In vitro salinity resistance of three ectomycorrhizal fungi

The growth models, diameter growth rates, biomass yield and Na⁺ contents of three ectomycorrhizal (ECM) fungi, Suillus bovinus (L. ex Fr.) O. Kuntze, Suillus luteus (L. ex Fr.) Gray, Boletus luridus Schaeff ex Fr., were investigated at nine NaCl levels (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 mol/L). The results showed that the growth models of the three ECM fungal species were not affected by the NaCl concentration, but the growth rates reduced with the increasing NaCl concentration. The growth rates of B. luridus and S. bovinus were significantly higher than that of S. luteus at the same NaCl level; the biomass yields of three ECM fungal species were different, S. bovinus < S. luteus < B. luridus. Of the three species, B. luridus exhibited the highest growth rates, best biomass yield, and greatest Na⁺ concentration in the mycelia over the NaCl gradient tested, indicating B. luridus has the most tolerance to NaCl stress and assimilation to Na⁺ under salt stress. The growth rate of S. luteus was the lowest, but the biomass yield and Na⁺ concentration in the mycelia were only lower than those of B. luridus. S. bovinus was the most sensitive to NaCl stress and its growth rate was faster than that of S. luteus, but the biomass yield and Na⁺ concentration in the mycelia were the lowest.     

Direct estimates of C:N ratios of ectomycorrhizal mycelia collected from Norway spruce forest soils

Direct estimates of C:N ratios of ectomycorrhizal (EM) mycelia growing in situ in forest soils have been obtained for the first time. The mycelial samples were collected from sand-filled mesh bags that were buried in the soil and incubated for 12-18 months in two Norway spruce forests in southern Sweden. At harvest the mesh bags were heavily colonized and the mycelia were extracted from the sand with water. The collected mycelia had earlier been identified as belonging to EM fungi based on their C isotopic composition. The mean value of the C:N ratio for mycelia was 20.2±0.8 (n=25). EM mycelia collected at different soil depths (5, 15 and 30 cm) had similar C:N ratios. C:N ratios of microbial biomass obtained by fumigation-extraction of similar soils have usually been lower (6-13) so possible differences in the extraction efficiency of C and N from bacteria and fungi are discussed.     

影响人工接种外生菌根效果的初步研究

为了提高接种效果．在黑龙江省大兴安岭塔河林业局中心苗圃．对落叶松和樟子松苗木进行了３年人工接种外生菌根真菌的试验研究。对不同基质、苗龄型、接种时间及长短、施菌量等各项因子进行试验研究。结果表明：所使用的Ｓｕｉｌｌｕｓｇｒｅｖｉｌｌｅｉ等６个菌种在不同基质上均能形成菌根．而有利的土壤基质更能促进菌根的形成和苗木的生长；苗龄不同。菌根的感染率不同。随着苗龄的增加．菌根的感染率减少．故应在幼苗期接种；最佳的接种时间应在苗木长出第一级侧根时进行．为了不增加成本、在播种时接种亦可；适宜的施菌量为２５０ｇ／ｍ￣２。     

A genotype dependent-response to cadmium contamination in soil is displayed by Pinus pinaster in symbiosis with different mycorrhizal fungi

Soil contamination with Cd is of primary concern and beneficial soil restoration strategies urge. The aim of this work is to evaluate the response of two different genotypes of Pinus pinaster (wild and selected) to Cd contamination and to assess how inoculation with ectomycorrhizal fungi, Suillus bovinus and Rhizopogon roseolus, influenced each genotype. Seedlings were exposed to soil contaminated at 15 and 30 mg Cd kg⁻¹. Plant growth, mycorrhizal traits and Cd accumulation in different tissues of the plant were determined at harvest. The fungal community was assessed by denaturing gradient gel electrophoresis. At 15 mg Cd kg⁻¹ S. bovinus increased aboveground development in both genotypes. At 30 mg Cd kg⁻¹ non-inoculated wild genotype accumulated more Cd in the shoots (1.7-fold) than the selected genotype; inoculation with R. roseolus decreased Cd concentration in the roots of the selected genotype whereas the opposite occurred in the wild genotype. Cd concentration in the root system was the parameter most influenced by the interaction between the three studied variables. The fungal community established was affected by the Cd concentration in the soil. Results show that different genotypes of P. pinaster react differently to Cd exposure depending on the mycorrhizal association. The importance of considering the combination between plant genotype and its symbiotic partners when aiming at the forestation of degraded land is highlighted.     

树木外生菌根真菌多样性研究方法进展

树木外生菌根真菌在森林生态系统中发挥着重要的作用,其多样性研究能反映外生菌根真菌的种群结构。随着分子生物学技术在多样性研究中的应用,打破了传统方法诸如大多数微生物处于不可培养状态的局限性,提高了人们对外生菌根真菌群落结构的认识。本文主要介绍了几种外生菌根真菌多样性研究常用的方法,综述了它们在菌根研究中的应用状况,为森林生态系统生物多样性研究提供参考。     

外生菌根真菌的氮营养特性研究进展

根据国内外菌根文献资料,综述了外生菌根真菌的氮营养吸收特性,并阐述了重金属污染对外生菌根真菌氮营养吸收的影响。由于外生菌根真菌能增强寄主植物的氮营养吸收状况,所以找出适合外生菌根真菌大量快速繁殖的氮源,为菌根生物技术更好的应用与农林生产实践提供科学依据。     

RETRACTED ARTICLE: Abundance of Collembola collected from ectomycorrhizal hyphal mats and fruiting bodies of Tricholoma matsutake

Collembolans collected from hyphal mat soil and fruit bodies of Tricholoma matsutake were examined to investigate whether mycophagous microarthropods are a potential insect pest of this fungus in forest soils. The number of collembolans collected in hyphal mat soil did not differ significantly from that in adjacent nonmat soil. Fungal materials contained in the gut of collembolans consisted mostly of hyphal fragments of dematiaceous fungi and unknown basidiomycetes. There were few collembolans on the fruit bodies of T. matsutake, which has the largest fruit body of the fungi at the study site. Our findings suggested that collembolans are not significant feeders on the hyphal mat and fruit body of T. matsutake. An erratum to this article is available at .     

毛白杨外生菌根类型及其生态学特性的研究

根据形态和解剖特征,将中原地区的毛白杨外生菌根划分成14种类型,它们与宿主的共生关系大多差或极差。菌根分布特征指标统计结果表明,毛白杨(Populus tomentoso)林地土壤中,普遍缺乏能与毛白杨形成良好共生关系的外生菌根真菌,共生关系良好的菌根主要分布在pH值小于7.5的土壤中;共生关系差或极差的菌根和假菌根则在强碱性土壤中占优势,土壤pH大于7.5的育苗地中,毛白杨幼苗形成的菌根比较单一,以假菌根-5号类型为主。树木年龄对毛白杨林的菌根形成没有影响。     

应用RAPD分析快速鉴定外生菌根蘑菇分离物的真伪

采用DNA指纹比较技术对部分外生菌根蘑菇分离菌株的真伪进行了鉴定，结果表明：不同来源的点柄乳牛肝菌Suillus granulatus子实体之间的DNA相似系数为0.939。但各菌丝体分离菌株与其来源子实体的DNA相似系数为1.000，每个供试引物获得的RAPD指纹图谱全部对应相同，证实分离物为真正的牛肝菌分离菌株。试验还鉴定与子实体DNA具极高同源性的细裂硬皮马勃Sclerodema areolatum的组织分离菌丝体是真正的分离菌株。供试大红菇Russula rubra分离培养物与供试子实体之间存在很大的DNA异质性，因此判定该分离物为杂菌或其它生物体分离物，并非大红菇的分离菌株。试验结果显示：RAPD指纹技术是外生菌根蘑菇分离物真伪鉴定的一种快速可靠的方法。文章就RAPD鉴定共生真菌分离菌株的可靠性与技术范围进行了讨论。     

Distinctive fungal and bacterial communities are associated with mats formed by ectomycorrhizal fungi

The distinct rhizomorphic mats formed by ectomycorrhizal Piloderma fungi are common features of the organic soil horizons of coniferous forests of the Pacific Northwest. These mats have been found to cover 25-40% of the forest floor in some Douglas-fir stands, and are associated with physical and biochemical properties that distinguish them from the surrounding non-mat soils. In this study, we examined the fungal and bacterial communities associated with Piloderma mat and non-mat soils. Each mat and non-mat area was repeatedly sampled at four times throughout the year. Characterization of the mat activity and community was achieved using a combination of N-acetylglucosaminidase (NAGase) enzyme assays, and molecular analysis of fungal and bacterial communities using T-RFLP profiles, clone libraries, and quantitative PCR. Piloderma mats had consistently greater NAGase activity across all dates, although the magnitude of the difference varied by season. Furthermore, we found distinct fungal and bacterial communities associated with the Piloderma mats, yet the size of the microbial populations differed little between the mat and non-mat soils. Significant temporal variation was seen in the NAGase activity and in the sizes of the fungal and bacterial populations, but the community composition remained stable through time. Our results demonstrate the presence of two distinct microbial communities occupying the forest floor of Douglas-fir stands, whose populations and activities fluctuate seasonally but with little change in composition, which appears to be related to the physiochemical nature of mat and non-mat habitats.