellulose part in pretreated barley straw into ethanol with the aid of beta-glucosidase from C. thermocellum. The use of complexed enzyme systems is one of the strategies for effective lignocellulosic biomass hydrolysis. Enzyme complexes were formed via the interaction of a dockerin domain with cohesin modules in the scaffolding protein. Accelerating the biological degradation of lignocellulosic materials will benefit from the development of useful recombinant enzymes with hydrolysis ability. In future research, construction of designer enzyme complexes containing other lignin degrading enzymes could be used to develop biocatalysts that can completely degrade lignocellulose into single sugars.
Funnelimoris mosseae alters soil fungal community dynamics and composition during litter decomposition
- H. Gui
- W. Purahong
- K. Hyde
- P. Mortimer
Although arbuscular mycorrhizal fungi (AMF) are believed to be non–saprophytic, recent studies have indicated that AMF are able to influence litter decomposition through interacting with the soil fungal community. However, it remains unclear exactly which constituent groups of the soil fungal community respond to AMF during litter decomposition, and in what ways. In order to fill this knowledge gap, we investigated the effect of AMF on soil fungal communities in a subtropical forest in southwestern China. Our experimental set–up included a dual microcosm unit with two treatments: inoculated with AMF (AM) and uninoculated (NM). Destructive soil sampling was carried out at different times (T0, T90, T120, T150 and T180) and Illumina sequencing was used to detect changes in soil fungal community composition. We found that the composition and operational taxonomic unit richness of the fungal community, at higher taxonomical levels (e.g. phyla, order), remained stable across treatments. However, the relative abundance of some key genera including Mycena, Glomerella, Pholiotina, and Sistotrema were significantly affected by AMF inoculation. Soil fungal community structure was also significantly altered by AMF inoculation during the later stages of litter decomposition, but the diversity of the soil fungal community was unaffected. Our study provides new insight into understanding the interaction between AMF and soil fungal communities during litter decomposition.
Multiple lines of evidence suggest alternative hosts are involved in the development of Cercospora Leaf Blight of soybean in Louisiana
- V. Doyle
- Z. Carver
- P. Price
Recent phylogenetic studies have changed our understanding of the diversity of Cercospora species associated with Cercospora leaf blight (CLB) and Purple seed stain (PSS) of soybean. Cercospora kikuchii has long been considered the causal agent of CLB and PSS, but we now recognize a composite of species are associated with the disease. These studies suggest most of the species associated with CLB and PSS are not host specific, in contrast to our current understanding of C. kikuchii. Given the limited host range of C. kikuchii, the frequently observed uniformity of disease symptoms in the field, and the fact that the pathogen is seed borne, it has been assumed that the primary source of inoculum for the disease is soybean seed. However, this assumption needs to be revisited in light of the diverse host preferences of C. cf. flagellaris and C. cf. sigesbeckiae, two of the predominant species associated with CLB and PSS. The aim of our current work is to determine the principal sources of inoculum of CLB and PSS through field trials and molecular ecology/epidemiology. We examined the role of seed borne inoculum by eliminating all microbes from the seed prior to planting and monitoring disease incidence and severity over the course of two field seasons. We also characterized the diversity of Cercospora species on soybean seed prior to planting, from blighted leaves, and from harvested seed to examine changes in the composition of the Cercospora community over the course of a season. Finally, we looked for direct evidence of gene flow between alternative hosts both proximate to and distant from agricultural fields. Despite eliminating all microbes from the soybean seed prior to planting, we did not observe a reduction in disease incidence or severity at two different sites in Louisiana over two field seasons, consistent with planted seed not being the primary source of inoculum. We also found that the composition of Cercospora species present in the community at the time of planting (seed) significantly differs from that responsible for leaf blight and seed stain at the time of harvest. In the first season, regardless of the frequency of each of C. kikuchii, C. cf. sigesbeckiae, and C. cf. flagellaris on seed at the time of planting, C. cf. flagellaris dominates the community on blighted leaves and harvested seed. This shift in the community over the course of the field season also indicates seed is not the primary source of inoculum. We are currently working on replicating this study with collections from a second field season. Finally, genotype data of C. cf. flagellaris (n=72) and C. cf. sigesbeckiae (n=14) at 19,670 SNP loci indicate ongoing gene flow between alternative hosts proximate to agricultural areas and those on soybean. However, the lack of differentiation among isolates from seed in distant geographical areas coupled with significant differentiation among agricultural and non-agricultural populations (alternative hosts), suggests the movement of seed has historically been a significant source of inoculum in soybean fields.
Climate change effect on ochratoxin A production and gene expression in Aspergillus carbonarius
- G. Perrone
- A. Gallo
- L. Piemontese
- D. Magistà
- M. Solfrizzo
- C. Cervini
AbstractOchratoxin A (OTA) is a potent pentaketide nephrotoxin diffusely distributed in food and feed products (grains, legumes, coffee, dried fruits, meat derived products, beer and wine); it is also carcinogenic, neurotoxic, teratogenic and immunotoxic. This mycotoxin is produced by species belonging to the genus Aspergillus and Penicillium. OTA is the primary mycotoxin risk in wine and dried vine fruits, its maximum level is regulated by law. Several studies focused on Aspergillus section Nigri, due to their role as causative agents of black rot of grapes, and subsequently as cause of ochratoxin A contamination. In particular, Aspergillus carbonarius has been identified as the major cause of contamination in grape berries. This contamination is strongly related to climatic conditions, geographical regions, grape varieties, damage by insects, growing season; in particular great variations may occur from one year to another. So, climate represents an important key-factor in the agro-ecosystem, influencing fungal colonization and ochratoxin A production in grapes. Climate change is expected to have a profound effect on our landscape worldwide, and also to have an important impact on sustainable food production system. Recent studies have reported how the climate change may affect mycotoxins production in the fields and the relevant risk on economically important crops.
In this regard, the interacting effect of water stress (aw 0.99-0.93) and different day/night climate conditions simulating nowadays (18-31 and 15-28°C) and climate change scenarios (18-34 and 20-37 °C) in high OTA risk area of southern Italy during the ripening season, were studied. Mycelial growth rate, OTA production and molecular expression of key genes (PKS, NRPS, Hal, p450, bZIP) of OTA biosynthetic cluster by A. carbonarius ITEM 5010 were measured. Our results showed that, in water stress conditions (0.93 aw), no OTA production was observed and, except at 20-37°C, the growth rate was slower compared to 0.99 aw. A significantly higher amount of OTA was observed at 0.99 aw and 18-34°C climate change scenario. Gene expression, monitored by quantitative real time RT-PCR, gave evidence of the high expression levels of OTA biosynthetic genes in this condition, in particular NRPS and Hal genes were strongly expressed. These preliminary and new results on A. carbonarius in a climate change scenario suggest that a possible slight increase of temperature may lead to higher OTA contamination and to a possible expansion of the risk area in the Mediterranean basin.
Effects of prescribed burning on wood-decay fungi in the forests of northwest Arkansas
- N. Alshammari
Prescribed burning is a widely used management technique in the forests of Northwest Arkansas, but it is not known to what extent it can affect the biodiversity of wood-decay fungi. The present study was carried out to characterize the different species of wood-decay fungi present in burned (BPR) and unburned (UPR) areas of Pea Ridge National Military Park (PRMP) and an unburned area of Devil’s Den state park (DDP). In order to do this, we extracted genomic DNA from 140 specimens of wood-decay fungi collected from these three study areas. This was done using the Promega DNA isolation kit. The Internal transcribed Spacer (ITS) region of fungal ribosomal DNA was amplified using ITS1 and ITS4 primers and sent for Sanger sequencing after quality checking of amplicons by means of 1% agarose gel electrophoresis. Altogether, 110 out of 140 sequences that passed quality checking were further used for identification of species of fungi by nucleotide BLAST searching against the NCBI database. From all study areas, 61 different species of fungi species were identified, with 30, 23, and 28 different species present on DDP, UPR, and BPR, respectively. Only six species were common between the two forests areas (PRMP and DDP) and only four between BPR and UPR of PRMP, indicating that an appreciable difference appears to exist for burned and unburned areas. The relative abundance of Stereum ostrea voucher She2067 was highest in BPR (24%) as compared to the other study areas (UPR, 17% and DDP, 3%). The present study is ongoing and will be continued during the 2018 field season.
Effects of arbuscular mycorrhizal fungi on growth of Medicago sativa in acidic soil
- F. Li
- Y. Li
- T. Duan
Acidic soils are harsh environments for plants. Arbuscular mycorrhizal (AM) fungi play an important role in protecting plant growth against such stresses as acidic soil. To understands the relationship between AM fungi colonisation and soil acidity to evaluate the possibility that AM fungi facilitate the existence of plants on acidic soils, the effects of arbuscular mycorrhizal (AM) fungi Claroideoglomus etunicatum, Rhizophagus intraradices and the mix of the two AM fungi on the growth of alfalfa (Medicago sativa) were assessed at three of soil pH by growing plants in a greenhouse experiments, with and without AM fungi inoculation, individually in pots. The different acid growth medium were established with H2SO4 to pH 3.0, 5.0 and 6.58. The results showed that the C. etunicatum, R.intraradices individual and the mix of the two AMF increased plants dry weight and P uptake at all acid treatments compared with un-inoculation of AM fungi treatment (P<0.05). Plants shoot height, leaf numbers, shoot dry weight, root dry weight and total dry weight were averagely increased by 214.77%, 312.67%, 105.39%, 95.46% and 101.85%, respectively by the mix of two AMF compared with un-inoculated treatments. Acid decreased the total dry weight, chlorophyll content, superoxide dismutase (SOD) and peroxidase (POD) activity, of which the above mentioned index were 17.59%, 21.94%, 29.51% and 51.26% lower at pH 3 than that at pH 6.58. The inoculation of AM fungi averagely increased SOD and POD activity of plant by 108.7% and 49.68%, respectively, and decreased malondialdehyde (MDA) of plants dramatically compared to un-inoculated plants (P<0.05).
A twenty-year morphological and molecular study of macrofungi in the driftless (unglaciated) region of southwestern Wisconsin, USA.
- S. Aspenson
- T. Osmundson
- T. Volk
Southwestern Wisconsin was unaffected by the glacial drifts that ended some 10,000 years ago, and is now referred to as the driftless area. This area is known for the forested hillsides of limestone-based soils with deep valleys called coulees. These ridges and coulees centered on the Mississippi River offer relicts of forests, prairies, wetlands and grasslands that house a diverse array of organisms. A 20-year survey of fruiting bodies of three older growth forests found approximately 1200 species of macrofungi that include some species with disjunct geographical distributions. Previous graduate students as well as students from the UW-La Crosse Mycology class have been making these collections every year on a three-week rotation. At least 500 students and visitors from three mycological forays have been involved in these collecting efforts. Despite their physical proximity, it is surprising that the total overlap within the three sites is just 303/1200 species (~25%). Some Appalachian relict species have been collected (e.g. Boletus frostii and Ciboria americana), as well as unusually high population densities of some fungi considered to be rare elsewhere (eg. Phlebia coccineofulva). Preliminary data from groundwork DNA sequencing suggest that, because of its isolation, the driftless area may also be home to cryptic species of fungi. In our study, all 1800 specimens of nearly 1200 morphological species from the three study sites are being sequenced, using the ITS region as the primary region of interest. Primers with reference tags are added to the specimens DNA, with different tags on both the forward and reverse strands. These tags allow the delineation of species after the samples are sequenced through Illumina sequencing. Having both morphological and sequence identification will allow for the better understanding of fungi associated with this area, along with confirmation of the species already identified by morphology. These data will also allow for comparisons of geographical regions and revelations of cryptic species. This study is novel because of the large number of specimens and species involved, as well as the length of time (20 years) over which the collections were made.
The influence of fungicides on the grapevine wood mycobiome: a case study on tracheomycotic ascomycete Phaeomoniella chlamydospora
- G. Del Frari
- A. Gobbi
- P. Talhinhas
- H. Oliveira
- L. Hestbjerg Hansen
- R. Boavida Ferreira
Grapevine trunk diseases are the major threat to viticulture of our days. They affect the perennial organs of grapevines (Vitis spp.) causing decline, loss in quantity and quality of yield, and early death of the plants, resulting in enormous costs for the industry. Phaeomoniella chlamydospora is a tracheomycotic ascomycete which colonizes the xylem of grapevines causing wood discoloration and necrosis, plant decline, and it is believed to be indirectly responsible for other symptoms as well. Phaeomoniella chlamydospora is associated mainly with four syndromes of grapevines: brown wood streaking of rooted cuttings, Petri disease, grapevine leaf stripe disease and esca proper. The incidence of these syndromes in vineyards has greatly increased over the last 20-30 years and the most puzzling question remains – why has P. chlamydospora become so successful? This work aimed to answer this question by formulating the hypothesis that fungicides commonly used in vineyards to control downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necator) interact with the wood mycobiome causing a change in its composition, which may favor the wood colonization by P. chlamydospora. To test this hypothesis, we worked on one-year old rooted cuttings of 'Cabernet Sauvignon', under greenhouse conditions. Grapevines were inoculated with either a spore suspension of P. chlamydorpora (strain CBS 161.90), with an artificial mycobiome or with a combination of both, and treated with three combinations of fungicides and a control. We used metabarcoding (Illumina sequencing) with two sets of universal primers (ITS1F2F/ITS2R and ITS86F/ITS4R) in order to understand the changes that the wood mycobiome incurs due to the application of fungicides and Real-Time PCR to quantify the abundance of P. chlamydospora. Our results show that the application of different fungicides changes the relative abundance of several fungal species in the grapevine wood, including that of P. chlamydospora. The colonization of the wood by this ascomycete is also greatly reduced when co-inoculated with the artificial mycobiome. Sequencing results are partially supported by quantitative analyses. This study demonstrates that fungicides applied as foliar sprays can indirectly interfere with the fungal communities in the grapevine wood giving an advantage to some communities over others, allowing speculations on the role that this changes play in triggering disease mechanisms.
Thyriothecial fungi and fossil evidence of Dothideomycetes
- L. Le Renard
- M. Berbee
- R. Stockey
Critical reinterpretations of morphological characters in fossil fungi have the potential to improve estimates of the geological timing of fungal radiations. Some of the best fungal fossils are thyriothecia. A thyriothecium is a minute ascomatal type, with a flat scutellum, a shield-like upper surface, with a distinctive cell pattern that is formed by a sequence of hyphal branching and septation. The fossil record rarely provides diagnostic characters such as asci but the diversity of fossil scutella offers great potential to calibrate ages of extant fungal lineages. However, both DNA sequence data for genera of thyriothecia-forming fungi and illustrations of scutella remain sparse in public databases. We present an updated phylogeny of thyriothecial Dothideomycetes based on 4251 positions for 320 taxa, contributing new LSU and SSU rDNA sequence data for 14 thyriothecial fungi. We define thyriothecia as flattened, superficial ascomata lacking a differentiated lower wall, with varied scutellum patterns, many, but not all, radiate. We coded character states for taxa including 60 thyriothecial species and then estimated ancestral character states over the Bayesian posterior distribution of topologies from our dataset to account for the phylogenetic uncertainty. Radiate thyriothecia were only found in Class Dothideomycetes, where they seem to have evolved independently at least five times. Clades containing thyriothecia are mostly folicolous and caulicolous, and it remains unclear whether these ascomata were derived from perithecioid or apothecioid ancestors. Genera traditionally recognized in the order Asterinales were polyphyletic and formed two independent clades (Asterinales and Asterotexiales). Morphological distinction between thyriothecia of these orders was impossible because they share a combination of scutellum and mycelium characters. In contrast, the most typical members of Microthyriales and Aulographaceae were readily recognizable from the organization of cells at their scutellum margins, patterns of septation and branching of the scutellum hyphae. We used our newly defined characters to interpret published fossil thyriothecia. We show which of the lineages now sampled for DNA are represented in the fossil record of fungi and present potential Dothideomycetes calibration points available in fossil occurrences of thyriothecia. A phylogenetically congruent distribution of character states among modern thyriothecial clades will help to improve interpretation of fossil material, and will increase the precision of Ascomycota age estimates.
Analysis of coral-associated fungal and microbial communities in Fiji using high throughput amplicon sequencing
- R. Longley
- O. Alian
- G. Bennucci
- X. Pochon
- V. Bonito
- G. Bonito
Coral reefs are biological hot-spots on Earth and provide important habitats for a wide variety of marine species. For this reason, sections of many reefs have been the targets of conservation projects that aim to protect coral and other species that make up the reef ecosystem. Microbial communities make up an integral part of a healthy reef ecosystem, and therefore must be considered when assessing the success of conservation efforts. To this end, corals were sampled from four different genera: Porites, Montipora, Acropora, and Sinularia. Sampling occurred in two adjacent shallow reef areas: 1) a no-take marine protected area with relatively low disturbance, and 2) a fished area with relatively high disturbance from fishing pressure and watershed discharge. These samples were then analyzed for communities of Fungi, Bacteria, and the endosymbiotic dinoflagellate, Symbiodinium. Microbial communities were targeted using primers specific to the Fungal ITS-1 region, the Bacterial 16s region, and the Symbiodinium ITS-2 rDNA region. Amplicons from these primers were then tagged with barcodes and pooled into libraries for sequencing on an Illumina’ Miseq platform. Sequence data were then run through a non-biased bioinformatic pipeline and the unoise algorithim in usearch to cluster OTUs for each group by a single nucleotide difference in sequence. The initial analysis on the entire sample set for Fungi recovered a broad diversity of species dominated by Ascomycota (65%) and Basidiomycota (33%). The Ascomycetes were dominated by Cladosporiaceae (15%) and Aspergillacea (10%); while the Basidiomycetes were predominantly Malasseziaceae (45%) and Nectriaceae (15%). The bacterial communities were predominantly Cyanobacteria (51%), Proteobacteria (37%), and Bacteroidetes (8%). Within the bacterial communities, the Cyanobacteria were dominated by Ulvophyceae (84%), Proteobacteria were dominated by Endozoicimonaceae (36%), Bacteroidetes were most highly represented by Chitinophagacae (30%). Symbiodinium communities were dominated by clade C (96%), but clades D (3%), as well as A and G were also present at low levels. This preliminary data on the sample set shows diverse microbial communities and lays the framework for comparing the microbiomes of corals in protected and unprotected areas.
Regional variation of endophyte community diversity in Dalea purpurea (purple prairie-clover)
- M. Demers
- G. May
Fungal endophytes are found living asymptomatically in the tissues of most plants, and some endophytes may provide benefits to their hosts. The factors affecting the assembly of endophyte communities are not well understood, since the results of current studies differ regarding the relative importance of host species and genotype, abiotic factors, and random sampling of inocula from the environment. To understand the ecological factors affecting the diversity and taxonomic composition of endophyte communities, we sampled foliar endophytes from sixteen populations of purple prairie-clover (Dalea purpurea) in remnant prairies in four regions in Minnesota: northwest, west-central, southwest and southeast. We compared the beta diversity among these communities and found strong clustering in the northwest compared the other regions, indicating that the northwest communities were more similar in composition to each other than to other sites. The genetic results are consistent with our observations of morphological traits such as pigmentation because cultures sampled from the northwest were consistently more similar than cultures sampled from other regions. Since distances between sites in the northwest are comparable to or greater than distances between sites within other regions, abiotic conditions particular to these northwest sites may be responsible for the similarity of their endophyte communities.
Cleaning a multinuclear single cell during fruiting body formation of myxomycetes
- Y. Yajima
Myxomycetes (true slime molds) have a multinuclear single cell stage, plasmodium, which makes fruiting bodies containing numerous myxomycete spores. It has been fragmentary reported that degradation of cellular comportments such as organelle degeneration and deterioration of a layer of peripheral cytoplasm during fruiting body formation. The possible roles of such degradations in the life cycle of myxomycetes also have been barely discussed, however, the risk of its insufficiency has not been emphasized. For cellular integrity, it is critical to clean the cell of damaged organelles, aggregated proteins and invaders. The objective of this study is to determine how a single cell itself cleans up own used/aged cell components to generate pre-gamete cells, i.e., myxomycete spores. Sequential steps of cell cleaning behavior in myxomycete fruiting body formation analysed by two- and three-dimensional imaging. Organelle clearances especially on nucleus were observed with broad visual field and electron microscopic 2D/3D. DNA fragmentation was examined with cryo-fixed cell. Cleaning process during fruiting body formation were different among species, and the relation with construction of fruiting body structures was observed. DNA fragmentation was detected in multiple nuclei, and its distribution in a single cell differed in the stages of fruiting body formation. The selection of reduction processes in the number of nuclei was also depended on the stages. The results suggested that a myxomycete cell behave sensibly during the fruiting body formation, and cleans up own single cell without rupture or complete cell death.