Daniel Durall - Academia.edu (original) (raw)

Papers by Daniel Durall

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

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.

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 (<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

Wine and viticulture journal, Dec 1, 2019

Functional Ecology, Mar 19, 2010

Research Square (Research Square), Jan 4, 2021

Scientific Reports, Nov 10, 2014

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

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,

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

Canadian Journal of Forest Research, 1997

ABSTRACT

Canadian Journal of Forest Research, 1999

Mycological research, Aug 1, 2002

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.

Canadian Journal of Forest Research, Nov 1, 1997

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

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.

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 (<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

Wine and viticulture journal, Dec 1, 2019

Functional Ecology, Mar 19, 2010

Research Square (Research Square), Jan 4, 2021

Scientific Reports, Nov 10, 2014

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

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,

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

Canadian Journal of Forest Research, 1997

ABSTRACT

Canadian Journal of Forest Research, 1999

Mycological research, Aug 1, 2002

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.

Canadian Journal of Forest Research, Nov 1, 1997