Ectomycorrhizal mycelial species composition in apatite amended and non-amended mesh bags buried in a phosphorus-poor spruce forest

We studied the effect of apatite amendment on ectomycorrhizal (EM) mycelial biomass production and species composition in a phosphorus-poor spruce forest using sand-filled mesh bags. Control and apatite-amended bags were buried in pairs in the lower part of the organic horizon for one growth season. DNA extraction, PCR of the ITS region, cloning and random sequencing were used to examine the fungal species composition in each bag. Sequences were identified by comparison with the UNITE database and GenBank. Our study confirmed previous results that the major fungal ingrowth in mesh bags was of EM origin. On average 13 species were detected in each bag. Tylospora fibrillosa, Amphinema sp., Tomentellopsis submollis, and Xerocomus badius made up almost 80 % of the EM sequences. High biomass was related to increased dominance of specific species. There were no statistically significant differences in biomass production estimated from PLFA 18:2ω6, 9, or between fungal communities of apatite-amended and control bags estimated from DNA after one growth season. The potential of the mesh bag method in studies of functional diversity of EM mycelia in the field is discussed.     

菌丝桥在日本落叶松幼苗间磷传递和植株生长中的作用

 应用四室隔网系统研究了菌丝桥在日本落叶松(Larix kaempferi)幼苗间传递磷的作用。结果表明,供体接种卷缘桩菇(Paxillus involutus)和彩色豆马勃（Pisolithus tinctorius）后,其外延菌丝可以穿过隔离层侵染受体落叶松,在供体和受体落叶松间形成了菌丝桥。供体植株接种菌根真菌后生物量明显增加,但是对受体植株没有显著的影响。菌根真菌侵染的供体和受体植株的根、地上部吸磷量均分别显著高于对照,而且供体植株根、地上部吸磷量增加的程度明显高于受体。被卷缘桩菇和彩色豆马勃侵染的受体植株体内32P的放射性强度分别是对照的10倍和6倍,两者形成菌丝桥后传递到受体植株的32P分别为供体植株体内32P的1.10%和0.22%。供体植株吸收的32P可以通过菌丝桥传递给受体,但是绝对数量十分有限,对受体植株磷营养没有产生显著的影响,但P. involutus和P. tinctorius侵染受体植株后,促进了受体落叶松对磷的吸收,这是菌丝桥形成后,真菌帮助受体植株吸收磷引起的。     

A PCR-based method for detecting the mycelia of stipitate hydnoid fungi in soil

To reduce the reliance on sporocarp records for conservation efforts, information on the below-ground distribution of specific fungal species, such as stipitate hydnoid fungi, is required. Species-specific primers were developed within the internal transcribed spacer (ITS1 and ITS2) regions for 12 hydnoid fungal species including Bankera fuligineoalba, Hydnellum aurantiacum, H. caeruleum, H. concrescens, H. ferrugineum, H. peckii, Phellodon confluens, P. melaleucus, P. niger, P. tomentosus, Sarcodon glaucopus and S. squamosus. The specificity of the primer pairs was tested using BLAST searches and PCR amplifications. All primers amplified DNA only of the target species with the exception of those designed for P. melaleucus. In order to assess the ability of the primers to detect DNA from mycelium in soil, DNA extracted from soil samples taken from around solitary H. peckii sporocarps was amplified with the H. peckii primer 1peck and ITS2. H. peckii DNA was detected in 70% of all soil samples and up to 40 cm away from the base of individual sporocarps. The development of these species-specific primers provides a below-ground alternative for monitoring the distribution of these rare fungi.     

木材腐朽菌培养特性的研究综述

论述了研究木材腐朽菌培养特性的意义,对自1889年以来有关木材腐朽菌培养特性的研究文献进行了回顾。通过综合分析以往国内外对木材腐朽菌培养特性研究的结果,得出了对木材腐朽菌培养特性研究的总体结论。     

Ectomycorrhizal root growth in scots pine stands in response to manipulation of litter and humus layers

 The effect on ectomycorrhizal root growth in a nitrogen-enriched planted stand of Scots pine (Pinus sylvestris L.) on podzolic sandy soil to manipulation of litter and humus layers (removal, doubling and control treatments) was examined, and compared to ectomycorrhizal root growth in an untreated naturally established Scots pine stand on nutrient-poor non-podzolic sandy soil. Half a year after manipulation of litter and humus layers in the planted stand, ingrowth-cores to a depth of 60 cm were installed in both stands. Scots pine roots were sampled four times during two growing seasons. Ectomycorrhizal roots were found at all sampled soil depths to 60 cm in all plots. Root growth and ectomycorrhizal development were greater in the naturally established stand than in all plots in the planted stand. Numbers of ectomycorrhizal root tips in the litter and humus removal plots were generally higher than in the control plots in the planted stand until May 1992. Doubling litter and humus did not significantly affect root length or the numbers of ectomycorrhizal root tips. The N _dissolved , NH₄ ⁺ and NO₃ ^– concentrations and the organic matter content in the upper 5 cm of the mineral soil in the planted stand on podzolic sandy soil were generally higher and the pH significantly lower than in the naturally established stand on non-podzolic sandy soil. Root growth and ectomycorrhizal development in the secondary stand may have been negatively affected by the chemical composition of the podzolic sandy soil. Accepted: 19 March 1997     

Basidiomycete fungal communities in Australian sclerophyll forest soil are altered by repeated prescribed burning

Soil basidiomycetes play key roles in forest nutrient and carbon cycling processes, yet the diversity and structure of below ground basidiomycete communities remain poorly understood. Prescribed burning is a commonly used forest management practice and there is evidence that single fire events can have an impact on soil fungal communities but little is known about the effects of repeated prescribed burning. We have used internal transcribed spacer (ITS) terminal restriction fragment length polymorphism (T-RFLP) analysis to investigate the impacts of repeated prescribed burning every two or four years over a period of 30 years on soil basidiomycete communities in an Australian wet sclerophyll forest. Detrended correspondence analysis of ITS T-RFLP profiles separated basidiomycete communities in unburned control plots from those in burned plots, with those burned every two years being the most different from controls. Burning had no effect on basidiomycete species richness, thus these differences appear to be due to changes in community structure. Basidiomycete communities in the unburned control plots were vertically stratified in the upper 20 cm of soil, but no evidence was found for stratification in the burned plots, suggesting that repeated prescribed burning results in more uniform basidiomycete communities. Overall, the results demonstrate that repeated prescribed burning alters soil basidiomycete communities, with the effect being greater with more frequent burning.     

Interactions between extraradical ectomycorrhizal mycelia, microbes associated with the mycelia and growth rate of Norway spruce (Picea abies) clones

Despite their ecological relevance, field studies of the extraradical mycelia of ectomycorrhizal (ECM) fungi are rare. Here we examined in situ interactions between ECM mycelia and host vigour. Ectomycorrhizal mycelia were harvested with in-growth mesh bags buried under Norway spruce (Picea abies) clones planted in 1994 in a randomized block design. Mycelial biomass was determined and fungal species were identified by denaturing gradient gel electrophoresis (DGGE) and sequencing of the internal transcribed spacer 1 (ITS1) region. Microbial community structure in the mycelium was investigated by phospholipid fatty acid (PLFA) profiling. Compared to slow-growing spruce clones, fast-growing clones tended to support denser mycelia where the relative proportions of Atheliaceae fungi and PLFAs indicative of Gram-positive bacteria were higher. Ascomycetes and PLFAs representative of Gram-negative bacteria were more common with slow-growing clones. In general, the ECM mycelial community was similar to the ECM root-tip community. Growth rate of the hosts, the ECM mycelial community and the microbes associated with the mycelium were related, suggesting multitrophic interactions between trees, fungi and bacteria.     

外源养分和激素对AM真菌侵染和产孢的影响

在温室30%强度Hoagland营养液半水培条件下,对寄主植物玉米Zea mays接种丛枝菌根(Arbuscular myeorrhizae,AM)真菌Glomus mosseae后施加不同浓度的葡萄糖、蔗糖、脯氨酸(Pro)、吲哚-3-乙酸(IAA)、赤霉素(GA3)和6-苄基腺嘌呤(6-BA)。结果表明:除低浓度GA3处理外,其他处理尤其是高浓度处理抑制了玉米植株的生长。中浓度蔗糖、脯氨酸(Pro)和吲哚-3-乙酸(IAA)处理显著提高玉米菌根侵染率,其中以中浓度蔗糖的处理最高,达92.3%。葡萄糖、赤霉素(GA3)和6-苄基腺嘌呤(6-BA)处理则降低菌根侵染率。施加不同有机养分和植物生长物质并未提高AM真菌产孢数量,相反,却减少了孢子的形成。高浓度氨基乙酸(Gly)和低浓度6-BA处理的产孢量分别为50和48个/管,高于其他处理,但低于对照(78个/管);可溶性糖处理的产孢数量最少,平均仅18个/管。本试验条件下菌根侵染率与产孢数量不具有相关性,而产孢数与根外菌丝量具相关性。认为通过外界不同的化学调控,对植物生长、菌根侵染、根外菌丝量和孢子发育产生了一定的影响,具有一定的调节作用。     

Suppression of the Root-knot Nematode Meloidogyne javanica by Alginate Pellets Containing the Nematophagous Fungi Hirsutella rhossiliensis , Monacrosporium cionopagum and M. ellipsosporum

The endoparasitic fungus Hirsutella rhossiliensis and the nematode-trapping fungi Monacrosporium cionopagum and M. ellipsosporum were formulated as hyphae in alginate pellets. In a soil microcosm experiment, dried pellets of all three fungi decreased the invasion of cabbage seedlings by the root-knot nematode Meloidogyne javanica when juvenile nematodes were placed 2 cm from roots; M. cionopagum was more effective than the other two fungi, reducing nematode invasion by 40-95% with 0.24-0.94 pellets cm - 3 of soil. In a field microplot experiment, in which neither H. rhossiliensis nor M. ellipsosporum suppressed nematodes, 0.5 pellets of M. cionopagum cm - 3 of soil suppressed M. javanica invasion of tomato seedlings by 73%. In a second microplot experiment with only M. cionopagum , again at 0.5 pellets cm - 3 of soil, the fungus suppressed the invasion of tomato seedlings whether the pellets were added 0, 5 or 14 days before planting; the population density of M. cionopagum increased to nearly 3000 propagules g - 1 of soil by day 8 and then declined to less than 300 by day 22. Enchytraeid worms were observed in and around damaged and apparently destroyed pellets in both microplot experiments. Whether enchytraeids consumed the fungi or otherwise affected biological control requires additional research.