镰刀菌属一个中国新记录种

从山西省13个主要土壤类型的1 012个土壤样品中分离出镰刀菌333株,依据布斯的镰刀菌属分类系统鉴定其中1株为中国新记录种——柔毛镰刀菌(Fusarium flocciferum Corda),并对其进行描述和讨论。菌种保存于山西农业大学农学院植物病理实验室。     

连栽杉木根际土壤镰刀菌属真菌群落变化规律

为探讨连栽对杉木(Cunninghamia lanceolata (Lamb.) Hook.)根际土壤镰刀菌属真菌多样性的影响,本研究应用DGGE技术研究连栽杉木根际土壤镰刀菌属(Fusarium)真菌在一代杉木人工林(first rotation Chinese fir plantation,FCP)、二代杉木人工林(second rotation Chinese fir plantation,SCP)与三代杉木人工林(third rotation Chinese fir plantation,TCP)的组成及含量变化,并结合qRT-PCR技术测定杉木根际土壤病原菌尖孢镰刀菌(Fusarium oxysporum)的绝对含量变化,从而揭示杉木连栽障碍土壤微生态失衡现象。DGGE结果表明,多代连栽后杉木根际土壤镰刀菌属真菌组成及含量均发生显著变化,优势菌尖孢镰刀菌含量随着栽植代数的增加显著上升。主成分分析能较好区分FCP、SCP与TCP根际土壤镰刀菌群落特征。聚类分析结果表明,TCP土壤镰刀属结构组成及百分含量与FCP、SCP差异显著。多样性分析结果显示,连栽杉木土壤镰刀菌多样性与丰富度均呈现FCPSCPTCP。qRT-PCR分析表明,FCP、SCP与TCP根际土壤尖孢镰刀菌的绝对含量随栽植代数增加不断上升,进一步验证了DGGE结果。由此推测,杉木连栽障碍与根际土壤微生态失衡密切相关,其中尖孢镰刀菌含量的上升是重要因素之一。     

生防菌根系定殖竞争作用对西瓜枯萎病发病机理的影响

【目的】西瓜枯萎病是由西瓜专化型尖孢镰刀菌(Fusarium oxysporum f.sp.niveum)引起的一种常见的毁灭性土传病害,对镰刀菌同属非致病性菌株与致病性菌株存在的竞争作用进行研究,有助于获得新的具有生防效果的菌株,从而拓宽西瓜枯萎病生物防治的手段。【方法】利用选择性培养基和稀释平板计数法对温室盆栽试验中西瓜根际和非根际土壤及植物组织中非致病性轮枝镰刀菌菌株(Fusarium verticillioides XA)与致病性尖孢镰刀菌(Fusarium oxysporum LD)进行计数,确定其在西瓜植株根际和组织中的定殖情况。【结果】将从田间西瓜枯萎病发病植株根部分离获得的菌株XA和LD接入健康土壤中,接种菌株XA既不会引起西瓜枯萎病发病症状,也不会影响西瓜植株生物量,但接种菌株LD导致严重发病症状。与单接种LD处理相比较,双接种(XA+LD)处理地上部鲜重和地上部干重都分别增加了151.2%和110%。XA菌株能成功定殖于西瓜根系,但在茎基部没有检测到。在接种菌株LD的处理中植物组织和土壤中致病性镰刀菌的数量达到(1.58 4.85)×104CFU/g。与单接种LD处理相比,双接种菌株XA和LD处理植物茎基部、根系、根际土壤和土体土壤致病性镰刀菌的数量分别下降63.3%、66.1%、3.3%和24.4%,根系、根际土壤和土体土壤非致病性镰刀菌的数量增加到(0.35 3.84)×104CFU/g;双接种处理对西瓜枯萎病的防效达57.8%。【结论】非致病性轮枝镰刀菌菌株XA可有效降低致病性尖孢镰刀菌LD对西瓜植株的定殖侵染能力,对西瓜枯萎病具有一定的生防效果。     

湖北省蔬菜根际土壤中的镰孢菌分布特征

为明确湖北省蔬菜产区镰孢菌(Fusarium spp.)的种类及分布特征,本研究从湖北省13个地级市蔬菜产区采集根际土壤样品55份,对土样中的镰孢菌进行分离、纯化和鉴定,获得271株镰孢菌;通过镰孢菌特异性引物扩增、测序等分子生物学技术,鉴定出尖孢镰孢菌(F. oxysporum)118株,占分离菌株43.6%;木贼孢菌(F. equiseti)46株,占17.0%;共享镰孢菌(F.commune)45株,占16.6%;茄病镰孢菌(F. solani)31株,占11.4%;藤仓镰孢菌(F. fujikuroi)11株,占4.1%;镰孢霉菌(F.delphinoides)6株,占2.2%;轮纹镰孢菌(F. concentricum)5株,占1.8%;三线镰孢菌(F. tricinctum)3株,占1.1%;镰孢菌属(Fusarium spp.)6株,占2.2%。通过与致病菌尖孢镰孢菌番茄专化型(F. oxysporum f. sp. lycopersici)菌株进行对峙培养,筛选出拮抗镰孢菌16株,包括尖孢镰孢菌(F. oxysporum)4株,茄病镰孢菌(F. solani)4株,轮纹镰孢菌(F. concentricum)3株,三线镰孢菌(F.tricinctum)3株,木贼孢菌(F. equiseti)和藤仓镰孢菌(F. fujikuroi)各1株。本研究明确了湖北省蔬菜产区的镰孢菌属真菌的种类和多样性特征,为蔬菜镰孢菌病害的防治提供科学依据。     

禾谷镰刀菌降解毒素基因Tri101的克隆和序列分析

禾谷镰刀菌Tri101基因编码的单端孢酶烯3-O-乙酰转移酶可通过加乙酰基的形式使禾谷镰刀菌产生的单族毒素(如DON)转变为较低的毒性。本研究利用RT-PCR技术从禾谷镰刀菌0623中扩增并克隆了Tri101基因的cDNA片段,测序结果表明,Tri101基因核苷酸序列阅读框架全长1356bp(GenBank序列号:GQ907236),编码451个氨基酸的多肽,推测分子量为49.45kD,等电点为5.14。氨基酸序列同源性比对结果表明,它与Kimura报道的禾谷镰刀菌Tri101氨基酸序列同源性最高,为99.56%,与其它13种镰刀菌的Tri101氨基酸序列的同源性分别为97.91%-75.68%。系统进化树分析结果表明,Fusarium graminearium0623与Fusarium sporotrichioides属于同一进化枝且与Fusarium asiaticum有较近的亲缘关系,而与F.oxysporum、F.moniliforme、F.nygamai、F.nisikadoi和F.decemcellulare的亲缘关系较远。     

三江平原地区大豆根腐病病株上镰孢菌的分离鉴定

为了明确引起三江平原地区大豆根腐病的镰孢菌(Fusarium)种类及优势种群,对该地区大豆根腐病样本进行了采集。通过组织分离和形态学鉴定,共鉴定出6种镰孢菌,分别为木贼镰孢(F.equiseti)、尖孢镰孢(F.oxysporum)、芬芳镰孢(F.redolens)、半裸镰孢(F.semitectum)、腐皮镰孢(F.solani)和拟轮枝镰孢(F.verticillioides)。其中尖孢镰孢(F.oxysporum)的分离频率最高,达16.67%。对6种镰孢菌的形态学特征进行了描述。     

辽宁地区药用植物根际土壤真菌多样性的研究

作者于2007和2008年的5-10月间在辽宁省的丹东、凤城、清原、桓仁等药材产区采集土壤样品200余份,通过采用稀释平板法和土壤颗粒平板法进行土壤真菌的分离和培养,共分离和鉴定出27属54种真菌,其中接合菌2属3种、子囊菌1属1种、无性型真菌24属50种。分离到的部分真菌种类是重要的药用植物病原菌,如Cylindrocarpon destructans、Fusarium oxysporum和F.solani。研究发现,Penicillium paxilli、P.expansum、Trichoderma atroviride及T.viride的分离频率最高,是辽宁省4个调查地区药用植物根际土壤真菌的优势菌群。     

西瓜枯萎病拮抗链霉菌分离鉴定及盆栽抗病试验

旨在筛选出能高效抑制西瓜枯萎病病原菌尖孢镰刀菌(Fusarium oxysporum f.sp.niveum)的天然拮抗菌。采用梯度稀释法分离连作辣椒根际土中的放线菌,纯化后用平板对峙法筛选出有拮抗作用的菌株,采用盆钵育苗基质拌菌法接种,进行盆栽抗病试验,并对拮抗效果最佳的菌株进行鉴定。结果显示,从连作辣椒根际土中,分离筛选出10株对西瓜枯萎病有拮抗作用的放线菌,其中菌株F22、F23、F32的拮抗作用显著。96 h抑菌圈直径分别达到1.70、1.17和1.47 cm。盆栽试验结果表明,拮抗菌株F32对西瓜枯萎病30 d的防治效果最佳,防效率达到66.7%,且抗菌谱性广。根据表型特征、生理生化特性和16S r DNA分子鉴定结果可知,菌株F32为链霉菌属(Streptomyces sp.),且对西瓜枯萎病有良好的防治作用,是一株具有应用价值的生防菌株。     

乌头根腐病病原菌的分离与鉴定

【背景】四川江油地区栽培乌头极易发生根腐病,植株染病后枯萎死亡,最终影响药材产量。因发病因素和致病菌多样,乌头根腐病的防治向来困难。【目的】鉴定四川江油地区栽培乌头根腐病病原菌,为病害诊断和防治提供理论基础。【方法】采用组织分离法进行病原菌分离;按照Koch’s法则对分离的病菌进行致病性验证;通过形态学观察和真菌r DNA-ITS序列分析,鉴定病原菌种类。【结果】从具有根腐病症状的乌头根部分离得到47株真菌,其中菌株GF3-3、GF3-6和GF6-1是乌头根腐病的致病菌;通过形态特征结合rDNA-ITS序列分析将菌株GF3-3、GF3-6和GF6-1分别鉴定为Fusariumsolani、F.oxysporum和F.proliferatum。【结论】茄腐镰刀菌(F.solani)、尖孢镰刀菌(F. oxysporum)和层出镰刀菌(F. proliferatum)是乌头根腐病的主要病原菌,其中层出镰刀菌引起乌头患根腐病为首次报道。     

偏肿栓菌内生木霉菌株18-21抑菌效果研究

为了筛选获得对植物根腐病及食用菌腐败等有效的生防菌,采用抑菌圈法和对峙培养法筛选生防菌株,通过形态学和16S r DNA分子鉴定确定生防菌分类地位。从1株野生偏肿栓菌Trametes gibbosa子实体中分离获得1株具有抑菌效果的生防菌,代号为18-21。筛选获得的这株生防菌对植物根腐病及食用菌腐败病原菌腐皮镰刀菌(Fusarium solani)、三线镰刀菌(Fusarium tricinctum)的抑制率分别为56.7%、65.8%,并对铜绿假单胞菌(Pseudomonas aeruginosa)、枯草芽胞杆菌(Bacillus subtilis)、侧芽胞杆菌(Bacillus latersprorus)、表皮葡萄球菌(Staphylococcus epidermidis)等病原细菌均具有显著的抑菌效果,通过形态学和分子生物学分类鉴定,确定为渐绿木霉(Trichoderma viridescens)。研究结果拓宽了生防菌的分离材料来源,丰富了生防资源,具有很大的应用潜力。     

临床常见镰刀菌的鉴别

目的从分子生物学角度寻找一种快速准确鉴定临床常见镰刀菌的方法。方法将受试镰刀菌接种于PDA培养基,观察其菌落及镜下形态,在此基础上PCR扩增受试镰刀菌的rDNA ITS并测其序列,在GenBank核酸序列数据库进行同源序列搜索及分析。选择限制性内切酶Dra Ⅱ和Cfr13 Ⅰ进行RFLP。设计了茄病镰刀菌的种特异性引物Sol1、Sol2,初步验证其特异性。结果形态学鉴定结果显示,茄病镰刀菌所占比例最高,除2株串珠镰刀菌外,其余镰刀菌ITS序列分析的结果与形态学鉴定结果一致。茄病、层生和串珠镰刀菌的Dra Ⅱ、Cfr13 I酶切带形互不相同。用Sol1、Sol2扩增受试菌的rDNA ITS,只有茄病镰刀菌为阳性。结论rDNA ITS序列测定及其PCR-RFLP可用于初步鉴别几种临床常见镰刀菌,合适的种特异性引物可以初步快速鉴定茄病镰刀菌。     

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.     

Antifungal activity of rhizospheric bacteria

Fluorescent Pseudomonad spp. were isolated from the rhizosphere of potato plants (Algeria) by serial dilutions of rhizosphere soils on Kings B medium and were tested for their antifungal activity. The antifungal activity of the Pseudomonas isolated from Potatoes rhizosphere was tested against Pythium ultimum, Rhizoctonia solani and Fusarium oxysporum in dual culture with bacteria on PDA. The Petri dish was divided into tow, on one the bacteria was spread and on the opposite side fungal plugs were inoculated and incubated for one week. Fourteen bacteria were isolated; only one isolate inhibited the growth of Pythium ultimum, Rhizoctonia solani, Fusarium solani; Fusarium oxysporum f.sp. albedinis and Fusarium oxysporum f. sp. Lycopersici with inhibition zones of 39.9, 33.7, 30.8, 19.9 and 22.5 mm respectively.     

牛蒡的研究现状

牛蒡为菊科牛蒡属两年生植物,其根、茎叶和果实均可入药。近年来关于牛蒡各方面的研究很多,本文拟从化学成分及其立体化学、药理活性和代谢几个方面对其进行综述,以便于进一步研究与开发。     

Non-pathogenic Fusarium solani represses the biosynthesis of nematicidal compounds in vitro and reduces the biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato

AIMS: The aim of the present investigation was to determine the influence of various Fusarium solani strains on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. METHODS AND RESULTS: Culture filtrates (CF) of P. fluorescens strain CHA0 and its diacetylphloroglucinol-overproducing derivative CHA0/pME3424 caused substantial mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with the growth medium of F. solani repressed the nematicidal activity of the bacteria. Methanol extract of F. solani CF resulting from Czapek's Dox liquid (CDL) medium without zinc amendment repressed the nematicidal activity of the bacteria while the CF obtained from CDL medium amended with zinc did not. Conidial suspension of F. solani strain Fs5 (repressor strain for the biosynthesis of nematicidal compounds in P. fluorescens) reduced biocontrol potential of the bacterial inoculants against M. javanica in tomato while strain Fs3 (non-repressor) did not. CONCLUSIONS: Fusarium solani strains with increased nematicidal activity repress the biosynthesis of nematicidal compounds by P. fluorescens strains in vitro and greatly alter its biocontrol efficacy against root-knot nematode under natural conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Fusarium solani strains are distributed worldwide and found in almost all the agricultural fields which suggest that some mycotoxin-producing strains will also be found in almost any soil sample taken. Besides the suppressive effect of these metabolite-producing strains on the production of nematicidal compound(s) critical in biocontrol, F. solani strains may also affect the performance of mycotoxin-sensitive biocontrol bacteria effective against plant-parasitic nematodes.     

Morphological and Molecular Characterization of Fusarium solani Isolates

Fusarium solani is a species complex (FSSC) containing isolates that cause diseases in important crops such as root and fruit rot of Cucurbita spp., root and stem rot of pea, sudden death syndrome of soybean, foot rot of bean and dry rot of potato tubers during storage. Based on host range tests, F. solani were subdivided into different formae specialis (f. sp.) and varieties, while DNA sequences of 28S rDNA, internally transcribed spacers (ITS) rDNA and elongation factor (EF-1α) distinguished the ' F. solani complex' in 50 subspecific lineages. In this study we characterized, by cultural, morphological and molecular criteria, 34 isolates of F. solani obtained from potato, other crops and soil. The 34 isolates in the FSSC showed wide variability for their cultural, morphological and molecular traits. The wide variability observed with amplified fragment-length polymorphism (AFLP) and mini-microsatellite analyses is in agreement with the polymorphism observed, in a previous study, within FSSC. Nine of 34 isolates in the FSSC, classified as F. solani var. coeruleum , were morphologically distinguishable from the other F. solani isolates but they were distributed in different clusters; moreover, the nine isolates showed instability of the coeruleum pigmentation of the colonies, supporting the ambiguity of the taxa of this variety of F. solani. Using sequence data from ITS plus 5.8S rDNA region, the isolates were classified into different clades. In particular eight isolates were classified into a well-supported clade including F. solani f. sp . pisi , nine into a clade including only isolates of F. solani f. sp . radicicola and four into a clade including F. solani f. sp . cucurbitae , but this classification could not be used if is not in agreement with host specificity. Two of the nine F. solani var. coeruleum isolates were phylogenetically distinct from all the other FSSC strains.     

Differentiation of Fusarium oxysporum from Fusarium solani by growth and pigmentation on media containing sugar alcohols

The growth and pigmentation of 99 strains of Fusarium , mainly of Fusarium oxysporum and F. solani , on ammonium salts agar containing either mannitol, sorbitol or xylitol as sole source of carbon is described. After 7–14 d incubation strains of F. oxysporum could be distinguished from F. solani by both their pigmentation and the size and shape of conidiogenous cells. The application of these media to routine screening of isolates is discussed.     

长期连作对大豆根际土壤镰孢菌种群的影响

利用中国科学院海伦农业生态试验站大豆连作长期定位试验区,进行了大豆根际土壤镰孢菌分离鉴定及大豆根腐病致病力检测,结合核酸序列和限制性片段长度多态性(RFLP)的系统发育分析,研究了长期连作(20年)较短期连作(3年)对大豆根际土壤镰孢菌种群密度和结构、致病力及遗传多样性的影响.结果表明： 3年连作大豆根际土壤镰孢菌种群密度为6.0×10⁴ CFU·g^-1,且以强致病力的尖镰孢菌、禾谷镰孢菌、轮枝镰孢菌及中等致病力的腐皮镰孢菌为优势种;连作20年大豆根际土壤镰孢菌种群密度和优势菌的优势度均显著低于3年连作,其中尖镰孢菌、禾谷镰孢菌和腐皮镰孢菌的种群密度仅为3年连作的36%、32%和22%,没有分离到致病力最高的轮枝镰孢菌,而种群多样性和均匀度显著高于3年连作;仅分离自20年连作土壤的三线镰孢菌、砖红镰孢菌及燕麦镰孢菌均为非致病菌种,且与强致病力镰孢菌种在基于转录间隔区(ITS)和转录延长因子(EF-1α)序列的聚类分析中显示了系统进化亲缘关系的差异性.因此,大豆20年连作会导致根际土壤镰孢菌种群生长受抑制、使其种群结构和遗传多样性发生改变,同时降低大豆根腐病菌种群致病力.     

Identification, Pathogenicity and Comparative Virulence of Fusarium spp. Associated with Diseased Euphorbia spp. in Europe

Fusarium spp. isolated from diseased Euphorbia spp. in Europe were assessed for pathogenicity to North American accessions of leafy spurge ( Euphorbia esula/virgata ). Of the nine strains of Fusarium spp. isolated from diseased E. stepposa or E. virgata in the Caucasus region of Russia and E. esula/virgata in southern France, all were pathogenic to leafy spurge. There were significant differences in virulence among strains. Four strains, including the two that were most virulent, were identified as F. oxysporum . Four of the five other strains were identified as F. solani and one was identified as F. proliferatum . Three of the four most virulent strains to leafy spurge were isolated from E. stepposa . The most virulent strain was associated with root damage caused by insect biological control agents, as found earlier with domestic strains of Fusarium spp. pathogenic to leafy spurge. Two strains identified as F. solani were vegetatively compatible. It was concluded that further screening of a larger set of strains of foreign Fusarium spp. under quarantine conditions in the US or in limited overseas facilities would be justified, and could yield promising biological control agents for leafy spurge.     

Soil fungistasis: elevation of the exogenous carbon and nitrogen requirements for spore germination by fungistatic volatiles in soils.

Axenic, washed conidia of Fusarium solani f. sp. phaseoli, Aspergillus flavus, and Verticillium albo-atrum were placed on washed Difco purified agar discs along with an inorganic salt solution containing various levels of carbon and nitrogen substrates. These discs were exposed to volatiles from six soils (pH 5.1-8.6). Fusarium solani macroconidial germination was inhibited mostly by volatiles from soils of pH 5.1, 6.1, 7.0, and 7.5, but high levels of glucose and NH4Cl reversed this inhibition, raising germination to that of no-soil, no-carbon or nitrogen controls. Conidial germination of A. flavus was inhibited mainly by volatiles from high pH (7.0, 7.8, and 8.6) soils, and increased levels of glucose plus an amino acid mixture nullified this inhibition. Volatiles from soils of pH 5.1, 6.1, and 7.5 stimulated A. flavus conidial germination. Assays after the removal of CO2 from the air above soil of pH 5.1 demonstrated that volatiles inhibitory to A. flavus were produced by this soil. Assays indicated that a KOH-soluble compound was a fungistatic soil volatile to F. solani macroconidial germination. The nullification by carbon and nitrogen substrates of F. solani and A. flavus inhibition caused by soil volatiles parallels that for soil fungistasis. Conidial germination of V. albo-atrum was markedly stimulated by volatiles in all soils tested, and was not affected by removal of CO2. Inhibitory soil volatiles may increase the nutritional requirements for spore germination of certain fungi.