松口蘑的研究热点

揭开松口蘑与松科植物的共生关系，开发松口蘑的人工栽培技术已成为国际性的松口蘑研究课题。近年来，日本、瑞典、美国、韩国和新西兰等国的研究人员为鉴别松口蘑及其近缘种提供了有效的分子生物学手段，从形态解剖学、生理学上验证了松口蘑是典型的外生菌根菌的理论，同时也提出了松口蘑-宿主是一个动态的共生关系。松口蘑快速人工菌根的合成体系已经建立，为松口蘑人工子实体的诱导奠定了不可缺少的基础。这一领域的研究必将与植物学、菌物学和土壤学的研究紧密地结合起来，以共同开发松口蘑的人工栽培技术。     

滇西北高山针叶林区主要林型下外生菌根真菌的分布

1985年和1986年,我们在云南西北部高山针叶林内,采用标准地调查和路线踏查相结合的方法,在杜鹃-冷杉林等7个主要林型中进行了外生菌根真菌调查。经对采集标本的鉴定,计有33个属约140余种外生菌根真菌。它们在各种林型下的分布有着一定的规律。其种类组成和分布的多度与林木的组成、土壤和地形条件,如海拔高度、坡向、坡度等有密切的关系。     

Short Root Densities and Surface Phosphatase Activities of Ectomycorrhizal Morphotypes in a Slash Pine Plantation

Abstract

Mineralization is the dominant process controlling soil-solution P in the Spodosols of the southeastern United States. Pine trees growing in these soils are typically colonized by ectomycorrhizal (EM) fungi that are known to produce phosphatases. Little, however, is known of the dynamics of EM short roots or phosphatase activity in tree plantations. To address this question, short root densities, EM morphotypes, and associated surface acid phosphomonoesterase in a 12-year-old Pinus elliottii plantation in northern Florida were evaluated. The density of total (living and dead) short roots changed little from February through June, with a mean of 7.6 cm³ soil. The majority of the short roots, however, were inactive or dead with only 14 to 38% appearing viable upon visual inspection. The majority of the viable short roots were mycorrhizal. The most abundant morphotypes were formed by Cenococcum and Thelephora but these had low phosphatase activity. In contrast, less frequently observed morphotypes had substantially higher rates of enzyme production and these may play an important role in sustainable P nutrition of plantation trees.     

樟子松幼苗盆栽与圃地接种菌根真菌生长效应的初步研究

本文通过对盆苛与大田樟子松幼苗接种各种菌根真菌试验，筛选出黄空柄牛肝菌（Ｇｙｒｏｐｏｒｕｓｃｙａｎｅｓｃｅｎｓ）与彩色豆马勒２７０号菌株（Ｐｉｓｏｌｉｔｈｕｓｔｉｎｃｔｏｒｉｕｓ２７０）为樟子松（ＰｉｎｕｓｓｙｌｖｅｓｔｒｉｓＬ．Ｖａｒ．ｍｏｎｇｏｌｉｃａＬｉｔｖ．）的两个优良共生菌根真菌。     

Negligible contribution from roots to soil-borne phospholipid fatty acid fungal biomarkers 18:2ω6,9 and 18:1ω9

The phospholipid fatty acid biomarkers 18:1ω9, 18:2ω6,9 and 18:3ω3,6,9 are commonly used as fungal biomarkers in soils. They have, however, also been found to occur in plant tissues, such as roots. Thus, the use of these PLFAs as fungal biomarkers in sieved soil, which may still contain small remains of roots, has been questioned. We used data from a recent beech tree girdling experiment to calculate the contribution of roots to these biomarkers and were able to demonstrate that not more than 0.61% of 18:1ω9 and 18:2ω6,9 in sieved soil samples originated from roots (but 4% of 18:3ω3,6,9). Additionally, the abundance of the biomarker 18:2ω6,9 in the soil was found to be highly correlated to ectomycorrhizal root colonization, which further corroborates its fungal origin. PLFA biomarkers were substantially reduced in vital roots from girdled trees compared to roots of control trees (by up to 76%), indicating that the major part of PLFAs measured in roots may actually originate from ectomycorrhizal fungi growing inside the roots. We calculated, that even a near to 50% reduction in fine root biomass - as observed in the girdling treatment - accounted for only 0.8% of the measured decrease of 18:2ω6,9. Our results demonstrate that both 18:1ω9 and 18:2ω6,9 are suitable biomarkers for detecting fungal dynamics in soils and that especially 18:2ω6,9 is a reliable biomarker to study mycorrhizal dynamics in beech forests.     

Physical extent,frequency, and intensity of phosphatase activity varies on soil profiles across a Douglas-fir chronosequence

In forest soils, the availability of phosphate is largely dependent on phosphatase activity. We used soil imprinting to compare in situ activity and fine-scale distribution of phosphatase on soil profiles located across forest chronosequences of four age classes young (5–6 yrs), canopy closure (24–30 yrs), stem exclusion (61–71 yrs), and older (90–103 yrs) of mixed Douglas-fir/paper birch stands regenerated after fire or clearcutting in southern interior British Columbia, Canada. Chromatography paper treated with a mixture of substrate and colorimetric reagent was applied directly to vertical soil surfaces, accessed through root windows. Stands older than 61 years had both the highest level of in situ phosphatase activity and larger, more intense regions of activity. Bray-extractable phosphorus was negatively related to imprintable phosphatase activity. We compared the changes in phosphatase activity with differences in the ectomycorrhizal fungal (EMF) community that had been documented previously in the same stands. Of 84 ectomycorrhizal fungi found on roots in at least two of the stand-age classes, eight taxa were positively correlated and one taxon (Rhizopogon vinicolor/vesiculosus) negatively correlated with high phosphatase activity. The frequency of three taxa appeared to be positively correlated with larger areas of activity on the soil profiles. By using an imprinting approach, this study was able to demonstrate, for the first time, that in situ phosphatase activity and physical attributes of that activity (i.e., number, size, and relative rates of each area of activity) were related to concentrations of soil nutrients and with the frequency of individual ectomycorrhizal fungi.     

Alkali-extractable soil organic matter: An important factor affecting the mycelial growth of ectomycorrhizal fungi

Significant effects of two fractions of alkali-extractable soil organic matter (AEOM) extracted from three different soils (agricultural soil, soil from deciduous forest, soil from spruce monoculture) on mycelial growth of 17 isolates of ectomycorrhizal fungi were observed. Growth of Lactarius deterrimus, Meliniomyces bicolor and one of the isolates of Leccinum aurantiacum was significantly stimulated by acid-insoluble fraction extracted from all three soils. The stimulatory effects were frequent but inhibition of mycelial growth of some isolates was also observed. The fungal response to the presence of the organic extract in the nutrient medium was isolate-specific rather than species-specific. Organic matter extracted from different source soils affected differently the mycelial growth, the largest number of stimulatory effects being observed in an experiment where the extract was richest in trace elements Zn and Cu. At the same time, the observed stimulatory effects were not attributable to increased concentrations of trace elements in the nutrient medium. The results indicate that soil may be used as a source of extractable organic fractions which, when used as a cultivation medium additive, may significantly improve the growth of responsive fungal isolates. Under natural conditions, AEOM (traditionally designated humic substances) represent a potential factor affecting the composition of cenosis of ectomycorrhizal fungi in soil.     

Species richness of ectomycorrhizal hyphal necromass increases soil CO2 efflux under laboratory conditions

The ectomycorrhizal mycelium is a large component of boreal and temperate forest soil microbial biomass and the resulting necromass is likely to be an important source of nutrients for saprotrophic microorganisms. Here we test the effects of species richness of ectomycorrhizal mycelial biomass on short-term CO₂ efflux by amending forest soil with necromass from 8 fungal species added separately and in mixtures of 2, 4 and 8 species. All additions of necromass rapidly increased soil CO₂ efflux compared to unamended controls but CO₂ efflux increased significantly with species richness. Efflux of CO₂ did not correlate with the carbon (C) or nitrogen (N) contents or the C:N ratio of the added necromass. The study demonstrates that species diversity of dead ectomycorrhizal fungal hyphae can have important consequences for soil CO₂ efflux, and suggests decomposition of hyphae is regulated by specific constituents of the nutrient pools in the necromass rather than the total quantities added.     

厚环乳牛肝的原生质体分离与再生

探讨了外生菌根菌耳环乳牛肝（Ｓｕｉｌｌｕｓｇｒｅｖｉｌｌｅｉ）的原生质体制备及再生条件。用ＭＹＧ培养基培养菌丝７天、宋用１．５％Ｌｙｗａｌｌｚｙｍｅ，以０．６ｍｏｌ甘露醇为稳渗剂，在酶解液ｐＮ值５．５，温度３１℃，酶解４ｈｒ的条件下，每０．１ｇ湿菌丝的原生质体产量这６×１０￣６／ｍｌ。用ＳＯ培养基培养菌丝能提高原生质体产量，但再生率下降。综合产量和再生率考虑以ＭＹＧ培养菌丝效果较好。     

The lateral spread of tree root systems in boreal forests: Estimates based on N uptake and distribution of sporocarps of ectomycorrhizal fungi

In nutrient poor environments, such as boreal forests, many of the most important interactions between plants take place belowground. Here, we report the results of two approaches to obtain estimates of the lateral spread of tree roots.