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1.
贝莱斯芽胞杆菌Bacillus velezensis YL2021是一株对多种病原细菌均有良好防治效果的生防菌,基因组中含有完整的儿茶酚型（2,3-Dihydroxybenzoate,DHB）嗜铁素合成基因簇。为了探明贝莱斯芽胞杆菌YL2021嗜铁素的功能,本研究以嗜铁素合成基因dhbC为对象,构建重组质粒pMD19-dhbc（cm）,利用同源重组技术获得突变株ΔdhbC。生防相关性状研究结果表明,与野生型菌株YL2021相比,突变株ΔdhbC泳动能力和生物膜形成能力明显下降,但是群集运动能力未发生改变。在营养丰富的LB培养基中,野生型菌株YL2021和突变株ΔdhbC均不产生嗜铁素,生长能力未发生改变,室内抑菌能力相当;但在缺铁M9培养基中,野生型菌株YL2021能产生儿茶酚型嗜铁素,生长缓慢,对供试细菌有较强的抑菌作用,突变株ΔdhbC不能产生嗜铁素,生长能力明显下降,完全丧失抑菌能力。本文结果表明,缺铁条件下,dhbC基因是贝莱斯芽胞杆菌YL2021嗜铁素生物合成的关键基因,嗜铁素是菌株YL2021发挥生防作用的重要抑菌物质。 相似文献
2.
绿针假单胞菌Pseudomonas chlororaphis YL-1是从大豆根围分离获得的,对多种病原细菌和病原真菌有较强抑制作用。为了探明绿针假单胞菌YL-1生防相关基因的功能,本研究以嗜铁素转录调控因子PvdS编码基因为对象,建立了一套基于负选择标记基因sacB的绿针假单胞菌无标记基因敲除技术,构建重组质粒pEX18-pvdS,通过改良的细菌接合转移技术将重组质粒导入野生型菌株YL-1中,利用同源重组技术获得缺失突变株ΔpvdS。生防相关性状研究结果表明,与野生型菌株YL-1相比,突变株ΔpvdS泳动能力和生长能力未发生改变,但是群集运动能力显著下降。同时突变株ΔpvdS合成嗜铁素的能力也显著下降,pvdS基因互补后突变株能恢复合成嗜铁素的功能。本文结果表明,已成功建立了适用于YL-1的基因定向敲除技术和功能基因互补体系,为深入研究YL-1的生防机制奠定了重要基础。 相似文献
3.
本研究从新疆、山东及河北等地区采集的健康葡萄根际土壤中分离生防菌，以葡萄灰霉病菌Botrytis cinerea为靶标菌，通过平板对峙试验、葡萄叶片和果实上的离体抑菌试验，筛选获得4株生防菌BF1-1、BF2-1、BF3-1和BF4-1具有较好的拮抗作用，经形态学和分子生物学方法分别鉴定为地衣芽胞杆菌Bacillus licheniformis、解淀粉芽胞杆菌B.amyloliquefaciens、枯草芽胞杆菌B.subtilis和蜡样芽胞杆菌B.cereus；4株生防菌所制成的生物菌肥，对葡萄灰霉病的田间防效可达到66.50%～85.68%，具有开发应用潜力。 相似文献
4.
番茄灰霉病是由灰葡萄孢菌Botrytis cinerea引起的番茄上重要的土传病害之一，危害番茄果实、叶、茎等部位，严重制约番茄的安全生产，微生物菌剂的施用被认为是防治该病害的有效措施。前期研究发现贝莱斯芽胞杆菌5YN8能够显著防治番茄灰霉病，本研究通过构建相关基因突变体，探究生物被膜在5YN8防病过程中的作用，结果显示生物被膜增强突变体具有更致密的褶皱，而减弱突变体生物被膜光滑。进一步研究发现，菌株5YN8及其突变体处理14 d后，生物被膜减弱突变显著减少细菌在叶面的定殖，而增强突变则提升其定殖。另外，生物被膜减弱突变体防病效果显著降低，∆spo0A对灰霉病防效仅为16.02%，而生物被膜增强突变体∆abrB、∆sinR防病效果显著增强，分别达80.77%、78.94%。相关性分析表明，5YN8的抑菌率、叶面定殖与其防效显著正相关。综合结果表明，5YN8生物被膜的形成依赖保守基因的调控，通过改变生防菌定殖及抑菌能力影响对番茄灰霉病防效。上述研究将为生防菌5YN8的功能修饰增强及在番茄灰霉病的应用提供理论基础。 相似文献
5.
为获得对小麦全蚀病菌有良好拮抗效果的生防菌株,分别从河南省商丘市及驻马店市小麦全蚀病发生田块中采集小麦根际土样,采用稀释平板涂布法共分离到1051株细菌,通过与全蚀病菌G1037菌株进行平板对峙筛选,最终获得9株具有明显拮抗效果且生长状况良好的菌株。16S rDNA序列比对及生理生化性状分析结果表明：菌株P155、P154、P16及P147为荧光假单胞菌Pseudomonas fluorescens,菌株P188和P97为恶臭假单胞菌Pseudomonas putida,菌株LY3为产酶溶杆菌Lysobacter enzymogenes,菌株S38为嗜根寡养单胞菌Stenotrophomonas rhizophila,菌株B20为洋葱伯克霍尔德Burkholderia cepacia。产抗生素相关基因的检测结果发现,菌株P147含吩嗪和硝吡咯菌素合成基因,菌株B20含硝吡咯菌素合成基因。除B20、LY3、S38和P147外,其余菌株均可产生嗜铁素。9株细菌都产蛋白酶。除P97、B20和S38外,其余菌株均可产脂肽类物质。盆栽试验结果表明,9株生防菌对小麦全蚀病都具有较好的防治效果,菌株P155和P154的防治效果最好,相对防效分别为67.11%和63.82%,略高于3%的苯醚甲环唑种衣剂的防治效果。研究结果表明这些细菌具有作为小麦全蚀病生防菌的潜力。 相似文献
6.
7.
本研究从节瓜根际分离到一株具有防病促生功能的荧光类假单胞菌FP1761。该菌株对部分植物病原真菌和细菌具有拮抗能力,能够解钾、解有机磷和无机磷,可产生氨、蛋白酶、嗜铁素、吲哚乙酸。生物测定表明菌株FP1761可显著促进小麦生长。生理生化、平均核苷酸相似度、16S rDNA和多基因分析将FP1761鉴定为摩拉维亚假单胞菌(Pseudomonas moraviensis)。菌株FP1761基因组草图全长6.12 Mb,(G+C)含量为59.9%,共编码5467个基因序列。将该菌株与种内3个代表性菌株进行泛基因组和核心基因组分析,共产生 4 357个共有基因,菌株FP1761特有基因327个。利用antiSMASH对菌株次生代谢基因簇进行预测,发现其含有8个潜在的次生代谢产物基因簇。其中两个基因簇与嗜铁素pyoverdine合成相关,未见聚酮类合成基因。基因组分析发现,该菌株具有与病原性假单胞菌相似的III型分泌系统,但丢失了效应蛋白调控因子hrpS和转运相关的hrpH和hrpK1基因。对全基因组扫描,菌株FP1761仅保留了病原性假单胞菌的保守效应蛋白AvrE和HopAA1-1。FP1761是目前已发现的唯一具有III型分泌系统的摩拉维亚假单胞菌。本研究表明摩拉维亚假单胞菌FP1761具有潜在的植物防病促生功能,但其III型分泌系统与植物益生互作机制有待进一步解析。 相似文献
8.
中国猕猴桃细菌性花腐病菌的鉴定 总被引：4，自引：0，他引：4
从福建、湖南和湖北猕猴桃病花上分离到能引起花腐病的32个细菌菌株,经细菌学和BiologGN测试板测定,可以看出中国的猕猴桃细菌性花腐病菌与新西兰的猕猴桃花腐病菌、丁香假单胞菌丁香致病变种Pseudomonas syringae pv.syringae和绿黄假单胞菌P.viridiflava相似,与萨氏假单胞菌P.savastanoi和猕猴桃溃疡病菌P.syringae pv.actinidiae有更多的不同,但是DNA/DNA同源性测定结果却显示出中国的菌株可分为2个类型:第1个类型与新西兰猕猴桃花腐病菌和萨氏假单胞菌有很高的同源性,第2类型与绿黄假单胞菌有很高的同源性,说明中国菌株分别属于这2个种。第1类型来自于福建和湖北,第2类型来自于湖南。 相似文献
9.
贝莱斯芽胞杆菌Bacillus velezensis YL2021是一株对多种植物病原菌具有良好防治效果的生防菌,其基因组中含有完整的儿茶酚型嗜铁素合成基因簇,在缺铁条件下能产生具有抑菌作用的嗜铁素。为了提高贝莱斯芽胞杆菌YL2021嗜铁素的产量,采用摇瓶培养发酵,通过Plackett-Burman(PB)试验、中心组合试验(central composite design,CCD)和响应曲面法(response surface methodology,RSM)分析,优化菌株YL2021高产嗜铁素的发酵培养基成分和培养条件。结果表明,菌株YL2021高产嗜铁素的最优培养基配方：葡萄糖19.43 g/L、NH4Cl 1.93 g/L、KH2PO4 9.02 g/L、谷氨酸钠6.00 g/L、Mg SO4 1.75 g/L和Ca Cl20.08 g/L;最优培养条件为：温度30℃、初始p H值7.0、接种量5%、培养时间36.5 h、转速200 r/min和装液量75 m L(25... 相似文献
10.
豆薯细菌性角斑病的病原鉴定 总被引：2，自引：1，他引：1
在安徽滁州的豆薯叶片上发现一种由细菌侵染引起角斑症状的病害,从角斑上分离到具有致病性的非荧光的杆状细菌,菌株的表型特征、细菌学特征、LOPAT试验和生理生化试验表明该细菌与丁香假单胞菌(Pseudomonas syringae van Hall)相似,BIOLOG系统鉴定结果与丁香假单胞菌豌豆致病变种(P.syringae pv.pisi)相近,接种试验表明豆薯菌株能侵染大豆、菜豆和眉豆,但对豌豆的致病性差;在豇豆、绿豆和蚕豆上不表现症状。结果表明豆薯细菌性角斑病是一种新病害,病原菌属于丁香假单胞菌群的一个新的致病变种,命名为P.syringae pv.pachyrhizus nov. 相似文献
11.
Siderophore-mediated competition for iron and induced resistance in the suppression of fusarium wilt of carnation by fluorescent Pseudomonas spp 总被引：4，自引：0，他引：4
Ben J. Duijff Jan W. Meijer Peter A. H. M. Bakker Bob Schippers 《European journal of plant pathology / European Foundation for Plant Pathology》1993,99(5-6):277-289
The mechanisms of suppression of fusarium wilt of carnation by two fluorescentPseudomonas strains were studied.Treatments of carnation roots withPseudomonas sp. WCS417r significantly reduced fusarium wilt caused byFusarium oxysporum f. sp.dianthi (Fod). Mutants of WCS417r defective in siderophore biosynthesis (sid–) were less effective in disease suppression compared with their wild-type. Treatments of carnation roots withPseudomonas putida WCS358r tended to reduce fusarium wilt, whereas a sid– mutant of WCS358 did not.Inhibition of conidial germination of Fod in vitro by purified siderophores (pseudobactins) of bothPseudomonas strains was based on competition for iron. The ferrated pseudobactins inhibited germination significantly less than the unferrated pseudobactins. Inhibition of mycelial growth of Fod by bothPseudomonas strains on agar plates was also based on competition for iron: with increasing iron content of the medium, inhibition of Fod by thePseudomonas strains decreased. The sid– mutant of WCS358 did not inhibit Fod on agar plates, whereas the sid– mutants of WCS417r still did. This suggests that inhibition of Fod by WCS358r in vitro was only based on siderophore-mediated competition for iron, whereas also a non-siderophore antifungal factor was involved in the inhibition of Fod by strain WCS417r.The ability of thePseudomonas strains to induce resistance against Fod in carnation grown in soil was studied by spatially separating the bacteria (on the roots) and the pathogen (in the stem). Both WCS417r and its sid– mutant reduced disease incidence significantly in the moderately resistant carnation cultivar Pallas, WCS358r did not.It is concluded that the effective and consistent suppression of fusarium wilt of carnation by strain WCS417r involves multiple mechanisms: induced resistance, siderophore-mediated competition for iron and possibly antibiosis. The less effective suppression of fusarium wilt by WCS358r only depends on siderophore-mediated competition for iron. 相似文献
12.
The ability of selected strains of fluorescent Pseudomonas spp. to cause induced systemic resistance (ISR) in Eucalyptus urophylla against bacterial wilt caused by Ralstonia solanacearum was investigated. Four of the five strains used can produce salicylic acid (SA) in vitro and, therefore, chemical SA, that is known to induce resistance in many plant species, was used as a reference treatment.
Whereas a soil drench with SA did induce systemic resistance in E. urophylla, infiltration of SA into leaves did not. None of the fluorescent Pseudomonas spp. strains caused ISR against bacterial wilt when applied to the soil, but two strains, P. putida WCS358r and P. fluorescens WCS374r triggered ISR when infiltrated into two lower leaves 3–7 days before challenge inoculation. A mutant of strain WCS358r
defective in the biosynthesis of the fluorescent siderophore pseudobactin, did not cause ISR, while the purified siderophore
of WCS358r did, suggesting that pseudobactin358 is the ISR determinant of WCS358. A siderophore-minus mutant of WCS374r induced
the same level of disease resistance as its parental strain, but the purified siderophore induced resistance as well, indicating
that both the siderophore and another, unknown, inducing determinant(s) of WCS374r can trigger ISR in Eucalyptus. A possible role of WCS374r-produced SA remains uncertain. Transformation of a siderophore-minus mutant of WCS358 with the
SA biosynthetic gene cluster from WCS374 did not enable this transformant to cause ISR in E. urophylla. 相似文献
13.
M. Leeman F. M. Den Ouden J. A. Van Pelt C. Cornelissen A. Matamala-Garros P. A. H. M. Bakker B. Schippers 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(1):21-31
In an earlier study, treatment of radish seed with the bacteriumPseudomonas fluorescens WCS374 suppressed fusarium wilt of radish (Fusarium oxysporum f. sp.raphani) in a commercial greenhouse [Leemanet al., 1991b, 1995a]. In this greenhouse, the areas with fusarium wilt were localized or expanded very slowly, possibly due to disease suppressiveness of the soil. To study this phenomenon, fungi were isolated from radish roots collected from the greenhouse soil. Roots grown from seed treated with WCS374 were more abundantly colonized by fungi than were roots from nonbacterized plants. Among these were several species known for their antagonistic potential. Three of these fungi,Acremonium rutilum, Fusarium oxysporum andVerticillium lecanii, were evaluated further and found to suppress fusarium wilt of radish in a pot bioassay. In an induced resistance bioassay on rockwool,F. oxysporum andV. lecanii suppressed the disease by the apparent induction of systemic disease resistance. In pot bioassays with thePseudomonas spp. strains, the pseudobactin-minus mutant 358PSB– did not suppress fusarium wilt, whereas its wild type strain (WCS358) suppressed disease presumably by siderophore-mediated competition for iron. The wild type strains of WCS374 and WCS417, as well as their pseudobactin-minus mutants 374PSB– and 417PSB– suppressed fusarium wilt. The latter is best explained by the fact that these strains are able to induce systemic resistance in radish, which operates as an additional mode of action. Co-inoculation in pot bioassays, ofA. rutilum, F. oxysporum orV. lecanii with thePseudomonas spp. WCS358, WCS374 or WCS417, or their pseudobactin-minus mutants, significantly suppressed disease (except forA. rutilum/417PSB– and all combinations with 358PSB–), compared with the control treatment, if the microorganisms were applied in inoculum densities which were ineffective in suppressing disease as separate inocula. If one or both of the microorganism(s) of each combination were applied as separate inocula in a density which suppressed disease, no additional suppression of disease was observed by the combination. The advantage of the co-inoculation is that combined populations significantly suppressed disease even when their individual population density was too low to do so. This may provide more consistent biological control. The co-inoculation effect obtained in the pot bioassays suggests that co-operation ofP. fluorescens WCS374 and indigenous antagonists could have been involved in the suppression of fusarium wilt of radish in the commercial greenhouse trials.Abbreviations CFU
colony forming units
- KB
King's B
- PGPR
plant growth-promoting rhizobacteria
- CQ
colonization quotient 相似文献
14.
M. Leeman J. A. van Pelt F. M. den Ouden M. Heinsbroek P. A. H. M. Bakker B. Schippers 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(6):655-664
Pseudomonas fluorescens-mediated induction of systemic resistance in radish against fusarium wilt (Fusarium oxysporum f. sp.raphani) was studied in a newly developed bioassay using a rockwool system. In this bioassay the pathogen and bacterium were confirmed to be confined to spatially separate locations on the plant root, throughout the experiment. Pathogen inoculum obtained by mixing peat with microconidia and subsequent incubation for four days at 22 °C, yielded a better percentage of diseased plants than a microconidial suspension drench, an injection of a microconidial suspension into the hypocotyl, or a talcum inoculum.Pseudomonas fluorescens strain WCS374 applied in talcum or peat, but not as a suspension drench, induced systemic resistance. A minimal initial bacterial inoculum density of 105 CFU WCS374 root–1 was required to significantly reduce the percentage diseased plants. At least one day was necessary between bacterization of strain WCS374 in talcum on the root tips and inoculation of the pathogen in peat on the root base, for an optimal induction of systemic resistance. Strain WCS374 induced systemic resistance in six radish cultivars differing in their susceptibility toF. oxysporum f. sp.raphani. Significant suppression of disease by bacterial treatments was generally observed when disease incidence in the control treatment, depending on pathogen inoculum density, ranged between approximately 40 to 80%. Strains WCS374 and WCS417 ofPseudomonas fluorescens induced systemic resistance against fusarium wilt, whereasP. putida WCS358 did not. This suggests that the induction of systemic resistance byPseudomonas spp. is dependent on strain-specific traits.Abbreviations CFU
colony forming units
- IFC
immunofluorescence colony-staining
- ISR
induced systemic resistance
- PBS
phosphate buffered saline
- SAR
systemic acquired resistance 相似文献
15.
ABSTRACT The role of bacterially produced salicylic acid (SA) in the induction of systemic resistance in plants by rhizobacteria is far from clear. The strong SA producer Pseudomonas fluorescens WCS374r induces resistance in radish but not in Arabidopsis thaliana, whereas application of SA leads to induction of resistance in both plant species. In this study, we compared P. fluorescens WCS374r with three other SA-producing fluorescent Pseudomonas strains, P. fluorescens WCS417r and CHA0r, and P. aeruginosa 7NSK2 for their abilities to produce SA under different growth conditions and to induce systemic resistance in A. thaliana against bacterial speck, caused by P. syringae pv. tomato. All strains produced SA in vitro, varying from 5 fg cell(-1) for WCS417r to >25 fg cell(-1) for WCS374r. Addition of 200 muM FeCl(3) to standard succinate medium abolished SA production in all strains. Whereas the incubation temperature did not affect SA production by WCS417r and 7NSK2, strains WCS374r and CHA0r produced more SA when grown at 33 instead of 28 degrees C. WCS417r, CHA0r, and 7NSK2 induced systemic resistance apparently associated with their ability to produce SA, but WCS374r did not. Conversely, a mutant of 7NSK2 unable to produce SA still triggered induced systemic resistance (ISR). The possible involvement of SA in the induction of resistance was evaluated using SA-nonaccumulating transgenic NahG plants. Strains WCS417r, CHA0r, and 7NSK2 induced resistance in NahG Arabidopsis. Also, WCS374r, when grown at 33 or 36 degrees C, triggered ISR in these plants, but not in ethylene-insensitive ein2 or in non-plant pathogenesis- related protein-expressing npr1 mutant plants, irrespective of the growth temperature of the bacteria. These results demonstrate that, whereas WCS374r can be manipulated to trigger ISR in Arabidopsis, SA is not the primary determinant for the induction of systemic resistance against bacterial speck disease by this bacterium. Also, for the other SAproducing strains used in this study, bacterial determinants other than SA must be responsible for inducing resistance. 相似文献
16.
Control of Fusarium Wilt of Radish by Combining Pseudomonas putida Strains that have Different Disease-Suppressive Mechanisms 总被引：1，自引：0，他引：1
de Boer M Bom P Kindt F Keurentjes JJ van der Sluis I van Loon LC Bakker PA 《Phytopathology》2003,93(5):626-632
ABSTRACT Biological control of soilborne plant pathogens in the field has given variable results. By combining specific strains of microorganisms, multiple traits antagonizing the pathogen can be combined and this may result in a higher level of protection. Pseudomonas putida WCS358 suppresses Fusarium wilt of radish by effectively competing for iron through the production of its pseudobactin siderophore. However, in some bioassays pseudobactin-negative mutants of WCS358 also suppressed disease to the same extent as WCS358, suggesting that an, as yet unknown, additional mechanism may be operative in this strain. P. putida strain RE8 induced systemic resistance against fusarium wilt. When WCS358 and RE8 were mixed through soil together, disease suppression was significantly enhanced to approximately 50% as compared to the 30% reduction for the single strain treatments. Moreover, when one strain failed to suppress disease in the single application, the combination still resulted in disease control. The enhanced disease suppression by the combination of P. putida strains WCS358 and RE8 is most likely the result of the combination of their different disease-suppressive mechanisms. These results demonstrate that combining biocontrol strains can lead to more effective, or at least, more reliable biocontrol of fusarium wilt of radish. 相似文献
17.
Induced systemic resistance in Trichoderma harzianum T39 biocontrol of Botrytis cinerea 总被引：11，自引：0，他引：11
Geert De Meyer Joseph Bigirimana Yigal Elad Monica Höfte 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(3):279-286
Biocontrol of Botrytis cinerea with Trichoderma spp. is generally believed to result from direct interaction of the biocontrol agent with the pathogen or from a Trichoderma-induced change in environmental conditions that affects B. cinerea development. In this work we provide arguments for the participation of induced plant defence in T. harzianum T39 control of B. cinerea. In tomato, lettuce, pepper, bean and tobacco, T. harzianum T39 application at sites spatially separated from the B. cinerea inoculation resulted in a 25–100%percnt; reduction of grey mould symptoms, caused by a delay or suppression of spreading lesion formation. Given the spatial separation of both micro-organisms, this effect was attributed to the induction of systemic resistance by T. harzianum T39. The observation that in bean the effect of T. harzianum T39 was similar to that of the rhizobacterium Pseudomonas aeruginosa KMPCH, a reference strain for the induction of systemic resistance, confirmed this hypothesis. Since B. cinerea control on tobacco leaves sprayed with T. harzianum T39 was similar to the control on leaves from T. harzianum T39 soil-treated plants, induction of plant defence might also participate in biocontrol on treated leaves. 相似文献
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《Physiological and Molecular Plant Pathology》2007,70(1-3):77-87
In an attempt to overcome the enhanced disease susceptibility phenotype that is typical for transgenic ethylene-insensitive tobacco (Tetr), Tetr plants were treated with chemical agents that induce resistance or with antagonistic rhizobacteria. Treatments with β-aminobutyric acid (BABA), benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), methyl jasmonate (MeJA), or salicylic acid (SA) induced PR-genes generally to a lesser extent than in non-transformed plants and did not reduce wilting symptoms upon infection with Pythium sp., except for a marginal effect of SA. In Tetr lines overexpressing PR-1g, PR-5c, or both, no significant reduction in disease development was apparent. Also treatment of Tetr plants with the antagonistic rhizobacteria Bacillus cereus UW85, Pseudomonas aeruginosa 7NSK2, Pseudomonas fluorescens WCS417r or Q8r-196, Pseudomonas putida WCS358r, or antibiotic-producing derivatives of WCS358r, did not reduce symptoms caused by Pythium. 相似文献
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Ben J. Duijff Daniel Pouhair Chantal Olivain Claude Alabouvette Philippe Lemanceau 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(9):903-910
Fluorescent pseudomonads and nonpathogenic Fusarium oxysporum have been shown to suppress fusarium wilts. This suppression has been related to both microbial antagonism and induced resistance.The aim of the present study was to assess the relative importance of systemic induced resistance in the suppression of fusarium wilt of tomato in commercial-like conditions by a reference strain of each type of microorganism (P. fluorescens WCS417r and nonpathogenic F. oxysporum Fo47). The spatial separation of the pathogen and the biocontrol strains excluded any possible microbial antagonism and implicated the involvement of the systemic induced resistance; whereas the absence of any separation between these microorganisms allowed the expression of both mechanisms. Since systemic induced resistance has often been associated with the synthesis of PR-proteins, their accumulation in tomato plants inoculated with WCS417r or with Fo47 was determined.The analysis of the results indicates that the suppression of fusarium wilt by P. fluorescens WCS417r was ascribed to systemic induced resistance without any detection of the PR-proteins tested (PR-1 and chitinases). In contrast, the suppression achieved by nonpathogenic F. oxysporum Fo47 appeared to be mainly ascribed to microbial antagonism but also to a lesser extent to systemic induced resistance. This induced resistance could be related to the accumulation of PR-1 and chitinases.The possible relationship between the ability of Fo47 to suppress fusarium wilt more efficiently than WCS417r and its ability to show both mechanisms is discussed. 相似文献