Culture-based identification to examine spatiotemporal patterns of fungal communities colonizing wood in ground contact.

Timber durability is often assessed using small wood stakes exposed in direct soil contact, and the assessment generally emphasizes effects on wood rather than organisms involved. Understanding fungal colonization patterns can help identify key decay agents under varying conditions and use these patterns to improve wood protection strategies. Fungal colonization of red alder (Alnus rubra), Douglas-fir (Pseudotsuga menziesii) heartwood/sapwood, and western redcedar (Thuja plicata) field stakes was assessed over 2 y in western Oregon. Spatiotemporal fungal community variations were identified via culturing and DNA sequencing, where 814 isolates were identified from 84 stakes. Forty-six ascomycete genera were identified, with Phialophora, Trichoderma, and Epicoccum species occurring most frequently. Twenty-three basidiomycete genera were identified, with Trametes and Phanerochaete being the most common. Douglas-fir and western redcedar stakes contained the highest and lowest diversity levels, respectively, reflecting natural durability differences of these species. Fungal species abundance was higher below ground than in the above ground and groundline zones, likely reflecting more stable moisture regimes, proximity to soil-based fungi, and potential nutrient migration into wood beneath the soil surface. Ascomycetes were proportionally more abundant early in the exposure period, but basidiomycetes were also observed early in the process, and there appeared to be no consistent colonization pattern.

Physiological and Molecular Characterization of Biosurfactant Producing Endophytic Fungi Xylaria regalis from the Cones of Thuja plicata as a Potent Plant Growth Promoter with Its Potential Application.

Currently, there is an absolute concern for all nations in agricultural productivity to meet growing demands of human population. In recent time, biosurfactants produced by diverse group of microorganisms are used to achieve such demands as it is known for its ecofriendly use in elimination of plant pathogens and for increasing the bioavailability of nutrients for plants. Endophytic fungi are the important source of secondary metabolites and novel bioactive compounds for different biological applications. In the present study, endophytic fungi Xylaria regalis (X. regalis) recovered from the cones of Thuja plicata was evaluated for its biosurfactant producing ability and plant growth-promoting abilities through various screening methods and also via its antagonistic activity against phytopathogens like Fusarium oxysporum and Aspergillus niger. In addition, X. regalis was also tested in vivo for a various range of growth parameters in chilli under greenhouse conditions. Significant increase in shoot and root length, dry matter production of shoot and root, chlorophyll, nitrogen, and phosphorus contents of chilli seedlings was found, which reveals its ability to improve the growth of crop plants. Hence, this study suggests the possibility of biosurfactant producing endophytic fungi X. regalis as a source of novel green biosurfactant for sustainable agriculture to achieve growing demands.

Exploring the symbiont diversity of ancient western redcedars: arbuscular mycorrhizal fungi of long-lived hosts.

Arbuscular mycorrhizal fungi (AMF) are globally distributed, monophyletic root symbionts with ancient origins. Their contribution to carbon cycling and nutrient dynamics is ecologically important, given their obligate association with over 70% of vascular plant species. Current understanding of AMF species richness and community structure is based primarily on studies of grasses, herbs and agricultural crops, typically in disturbed environments. Few studies have considered AMF interactions with long-lived woody perennial species in undisturbed ecosystems. Here we examined AMF communities associated with roots and soils of young, mature and old western redcedar (Thuja plicata) at two sites in the old-growth temperate rainforests of British Columbia. Due to the unique biology of AMF, community richness and structure were assessed using a conservative, clade-based approach. We found 91 AMF OTUs across all samples, with significantly greater AMF richness in the southern site, but no differences in richness along the host chronosequence at either site. All host age classes harboured AMF communities that were overdispersed (more different to each other than expected by chance), with young tree communities most resembling old tree communities. A comparison with similar clade richness data obtained from the literature indicates that western redcedar AMF communities are as rich as those of grasses, tropical trees and palms. Our examination of undisturbed temperate old-growth rainforests suggests that priority effects, rather than succession, are an important aspect of AMF community assembly in this ecosystem.

Fungal and bacterial community succession differs for three wood types during decay in a forest soil.

Wood decomposition by soil microorganisms is vital to carbon and nutrient cycles of forested ecosystems. Different wood types decompose at different rates; however, it is not known if there are differences in microbial community succession associated with the decay of different wood types. In this study, the microbial community associated with the decay of pine (decay-susceptible wood), western red cedar (decay resistant) and ACQ-treated pine (Ammoniacal Copper Quaternary, preservative-treated pine for decay resistance) in forest soil was characterized using DNA sequencing, phospholipid fatty acid (PLFA) analysis, and microbial activity over a 26-month period. Bray-Curtis ordination using an internal transcribed spacer (ITS) sequence and PLFA data indicated that fungal communities changed during succession and that wood type altered the pattern of succession. Nondecay fungi decreased over the 26 months of succession; however, by 18 months of decay, there was a major shift in the fungal communities. By this time, Trametes elegans dominated cedar and Phlebia radiata dominated pine and ACQ-treated pine. The description of PLFA associated with ACQ-treated pine resembled cedar more than pine; however, both PLFA and ITS descriptions indicated that fungal communities associated with ACQ-treated pine were less dynamic, perhaps a result of the inhibition by the ACQ preservative, compared with pine and cedar. Overall, fungal community composition and succession were associated with wood type. Further research into the differences in community composition will help to discern their functional importance to wood decay.

Effects of leaching on fungal growth and decay of western redcedar.

We tested the effect of leaching on the concentration of western red cedar (WRC; Thuja plicata Donn ex D. Don) heartwood extractives that are known to exhibit antimicrobial activity and correlated this with fungal growth and decay. We assessed the extractive tolerance of the following fungal species: Acanthophysium lividocaeruleum, Coniophora puteana, Heterobasidion annosum, Pachnocybe ferruginea, Phellinus sulphurascens, and Phellinus weirii by measuring their growth rate (mm/day) on media with or without WRC leachate. These data were correlated with the ability of the fungal species to grow on and decay leached versus nonleached WRC. We used an ergosterol assay to estimate growth and a standard soil-block test to assess decay. We estimated that leaching reduced the concentration of 5 major extractives: (-)-plicatic acid, beta-thujaplicin, gamma-thujaplicin, beta-thujaplicinol, and thujic acid by approximately 80%. Phellinus sulphurascens exhibited the lowest extractive-tolerance in vitro, grew poorly on and caused minimal decay in nonleached WRC, but it grew well on and decayed pine and leached WRC. Coniophora puteana, H. annosum, and P. weirii displayed moderate to high tolerance to leachate, grew on and caused decay in nonleached as well as leached WRC, but their growth and decay were always greatest on leached WRC and pine, suggesting that leaching enhances decay by these fungi. Acanthophysium lividocaeruleum and Pachnocybe ferruginea exhibited high extractive-tolerance. Whereas A. lividocaeruleum clearly caused decay on all types of wood, no decay was observed with Pachnocybe ferruginea, which grew very slowly in the different wood species, and it may or may not be able to decay wood.

Ineficiência da Thuja occidentalis no tratamento dos poxvirus aviários / Thuja occidentalis ineficiency in avian poxviruses treatment

Medicações à base de Tuia (Thuja occidentalis) são comuns em tratamentos homeopáticos e fitoterápicos, na medicina humana e veterinária. Suas propriedades imunoestimulantes e antivirais são descritas e sua utilização empírica no tratamento das poxviroses aviárias é recomendada por criadores e veterinários. Para avaliar o potencial terapêutico da Tuia sobre estas infecções, dois grupos (controle e teste) de dez aves jovens foram inoculados por escarificação, com uma amostra de campo de poxvírus aviário. As aves inoculadas foram examinadas diariamente, quanto ao início e evolução das lesões, registrando-se o número e tamanho destas, até a cicatrização. Após o surgimento das lesões, o grupo teste recebeu a tintura alcoólica diluída na água de consumo. A análise experimental indicou que, nas condições empregadas, a utilização da Tuia não favoreceu a regressão ou restrição no desenvolvimento das lesões de pele promovidas pela infecção experimental.

Fungal diversity from western redcedar fences and their resistance to beta-thujaplicin.

The work reported here investigated the fungal community inhabiting western redcedar fence material with a focus on species colonizing wood below the surface, of which little is known. From seven pieces of fence material, twenty-three different fungal species were isolated and characterized using both traditional morphology and molecular identification methods. The species identified included thirteen ascomycetous and ten basidiomycetous fungi. Isolates were tested for their resistance to beta-thujaplicin - one of the principle fungicidal agents of western redcedar heartwood extractives. Generally, ascomycetous fungi exhibited greater resistance to beta-thujaplicin than basidiomycetous fungi. Interestingly, three ascomycetous and two basidiomycetous species frequently isolated had high tolerance to this compound. These species could be candidate 'pioneer' species that invade and detoxify western redcedar extractives, paving the way for colonization by decay fungi.

Thuja plicata exclusion in ectomycorrhiza-dominated forests: testing the role of inoculum potential of arbuscular mycorrhizal fungi.

The ability of trees dependent on arbuscular mycorrhizal (AM) fungi to establish in ectomycorrhizal forests is unknown. On northern Vancouver Island, Canada, there are sharp boundaries between mixed red cedar (Thuja plicata)-hemlock (Tsuga heterophylla) (CH) stands, and stands of hemlock and amabilis fir (Abies amabilis) (HA). We tested differences in AM colonization of red cedar between ectomycorrhiza-dominated (HA) stands and stands containing red cedar (CH), across a range of light levels. We used a soil bioassay approach to determine whether there was sufficient AM fungal inoculum in the HA tree stands to colonize red cedar seedlings. Seeds of hemlock and red cedar were sown in forest floor samples collected from the two types of forests, and shade treatments ranging from < 1 to 53% of full sunlight were imposed. After 6 months, seedling survival and root and shoot biomass were quantified, and red cedar seedlings were sampled for AM fungal colonization. Hemlock survival and growth did not differ between soil types, suggesting there was no substrate-associated limitation to its establishment in either forest type. Red cedar colonization by AM fungi was significantly correlated with light levels in CH soils but arbuscular mycorrhizas were absent in roots of red cedar seedlings grown in HA soil. Red cedar survival and relative growth rate were significantly greater in the CH than in HA soil; higher growth was due primarily to greater shoot growth in CH soils at high light levels. The low soil inoculum potential for red cedar in ectomycorrhiza-dominated stands may account for the virtual exclusion of red cedar seedlings from these forests.