北京地区苹果及葡萄根际捕食线虫真菌的种类及分布

对北京郊区果园的苹果和葡萄根际的捕食线虫真菌进行调查,发现苹果和葡萄的根际不同位置的捕食线虫真菌数量不同,内根际（包括根表）捕食线虫真菌数量大于外根际,而外根际捕食线虫真菌数量又大于游离土壤中的捕食线虫真菌数量;在苹果根际发现的捕食线虫真菌共有９种：Ａｒｔｈｒｏｂｏｔｒｙｓｄａｃｔｙｌｏｉｄｅｓ,Ａ．Ｃｌｉｇｏｓｐｏｒａ,Ａ．Ｍｕｓｉｆｏｒｍｉｓ,Ａ．Ｃｌａｄｏｄｅｓ,Ａ．Ｂｒｏｃｈｏｐａｇａ,Ａｒｔｈｒｏｂｏｔｒｙｓｓｐ．,Ｍｏｎａｃｒｏｓｐｏｒｉｕｍｅｕｄｅｒｍａｔｕｍ,Ｍ．Ｓｐｈ     

中国的捕食线虫真菌Ⅰ.

采用8种不同分离方法从我国贵州、云南、四川、广西等省的土壤、食用菌菇床上分离到10种捕食线虫真菌。8种方法中,以改良Drechsler法和直接分离法较好。10种捕食线虫真菌中,除Arthrobotrys oligospora曾记载腐生于河北棉桃外,其余均为我国新纪录种,它们是:Arthrobotrys superba,A.conoides A.oviformis,A.haptotyla,A.haptospora,A.cladodes,Monacrosporium lysipaga,M.ellipsopora,M.megalospola     

Occurrence and colonization of nematophagous fungi in different substrates,agricultural soils and root galls

Seventeen species of nematophagous fungi were recorded, three species were endoparasitic and fourteen species were predacious fungi. Among the predacious fungi Arthrobotrys oligospora, Dactylaria brochopaga and Monacrosporium eudermatum were very frequent, whereas others were recorded at lower frequency. Twelve species of nematophagous fungi from compost as well as cow dung manure, 15 species from leaf litter and only eight species from agricultural soils were recorded. In general, substrate colonization by nematophagous fungi was higher in leaf litter, compost and cow dung manure. The agricultural soil amended with FYM (farm yard manure) recorded nine species of nematophagous fungi while unamended soil recorded only seven species. Thirteen species of nematophagous fungi were recorded from soils under banyan tree. Of all these fungi unidentified net-forming fungus, M. eudermatum, A. cladodes, D. brochopaga, S. hadra, A. oligospora and A. dactyloides had higher percentage of soil colonization. In soil collected under pipal tree only eight species were recorded, of which A. oligospora, A. cladode and an unidentified fungus were more predominant as their percentage colonized in soil samples was higher. Few studies have examined root galls as a substratum for colonization of nematophagous fungi. Of all the root gall samples, okra root galls recorded maximum colonization by predacious fungi. Maximum percentage of root gall colonization was recorded for M. eudermatum followed by A. oligospora and M. ellipsosporum. M. eudermatum was also most predominant colonizer of balsam, brinjal and rice root galls.     

Dialysis membrane technique for ultrastructural studies of microbial interactions

A dialysis membrane technique was developed that enabled ultrastructural investigations of the interaction of nematode-trapping fungi and their nematode prey. It allowed the sectioning of individual traps that had been selected by light microscopy and was used in kinetic studies on trap formation, nematode capture, and subsequent nematode digestion. The method can also be used for enzyme cytochemical experiments.     

Dialysis membrane technique for ultrastructural studies of microbial interactions.

A dialysis membrane technique was developed that enabled ultrastructural investigations of the interaction of nematode-trapping fungi and their nematode prey. It allowed the sectioning of individual traps that had been selected by light microscopy and was used in kinetic studies on trap formation, nematode capture, and subsequent nematode digestion. The method can also be used for enzyme cytochemical experiments.     

Control of plant-parasitic nematodes by Paecilomyces lilacinus and Monacrosporium lysipagum in pot trials

The common soil inhabiting nematophagous fungus Paecilomyces lilacinus (Thom) Samson and the nematode trapping fungus Monacrosporium lysipagum (Drechsler) Subram were assayed for their ability to reduce the populations of three economically important plant-parasitic nematodes in pot trials. The fungi were tested individually and in combination against the root-knot nematode Meloidogyne javanica (Treub) Chitwood, cereal cyst nematode Heterodera avenae Wollenweber, or burrowing nematode Radopholus similis (Cobb) Thorne on tomato, barley and tissue cultured banana plants, respectively. In all cases, nematode populations were controlled substantially by both individual and combined applications of the fungi. Combined application of P. lilacinus and M. lysipagum reduced 62% of galls and 94% of M.␣javanica juveniles on tomato when compared to the experiment with no fungi added. Sixty five percent of H. avenae cysts were reduced on barley by combined application of fungi. Control of R. similis on banana, both in the roots and in the soil, was greatest when M. lysipagum was applied alone (86%) or in combination with P. lilacinus (96%), using a strategy where the fungi were inoculated twice in 18 weeks growth period. Overall, combined application of P. lilacinus and M. lysipagum was the most effective treatment in controlling nematode populations, although in some cases M. lysipagum alone was as effective as the combined application of fungi, particularly against M. javanica.     

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.     

Rhizosphere Colonization and Control of Meloidogyne spp. by Nematode-trapping Fungi

The ability of nematode-trapping fungi to colonize the rhizosphere of crop plants has been suggested to be an important factor in biological control of root-infecting nematodes. In this study, rhizosphere colonization was evaluated for 38 isolates of nematode-trapping fungi representing 11 species. In an initial screen, Arthrobotrys dactyloides, A. superba, and Monacrosporium ellipsosporum were most frequently detected in the tomato rhizosphere. In subsequent pot experiments these fungi and the non-root colonizing M. geophyropagum were introduced to soil in a sodium alginate matrix, and further tested both for establishment in the tomato rhizosphere and suppression of root-knot nematodes. The knob-forming M. ellipsosporum showed a high capacity to colonize the rhizosphere both in the initial screen and the pot experiments, with more than twice as many fungal propagules in the rhizosphere as in the root-free soil. However, neither this fungus nor the other nematode-trapping fungi tested reduced nematode damage to tomato plants.     

d-Mannose as a component of the macrophage surface receptor for macrophage-activating factor (MAF) in mice

Mouse peritoneal exudate macrophages were rendered cytostatic and cytolytic for various mouse tumor cells in vitro by exposure to partially purified lymphokines containing macrophage-activating factor (MAF) at 37 °C for 2 hr. The macrophage activation disappeared completely when either 0.1 Md-mannose or 0.1 M methyl-d-mannoside was present with MAF. On the other hand, neither d-galactose nor d-glucose inhibited the activation, and l-fucose, l-rhamnose, and N-acetyl-d-glucosamine inhibited it only partially. Incubation of either macrophages or MAF with 0.1 Md-mannose for 2 hr had no effect on activation of the macrophages by the MAF. Treatment of the macrophages by α-d-mannosidase rendered them no longer responsive to MAF. Macrophages treated by either neuraminidase or proteolytic enzymes, but not with β-d-galactosidase lost their ability to respond to MAF. Treatment of MAF with α-d-mannosidase did not affect MAF activity. In addition, MAF activity was not reduced by passage through a column of immobilized concanavalin A. In an absorption experiment, the presence of d-mannose was shown to prevent the adsorption of MAF to macrophages, while d-galactose did not. Treatment of macrophages with plant lectins having affinity for d-mannose, sialic acid or l-fucose prevented the adsorption of MAF, but the other lectins did not. Mouse MAF failed to adsorb to guinea pig peritoneal exudate macrophage, which were suggested as having a fucose-containing glycolipid as a lymphokine receptor. Taken together, these results strongly suggest that the receptor for MAF on mouse macrophages may be a glycoprotein containing d-mannose and sialic acid as essential components.     

弯孢节丛孢和厚皮单顶孢菌株的RAPD分析

对来自不同地方的7个弯孢节丛孢（ArthrobotrysmusiformisDrechsler）和9个厚皮单顶孢（Monacrosporiumeudermatum（Drechsler）Subram）标准菌株用4个随机引物（OPW-18、OPW－16、OPM-1、OPK-19）进行了随机扩增多态性DNA（RAPD）分析。扩增谱带聚类分析结果不能将弯孢节丛孢和厚皮单顶孢的菌株分开,具有附属丝的菌株没有被聚在一起,菌株间地理起源上的亲缘关系也没有体现,证明RAPD分析不能作为节丛孢属和单顶孢属的属间鉴别分析,附属丝地捕食线虫真菌不具分类学意义,不能以之作为成立小掘氏霉属的证据,系统聚类关系与地理来源基质也没有相关性。     

Diversity of nematode destroying fungi in Taita Taveta,Kenya

The diversity of nematode destroying fungi in Taita Taveta, Wundanyi division, Coast Province, Kenya, was investigated between May 2006 and December 2007 aiming at harnessing their potential in the biological control of plant parasitic nematodes in the area. Given that the intensity of land cultivation is continually increasing in the study area, it is prudent to document the status of the nematode destroying fungi before the remaining forest habitats are ultimately disrupted. Soil samples were collected from forest, maize/bean, napier grass, shrub and vegetable fields, which represented the main land use types in the study area. The soil sprinkle technique method was used to isolate the nematode destroying fungi from the soil. The fungi were identified to species level. Eighty-five isolates, distributed in eight genera and 14 taxa were identified as nematode destroying fungi. The species identified were Arthrobotrys dactyloides, Arthrobotrys oligospora, Arthrobotrys superba, Acrostalagamus obovatus, Dactyllela lobata, Harposporium aungulilae, Harposporium liltiputanum, Harposporium spp, Haptoglosa heterospora, Monacrosporium asterospernum, Monacrosporium cianopagum, Myzocytium, spp, Nematoctonus georgenious and Nematoctonus leptosporus. Vegetable land use had the highest diversity of nematode destroying fungi. The results show that the study area is rich in nematode destroying fungi with A. oligospora being widespread and a possible candidate for biological control of plant parasitic nematodes.     

The influence of saprophytic competition on nematode predation by nematode-trapping fungi

Competivive stress imposed by common soil saprophytes may cause an increase in predation by the nematode-trapping fungi, Arthrobotrys oligospora and Monacrosporium cionopagum, on the bacteria-feeding nematode Acrobeloides buetschli. Nematode-trapping species grown with saprophytic competitors in an artificial soil substrate increased their trapping activity compared to control cultures. The results support the hypothesis that competition stimulates the predatory activity of nematode-trapping fungi as an adaptation to overcome their low competitive saprophytic ability.     

Four endoparasitic nematode destroying fungi isolated from Sand Ridge State Forest soil

A survey to determine the endoparasitic nematode destroying fungi located within Sand Ridge State Forest of Illinois was conducted from 1 January to 3 April 1973. A total of seven nematode destroying fungal species were isolated from the collected soil samples. Harposporium helicoides, H. crassum, H. lilliputanum are endoparasitic nematophagous fungi that have been isolated previously from the forest soil. Acrostalagmus gonoides, A. obovatus, Cephalosporium balanoides, and Monacrosporium cionopagum are nematophagous fungal species that had not been isolated previously from Illinois soil. Soil pH's and soil nutrient levels were not important in the isolation frequency of the collected endoparasitic nematode destroying fungi.     

A lectin-mediated resistance of higher fungi against predators and parasites

Fruiting body lectins are ubiquitous in higher fungi and characterized by being synthesized in the cytoplasm and up-regulated during sexual development. The function of these lectins is unclear. A lack of phenotype in sexual development upon inactivation of the respective genes argues against a function in this process. We tested a series of characterized fruiting body lectins from different fungi for toxicity towards the nematode Caenorhabditis elegans, the mosquito Aedes aegypti and the amoeba Acanthamoeba castellanii. Most of the fungal lectins were found to be toxic towards at least one of the three target organisms. By altering either the fungal lectin or the glycans of the target organisms, or by including soluble carbohydrate ligands as competitors, we demonstrate that the observed toxicity is dependent on the interaction between the fungal lectins and specific glycans in the target organisms. The toxicity was found to be dose-dependent such that low levels of lectin were no longer toxic but still led to food avoidance by C. elegans. Finally, we show, in an ecologically more relevant scenario, that challenging the vegetative mycelium of Coprinopsis cinerea with the fungal-feeding nematode Aphelenchus avenae induces the expression of the nematotoxic fruiting body lectins CGL1 and CGL2. Based on these findings, we propose that filamentous fungi possess an inducible resistance against predators and parasites mediated by lectins that are specific for glycans of these antagonists.     

Trapping, parasitism, and poisoning of nematodes by fungi

Naturally occurring toxins and nematode-destroying fungi are the two major factors controlling soil nematode populations. Nematode-destroying fungi fall into two groups - hyphal forms, producing traps which capture nematodes, and endoparasitic forms, both common in natural soils. Nematode-destroying fungi have been used in attempts to control levels of pathogenic nematodes in agricultural soils with limited success.     

Morphological variability and molecular phylogeny of the nematophagous fungus Monacrosporium drechsleri

An isolate of the nematode-trapping fungus Monacrosporium drechsleri was collected from cultures of the root-knot nematode Meloidogyne arenaria that had been maintained on tomato roots in greenhouse pots in Beltsville, Maryland. The plant-parasitic nematodes Heterodera glycines, Meloidogyne incognita and Pratylenchus zeae and the free-living nematodes Caenorhabditis elegans and Panagrellus redivivus were placed on colonies of M. drechsleri grown in Petri dishes to study ability of the isolate to trap various nematode hosts. None of the nematodes placed near adhesive knobs were motile within 1 d. To determine where M. drechsleri fits within the existing phylogeny of nematode-trapping fungi, the ITS1-ITS2 regions of rDNA and the nuclear gene EF1-alpha were sequenced for the new isolate of M. drechsleri, for the species M. parvicolle and M. lysipagum, and for an isolate of M. ellipsosporum distinct from the one listed in GenBank. Parsimony trees were constructed showing the closest molecular relative of M. drechsleri to be the newly sequenced isolate of M. ellipsosporum; the latter had a highly divergent sequence from the sequence recorded in GenBank for a different isolate of M. ellipsosporum. Unique, consistent and discrete morphological characters are absent in these related taxa, so an independent molecular character should be considered essential for their accurate identification.