Screening for Siderophore-producing Endophytic Bacteria against Fusarium oxysporum

[Objective] With a strain of endophytic antagonistic bacteria with good disease control efficacy in pot as trial material,the paper was to explore the antagonistic mechanism of siderophore against Fusarium oxysporum.[Method] Whether the strain produced siderophore and its fluorescent property was judged by MSA（Modified Sugar-Aspartic acid） plate.The siderophore activity of strains in liquid MSA medium was determined through the absorbance values at particular wavelength.The inhibition effects of it siderophore against F.oxysporum under different concentrations of Fe3＋ were compared.Then the strain was preliminarily identified based on morphological,physiological and biochemical characteristics [Result] The fluorescent siderophore produced by the endophytic bacteria in MSA medium had a strong inhibition effect against F.oxysporum.With the increasing concentration of Fe3＋,the inhibition effect against the pathogen weakened.The preliminary analysis showed these strains belonged to Bacillus.[Conclusion] Bacillus could compete the absorption of Fe3＋ by secreting siderophore to inhibit the growth of F.oxysporum.

非致病性镰刀菌Fusarium oxysporum菌株47(FO47)对番茄枯萎病的防治效果

本实验对非致病镰刀菌Fusariumoxysporum菌株47号(简称FO47)对番茄枯萎病的生物防治效果进行了初步研究。通过对峙培养和多孔细胞培养板测试以及室内盆栽试验表明,FO47在对峙培养平板上对番茄枯萎病菌无拮抗作用;施用FO47的最佳时机是番茄播种至子叶平展期,最佳施用浓度为105～108分生孢子/毫升(简写为cfu·ml-1),防效为63.6%;结果还表明FO47液体培养的过滤液能有效抑制番茄枯萎病菌孢子的萌发,抑制萌发率为81.7%。

Inhibitive Activity of the Extracts of Plants in Artemisia against Fusarium oxysporum f. sp. vasinfectum and Fusarium momiliforme

[Objective]The aim was to provide theoretical basis for the control of cotton Fusarium wilt and cotton boll rot disease.[Method]The inhibitory activity of the extracts from three species of plants(Artemisia annual L.,Artemisia capillaris Thunb.,Artemisia argyi Levl.et Vant)against Fusarium oxysporum f.sp.vasinfectum and Fusarium moniliforme were studied under the condition of laboratory.[Result]The extracts of all the three plants in Artemisia showed strong antifungal activity against the tested pathogenic ...

Reactions of Oil Palm (Elaeis guineensis Jacq) Progenies to Fusarium Wilt Disease Caused by Fusarium oxysporum f.sp. Elaeidis under Natural Infection

The oil palm (Elaeisguineensis Jacq) is used worldwide in commercial agriculture for the production of palm oil, palm kernel oil and palm wine. It produces more oil per plant than any other oil-producing crop in the world. Production is constrained by several factors among which pests/diseases are of utmost importance. Vascular wilt (VW) caused by Fusarium oxysporum is the most devastating disease infecting this crop. Its soil-borne ecology has made the use of fungicides to manage this disease too expensive and inpragmatic. There is need for concerted research in the breeding and selection of wilt-tolerant progenies as an essential step in the management of Fusarium wilt disease. The study aims to assess the incidence and severity of vascular wilt among tested oil palm progenies, to evaluate the reduction in yield caused by the disease in the susceptible progenies and to identify the wilt-tolerant, high-yielding progenies. The study was carried out at Pamol Plantations Limited (PPL) in Ndian Estate (Ndian Division), in the Southwest Region of Cameroon. Three field trials were evaluated for tolerance/susceptibility to Fusarium wilt. Each trial consisted of 15 oil palm progenies replicated 4 times. Each progeny had 25 oil palm stands in each replicate. Hence, a total of 1500 oil palm stands were assessed. The experimental design was a randomized complete block (RCB) with trial codes: Trial 2001/1, planted in 2001;Trial 2001/2, planted in 2002;Trial 2001/3, planted in 2003. Each trail had an area of 12 ha, with a plant density of 143 palms·ha−1. Wilt incidence, severity, index, and yield were evaluated on 45 progenies from the 3 trails after identifying Fusarium oxysporum from oil palm plant part. Data was subjected to analysis of variance, Fischer’s least significant difference test (LSD) for mean separation. Identification of Fusarium was based on descriptive analysis. Incidence of VW in the 3 trials ranged from 1% - 39%. Also, 45% of infected plants were from progeny 676 while 1% was from progenies 689, 693, 694 and 710. Disease severity was from 0.9 in progeny 686 to 4.55 in 676. Wilt index ranged from 131 for progeny 694 and 710 to 495 for progenies 705. Out of the 45 progenies evaluated, 27 were tolerant (1 < 100) and 18 susceptible (1 ≥ 100). Within the tolerant progenies, 4 were significant (1 < 20) while 5 out of 18 were significantly susceptible (1 ≥ 185). Mean yield reduction of the susceptible progenies was 34.8% while in the tolerant progenies, it increased by 9.5% when compared to their controls. Progenies 702, 703 and 709 are recommended for planting based on the level of tolerance to Fusarium wilt disease and yield.

Isolation and Identification of Shoot-Tip Associated Endophytic Bacteria from Banana cv. Grand Naine and Testing for Antagonistic Activity against <i>Fusarium oxysporum</i>f. sp. <i>cubense</i>

Endophytic bacteria colonizing the shoot-tips of banana cv. Grand Naine were isolated and tested for the antagonistic activity against the Panama wilt pathogen Fusarium oxysporum f. sp. cubense (Foc). Pre-isolation, the suckers were given extensive disinfection treatments and the homogenate from the excised shoot-tip portion was plated on nutrient agar (NA) and trypticase soy agar (TSA). This yielded altogether 47 isolates: 26 on NA and 21 on TSA, respectively, from the 10 suckers collected during August to February. The number of bacterial isolates obtained per sucker varied from one to 15 based on colony characteristics registering up to 10 distinct species per shoot-tip based on 16S rRNA sequence analysis. The 47 isolates belonged to 19 genera and 25 species under the phylogenetic classes of Actinobacteria, α- and γ-Proteobacteria and Firmicutes. Actinobacteria constituted the predominant phylum (55% isolates) with the constituent genera of Arthrobacter, Brevibacterium, Corynebacterium, Curtobacterium, Kocuria, Kytococcus, Micrococcus, Naumanella, Rothia and Tessaracoccus spp. and an unidentified isolate belonging to the family Frankiaceae. Proteobacteria constituted the second major phylum (Brevundimonas, Enterobacter, Klebsiella, Pseudomonas, Serratia and Sphingomonas spp.) followed by Firmicutes (Bacillus and Staphylococcus spp.). Antagonistic activity of the endophytes against Foc was tested through agar plate assays (pit and spot applications on fungal lawn) employing potato dextrose agar and NA. Endophytic Pseudomonas aeruginosa (isolate GNS.13.2a) which was associated with a single sucker showed significant growth inhibition effect on Foc while Klebsiella variicola (GNS.13.3a) and Enterobacter cloacae (GNS13.4a) exhibited moderate inhibition. The study brings out considerable sucker to sucker variation in the associated cultivable endophytic bacteria in “Grand Naine” banana and identifies a few bacterial endophytes with biocontrol potential against the devastating Foc pathogen.

Biochar alleviates apple replant disease by reducing the growth of Fusarium oxysporum and regulating microbial communities

Apple replant disease(ARD)negatively affects plant growth and reduces yields in replanted orchards.In this study,biochar was applied to apple replant soil with Fusarium oxysporum.Our aim was to investigate whether biochar could promote plant growth and alleviate apple replant disease by reducing the growth of harmful soil microorganisms,changing soil microbial community structure and improving the soil environment.This experiment included five treatments:apple replant soil(CK),methyl bromide fumigation apple replant soil(FM),replant soil with biochar addition(2%),replant soil with F.oxysporum spore solution(8×10^(7)spores·mL^(-1)),and replant soil with biochar and F.oxysporum spore solution addition.Seedling biomass,the activity of antioxidant enzymes in the leaves and roots,and soil environmental variables were measured.Microbial community composition and community structure were analyzed using 16SrDNA and ITS2 gene sequencing.Biochar significantly reduced the abundance of F.oxysporum and increased soil microbial diversity and richness.Biochar also increased the soil enzyme activities(urease,invertase,neutral phosphatase,and catalase),the biomass(plant height,fresh weight,dry weight)and the activity of antioxidant enzymes(superoxide dismutase,peroxidase,and catalase).The root indexes of apple seedlings was also increased in replant soil by biochar.In sum,biochar promoted the growth of plants,improved the replant soil environment,and alleviated apple replant disease.

Tolerance of New Introgressive Hybrid and Backcross Forms Pathogenic Micromitisms (<i>Verticillium dahliae</i>Kleb and Fusarium oxysporum f.sp. vasinfectum)

The article is based on the use of experimental polyploidy method, with the introduction of new introgressive hybrid forms combining several species genotype with pathogenic Verticillium dahliae Kleb. and the effects of mycotoxins separated from the Fusarium oxysporum f.sp. vasinfectum micromicette on the yield of plant seeds. New artificial complex hypertension forms based on experimental polyploidy Verticillium dahliae Kleb. and Fusarium oxysporum f.sp. vasinfectum combine the potential of resistance to mycotoxins separated from microcrystals, making a tremendous contribution to the selection of new varieties and to the effectiveness of selection as a result of the use of genetic selective research as genetic-selective genetic-selector studies.

Construction of PEG-mediated Genetic Transformation and Gene Knockout System in Fusarium oxysporum f. sp.cubense Tropic Race 4

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense tropic race 4(Foc TR4), is a typical vascular and soil-borne disease which has significantly threatened the sustainable development of banana industry. In order to reveal the infection process and pathogenesis of Foc TR4, the young mycelia(66.7 mg/ml) of wild-type strain of Foc TR4(WT-Foc TR4) cultured for 18-20 h were lysed with enzyme mixture for protoplast formation, which consisted of 25 mg/ml driselase, 0.4 mg/ml chitinase, 15 mg/ml lysing enzyme and 1.2 mol/L potassium chloride. The resulted protoplasts of 2×10~7 cells/ml were used to test the efficiency of transformation mediated by polyethylene glycol, and up to 9 transformants per microgram of DNA were obtained. AmCyan, RFP and YFP genes were stably transferred into the WT-Foc TR4, separately, using the protoplast transformation system. The gene FoOCH1 encoding α-1, 6-mannosyltransferase in the WT-Foc TR4 was knocked out using the split-marker recombination technology. The genetic transformation and gene knockout system in this pathogen lays a foundation for the study of functional genomics and plant-pathogen interactions.

Performance of Natural Antagonists and Commercial Microbiocides towards <i>in Vitro</i>Suppression of Flower Bed Soil-Borne <i>Fusarium oxysporum</i>

Fusarium oxysporum is the causal agent for wilt diseases of many major ornamental and horticultural crops. In this study, we plated a local cut flower grower’s soil, with a persistent history of Fusarium wilt of scented stock, Matthiola incana but not the lettuce rotational crop. This yielded culture plates with characteristic pink to carmine red fungi, together with a mixed bacterial population, a percentage of which was visibly antagonistic to the Fusarium. Using molecular analyses via Polymerase Chain Reaction (PCR) assays, we identified that Fusarium oxysporum, Fusarium culmorum, Fusarium equiseti and Fusarium venenatum were prevalent in the soil. The co-habiting bacterial colonies that exhibited strong antagonistic activity (zone of clearance) towards the soil fungi corresponded to Bacillus subtilis, Bacillus amyloliquefaciens and Paenibacillus polymyxa species. Our results arising from an in vitro study involving Kirby-Bauer disc-diffusion agar assays, coupled with bio-imaging software techniques demonstrated that the three native soil bacteria were effective inhibitors of all Fusarium species tested, while Bacillus subtilis exhibited the highest antagonism towards the Fusarium oxysporum. Bioassay tests of micro-biocides Prestop (Gliocadium catenulatum), Serenade Max (Bacillus subtilis QST713) and commercial seaweed extract, AlgiVyt suppressed in vitro growth of Fusarium oxysporum infecting the scented stock flower to a greater extent, whilst fresh aqueous extracts of garlic (Allium sativum) and meadowsweet (Filipendula ulmaria) flowers were ineffective towards soil pathogen suppression. This scoping study offers cut flower growers additional options of tapping into populations of antagonistic bacteria found in soil persistently infected with the opportunistic soil phytopathogen Fusarium oxysporum, affecting cut flower crops, such as M. incana.

3株非致病性镰刀菌Fusarium oxysporum菌株对番茄枯萎病的生物防治效果

对3株非致病镰刀菌Fusariumoxysporum菌株IF 23、251/2和MSA35对于番茄枯萎病的生物防治效果进行了初步研究。温室盆栽试验表明:3株菌株对番茄枯萎病均有一定的抑制作用,其中105CFU/g浓度的IF 23菌株的防治效果最好;基质灭菌对于番茄枯萎病也有一定的抑制作用。

尖孢镰刀菌(Fusarium oxysporum Schl.)的生长特性

【研究目的】研究尖孢镰刀菌的生长特性,寻找培养过程的异质性指标。【方法】供试菌株为黄瓜尖孢镰刀菌F-H.6.5-030318-J2和花生尖孢镰刀菌F-P.5.0-030710,培养基采用PSA培养基,装液量为100ml/250ml,接菌量从培养7d的平板上打取3个6mm的菌片,培养温度为25±1℃,摇床转速为110r/min,培养10d,观察测定发酵液颜色、OD值、pH值、菌丝干重变化,并利用聚类分析方法划分生长阶段。【结果】在培养过程中,尖孢镰刀菌发酵液的颜色、OD值、pH值和菌丝干重都会随着培养时间而变化。在相同的培养条件下,来源于不同寄主的尖孢镰刀菌菌株之间在颜色和OD值变化存在着显著性差异,而pH值和菌丝干重变化未表现出显著性差异。来自黄瓜和花生的尖孢镰刀菌菌株的生长分为3个阶段:1￣2d为适应阶段,3￣5d为对数生长阶段,6￣10d为稳定阶段。【结论】尖孢镰刀菌在培养过程的色素变异和OD值的变化可作为菌株培养的表征性特征。

尖孢镰刀菌胡麻专化型(Fusarium oxysporum f.sp.lini)ISSR标记聚类分析

结合形态学特征和分子生物学方法对我国尖孢镰刀菌胡麻专化型菌株进行鉴定、聚类分析和遗传变异分析。结合传统分类方法和ITS序列分析,确定6省区96株菌株为尖孢镰刀菌。采用ISSR(简单重复序列区间)分子标记技术对这96株菌株进行分析,12条引物共扩增出800个条带,多态率条带数为797条,多态率为99.62%;在相似性系数为0.88处,96株供试菌株被分为5个类群。聚类结果表明,胡麻枯萎病菌种内存在明显的多态性,且ISSR类群与地理来源存在相关性。

甜瓜枯萎病菌(Fusarium oxysporum)专化型的初步研究

本研究获得的甜瓜枯萎病病株9株分离物(南通市6株,新疆3株),经PDA培养性状发现,其在菌落颜色、质地和生长速率方面存在差异,大型分生孢子的大小为(19.54～41.11)μm×(4.90～8.16)μm,与西瓜枯萎病菌的大型分生孢子有较大差异。胚根法成株期致病性测定结果发现,本研究的甜瓜枯萎病菌分离物在不同鉴别寄主和鉴别品种上致病性存在专化型和生理小种方面的差异,但分离物中不存在西瓜枯萎病菌。利用核糖体转录间隔区保守序列设计引物,PCR检测也证明本研究甜瓜枯萎病菌不同分离物中不存在西瓜枯萎病菌。

分蘖洋葱鳞茎粗提物对西瓜枯萎病病原菌(Fusarium oxysporum f.sp.niveum)的影响

采用分蘖洋葱鳞茎粗提物对西瓜枯萎病病原菌(Fusarium oxysporum f.sp.niveum)菌丝生长、孢子萌发、病原菌生物量及产孢量等抑制作用进行研究。结果表明,分蘖洋葱鳞茎粗提物对西瓜枯萎病病原菌的菌丝生长、孢子萌发率、病原菌生物量及产孢量均有一定的抑制作用。当分蘖洋葱鳞茎粗提物浓度为1 000 mg.mL-1时,对西瓜枯萎病病原菌的抑制作用最大,抑菌率达到69.21%。探索了分蘖洋葱鳞茎粗提物防治西瓜枯萎病的可行性,为今后指导西瓜无公害生产提供理论依据。

厚藤共生真菌(FusariumoxysporumY24-2)胞外多糖的化学组成和结构研究

从厚藤共生真菌(Fusarium oxysporum Y24-2)发酵液中提取得到胞外多糖,以Q-Sepharose Fast Flow阴离子交换柱和Superdex S-75凝胶色谱柱对其进行分离纯化,得到纯度高的多糖组分F1S。采用HPGPC和HPLC对F1S的分子量及单糖组成进行分析,结果表明F1S主要由Man、Glc和Gal组成,其摩尔比为1.0∶1.9∶2.1,分子量为37.3kD。F1S的GC-MS和1D,2D-NMR分析表明,该多糖是以→6)-β-Galf(1→为主链,以→2)-α-Glcp(1→,α-Glcp(1→和β-Manp(1→为支链的杂多糖,支链取代于→6)-β-Galf(1→的O-2位。该厚藤共生真菌的胞外多糖为富含呋喃型半乳糖的结构新颖的具有多分支结构的中性杂聚多糖。

应用巢式PCR检测黄瓜尖镰孢菌(Fusarium oxysporum f．sp．cucumbrum)

文章应用BIK2/BIK3和BIK1/BIK4两对引物,采用巢式PCR(Nested-PCR)技术对镰孢菌属26个菌株(代表了6个镰孢菌种)以及从黄瓜根际分离的20株真菌、6株细菌和7株放线菌共计59个菌株进行了扩增。结果显示,只有3个黄瓜尖镰孢菌的致病菌株能产生一条长度大约为800bp的片断。对接种黄瓜尖镰孢菌的黄瓜植株进行检测结果表明,巢式PCR能从接种5d后的黄瓜病样中特异性地检测出病原菌,而症状的出现需要10～13d时间。该项技术具有较高的灵敏度,适用于黄瓜枯萎病早期侵染检测研究。

棉花枯萎病菌(Fusarium oxysporum f.sp.Vasinfectum(ATK)Sndyder & Hansln的抑菌土初步研究

1987～1988年在河南新乡用相同接菌量种植感病品种,对棉花抗枯萎病品种86—1连作10年以上田块土样进行盆栽和田间小区试验。结果表明.枯萎病平均病指分别为29.4和4.4,与对照果园土比较抑菌效果分别为39.9％和85.8％。上述田块中86—1棉株根围5cm内土样,盆栽枯萎病平均病指19.5,抑菌效果60.5％。连作10年以上枯萎病圃土样,病指分别为27.2和6.8,抑菌效果为43.9％和76.2％。1990～1991年在辽宁省经作所试验结果,连作10年以上枯萎病圃田间抑菌效果56.2％,连作5年病圃抑菌效果17.6％。上述结果证明,枯萎病圃衰退的主要原因是棉花枯萎病菌抑菌土的产生和存在。土样内枯萎菌菌量测定结果表明,3个抑菌土土样内菌量比果园导菌土减少48.6％～59.2％。抑菌土经高压灭菌后抑菌效果完全消失,初步证明抑菌因子可能以生物因子为主。

几种药剂对辣椒枯萎病菌(Fusarium oxysporum)的毒力测定

采用菌丝生长速率法进行了5种药剂对辣椒枯萎病菌的毒力测定。结果表明,所采用的5种药剂均对辣椒枯萎病菌有抑制作用。药剂EC50大小顺序依次为甲霜·噁霉灵>噁霉灵>百菌清>科佳>腐霉利,其中甲霜·噁霉灵最高为19.4mg·L-1,腐霉利最低为5.4mg·L-1。

Effects of Medium Nutrients on Fusarium oxysporum Schl. f.sp

[Objective] To study the effects of different culture conditions on the Fusarium oxysporurn SchL f. sp. [Method] Based on species identification of the pathogenic organism of Fusarium oxysporum Schl. f. sp, effects of different cultures and different nutrients on the mycelial growth and conidial production of Fusarium oxysporum SchL f. sp were studied. [Result] The mycelial growth and conidial pro- duction of Fusarium oxysporum SchL f. sp was different under different culture con- ditions. PDA medium was the most suitable medium for the mycelial growth and had the highest conidial production; and the mycelial grew the fastest on the medium with maltose as carbon source or peptone as nitrogen source, which also had the highest conidial production. [Conclusion] This study provided experimental basis for the study of Fusarium oxysporum SchL f. sp and also provided theoretical basis for the study and control of Fusarium oxysporum Schl. f. sp.

从土壤中分离棉枯萎病菌(Fusarium oxysporum f.sp.vasinfetum (Atk) Synder & Hansen)选择性培养基研究

本文介绍一种用于分离检测土壤中棉枯萎病菌的选择性培养基—植选2号。其成分为:KH_2PO_41g,MgSO_4·7H_2O 0.5g,K_2S_2O_50.2g,KCl0.6g,NH_4NO_3 0.5g,蛋白胨5g,山梨糖10g,蔗糖5g,琼脂20g,蒸馏水1000ml,PCNB 620mg,Oxgall1g,硫酸链霉素300mg,盐酸金霉素75mg。根据棉枯萎病在此培养基上的形态特征,能较容易地识别和检测该病菌。