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Papers by Daniel Durall

Temporal allocation of 14C to extramatrical hyphae of ectomycorrhizal ponderosa pine seedlings

Tree Physiology, Jun 1, 1989

Ponderosa pine seedlings were inoculated with Hebeloma crustuliniforme either in growth pouches b... more Ponderosa pine seedlings were inoculated with Hebeloma crustuliniforme either in growth pouches before they were transplanted to root-mycocosms (P seedlings), or at the time of transfer to root-mycocosms (V seedlings). Uninoculated seedlings served as controls (U seedlings). The use of root-mycocosms allowed examination of portions of hyphae separate from roots and rooting substrate but still in symbiosis with the host. The results thus provided a quantitative basis for estimating hyphal mass and carbon allocation to extramatrical hyphae. The amount of (14)CO(2) fixed after a 2-h exposure was greatest for P seedlings and least for uninoculated seedlings. Four and nine days after exposure, (14)C content was greatest in uninoculated seedlings and least in inoculated seedlings. In isotope distribution and dry mass accumulation, V seedlings were more similar to U than to P seedlings. Calculated on a dry weight basis, the allocation of isotope to mycelium suggested that extramatrical hyphae of P seedlings were a stronger sink for carbon than extramatrical hyphae of V seedlings. Differences in inoculation methods resulted in differences in carbon allocation and physiology of extramatrical hyphae that could affect seedling establishment and survival. Seedlings inoculated by one method cannot serve as surrogates for mycorrhizal seedlings produced by other inoculation techniques.

Agriculture, Ecosystems & Environment, 1990

Topology of tree-mycorrhizal fungus interaction networks in xeric and mesic Douglas-fir forests

Journal of Ecology, Mar 9, 2015

Summary From the phytocentric perspective, a mycorrhizal network (MN) is formed when the roots of... more Summary From the phytocentric perspective, a mycorrhizal network (MN) is formed when the roots of two or more plants are colonized by the same fungal genet. MNs can be modelled as interaction networks with plants as nodes and fungal genets as links. The potential effects of MNs on facilitation or competition between plants are increasingly recognized, but their network topologies remain largely unknown. This information is needed to understand the ecological significance of MN functional traits. The objectives of this study were to describe the interaction network topologies of MNs formed between two ectomycorrhizal fungal species, Rhizopogon vesiculosus and R. vinicolor, and interior Douglas‐fir trees at the forest stand scale, identify factors leading to this structure and to contrast MN structures between forest plots with xeric versus mesic soil moisture regimes. Tuberculate mycorrhizas were sampled in six 10 × 10 m plots with either xeric or mesic soil moisture regimes. Microsatellite DNA markers were used to identify tree and fungal genotypes isolated from mycorrhizas and for comparison with reference tree boles above‐ground. In all six plots, trees and fungal genets were highly interconnected. Size asymmetries between different tree cohorts led to non‐random MN topologies, while differences in size and connectivity between Rhizopogon species‐specific subnetwork components contributed towards MN nestedness. Large mature trees acted as network hubs with a significantly higher node degree compared to smaller trees. MNs representing trees linked by R. vinicolor genets were mostly nested within larger, more highly connected R. vesiculosus‐linked MNs. Attributes of network nodes showed that hub trees were more important to MN topology on xeric than mesic sites, but the emergent structures of MNs were similar in the two soil moisture regimes. Synthesis. This study suggests MNs formed between interior Douglas‐fir trees and R. vesiculosus and R. vinicolor genets are resilient to the random loss of participants, and to soil water stress, but may be susceptible to the loss of large trees or fungal genets. Our results regarding the topology of MNs contribute to the understanding of forest stand dynamics and the resilience of forests to stress or disturbance.

Dominance of a Rhizopogon sister species corresponds to forest age structure

Mycorrhiza, Aug 13, 2015

Rhizopogon vesiculosus and Rhizopogon vinicolor are sister species of ectomycorrhizal fungi that ... more Rhizopogon vesiculosus and Rhizopogon vinicolor are sister species of ectomycorrhizal fungi that associate exclusively with Douglas-fir (DF). They form tuberculate mycorrhizas and they can be easily distinguished using molecular tools. We are not aware of studies relating their relative abundance in forests with different age classes. Our objective was to determine whether a change in the number or relative abundance of R. vesiculosus and R. vinicolor tubercules and genotypes was related to a change in the percent of DF in a regenerating phase (&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;50 years old). R. vesiculosus and R. vinicolor were located by excavating tuberculate mycorrhizas from the forest floor. A DNA Alu1 digest was used to distinguish between the two species. Microsatellite markers were used to identify genotypes. The number of R. vesiculosus tubercules correlated positively with an increasing proportion of DF in a regenerating phase, while the number of R. vinicolor tubercules was similar across all forest age structures. The number of R. vesiculosus genotypes did not correlate with forest age structure, whereas the number of R. vinicolor genotypes showed a negative relationship with an increasing proportion of DF in a regenerating phase. When the numbers of R. vesiculosus tubercules and genotypes were expressed as a relative abundance of the two species, there was a positive correlation with an increasing proportion of DF in a regenerating phase for both genotypes and tubercules. Our results suggest that the degree of DF regeneration or ecosystem factors related to DF regeneration affect the population dynamics of R. vesiculosus and R. vinicolor differently.

New Phytologist, Oct 29, 2009

• The role of mycorrhizal networks in forest dynamics is poorly understood because of the elusive... more • The role of mycorrhizal networks in forest dynamics is poorly understood because of the elusiveness of their spatial structure. We mapped the belowground distribution of the fungi Rhizopogon vesiculosus and Rhizopogon vinicolor and interior Douglas-fir trees (Pseudotsuga menziesii var. glauca) to determine the architecture of a mycorrhizal network in a multi-aged old-growth forest. • Rhizopogon spp. mycorrhizas were collected within a 30 • 30 m plot. Trees and fungal genets were identified using multi-locus microsatellite DNA analysis. Tree genotypes from mycorrhizas were matched to reference trees aboveground. Two trees were considered linked if they shared the same fungal genet(s). • The two Rhizopogon species each formed 13-14 genets, each colonizing up to 19 trees in the plot. Rhizopogon vesiculosus genets were larger, occurred at greater depths, and linked more trees than genets of R. vinicolor. Multiple tree cohorts were linked, with young saplings established within the mycorrhizal network of Douglas-fir veterans. A strong positive relationship was found between tree size and connectivity, resulting in a scale-free network architecture with smallworld properties. • This mycorrhizal network architecture suggests an efficient and robust network, where large trees play a foundational role in facilitating conspecific regeneration and stabilizing the ecosystem.

Fermentation: How sulfur dioxide addition at crush can affect wine yeasts, bacteria and sensory attributes

Wine and viticulture journal, Dec 1, 2019

Functional Ecology, Mar 19, 2010

indicates that a substantial simplification of the fungal community through other perturbations, ... more indicates that a substantial simplification of the fungal community through other perturbations, as expected with climate change, has the potential to affect ecosystem function.

Research Square (Research Square), Jan 4, 2021

Scientific Reports, Nov 10, 2014

Vertical partitioning between sister species ofRhizopogonfungi on mesic and xeric sites in an interior Douglas-fir forest

Molecular Ecology, Oct 25, 2012

Understanding ectomycorrhizal fungal (EMF) community structure is limited by a lack of taxonomic ... more Understanding ectomycorrhizal fungal (EMF) community structure is limited by a lack of taxonomic resolution and autecological information. Rhizopogon vesiculosus and Rhizopogon vinicolor (Basidiomycota) are morphologically and genetically related species. They are dominant members of interior Douglas-fir (Pseudotsuga menziesii var. glauca) EMF communities, but mechanisms leading to their coexistence are unknown. We investigated the microsite associations and foraging strategy of individual R. vesiculosus and R. vinicolor genets. Mycelia spatial patterns, pervasiveness and root colonization patterns of fungal genets were compared between Rhizopogon species and between xeric and mesic soil moisture regimes. Rhizopogon spp. mycelia were systematically excavated from the soil and identified using microsatellite DNA markers. Rhizopogon vesiculosus mycelia occurred at greater depth, were more spatially pervasive, and colonized more tree roots than R. vinicolor mycelia. Both species were frequently encountered in organic layers and between the interface of organic and mineral horizons. They were particularly abundant within microsites associated with soil moisture retention. The occurrence of R. vesiculosus shifted in the presence of R. vinicolor towards mineral soil horizons, where R. vinicolor was mostly absent. This suggests that competition and foraging strategy may contribute towards the vertical partitioning observed between these species. Rhizopogon vesiculosus and R. vinicolor mycelia systems occurred at greater mean depths and were more pervasive in mesic plots compared with xeric plots. The spatial continuity and number of trees colonized by genets of each species did not significantly differ between soil moisture regimes.

International Journal of Food Microbiology, Oct 1, 2016

Culture-independent methods of microbial identification have been developed, which allow for DNA ... more Culture-independent methods of microbial identification have been developed, which allow for DNA extraction directly from environmental samples without subjecting microbes to growth on nutrient media. These methods often involve next generation DNA sequencing (NGS) for identifying microbes and qPCR for quantifying them. Despite the benefits of extracting all DNA from the sample, results may be compromised by amplifying DNA from dead cells. To address this shortcoming , the use of propidium monoazide (PMA) has been used to deactivate DNA in non-viable cells. Nevertheless, its optimization has not been fully explored under a variety of conditions. In this study, we optimized the PMA method for both yeasts and bacteria. Specifically, we explored the effect different PMA concentrations and different cell densities had on DNA amplification (as part of next generation DNA sequencing) from both dead and viable bacterial and yeast cells. We found PMA was effective in eliminating DNA that was associated with dead yeast and bacterial cells for all cell concentrations. Nevertheless, DNA (extracted from viable yeast and bacterial cells) amplified most abundantly when PMA concentration was at 6 μM and when yeast densities ranged between 10 6 to 10 7 CFU/mL and bacterial densities were approximately 10 8 CFU/mL.

Role of mycorrhizal networks and tree proximity in ectomycorrhizal colonization of planted seedlings

Fungal Ecology, Feb 1, 2009

The importance of mycorrhizal network (MN)-mediated colonization under field conditions between t... more The importance of mycorrhizal network (MN)-mediated colonization under field conditions between trees and seedlings was investigated. We also determined the combined influences of inoculum source and distance from trees on the ectomycorrhizal (EM) community of seedlings. On six sites, we established trenched plots around 24 residual Pseudotsuga menziesii var. glauca trees and then planted seedlings at four distances (0.5, 1.0,

Phosphorus relationships and production of extrametrical hyphae by two types of willow ectomycorrhizas at different soil phosphorus levels

New Phytologist, Jun 1, 1990

summaryThere is much circumstantial evidence for a role of increased P uptake in the growth respo... more summaryThere is much circumstantial evidence for a role of increased P uptake in the growth response of plants to ectomycorrhizas. Full response curves with and without mycorrhizal infection along a P gradient in soil are, however, required to test this hypothesis fully. In this experiment, rooted cuttings of Salix viminalis L. cv. Bowles Hybrid were grown in a 1:2 mixture by volume of gamma‐irradiated soil and sterile sand, with bicarbonate‐extractable P concentrations of 4, 6, 10, 21, 60 or 90 mg P kg−1. The cuttings were inoculated by mixing peat/vermiculite spawn of Laccaria proxima (Boud.) Pat., or Thelephora terrestris (Ehrh.) Fr., or autoclaved spawn 1: 5 by volume with the soil: sand mixture. The plants showed a positive growth response to mycorrhizal infection by either fungus at the two lower P levels, and to L. proxima only at 10 mg P kg−1. At 21 mg kg−1and above, infection was reduced and neither mycorrhizal inoculation nor further P additions caused significant growth increases. These results imply that the growth responses to ectomycorrhizas in this experiment were solely due to increases in P uptake. Cuttings infected with L. proxima tended to be larger than those infected by T. terrestris. Estimates of percent mycorrhizal infection did not differ between the fungi at the lower P levels. However, overall production of extramatrical hyphae per gram of soil was highest in soil inoculated with L. proxima. At 10 mg P kg−1the length of L. proxima hyphae per unit length of mycorrhizal root, P uptake per unit root weight, and total P content in plants infected with L. proxima were significantly higher than for T. terrestris. This study confirms that increased P uptake can be an important component of growth stimulation by ectomycorrhizas. It also presents the first quantification of extramatrical ectomycorrhizal hyphae in soil and suggests a role for them in the growth response.

New Phytologist, Sep 1, 1998

 Eucalyptus coccifera Hook., a plant capable of forming both arbuscular mycorrhizas and ec... more  Eucalyptus coccifera Hook., a plant capable of forming both arbuscular mycorrhizas and ectomycorrhizas, was used to compare the effects of the two mycorrhizal types on phosphorus uptake and C allocation. Seedlings were grown in a P-deficient soil\sand mixture inoculated with peat\vermiculite spawn of Laccaria bicolor (Maire) Orton or Thelephora terrestris (Ehrh.) Fr. ; or with 250-µm sievings from leek colonized by Glomus caledonium (Nicol. & Gerd.) Trappe & Gerde., Glomus sp. type E3 or Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe or with autoclaved spawn (non-mycorrhizal control). Before the 89-d harvest, a subset of the harvested plants was labelled with "%C (45-60-min pulse, 202-h chase). Growth promotion and the increase in seedling P content was largest in the two ectomycorrhizal treatments. Production of fluorescein diacetate-stained external hyphae was three to seven times higher by ectomycorrhizal (ECM) fungi compared with arbuscular mycorrhizal (AM) fungi and was highly correlated with P uptake and shoot weight. Phosphorus inflow rates of ECM and AM seedlings were 3n8 times, and 2n0-2n7 times those of non-mycorrhizal seedlings. Phosphorus acquisition efficiencies were similar (11n2 and 10n0 µmol P mmol −" C for T. terrestris and Glomus E3 plants, respectively) for the two mycorrhizal types, and appeared to be greater than in uninoculated plants (7.2 µmol P mmol −" C) grown at the same P level.

OENO One, Jul 27, 2021

Each wine growing region hosts unique communities of indigenous yeast species, which may enter fe... more Each wine growing region hosts unique communities of indigenous yeast species, which may enter fermentation and contribute to the final flavour profile of wines. One of these species, Saccharomyces uvarum, is typically described as a cryotolerant yeast that produces relatively high levels of glycerol and rose-scented volatile compounds as compared with Saccharomyces cerevisiae, the main yeast in winemaking. Comparisons of fermentative and chemical properties between S. uvarum and S. cerevisiae at the species level are relatively common; however, a paucity of information has been collected on the potential variability present among S. uvarum strains. The objective of this study was to compare the fermentation kinetics and production of volatile compounds between indigenous and commercial Saccharomyces strains at different temperatures. We compared laboratory-scale fermentation of Chardonnay juice at 15 °C and 25 °C for 11 Saccharomyces yeast strains (six indigenous S. uvarum, one commercial S. uvarum, one indigenous S. cerevisiae and three commercial S. cerevisiae). Fermentation kinetics and the production of volatile compounds known to affect the organoleptic properties of wine were determined. The indigenous S. uvarum strains showed comparable kinetics to commercially sourced strains at both temperatures. Volatile compound production among the strains was more variable at 15 °C and resulted in unique chemical profiles at 15 °C as compared with 25 °C. Indigenous S. uvarum strains produced relatively high levels of 2-phenylethyl acetate and 2-phenylethanol, whereas these compounds were found at much lower levels in fermentations conducted by commercial strains of both S. cerevisiae and S. uvarum. Production of glycerol by indigenous S. uvarum strains did not differ from commercial strains in this study. Our findings demonstrate that indigenous strains of S. uvarum show functional variation among themselves. However, when compared with commercial S. cerevisiae and S. uvarum strains, they have comparable fermentation kinetics but unique volatile compound profiles, especially at low fermentation temperatures.

Ectomycorrhizal diversity on Betula papyrifera and Pseudotsuga menziesii seedlings grown in the greenhouse or outplanted in single-species and mixed plots in southern British Columbia

Canadian Journal of Forest Research, 1997

ABSTRACT

Canadian Journal of Forest Research, 1999

The mycelium extending from ectomycorrhizal fine roots is thought to be an important inoculum sou... more The mycelium extending from ectomycorrhizal fine roots is thought to be an important inoculum source for outplanted seedlings. The purpose of this study, carried out at a subalpine forest in British Columbia, was to investigate the effect of three different clear-cut sizes: 0.1, 1.0, and 10 ha, on the persistence and diversity of ectomycorrhizae. Over the course of the study, a total of 39 distinct mycorrhizal types were observed. The dominant types matched descriptions of E-strain mycorrhizae and of mycorrhizae formed by Cenococcum spp., two types of Lactarius spp., Piloderma spp., Hebeloma spp., Amphinema spp., and Cortinarius spp. One growing season after tree removal, there were no differences between the treatments in the numbers of active fine roots at any location nor were there any effects on the diversity of ectomycorrhizae with treatment. Two and three growing seasons after logging the persistence of some of the main morphotypes differed with treatment. Although there were no differences in the diversity indices at corresponding distances within the different opening sizes, after two and three growing seasons the numbers of active fine roots as well as the diversity of ectomycorrhizae in clearcuts was significantly reduced with distance from the forest edge. Résumé : Le mycélium qui irradie des racines fines mycorhizées serait une importante source d'inoculum pour les semis plantés. Le but de cette étude, menée dans une forêt subalpine de la Colombie Britannique, consistait à étudier l'effet de trois dimensions de coupe à blanc : 0,1, 1,0 et 10 ha, sur la persistance et la diversité des ectomycorhizes. Un total de 39 types différents de mycorhizes ont été observés au cours de cette étude. Les types dominants correspondaient à la description des mycorhizes de souche E et des mycorhizes formés par Cenococcum spp., deux types de Lactarius spp., Piloderma spp., Hebeloma spp., Amphinema spp. et Cortinarius spp. Une saison de croissance après la coupe, il n'y avait pas de différence entre les traitements dans le nombre de racines fines actives à aucun des endroits, ni aucun effet des traitements sur la diversité des ectomycorhizes. Deux et trois saisons de croissance après la récolte, la persistance de quelques-uns des principaux types morphologiques différait selon le traitement. Malgré l'absence de différences entre les indices de diversité à des distances correspondantes à l'intérieur des ouvertures de différentes dimensions, après deux et trois saisons de croissance, le nombre de racines fines actives de même que la diversité des ectomycorhizes dans les zones de coupe à blanc diminuaient à mesure qu'on s'éloignait de la limite de la forêt. [Traduit par la rédaction] Hagerman et al. 134

Mycological research, Aug 1, 2002

Two methods are currently being used to describe ECM fungal communities associated with root tips... more Two methods are currently being used to describe ECM fungal communities associated with root tips : molecular techniques and morphological classification. Previous studies have found that these two approaches give conflicting results, with several fungal genotypes being identified from different ectomycorrhizas within the same morphotype. This has led researchers to question the usefulness of the morphological approach. The objective of this study was to compare the two approaches on ectomycorrhizas collected from three plant species growing in two different environments. Specifically, mycorrhizas were classified using a detailed morphological approach and then were subjected to PCR-RFLP analysis of the ITS region of the rRNA gene repeat. Ectomycorrhizas of Douglas-fir (Pseudotsuga menziesii) and paper birch (Betula papyrifera) were sampled from three widely dispersed sites with different soil types in the southern interior of British Columbia. Ectomycorrhizas of Douglas-fir and arbutoid mycorrhizas from Arctostaphylos uva-ursi were sampled from a fourth site in a different biogeoclimatic zone. For eight of eleven dominant morphotypes, one main RFLP banding pattern was observed. Ninety-three % of the mycorrhizas analyzed in these eight morphotypes would have been classified in the same way by either method. Five of the eight morphotypes were positively identified as Russula nigricans, Lactarius sp., Leccinum scabrum, Rhizopogon sect. Villosuli, and Thelephora terrestris by matching the RFLPs to those of fungal fruit bodies in our database or by sequencing the ITS region. The other morphotypes producing one dominant RFLP pattern were designated as Cenococcum, E-strain and Mycelium radicis atrovirens (MRA) based on their morphology. Morphotyping did not distinguish amongst major RFLP types for mycorrhizas classified as Amphinema-like, Piloderma-like and Rhizopogon-like A. We conclude that detailed morphological classification can be very useful as the primary method of ectomycorrhizal classification, when used in conjunction with molecular techniques. This approach will allow for an efficient use of research funds.

Carbon use efficiency in mycorrhizas theory and sample calculations

New Phytologist, Sep 1, 1994

summaryThe benefit to a fungus by a mycorrhizal association is that it gains carbon from its host... more summaryThe benefit to a fungus by a mycorrhizal association is that it gains carbon from its host. A benefit to a host is usually a nutritional one, but any resulting increase in dry weight may be counteracted by the carbon consumed by the fungus. The carbon costs of mycorrhizal fungi have been calculated using 14C pulse‐chase experiments in the laboratory or by estimating turnover rates in the field. Both of these techniques have their limitations, but estimates have been remarkably consistent amongst most laboratory studies. Carbon demands of the fungus may not reduce theoretical growth enhancement in plants which are sink‐limited but would be expected to do so iii source‐limited plants. A model of carbon use efficiency is developed based on the economic concepts of cost and benefit. Efficiency is defined in terms of carbon gained via the growth response to infection, and the carbon expended supporting the fungus. Practical considerations of measuring carbon allocation, and calculating carbon use efficiency are discussed. In an experiment on Salix viminalis L., colonized by Thelephora terrestris (Ehrh.) Fr., the carbon use efficiency calculated by this method was on overage 85% based on shoot tissue production, and 95% based on whole plant production.

Ectomycorrhizal diversity on Betula papyrifera and Pseudotsuga menziesii seedlings grown in the greenhouse or outplanted in single-species and mixed plots in southern British Columbia

Canadian Journal of Forest Research, Nov 1, 1997