林下参内生球毛壳菌FS-01对人参病原真菌的抑制作用

为探究林下参内生真菌球毛壳菌(Chaetomium globosum)FS-01菌株对人参病原菌的抑菌作用,该研究在实验室条件下,测定了FS-01菌株菌丝、发酵液和孢子悬浮液对人参黑斑病菌(Alternaria panax)、人参菌核病菌(Sclerotinia schinseng)、人参灰霉病菌(Botrytis cinerea)、人参立枯病菌(Rhizoctonia solani)、人参根腐病菌(Fusarium solani)5种人参病原菌的抑制作用。结果表明:内生真菌球毛壳菌FS-01对5种病原菌均有抑制作用,其中,对人参黑斑病菌的抑制作用最高,为30.80%,其次是人参立枯病菌、人参菌核病菌、人参根腐病菌和人参灰霉病菌; 发酵液抑菌实验结果表明,在加入内生真菌球毛壳菌FS-01菌株发酵液的PDA培养基上,对人参灰霉病菌的抑制作用最高,为82.09%,其次是人参菌核病菌、人参黑斑病菌、人参立枯病菌和人参根腐病菌; 孢子抑菌实验结果表明,在加入内生真菌球毛壳菌FS-01菌株孢子悬浮液的PDA培养基上,对人参黑斑病菌的抑制作用最高,为83.72%,其次是人参灰霉病菌、人参立枯病菌、人参菌核病菌和人参根腐病菌。综上结果认为,内生真菌球毛壳菌FS-01菌株对人参病原菌均有很高的抑菌作用,可作为人参病原菌的生防菌株资源。     

Endophytic fungi occurring in fennel, lettuce, chicory, and celery — commercial crops in southern Italy

The occurrence of endophytic fungi in fennel, lettuce, chicory, and celery crops was investigated in southern Italy. A total of 186 symptomless plants was randomly collected and sampled at the stage of commercial ripeness. Fungal species of Acremonium, Alternaria, Fusarium, and Plectosporium were detected in all four crops; Plectosporium tabacinum was the most common in all crop species and surveyed sites. The effect of eight endophytic isolates (five belonging to Plectosporium tabacinum and three to three species of Acremonium) inoculated on lettuce plants grown in gnotobiosis was assessed by recording plant height, root length and dry weight, collar diameter, root necrosis, and leaf yellowing. P. tabacinum and three species of Acremonium, inoculated on gnotobiotically grown lettuce plants, showed pathogenic activity that varied with the fungal isolate. Lettuce plants inoculated with the isolates Ak of Acremonium kiliense, Ac of Acremonium cucurbitacearum, and P35 of P. tabacinum showed an increased root growth, compared to the non-inoculated control. The high frequency of P. tabacinum isolation recorded in lettuce plants collected in Bari and Metaponto, and in fennel plants from Foggia agricultural districts, suggests a relationship not only between a crop species and P. tabacinum, but also between the occurrence of the endophyte and the crop rotation history of the soil.     

Frequency and Diversity of Fungi Colonizing Tissues of Upland Cotton

A study of the mycoflora of upland cotton in Alabama was conducted throughout the 2000 and 2001 growing seasons. Plants were sampled at seedling, first bloom, full bloom, and maturity stages of development. Thirty-seven genera representing 58 species of fungi were isolated, including 9 species of Fusarium. Fusarium oxysporum, F. solani, and F. equiseti were the most common members of this genus occurring at all four sampling stages in both years. Eight species accounted for 67% of the total fungi isolated during the two-year study. Alternaria alternata was the most common fungus encountered, accounting for 19 and 10% of the total fungi isolated in 2000 and 2001, respectively. Twenty species of fungi are reported for the first time colonizing upland cotton tissues.     

Fungi of Orobanche aegyptiaca in Nepal with Potential as Biological Control Agents

A survey of pathogens of the root-parasitic weed Orobanche aegyptiaca Pers. was carried out in Nepal. More than 70% of the fungal strains isolated from infected plants belonged to the genus Fusarium. Other fungi isolated were Acremonium fusidioides, Alternaria alternata, Cladosporium cladosporioides, Epicoccum nigrum, Mortierella alpina, Papulaspora sp., Phoma spp., Sordaria fimicola , Rhizoctonia sp., Trichoderma spp. and Trichothecium roseum.     

Rhizosphere and rhizoplane fungi of Triticum vulgare cultivated in Saudi Arabia

131 species in addition to 7 varieties which belong to 40 genera were collected from the rhizosphere (36 genera and 120 species + 7 varieties) and rhizoplane (27 genera and 56 species + 2 varieties) of Triticum vulgare. More than 22 species and 3 varieties were not encountered previously from soils or other sources in Saudi Arabia.In the rhizosphere, Aspergillus and Penicillium contributed the broadest spectrum of species (26 species + 5 varieties; and 24 species, respectively). The most frequent fungi were Aspergillus niger, A. clavatus, A. flavus, A. terreus, A. carneus, Penicillium citrinum, P. notatum, P. chrysogenum and Fusarium solani. In the rhizoplane which is a more selective substratum for fungi than the rhizosphere, the picture of dominance became different and the most common fungi were Fusarium solani, F. oxysporum, F. moniliforme, Drechslera spicifera, Cephalosporium roseo-griseum, Stemphylium botryosum, Acremonium strictum and Rhizoctonia solani.     

Identification and pathogenic characterization of endophytic <Emphasis Type="Italic">Fusarium</Emphasis> species from cowpea seeds

Isolates of Fusarium were obtained and identified from seeds of cowpea, Vigna unguiculata (L.) Walp., by means of blotter tests and slide cultures. Species were differentiated according to the morphology of the macroconidia, microconidia and their arrangement in chains or false heads, the size and type of conidiophore, and the presence or absence of chlamydospores. The species were identified as F. semitectum, F. equiseti, F. oxysporum, F. solani, F. anthophilum, F. sporotrichioides, F. moniliforme, and Fusarium sp. Among the species, F. semitectum was the most frequently detected. None of these species were pathogenic when inoculated in susceptible cowpea cultivar (BR 17- Gurgueia). But, an isolate of F. oxysporum f. sp. tracheiphilum used as a standard of comparison for pathogenicity (control) induced symptoms of yellowing, vascular wilting, and death of a susceptible cowpea cultivar under the same environmental conditions.     

人参内生细菌ge21菌株的鉴定及抑菌活性测定

从人参根内分离到一株细菌ge21,经形态特征观察、生理生化特性测定和16SrDNA序列分析,表明该菌株同已知菌Paenibacillus granivorans的相似性最高,为96.89%,初步认定为类芽孢杆菌属的一个潜在新种。抑菌试验结果表明,该菌株对尖孢镰刀菌(Fusarium oxysporium)、寄生疫霉菌(Phytophthora parasitica)、剑麻炭疽病菌(Colletotrichum agaves)、烟草赤星病菌(Alternaria longipes)、稻瘟病菌(Pyricularia oryzae)、人参立枯病菌(Rhizoctonia solani)、人参疫病菌(Phytophthora cactorum)和人参菌核病菌(Sclerotinia schinseng)均有一定的抑菌活性。     

Fungal root endophytes from natural vegetation in Mediterranean environments with special reference to Fusarium spp

Surveys (in 2002 and 2003) were performed for fungal endophytes in roots of 24 plant species growing at 12 sites (coastal and inland soils, both sandy soils and salt marshes) under either water or salt stress in the Alicante province (Southeast Spain). All plant species examined were colonized by endophytic fungi. A total of 1830 fungal isolates were obtained and identified by morphological and molecular [internal transcribed spacer (ITS) and translation elongation factor-1alpha gene region (TEF-1alpha) sequencing] techniques. One hundred and forty-two fungal species were identified, belonging to 57 genera. Sterile mycelia were assigned to 177 morphospecies. Fusarium and Phoma species were the most frequent genera, followed by Aspergillus, Alternaria and Acremonium. Fungal root endophytic communities were influenced by the soil type where their respective host plants grew, but not by location (coastal or inland sites). Fusarium oxysporum, Aspergillus fumigatus and Alternaria chlamydospora contributed most to the differences found between endophytic communities from sandy and saline soils. Host preference was found for three Fusarium species studied. Fusarium oxysporum and Fusarium solani were especially isolated from plants of the family Leguminosae, while Fusarium equiseti showed a preference for Lygeum spartum (Gramineae). In some cases, specificity could be related to intra-specific variability as shown by sequencing of the TEF-1alpha in the genus Fusarium.     

Fungal populations on sunflower ( Helianthus annuus ) anthosphere and their relation to susceptibility or tolerance to Sclerotinia sclerotiorum attack

Analysis of the fungal flora from different floret parts of various sunflower (Helianthus annuus) varieties showed that there are differences in both fungal species and frequency, depending on whether the sunflower variety is susceptible (SV) or tolerant (TV) to attack of the flower heads by the ascomycete pathogen Sclerotinia sclerotiorum. The sunflower varieties analyzed were SV: HA 300 and Z 20028, and TV: HA 302, Z AV 8410 and Z 30629. The isolates showed different “in vitro” behavior as biocontrol agents. The most common types of interaction with Sclerotinia sclerotiorum were D2 and D2+ (hyphal contact) for isolates from SV and TV, while some of the isolates from TV displayed antibiosis. The microorganisms that colonize TV florets play a part in an indirect mechanism that protects flowers from ascospore germination and pathogen growth. This revised version was published online in June 2006 with corrections to the Cover Date.     

骏枣内生生防细菌的分离、筛选与鉴定

选择交城骏枣(Zizyphus jujube cv.Jiaocheng Junzao)作为分离内生细菌的材料,从中共分离到18株内生菌株,运用平板对峙法从中筛选出5株对大枣病原菌及部分植物病原菌有拮抗作用的内生细菌。抑菌试验结果表明:筛选出的5株细菌对刺盘胞菌Colletotrichum gloeosporides、链格孢菌Alternaria alternata、尖孢镰刀菌Fusarium oxysporium、烟草赤星病菌Alternarial longipes、稻瘟病菌Pyricularia oryzae、人参立枯病菌Rhizoctonia solani、人参菌核病菌Sclerotinia schinseng和小麦根腐病菌Bipolaris sorokiniana均有一定的抑菌活性。对这5株内生细菌进行了形态特征观察和生理生化鉴定。     

链孢粘帚霉几丁质酶的诱导及其抗真菌活性研究

链孢粘帚霉HL-1-1菌株在不同培养条件下产几丁质酶活性不同,核盘菌菌核对其几丁质酶的诱导作用高于几丁质;首次用菌核配制培养基成功诱导了几丁质酶的产生,其产酶的最适初始pH值为4.5,最适培养时间为6d。几丁质酶对10种病原菌都有不同的抑制作用,对小麦雪腐病、葡萄白腐病、玉米黄斑病及斑点落叶病等病原菌的孢子萌发具有明显的抑制作用;该几丁质酶还能明显抑制核盘菌和立枯丝核菌的菌核萌发。     

Mycoflora of Iranian Maize Harvested in the Main Production Areas in 2000

Maize is one of the most important cereals produced in, and imported into, Iran. The incidences of seed-borne fungi were determined in Iranian maize harvested in 2000 from four major production areas with different climatic conditions, namely Fars, Khuzestan, Kermanshah and Mazandaran provinces. This is the first study to compare the mycoflora of maize in the aforementioned areas. Mycological analyses showed a predominance of Fusarium species (38.5%), followed by Aspergillus species (8.7%), Rhizopus species (4.8%), Penicillium species (4.5%), Mucor species (1.1%), and four other fungal genera. Fusarium verticillioides was the most prevalent species (83% of Fusarium isolates and 52% of the total isolations), with the highest incidence in Mazandaran (59%), a region of Iran with the highest rainfall and relative humidity, high rate of esophageal cancer (EC) and high levels of fumonisins in maize. Aspergillus flavus was the most widely recovered Aspergillus species and 38% of samples were contaminated with this potentially aflatoxigenic fungus. The incidence of A. flavus was highest in Kermanshah, the province with lowest mean minimum temperature. Penicillium species were seen in all the samples and Fars had the highest incidence, with highly significant differences when compared to the other three provinces. Diplodia species were not isolated from any of the samples examined.     

RAPD-based Molecular Diagnosis of Mixed Fungal Infections on Oilseed Rape (Brassica napus): Evidence for Genus- and Species-specific Sequences in the Fungal Genomes

Oilseed rape ( Brassica napus ) is attacked by many parasitic fungi which often occur in mixed infections. Monitoring of these phytopathogens by morphological criteria is restricted due to their appearance especially in the later stages of disease development.
We have developed molecular markers for a clear-cut differentiation of a variety of rape seed pathogenic fungi based on randomly amplified polymorphic DNA (RAPD). Twenty polymorphic fragments have been selected in Southern hybridization experiments to test their taxon-specificity. In summary, only four amplification products gave unspecific cross-hybridization patterns, one fragment corresponds to a genetic element common to three species within the genus Alternaria , and 15 RAPD markers were highly specific for distinct fungal species. This report demonstrates the value of the RAPDPCR technique to amplify taxon-specific DNA fragments that can be used as hybridization probes for the diagnosis of a variety of rape seed pathogens ( Alternaria brassicae, A. brassicicola, A. raphani: Cylindrosporium concentricum; Fusarium moniliforme; Phoma lingam; Pythium sp.; Rhizoctonia solani, Sclerotinia sclerotiorum; Verticillium dahliae, V. latericium ).     

Fungal biodiversity in the air of Turin

The qualitative fungal composition of Turin 's atmospheric environment was surveyed, carrying out a twelve-month study and collecting with a single stage volumetric sieve sampler on Dermasel agar supplemented with 0.4 g l^–1 cycloheximide and 0.05 g l^–1 chloramphenicol. We isolated 165 species and 2 varieties of mesophilic fungi from 58 genera and 26 thermotolerant species from 12 genera. Penicillium, Aspergillus, Acremonium, Chrysosporium, Scopulariopsis, Malbranchea, Paecilomyces, Phialophora and Cladosporium were in sequence the genera most rich in mesophilic species; Aspergillus, Penicillium, Chrysosporium and Scopulariopsis the most rich in thermotolerant species. Many of the species isolated are rarely or never recorded in the atmospheric environment. Cycloheximide can thus be said to select among airborne fungi, giving a characteristic picture.Abbreviation CH Cycloheximide - cfu colony forming unit     

18份广东香蕉种质对枯萎病的抗性评价

【背景】香蕉枯萎病是世界性的香蕉毁灭性病害,尚无有效药剂防控,筛选抗病品种是目前理想的防治方法。【方法】采用组培苗伤根接种法,研究了18份香蕉种质对香蕉枯萎病菌4号生理小种的抗性水平,并根据病情指数进行抗性分级。【结果】在供试的18份香蕉种质中,2份(东莞大蕉、抗枯5号)高抗,2份(碧盛、大丰)抗病,3份(抗枯1号、粉杂、农科1号)中抗,7份(粤优抗1号、广东-741、泰国B9、大蕉、台湾8号、海贡蕉、威廉斯8818)感病,4份(巴西、广东2号、广粉1号、粉蕉)高感。【结论与意义】不同香蕉种质对香蕉枯萎病菌4号生理小种的抗病性存在较大差异,本研究初步筛选出7份抗枯萎病的香蕉种质,为香蕉枯萎病抗病育种提供了依据,为病区种植香蕉品种提供了有效参考。     

Czapek-Dox agar containing iprodione and dicloran as a selective medium for the isolation of Fusarium species

A new selective medium for Fusarium species has been developed using Czapek-Dox agar (CZ) containing the fungicides iprodione (3 mg/1) and dicloran (2 mg/1). This new medium (CZID) is selective against numerous species of Alternaria, Epicoccum, Penicillium and mucoraceous fungi. CZID was compared with CZ using samples of barley, malt, sorghum, bean and pea. Fusarium species produced large and easily recognizable colonies on CZID while isolates of Alternaria, Epicoccum and Rhizopus were significantly restricted on CZID compared with their growth on CZ. The use of CZID thus facilitates the isolation and subculturing of Fusarium species.     

Interaction of cruciferous phytoanticipins with plant fungal pathogens: indole glucosinolates are not metabolized but the corresponding desulfo-derivatives and nitriles are

Glucosinolates represent a large group of plant natural products long known for diverse and fascinating physiological functions and activities. Despite the relevance and huge interest on the roles of indole glucosinolates in plant defense, little is known about their direct interaction with microbial plant pathogens. Toward this end, the metabolism of indolyl glucosinolates, their corresponding desulfo-derivatives, and derived metabolites, by three fungal species pathogenic on crucifers was investigated. While glucobrassicin, 1-methoxyglucobrassicin, 4-methoxyglucobrassicin were not metabolized by the pathogenic fungi Alternaria brassicicola, Rhizoctonia solani and Sclerotinia sclerotiorum, the corresponding desulfo-derivatives were metabolized to indolyl-3-acetonitrile, caulilexin C (1-methoxyindolyl-3-acetonitrile) and arvelexin (4-methoxyindolyl-3-acetonitrile) by R. solani and S. sclerotiorum, but not by A. brassicicola. That is, desulfo-glucosinolates were metabolized by two non-host-selective pathogens, but not by a host-selective. Indolyl-3-acetonitrile, caulilexin C and arvelexin were metabolized to the corresponding indole-3-carboxylic acids. Indolyl-3-acetonitriles displayed higher inhibitory activity than indole desulfo-glucosinolates. Indolyl-3-methanol displayed antifungal activity and was metabolized by A. brassicicola and R. solani to the less antifungal compounds indole-3-carboxaldehyde and indole-3-carboxylic acid. Diindolyl-3-methane was strongly antifungal and stable in fungal cultures, but ascorbigen was not stable in solution and displayed low antifungal activity; neither compound appeared to be metabolized by any of the three fungal species. The cell-free extracts of mycelia of A. brassicicola displayed low myrosinase activity using glucobrassicin as substrate, but myrosinase activity was not detectable in mycelia of either R. solani or S. sclerotiorum.     

Genetic and physiological response to fumonisin and AAL-toxin by intact tissue of a higher plant

The differential phytotoxicity of purified AAL-toxin to lines of tomato isogenic for the Asc gene parallels resistance to Alternaria alternata f.sp. lycopersici. This relationship, as reported earlier, is consistent with the role of AAL-toxin as a host-specific toxin with the role of a primary chemical determinant of Alternaria stem canker. Current results indicate the pathogen and the AAL-toxin also can be recovered from ripe fruit with symptoms of the disease known as black mold. Fumonisins are structurally similar to the AAL-toxins but are secreted by Fusarium moniliforme which is taxonomically distinct from A. alternata. F. moniliforme, is not pathogenic on living tomato tissues but was recovered from ripe tomato fruit with symptoms of black mold. The penetration of ripe fruit and subsequent colonization by both fungi appears to be saprophytic. Fumonisins and AAL-toxins express equivalent genotype-specific activity against the isogenic Asc lines of tomato and produce equivalent necrotic symptoms in tomato leaflet bioassays. Evidence was obtained that the biosynthetic pathway for production of these toxins is present in several species of both Alternaria and Fusarium. Toxin biosynthesis was sensitive to nutritional regulation in both genera. However, pathogenicity on tomato was not altered by the medium used for inoculum production in either genera and remained restricted to A. alternata f.sp. lycopersici in the studies reported here. Differences in the amount of toxin produced were found among isolates of both genera while the magnitude of the differences was defined by the substrate on which the fungi were grown.     

Mechanisms of natural soil suppressiveness to soilborne diseases

Suppressive soils are characterized by a very low level of disease development even though a virulent pathogen and susceptible host are present. Biotic and abiotic elements of the soil environment contribute to suppressiveness, however most defined systems have identified biological elements as primary factors in disease suppression. Many soils possess similarities with regard to microorganisms involved in disease suppression, while other attributes are unique to specific pathogen-suppressive soil systems. The organisms operative in pathogen suppression do so via diverse mechanisms including competition for nutrients, antibiosis and induction of host resistance. Non-pathogenic Fusarium spp. and fluorescent Pseudomonas spp. play a critical role in naturally occurring soils that are suppressive to Fusarium wilt. Suppression of take-all of wheat, caused by Gaeumannomyces graminis var. tritici, is induced in soil after continuous wheat monoculture and is attributed, in part, to selection of fluorescent pseudomonads with capacity to produce the antibiotic 2,4-diacetylphloroglucinol. Cultivation of orchard soils with specific wheat varieties induces suppressiveness to Rhizoctonia root rot of apple caused by Rhizoctonia solani AG 5. Wheat cultivars that stimulate disease suppression enhance populations of specific fluorescent pseudomonad genotypes with antagonistic activity toward this pathogen. Methods that transform resident microbial communities in a manner which induces natural soil suppressiveness have potential as components of environmentally sustainable systems for management of soilborne plant pathogens. This revised version was published online in August 2006 with corrections to the Cover Date.