Control of Grapevine Grey Mould with Trichoderma harzianum T39

The efficacy of a formulation of Trichoderma harzianum T39 for control of grey mould (Botrytis cinerea) on grapevine was examined in 133 experiments conducted under diverse commercial conditions. The experiments were carried out between 1988 and 1994 in 19 countries and on 34 varieties. The average disease incidence in the untreated plots of all experiments was 42 2.3% (mean standard error). In general, the reduction of disease achieved by T. harzianum application was lower than that obtained by chemical fungicides: 36.3 2.7% disease reduction in biocontrol treatments and 52.3 2.6% in the exclusively chemical treatments. Control efficacy declined when the interval between application and assessment dates increased to 5 weeks. The experiments also included treatments in which T. harzianum was integrated with chemical fungicides, the two being applied alternately, and a reduced chemical treatment in which only chemicals were applied, and only at the times when chemicals were applied in the integrated treatment. The mean control efficacy in these treatments was 55.8 3.2% and 44.2 4.9% respectively. The roles of the integration of biological and chemical compounds in reducing pesticide residues in fruit at harvest and lowering the pressure towards development of fungicide-resistance populations of B. cinerea are discussed.     

Management of powdery mildew and gray mold of cucumber by Trichoderma harzianum T39 and Ampelomyces quisqualis AQ10

Two biocontrol preparations were tested for their ability to control Sphaerotheca fusca and Botrytis cinerea on greenhouse cucumber. Trichoderma harzianum T39 (TRICHODEX) spray reduced powdery mildew severity by up to 97% but its efficacy declined to 18–55% control as the epidemic progressed. Unlike on young leaves, on older leaves the control of powdery mildew by T. harzianum T39 was poor. Ampelomyces quisqualis (AQ10) was very effective against powdery mildew, achieving up to 98% of control. Its effectiveness declined with the progress of the epidemic but unlike the other biocontrol agent it retained significant control capability on older leaves. Two aliphatic petroleum distillate oil products improved the efficacy of both biocontrol agents. The co-application of T. harzianum T39 and A. quisqualis AQ10 was tested on cucumber plants infected with powdery mildew followed by fruit gray mold infection. It resulted in no improvement of the control of powdery mildew, and in an improvement of gray mold control, the latter probably because of the use of additive oil (ADDQ) along with the second biocontrol preparation. There was no significant interference between the biocontrol agents in the co-application treatment as compared with the application of each agent alone; the level of population of T. harzianum T39 remained similar and the parasitism of S. fusca by A. quisqualis was not nullified. The application of T. harzianum T39 to soil instead of spraying it resulted in 75–90% lower powdery mildew coverage on the leaves. It was concluded that the mode of action of T. harzianum T39 in powdery mildew control is induced resistance, not mycoparasitism or antibiotic action.     

番茄灰霉病生防链霉菌筛选及鉴定

【背景】由灰葡萄孢侵染所致的番茄灰霉病是一类重要的真菌病害,生物防治具有环境友好、病原菌不易产生抗药性等特点,是果蔬灰霉病绿色防控的有效措施。【目的】筛选对番茄灰霉病具有防病作用且能促进番茄种子发芽的广谱拮抗性链霉菌,并明确该菌株种级分类地位。【方法】采用琼脂块法筛选拮抗番茄灰霉病菌的链霉菌菌株,采用对峙培养法和生长速率法检测菌株T22抑菌谱,通过产胞外酶活性检测、离体叶片防效和种子发芽试验明确该菌株的防病促生相关特性,根据形态学特征、生理生化特性和分子生物学方法对该菌株进行种类鉴定。【结果】从分离的56株放线菌中筛选到14株对番茄灰霉病菌具有拮抗效果的放线菌菌株,其中链霉菌T22对番茄灰霉病菌抑制作用最强,且具有较广抑菌谱,同时菌株T22具有产生纤维素酶和几丁质酶的能力。菌株T22无菌发酵滤液对番茄灰霉病菌、桃褐腐病菌、黄瓜枯萎病菌抑菌率分别为84.6%、81.5%和79.1%;其无菌发酵滤液原液对番茄灰霉病离体防效为55.1%;100倍稀释液处理番茄种子,胚轴、胚根和种子活力指数分别增加15.1%、29.7%和43.9%。根据形态学特征、生理生化特性和多基因聚类分析将链霉菌T22鉴定为白黑链霉菌(Streptomycesalboniger)。【结论】白黑链霉菌T22具有较强的抗真菌、产胞外酶、防病和促生活性,在番茄灰霉病生物防治中具有较好的开发应用潜力。     

生防工程菌株BS-17A稳定性与抑菌活性初步研究

目的:BS-17是内生细菌,对番茄灰霉病菌、叶霉病菌和枯萎病菌具有显著抑菌活性,为了跟踪研究野生型菌株BS-17在番茄根围和叶围的定殖情况,构建了1株带有黄绿荧光蛋白基因标记的生防菌株BS-17A.方法:采用NYD连续培养的方法和平皿抑菌试验的方法对工程菌株的遗传稳定性和抑菌活性进行了初步研究.结果:该工程菌在无选择压力培养基中连续培养50h,质粒遗传稳定性为94%,对番茄灰霉病菌Botrytis cinerea、叶霉病菌Cladosporiumfulvum和枯萎病菌Fusarium oxysporum的抑制作用与野生菌无显著差异,平皿抑菌率分别为85.5%、86.5%和89.8%.结论:该工程菌具有较强的遗传稳定性和抑菌活性.     

Control of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in greenhouse tomato crops using the mating disruption technique

The effectiveness of mating disruption to control the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in greenhouse tomato crops was evaluated in four trials carried out in winter–spring and summer–winter growing seasons in Southwestern Sardinia (Italy). Pheromone dispensers loaded with 60 mg of the natural blend of the major and minor sex pheromone component (rate 90 : 10) were applied in disrupted greenhouses at a rate of 1000/ha (60 g of active ingredient/ha). Male captures in monitoring pheromone traps, percentage of tomato plants infested by T. absoluta and damage on leaves and fruits were monitored weekly and compared in disrupted and untreated (control) greenhouses. In greenhouses disrupted with 1000 dispensers/ha, a reduction of 93–97% in male trap captures was observed, compared with control. Leaf damage was significantly lower in greenhouses disrupted with 1000 dispensers/ha than in control ones, with a reduction of infestation throughout the growing season ranging from 57% to 85%. Pheromone dispensers applied at the density of 1000/ha significantly reduced the percentage of damaged fruits by 62–89%. In control greenhouses, the highest damage on leaves and fruits was generally observed in edge plants, while leaf and fruit infestation was uniformly distributed in pheromone‐treated greenhouses, indicating an even distribution of the pheromone cloud inside the greenhouse. Mating disruption showed to be an efficient strategy to control in greenhouse the tomato leafminer and can be included in the overall tomato integrated pest management programs.     

The expression of extracellular fungal cell wall hydrolytic enzymes in different Trichoderma harzianum isolates correlates with their ability to control Pyrenochaeta lycopersici

Four isolates of Trichoderma harzianum (ThN3, Th11, Th12 and Th16) were selected for their ability to control the in vitro development of the tomato root pathogen Pyrenochaeta lycopersici. Analysis of the mechanisms involved in biocontrol showed that the formation of non-volatile metabolites appears to be one of those involved in biocontrol of P. lycopersici by all T. harzianum isolates tested. Nevertheless, the higher secretion of chitinases, both in number of isoenzymes and activity by the Th11 strain, correlated well with its higher ability to control this agent in laboratory and greenhouse experiments as compared to the other T. harzianum isolates tested. The secretion of beta-1,3-endoglucanases and/or proteases appeared to have less significance than endochitinases in the biological control of P. lycopersici.     

Occupational exposure to airborne Bacillus thuringiensis kurstaki HD1 and other bacteria in greenhouses and vegetable fields

When microorganisms are used for pest control in vegetable production, the active organisms become part of the microbiota growers are exposed to. The aim of this study was to quantify vegetable growers' exposure to the bacterial strain Bacillus thuringiensis kurstaki strain HD1 (termed HD1) from the biocontrol agent Dipel®, and other airborne mesophilic bacteria. Personal (n=102) and stationary (n=43) measurements of exposure were performed in greenhouses and open fields. Air samples were analysed by plate counts, and total counts with a microscope. Isolates resembling HD1 were identified by PCR analysis. HD1-like bacteria were only detected in environments where Dipel® was used. In a greenhouse with Dipel® treated tomato plants, the growers' exposure to airborne HD1-like bacteria reached 5300 cfu/m³ and 1400 cfu/m³ during harvest and clearing of old plants, respectively. In untreated greenhouses, the highest concentration of total mesophilic bacteria, 1,100,000 cfu/m³, was detected in a cucumber greenhouse. The median concentrations of mesophilic bacteria in tomato greenhouses were significantly lower than the median concentrations in cucumber greenhouses. There was no significant difference in exposure to mesophilic bacteria in tomato greenhouses and in vegetable fields. We found that greenhouse workers, especially in cucumber production, were exposed to high concentrations of total bacteria. Thus, the already present airborne bacteria in greenhouses might have a greater influence on growers' health than applied biocontrol strains. However, further studies are needed to establish an occupational threshold limit for airborne bacteria and to secure a healthy working environment for vegetable growers.     

Use of GUS Transformants of Trichoderma harzianum Isolate T39 (TRICHODEX) for Studying Interactions on Leaf Surfaces

Trichoderma harzianum , isolate T39 (TRICHODEX), was transformed with the GUS ( βglucuronidase) reporter gene to visualize the interaction with Botrytis cinerea and to determine potential mechanisms involved in biocontrol. T39GUS transformants did not appear to penetrate the bean leaf epidermis nor grow into the mesophyll via stomata. No direct penetration or coiling was observed between hyphae and conidia of the T39GUS transformants and of B. cinerea , however, structures of the pathogen were stained blue. Similarly, blue substrate accumulated in various non-transformed fungi such as Alternaria sp., Colletotricum acutatum and the wild-type isolate T39 when co-inoculated on leaves and plates with the T39GUStransgenic strains of T. harzianum and Fusarium oxysporum f. sp. niveum . Therefore, the role of diffusible compounds, specifically from T. harzianum transformants, will need further investigation.     

Combined effects of Brassica napus seed meal and Trichoderma harzianum on two soilborne plant pathogens

The effects of soil amendment with rapeseed meal from Brassica napus cv. 'Dwarf Essex' (high glucosinolate concentrations) and 'Stonewall' (low glucosinolate concentrations) on the biological control activity of Trichoderma harzianum towards Sclerotinia sclerotiorum and Aphanomyces euteiches were evaluated. Trichoderma harzianum added to soil reduced myceliogenic germination of S. sclerotiorum by 94%, but did not affect carpogenic germination. In contrast, 100% reduction in carpogenic germination was observed in soil amended with Dwarf Essex meal, along with a 33% reduction in myceliogenic germination. With Stonewall meal as soil amendment, carpogenic germination was reduced by 44% and myceliogenic germination was not affected. Both Dwarf Essex and Stonewall meals inhibited colonization of sclerotia in soil by T. harzianum, from 100% to 0% and 8%, respectively, so that biocontrol activity of T. harzianum was reduced in the presence of either meal. Aphanomyces euteiches root rot of pea was significantly reduced by T. harzianum alone (100%), by amendment with Dwarf Essex meal alone (77%), and by T. harzianum in combination with Dwarf Essex meal (100%). Amendment with Stonewall meal alone did not control root rot, and combination of Stonewall meal with T. harzianum reduced the biocontrol efficacy of T. harzianum.     

Biological control of Sclerotinia sclerotiorum attacking soybean plants. Degradation of the cell walls of this pathogen by Trichoderma harzianum (BAFC 742)

Two experiments of biological control of Sclerotinia sclerotiorum, one in the greenhouse and the other in the field, were carried out with soybean and Trichoderma harzianum as host and antagonist, respectively. Significant control of disease was achieved in both experiments, but there were no significant differences in plant growths. In the greenhouse, the application of T. harzianum as alginate capsules, increased the survival of soybean plants more than 100% with respect to the disease treatment. In the field, T. harzianum treated plants survived 40% more than those from the disease treatment, showing a similar survival level to control plants. Besides, a significant reduction (62.5%) in the number of germinated sclerotia was observed in the Trichoderma treated plot. Chitinase and 1,3-β- glucanase activities were detected when T. harzianum was grown in a medium containing Sclerotinia sclerotiorum cell walls as sole carbon source. In addition, electrophoretic profiles of proteins induced in T. harzianum showed quantitative differences between major bands obtained in the media induced by S. sclerotiorum cell walls and that containing glucose as a sole carbon source. This revised version was published online in June 2006 with corrections to the Cover Date.     

Trichoderma harzianum enhances the production of nematicidal compounds in vitro and improves biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato

AIMS: To determine the influence of soil-borne fungus Trichoderma harzianum on the biocontrol performance of Pseudomonas fluorescens strain CHA0 and its 2,4-diacetylphloroglucinol (DAPG) overproducing derivative CHA0/pME3424 against Meloidogyne javanica. METHODS AND RESULTS: Amendment of the culture filtrate (CF) or methanol extract of the CF of a T. harzianum strain Th6 to P. fluorescens growth medium enhanced the production of nematicidal compound(s) by bacterial inoculants in vitro. In addition, bacteria overwhelmingly expressed phl'-'lacZ reporter gene when the medium was amended with CF of T. harzianum. Pseudomonas fluorescens and T. harzianum applied together in unsterilized sandy loam soil caused greater reduction in nematode population densities in tomato roots. CONCLUSIONS: Trichoderma harzianum improves root-knot nematode biocontrol by the antagonistic rhizobacterium P. fluorescens both in vitro and under glasshouse conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The synergistic effect of T. harzianum on the production of nematicidal compound(s) critical in biocontrol may improve the efficacy of biocontrol bacteria against plant-parasitic nematodes. Considering the inconsistent performance of the biocontrol agents under field conditions, application of a mixture of compatible T. harzianum and P. fluorescens would more closely mimic the natural situation and might broaden the spectrum of biocontrol activity with enhanced efficacy and reliability of control.     

Major secondary metabolites produced by two commercial Trichoderma strains active against different phytopathogens

AIMS: Trichoderma harzianum strains T22 and T39 are two micro-organisms used as active agents in a variety of commercial biopesticides and biofertilizers and widely applied amongst field and greenhouse crops. The production, isolation, biological and chemical characterization of the main secondary metabolites produced by these strains are investigated. METHODS AND RESULTS: Of the three major compounds produced by strain T22, one is a new azaphilone that shows marked in vitro inhibition of Rhizoctonia solani, Pythium ultimum and Gaeumannomyces graminis var. tritici. In turn, filtrates from strain T39 were demonstrated to contain two compounds previously isolated from other T. harzianum strains and a new butenolide. The production of the isolated metabolites was also monitored by liquid chromatography/mass spectrometry during in vitro interaction with R. solani. CONCLUSIONS: This paper reports the isolation and characterization of the main secondary metabolites obtained from culture filtrates of two T. harzianum strains and their production during antagonistic interaction with the pathogen R. solani. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first work on secondary metabolites produced by the commercially applied strains T22 and T39. Our results provide a better understanding of the metabolism of these fungi, which are both widely used as biopesticides and/or biofertilizers in biocontrol.     

Chronological Events Associated with the Antagonistic Properties of Trichoderma harzianum against Botrytis cinerea: Indirect Evidence for Sequential Role of Antibiosis and Parasitism

Chronological events associated with the degradation of Botrytis cinerea by a strain of Trichoderma harzianum selected for superior biocontrol ability were studied using ultrastructure and cytochemical investigations in an attempt to define the relative roles of antibiosis and parasitism in the antagonistic process. The first ultrastructural changes were observed 12 h before contact between the organisms, and were characterized by punctuated invaginations of the Botrytis plasmalemma. These reactions were followed by a gradual retraction of the plasmalemma, disorganization of the cytoplasm, loss of turgor pressure and cell death within 48 h of contact between hyphae of the interacting fungi. The first evidence of penetration of B. cinerea by T. harzianum was recorded 72 h after contact. This penetration was apparently mediated by either mechanical pressure or localized wall digestion at points of entry, as there was no clear evidence of chitinolytic degradation of the B. cinerea cell wall, as determined by cytochemical labelling of chitin with a lectin-gold conjugate. However, after 10 days there was clear indication of chitin degradation, based on the random and reduced presence of gold particles over the cell wall of B. cinerea. These results suggest that the strain of T. harzianum antagonized first and foremost by antibiosis, leading to cell death, followed by degradation of the cell by means of chitinolytic enzymes. The production of antibiotics may, therefore, be more important than that of chitinolytic enzymes in conferring superior biocontrol properties to T. harzianum.     

The beneficial effect of Trichoderma spp. on tomato is modulated by the plant genotype

Rhizosphere-competent fungi of the genus Trichoderma are widely used as biofertilizers and biopesticides in commercial formulates because of the multiple beneficial effects on plant growth and disease resistance. In this work, we demonstrate that genetic variability among wild and cultivated tomato lines affects the outcome of the interaction with two 'elite' biocontrol strains of T. atroviride and T. harzianum. The beneficial response, which included enhanced growth and systemic resistance against Botrytis cinerea, was clearly evident for some, but not all, the tested lines. At least in one case (line M82), treatment with the biocontrol agents had no effect or was even detrimental. Expression studies on defence-related genes suggested that the fungus is able to trigger, in the responsive lines, a long-lasting up-regulation of the salicylic acid pathway in the absence of a pathogen, possibly activating a priming mechanism in the plant. Consequently, infection with B. cinerea on plants pretreated with Trichoderma is followed by enhanced activation of jasmonate-responsive genes, eventually boosting systemic resistance to the pathogen in a plant genotype-dependent manner. Our data indicate that, at least in tomato, the Trichoderma induced systemic resistance mechanism is much more complex than considered so far, and the ability of the plant to benefit from this symbiotic-like interaction can be genetically improved.     

Isolation of Microbial Antagonists for Biocontrol of Grey Mould Disease of Strawberries

A screening programme is described for the assessment of the potential of biocontrol agents to control grey mould of strawberries caused by Botrytis cinerea. Bacteria were isolated from strawberry fruits, leaves and flowers from a commercial field site and screened for antagonism towards B. cinerea using two in vitro and one in vivo screening techniques. From 559 microorganisms isolated, 108 inhibited pathogen growth on agar plates and 27 of these prevented spore germination on Cellophane membranes. The ability of these 27 isolates to inhibit infection of young strawberry leaves by B. cinerea on whole plants under glass was then tested. Seven isolates reduced grey mould development and were subsequently assessed in a field trial. Two isolates, one of Bacillus pumilus and one of Pseudomonas fluorescens, were as effective or more effective than standard dichlofluanid sprays and may therefore be of potential value as antagonists of B. cinerea.     

Activity of Fluazinam against Strains of Botrytis cinerea Resistant to Benzimidazoles and/or Dicarboximides and to a Benzimidazole-phenylcarbamate Mixture

Fluazinam is a new active ingredient for the control of grey mould, belonging to the novel broad spectum phenylpyridinamine fungicides. The effect of fluazinam was studied on one wild type and four strains of Botrytis cinerea , which had been isolated from vegetable crops in Greece, and were resistant to benzimidazoles and/or dicarboximides and to the mixture of benzimidazoles (carbendazim) + phenylcarbamates (diethofencarb). In vitro fluazinam was found to be highly active against strains of B. cinerea which were sensitive or resistant to benzimidazoles or exhibited multiple resistance to benzimidazoles, dicarboximides and to the mixture carbendazim + diethofencarb [EC₅₀ and EC₉₅ values (concentration of active ingredient that suppresses mycelial growth to 50 and 95%, respectively, of that of the fungus on fungicide-free agar medium) calculated with probit analysis, ranged from 0.044 to 0.069 and 0.58 to 1.6 μg/ml, respectively]. No cross-resistance was observed between fluazinam and the market products benomyl, iprodione or carbendazim + diethofencarb. Preventive applications of fluazinam in vivo completely inhibited infections of cucumber seedlings by all the above-mentioned resistant strains of B. cinerea . Benomyl and iprodione did not effectively control the benzimidazole- and dicarboximide-resistant strains. The mixture of carbendazim + diethofencarb insufficiently controlled the strain of B. cinerea with moderate resistance to benzimidazoles. The results of this investigation indicate that it should be possible to use fluazinam as an alternative in resistance management programmes against grey mould.     

Editorial note

Generalist herbivores can face many challenges when choosing their host plant. This can be particularly difficult if their choice and performance are affected by host experience. Greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), is an invasive generalist herbivore, which has established in year‐round greenhouses at northern latitudes where it cannot overwinter outdoors. It mainly uses crops such as cucumber (Cucumis sativus L.), tomato (Solanum lycopersicum L.), and ornamentals as host plants. However, every summer the insect escapes greenhouses and is exposed to natural vegetation. We evaluated the performance of T. vaporariorum on diverse vegetation outside greenhouses after prolonged experience of greenhouse crops. First, we surveyed the vegetation near infested greenhouses. Development success of the insect differed among wild hosts. We identified five new hosts among 12 plant species that bore pupae and were thus considered suitable as the insect's host plants. Members of the Urticaceae and Onagraceae were the most preferred and frequently inhabited by all insect life stages. The highest abundance of insects occurred in plots with low plant species richness, independent of plant family in these habitats. We then studied experimentally the impact of 1 year of preconditioning to one of three common greenhouse crops, cucumber, tomato, or poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch), on the performance of the preconditioned adults and their progeny on four wild plants. Adults from tomato and poinsettia preferred the novel host species over the species to which they were preconditioned. The whitefly population preconditioned to cucumber was the most fecund on all offered hosts. We conclude that generalist herbivores can have large variation in performance, despite polyphagy, on novel hosts as shown by the variable abundance of T. vaporariorum pupae among outdoor hosts. Furthermore, performance of whiteflies on natural vegetation was affected by experience on greenhouse crops. Based on our observations, we provide insights and recommendations for pest management.     

不同寄主来源的灰葡萄孢对番茄的致病力分化研究

从安徽合肥、蚌埠、长丰、和县等市、县的番茄、辣椒、草莓、葡萄等发病寄主上分离鉴定获得18个灰葡萄孢Botrytis cinerea菌株,采用菌丝块创伤接种法,分别测定了上述不同寄主来源的灰葡萄孢菌对番茄果实和叶片的致病力.结果表明,所有供试菌株接种番茄果实后均引起发病,但不同菌株所致病斑的平均直径有显著差异,显示灰葡萄孢菌株间对番茄果实的致病力存在明显分化.按照在番茄果实上所致病斑的平均直径大小可将供试菌株致病力划分为较强、中等和较弱3种类型.总体来说,来自番茄的菌株对番茄果实的致病力较强,来自草莓、葡萄和辣椒的菌株对番茄果实的致病力较弱,但来自相同寄主的菌株间致病力也存在差异,菌株致病力差异与菌株地域来源无明显相关.供试灰葡萄孢菌株接种番茄叶片后,除CF1外,均可引起番茄叶片发病,但不同菌株所致番茄叶片病斑的平均直径也有显著差异;供试菌株对番茄叶片的致病力差异与菌株的寄主和地域来源无显著相关.     

木霉菌在玉米病害生物防治中的作用机制及应用

目前,世界上共有分属于10个属（Trichoderma,Gliocladium,Chaetomium,Bacillus,Burkhoderia,Streptomyces and Pseudomonas,Pantoea,Enterobacter,Macrobacterium）中的微生物被试验用于玉米病害的生物防治,其中细菌14种,真菌17种,放线菌1种。国际上由木霉菌开发的生物杀菌剂和生物肥料有50余种,其中以哈茨木霉T22菌株开发的产品最为著名。目前在我国也开发出了4种木霉菌剂型（可湿性粉剂、颗粒剂、水分散粒剂和种衣剂）,正式登记的木霉菌杀菌剂有7种,其中6种为可湿粉剂,1种为水分散粒剂,主要登记用于防治番茄、观赏百合、黄瓜的立枯病、猝倒病、根腐病、灰霉病、霜霉病以及小麦的纹枯病,但尚无木霉菌生物农药被登记用于防治玉米病害。以木霉菌为主要成分登记的菌肥产品有11种,其中在玉米上应用的有2种。由课题组研制的木霉菌颗粒剂和种衣剂通过土壤穴施和种子包衣可有效防治玉米茎腐病和纹枯病,其中木霉菌颗粒剂防效达65%-87%。近期研制的木霉菌可湿性粉剂对玉米小斑病的防效达50%-60%。国际上已鉴定出多种可诱导玉米获得系统抗性的木霉菌源激发子,其中包括Sm1、纤维素酶、疏水蛋白和Avr4 /Avr9等效应因子。本课题组近年鉴定出Thc6（锌指蛋白类转录因子）、PAF-AH和Thph1/Thph2的编码产物在系统诱导以JA/ET信号调控的玉米抗弯孢菌叶斑病中具有重要作用,符合植物免疫MAMPs模式,为全面认识木霉菌诱导免疫机理提供了重要理论依据。木霉菌诱导玉米从根至叶片的防御反应系统传导机制还需深入研究。     

不同寄主来源的灰葡萄孢对番茄的致病力分化研究

Eighteen isolates of Botrytis cinerea were obtained from the diseased plant tissue collected in Hefei, Bengbu, Changfeng and Hexian in Anhui province, by means of tissue isolating method. The pathogenicity of the isolates of B. cinerea from different hosts to the fruits and leaves of tomato were investigated by applying wound inoculation with mycelial blocks. The results showed that all of the tested isolates caused grey mould on tomato fruits, but there was significant difference in the average diameters of the lesions caused by different isolates, suggesting that there was significant differentiation in pathogenicity of B. cinerea strains to tomato fruits among isolates. According to the average diameters of the lesions on tomato fruits, the pathogenicity of the all isolates was classified into three categories: strong, intermediate and weak. In general, the isolates from tomato were more strongly pathogenic to tomato fruits than the isolates from strawberry, grape and capsicum. However, there was difference in pathogenicity among the different isolates from the same host, and the pathogenicity difference was not obviously related to the localities of isolates. After inoculating of tomato leaves, all of the tested isolates except CF3 caused grey mould on tomato leaves, but there was significant difference in the average diameters of the lesions caused by different isolates; and the difference in pathogenicity to tomato leaves was not obviously related to the host and locality of isolates.