枯草芽胞杆菌B1409对番茄和辣椒的防病促生作用

为探讨枯草芽胞杆菌Bacillus subtilis菌株B1409对番茄早疫病和辣椒疫霉病的防效和生防机制,采用平板对峙法和盆栽法测定了该菌株对番茄早疫病菌和辣椒疫霉病菌菌丝生长的抑制作用、对2种病害的盆栽防效以及对番茄和辣椒植株促生长效果和防御酶活性的影响。结果表明:菌株B1409能明显抑制番茄早疫病菌和辣椒疫霉病菌菌丝生长,且导致菌丝发生畸变。10~8CFU/mL菌株B1409菌液对番茄早疫病和辣椒疫霉病的预防效果分别为67.82%和61.22%,治疗效果分别为41.22%和56.43%。不同浓度B1409菌液均能促进番茄和辣椒植株生长,并能增强其体内超氧化物歧化酶、过氧化物酶和过氧化氢酶活性,且浓度越高促进效果越明显。番茄和辣椒植株的平均干重分别在10~2CFU/mL和10~4CFU/mL B1409菌液处理后显著高于对照,增长率分别为42.35%和4.87%。番茄和辣椒植株经10~2CFU/mL B1409菌液处理后,体内超氧化物歧化酶活性比对照显著增加,增长率分别为91.23%和19.58%。研究表明枯草芽胞杆菌B1409菌株可通过直接抑制菌丝生长及诱导植物体自身抗病性等方式来有效防治番茄早疫病和辣椒疫霉病。     

丛枝菌根真菌和甜菜夜蛾的相互作用

为探索丛枝菌根(arbuscular mycorrhiza,AM)真菌与植食性昆虫的相互作用,将摩西管柄囊霉(Funneliformis mosseae BEG167,Fm)、根内球囊霉(Glomus intraradices BEG141,Gi)和地表球囊霉(Glomus versiforme Berch,Gv)3种AM真菌以及甜菜夜蛾Spodoptera exigua分别接种至花生和番茄上,通过测定AM真菌的侵染定殖和甜菜夜蛾的生长发育指标分析AM真菌与甜菜夜蛾的相互作用。结果显示,甜菜夜蛾取食菌根花生植株后,Fm、Gv和Gi的侵染率和泡囊数均有增加,侵染率分别是未取食的1.15、1.10和1.11倍,而Fm的泡囊数增加最显著,是未取食的1.27倍。在菌根番茄植株上,Fm和Gv的侵染率显著增加,分别是未取食的1.24倍和1.94倍,Fm、Gv和Gi的泡囊数均显著增加,分别是未取食的1.50、1.98和1.42倍。甜菜夜蛾取食菌根花生和菌根番茄植株后,幼虫存活率下降,幼虫历期和蛹期明显延长;Fm对其影响最显著,甜菜夜蛾在花生上的存活率、幼虫历期和蛹期分别为26.67%、26.78 d和10.67 d,在番茄上分别为35.52%、24.33 d和10.39 d,与取食非菌根植株处理差异显著。表明甜菜夜蛾能在一定程度上促进AM真菌的侵染和定殖,而AM真菌能抑制甜菜夜蛾的生长和发育,但其影响因AM真菌种类而不同。     

Local and systemic resistance to fungal pathogens triggered by an AVR9-mediated hypersensitive response in tomato and oilseed rape carrying the Cf-9 resistance gene

Tomato and transgenic oilseed rape plants expressing the Cf-9 resistance gene develop a hypersensitive response (HR) after injection of the corresponding Avr9 gene product. It was investigated whether induction of a HR conferred resistance to different fungal pathogens in tomato and oilseed rape. Induction of an AVR9 mediated HR at the pathogen infection site delayed the development of the biotrophs Oidium lycopersicum in tomato and Erysiphe polygoni in oilseed rape, but enhanced the development of the necrotrophs Botrytis cinerea and Alternaria solani in tomato and Sclerotinia sclerotiorum in oilseed rape. Interestingly, delayed fungal disease development was observed in plant tissues surrounding the HR lesion regardless of whether a necrotrophic or biotrophic pathogen was used. In tomato, AVR9 injection induced systemic expression of PR1, PR2 and PR3 defence genes but did not induce systemic resistance to O. lycopersicum, B. cinerea or A. solani. In oilseed rape, AVR9 injection temporarily induced systemic resistance to Leptosphaeria maculans and E. polygoni, but did not induce detectable systemic expression of PR1, PR2 or Cxc750. These results give new insights into the potential uses of an induced HR to engineer disease resistance.     

Interaction ofPseudomonas fluorescens withRhizobium for their effect on the management of peanut root rot

A biocontrol agent (Pseudomonas fluorescens) and a phytostimulator (Rhizobium) have been shown to have beneficial effects on plant growth and health. The study of plants inoculated withPseudomonas andRhizobium requires special attention because of the possibility that these agents may influence each other. Our study was conducted to test the effect of these inoculants on co-inoculation in peanut to control root rot, a severe soilborne disease caused byMacrophomina phaseolina. One fluorescent pseudomonad strain, Pf 1, which effectively inhibited the mycelial growth ofM. phaseolina underin vitro conditions, was studied for its compatibility with the biofertilizer bacterial strainRhizobium TNAU 14. Dual culture and colorimetric studies indicated the existence of a positive interaction between the microbial inoculants. However, glasshouse and field studies showed seed treatment and soil application ofPseudomonas fluorescens Pf 1 to be the most effective treatment in reducing root rot incidence and improving the crop vigor index, in comparison with treatments in which both inoculants were applied. http://www.phytoparasitica.org posting Feb. 11, 2002.     

水分胁迫下AM真菌和根瘤菌对沙打旺生长及养分吸收的影响

利用温室盆栽试验研究水分胁迫下接种丛枝菌根（Arbuscular mycorrhizal,AM）真菌和根瘤菌（Rhizobium meliloti）对沙打旺(Astragalus adsurgens Pall.) 生长和养分吸收的影响。在土壤相对含水量65%和35%条件下,分别设不接种（对照）、单接根瘤菌、单接摩西球囊霉(Glomus mosseae)和双接根瘤菌与摩西球囊霉等4个处理。结果发现：干旱胁迫显著抑制沙打旺AM真菌侵染率（P<0.05）,而接种根瘤菌在两种水分条件下均显著促进摩西球囊霉对沙打旺根系的侵染（P<0.05）。接种AM真菌不仅显著提高沙打旺对P的吸收（P<0.05）,而且明显促进根瘤的生长。无论是在干旱条件下或是在正常供水条件下,双接根瘤菌与摩西球囊霉处理对沙打旺生长及养分吸收的效应显著高于单接菌处理,植株地上部、地下部生物量以及N、P、K等吸收量均为最大。结果表明：AM真菌与根瘤菌双接种技术在干旱、半干旱区受损生态系统的植被恢复中具有一定的应用潜力。     

Induction of systemic resistance by a hypovirulent Rhizoctonia solani isolate in tomato

A polynucleate Rhizoctonia isolate (R3) was analysed for virulence, growth characteristics, enzyme production and presence of dsRNAs. Taxonomic position was assessed morphologically and by anastomosis group (AG) testing and ITS sequence analysis. Results indicated that R3 is a hypovirulent R. solani AG 4. Mechanisms underlying biocontrol towards virulent R. solani and Botrytis cinerea were investigated and plant-mediated resistance was followed using biochemical markers of defence (PR1, laminarinase, chitinase). Control apparently relies on spatial and nutrient competition in soil, and on systemic induced resistance. This is the first report on induction of systemic resistance and of defence markers by a hypovirulent strain of R. solani.     

Selective accumulation of Trichoderma species in soils suppressive to radish damping-off disease after repeated inoculations with Rhizoctonia solani, binucleate Rhizoctonia and Sclerotium rolfsii

Artificial suppression of radish damping-off disease was induced by repeated soil inoculations with Rhizoctonia solani, binucleate Rhizoctonia (BNR) and Sclerotium rolfsii in pot systems. Soils repeatedly inoculated with R. solani and BNR showed suppressive to disease caused by R. solani and S. rolfsii, while soils repeatedly inoculated with S. rolfsii were suppressive to disease caused by S. rolfsii but not by R. solani. Species of Trichoderma were consistently isolated from soils repeatedly inoculated with R. solani, BNR and S. rolfsii. These Trichoderma spp. accumulated selectively in relation to the fungal species that was repeatedly added to the soils. The ratios of the frequencies of T. viride, T. harzianum and T. hamatum were 5:2:2 and 8:5:2 in soils repeatedly inoculated with R. solani and BNR, respectively. In S. rolfsii- inoculated soils, T. koningii was predominantly isolated. T. viride, T. harzianum and T. hamatum isolates obtained from either R. solani or BNR after repeated additions to the soils suppressed radish damping-off disease caused after challenge inoculations with R. solani or S. rolfsii. Among the Trichoderma species, T. viride consistently yielded high levels of suppression. However, isolates of T. koningii obtained from S. rolfsii-infested soils suppressed disease caused by S. rolfsii but failed to suppress disease caused by R. solani. Generally, the species of Trichoderma accumulated in a selective pattern that was closely related to the species of fungal pathogen used to induce the suppressive soil.     

Enhancing Resistance of Tomato and Hot Pepper to Pythium Diseases by Seed Treatment with Fluorescent Pseudomonads

Twenty isolates of fluorescent pseudomonads were evaluated for their ability to control damping-off in tomato (Lycopersicon esculentum) and hot pepper (Capsicum annuum). These isolates were characterized as Pseudomonas fluorescens and Pseudomonas putida. Two isolates, PFATR and KKM 1 belonged to P. putida and the remaining 18 isolates belonged to P. fluorescens. Among these isolates, P. fluorescens isolate Pf1 showed the maximum inhibition of mycelial growth of Pythium aphanidermatum and increased plant growth promotion in tomato and hot pepper. P. fluorescens isolate Pf1 was effective in reducing the damping-off incidence in tomato and hot pepper in greenhouse and field conditions. Isolate Pf1 was further tested for its ability to induce production of defense-related enzymes and chemicals in plants. Earlier and increased activities of phenylalanine ammonia lyase (PAL), peroxidase (PO) and polyphenol oxidase (PPO) were observed in P. fluorescens Pf1 pretreated tomato and hot pepper plants challenged with Pythium aphanidermatum. Moreover, higher accumulation of phenolics was noticed in plants pretreated with P. fluorescens isolate Pf1 challenged with Pythium aphanidermatum. Thus, the present study shows that in addition to direct antagonism and plant growth-promotion, induction of defense-related enzymes involved in the phenyl propanoid pathway collectively contributed to enhance resistance against invasion of Pythium in tomato and hot pepper.     

泽兰实蝇寄生对紫茎泽兰生长和防御能力的影响

为明确泽兰实蝇Procecidochares utilis寄生对紫茎泽兰Ageratina adenophora生长及防御能力的影响,在温室内设置泽兰实蝇寄生与未寄生紫茎泽兰2组盆栽处理,测定泽兰实蝇寄生对紫茎泽兰生长特性、生物量、叶片营养物质、次生代谢物质和保护酶的影响。结果表明,泽兰实蝇寄生显著降低了紫茎泽兰的株高、茎粗、叶片厚度和叶片数,分别显著降低了24.80%、16.86%、42.31%和27.82%;同时,地上生物量、根部生物量和总生物量分别显著降低了58.89%、54.29%和57.60%。泽兰实蝇寄生还导致紫茎泽兰的营养成分发生显著变化,其中可溶性蛋白、可溶性糖、可溶性淀粉和叶绿素含量分别显著降低了41.18%、11.75%、34.57%和29.96%。泽兰实蝇寄生改变了紫茎泽兰的保护酶活性,其过氧化氢酶和超氧化物歧化酶活性分别比未寄生植株显著升高了59.36%和108.06%,过氧化物酶活性降低了25.69%;同时使紫茎泽兰单宁酸含量显著降低了21.67%,总酚和类黄酮的含量分别显著上升了1.21倍和2.09倍。泽兰实蝇寄生的紫茎泽兰总生物量与次生代谢物质总酚和类黄酮的含量呈显著负相关,相关系数r分别为-0.06和-0.43,对照组则不存在相关性。表明泽兰实蝇寄生可能促使紫茎泽兰改变自身的生长与防御能量分配,减少了营养和生长的投入,将更多的资源投向繁殖和防御。     

沼泽红假单胞菌PSB-06菌剂对番茄褪绿病的防效及其作用机制

为明确沼泽红假单胞菌Rhodopseudomonas palustris PSB-06菌剂对番茄褪绿病毒（tomato chlorosis virus,ToCV）的抑制作用,连续3年在田间进行沼泽红假单胞菌PSB-06菌剂对ToCV的药效试验,并在室内研究其抗病毒的作用机制。田间试验结果显示,PSB-06菌剂处理能降低ToCV的发生,植株发病率均低于50%,均显著低于清水和氨基寡糖素处理;室内试验结果显示,PSB-06菌剂处理能抑制病毒传播,喷施PSB-06菌剂后的感病番茄的SA含量达532.67 mg/g,PI II和NPR1基因表达量也相对上升;同时,健康番茄与感病番茄的叶绿素含量均明显升高;经PSB-06喷施后番茄植株上的烟粉虱Bemisia tabaci生存数量降低。蛋白组学分析结果表明,PSB-06处理促使植物代谢及防御的相关蛋白均上调。表明沼泽红假单胞菌PSB-06菌剂能增强植物免疫和防御烟粉虱的能力,从而有效地控制ToCV的发生及传播。     

球孢白僵菌定殖提高番茄对灰霉病抗性及其作用机理

为明确球孢白僵菌Beauveria bassiana定殖对番茄植株抗病性的影响及作用机理,采用灌根法将球孢白僵菌芽生孢子悬浮液接种于番茄植株内,并通过人工接种灰霉菌Botrytis cinerea评价球孢白僵菌定殖后番茄对灰霉病的抗性水平;检测灰霉菌胁迫下番茄植株不同位置叶片内球孢白僵菌的相对含量;测定番茄叶片内草酸氧化酶（oxalate oxidase,OXO）、几丁质酶（chitinase,CHI）和ATP合成酶（ATP synthase,atpA）3种抗病相关基因的表达量。结果表明,球孢白僵菌定殖能够提高番茄植株对灰霉病的抗性,接种灰霉菌第5天,番茄植株发病率、病斑直径和病情指数分别下降了61.6%、41.4%和26.4%;在灰霉菌胁迫下番茄植株内球孢白僵菌偏好于在病原菌感染位置定向聚集,并且引起植物抗病基因OXO、CHI和atpA的表达量上调。表明球孢白僵菌能通过内生定殖与植物互作提高植物抗病性,在植物病害生物防治领域有较大应用潜力。     

番茄早疫病菌对啶菌噁唑敏感基线建立及药剂作用方式初探

从中国山西、内蒙古、山东、海南、江苏、福建和陕西省 (自治区) 不同市、县从未使用过啶菌噁唑的露地或保护地采集并经单孢分离获得 166 株番茄早疫病菌,采用菌丝生长速率法测定了病原菌群体对啶菌噁唑的敏感性。结果表明:啶菌噁唑对番茄早疫病菌的 EC50 值范围在 0.11~2.29 mg/L 之间,敏感性频率呈正态分布,其均值 (0.56 ± 0.39) mg/L 可作为番茄早疫病菌对啶菌噁唑田间抗性监测的敏感基线;不同采集地菌株对啶菌噁唑的敏感性存在差异,其中采自福建省的菌株敏感性最高,而山西省大同、晋中和长治市的菌株敏感性最低。200 mg/L啶菌噁唑对番茄早疫病防治具有优异的保护和治疗作用,且接菌前 4 d 内施药和接菌后 1~2 d内施药防效最佳。研究表明,啶菌噁唑对番茄早疫病防治具有良好的实际应用前景。     

荧光素酶标记无致病力青枯雷尔氏菌的生物学和定殖特性

为示踪青枯雷尔氏菌Ralstonia solanacearum无致病力菌株FJAT1458在番茄植株及根际土壤中的定殖特性,采用电击法对菌株FJAT1458进行荧光素酶(luciferase,LUC)基因标记,并于室内采用生测法测定标记菌株的生物学特性、遗传稳定性、致病力及在番茄植株和根际土壤中的定殖能力。结果表明,成功将luc基因整合至无致病力菌株FJAT1458染色体上,标记菌株FJAT1458-LUC发出强烈的荧光,且PCR扩增出1 612 bp的luc基因片段;与野生型菌株FJAT1458相比,标记菌株FJAT1458-LUC的生长明显滞后,培养8h之后标记菌株FJAT1458-LUC的OD_600nm值均小于野生型菌株FJAT1458;且标记菌株FJAT1458-LUC连续传代20次后菌体浓度显著增加,发光菌体比例显著降低,LUC活性和luc基因表达量均随着传代数增加而显著降低;标记前、后菌株FJAT1458的弱化指数分别为0.90和0.89,且接种番茄植株30 d均未引起植株发病。标记菌株FJAT1458-LUC能在番茄根际土壤、根及茎中定殖,定殖数量呈...     

长枝木霉菌株TL16防治南方根结线虫的作用机理

为探明长枝木霉Trichoderma longibrachiatum菌株TL16防治南方根结线虫Meloidogyne incognita的作用机理,采用原生质体转化法获得绿色荧光蛋白(green fluorescent protein,GFP)标记菌株GFP-TL16,通过测定菌株TL16和GFP-TL16对南方根结线虫卵和2龄幼虫(2nd-stage juvenile,J2)的寄生与致死作用,其发酵液对卵孵化的抑制作用和对J2的致死作用,以及菌株GFP-TL16在黄瓜根系的定殖情况和菌株TL16对番茄根结形成的抑制作用来综合分析其作用机理。结果显示:菌株TL16菌丝对南方根结线虫卵无寄生作用,处理19 d后卵降解率为26.33%,致死作用较低;菌株TL16分生孢子悬浮液处理南方根结线虫J2后72 h的致死率为1.65%,且无寄生作用。菌株TL16发酵液处理南方根结线虫J2后48 h的校正死亡率为10.71%,处理卵15 d后对卵孵化的相对抑制率为77.11%。菌株GFP-TL16可定殖于黄瓜根系中,经菌株TL16处理后接种南方根结线虫J2,番茄根结减退率为55.88%。表明长枝木霉菌株TL16可通过抑制根结线虫卵孵化和诱导番茄产生抗病性来防治根结线虫病。     

A Greenhouse Test for Screening Sugar Beet (Beta Vulgaris) for Resistance to Rhizoctonia Solani

Rhizoctonia solani Kühn is a serious plant pathogenic fungus, causing various types of damage to sugar beet (Beta vulgaris L.). In Europe, the disease is spreading and becoming a threat for the growing of this crop. Plant resistance seems to be the most practical and economical way to control the disease. Experiments were carried out to optimise a greenhouse procedure to screen plants of sugar beet for resistance to R. solani. In the first experiment, two susceptible accessions were evaluated for root and leaf symptoms, after being grown in seven different soil mixtures and inoculated with R. solani. The fungus infected all plants. It was concluded that leaf symptoms were not reliable for the rating of disease severity. Statistically significant differences between the soil mixtures were observed, and there were no significant differences between the two accessions. The two soil mixtures, showing the most severe disease symptoms, were selected for a second experiment, including both resistant and susceptible accessions. As in the first experiment, root symptoms were recorded using a 1–7 scale, and a significant expression of resistance was observed. The average severity of the disease in the greenhouse experiment generally was comparable with the infection in field experiments, and the ranking of the accessions was the same in the two types of experiments. It was concluded that evaluation procedures in the greenhouse could be used as a rapid assay to screen sugar beet plants for resistance to R. solani.     

枸杞根腐病病原菌鉴定及其拮抗菌的筛选

为了针对根腐病实施有效的生物防治,分离鉴定枸杞根腐病病原菌及其拮抗菌,采用组织分离法获得腐根上的病原菌,结合形态学与分子生物学特征鉴定病原菌;利用稀释涂布、滤纸片法和共培养法从健康根际土壤筛选拮抗细菌,通过形态学观察、生理生化鉴定和16S rDNA序列分析对拮抗效果较好的菌株进行鉴定。结果表明：从枸杞根腐病分离得到腐皮镰刀菌（Fusarium solani）和尖孢镰刀菌（Fusarium oxysporum）两种主要致病菌,从健康枸杞根际土壤中分离获得12株对两种镰刀菌具有拮抗作用的细菌,其中J7-3、J7-8、J7-9和J10-8对腐皮镰刀菌的抑菌率均在80%以上,J7-3和J10-8对尖孢镰刀菌的抑菌率均在70%以上。菌株J7-3和J10-8对根腐病病原菌的抑菌作用较好,分别鉴定为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）和枯草芽孢杆菌（Bacillus subtilis）,其中J10-8的拮抗作用和溶菌效果最好,可作为研发微生物菌剂的菌种资源。     

寡雄腐霉发酵液对温室番茄生长及灰霉病的防治作用

为了研制高效、无毒的生物农药,采用自主分离的寡雄腐霉生防菌株Pythium oligandrum CQ2010制备发酵液,研究其对温室番茄生长及灰霉病的防治作用。结果表明,寡雄腐霉发酵液(Pythium oligandrum broth,POB)能显著提高番茄叶绿素含量,增强根系活力,增加氮、磷、钾吸收,促进植株生长,使生物量比对照提高65.14%;同时能激活与叶片抗病性相关的过氧化物酶和过氧化氢酶活性,诱导植株产生抗病性反应,提高抗病能力,其效果优于寡雄腐霉卵孢子制剂;而且POB能显著抑制离体灰葡萄孢菌的菌丝生长和孢子萌发;施用POB能使番茄灰霉病发病率下降22.28%~31.05%,病情指数从52.5(对照)下降至22.5~27.5,相对防治效果达47.62%~57.14%,叶片丙二醛含量显著降低,说明POB减轻了灰葡萄孢菌对细胞膜的伤害。表明POB兼具促进番茄生长及防治灰霉病的作用。     

Identification of Rhizoctonia solani AG 1-IB in Lettuce, AG 4 HG-I in Tomato and Melon, and AG 4 HG-III in Broccoli and Spinach, in Brazil

Fungi isolated in Brazil, from lettuce, broccoli, spinach, melon and tomato, were identified as Rhizoctonia solani. All lettuce isolates anastomosed with both AG 1-IA and IB subgroups and all isolates from broccoli, spinach, melon and tomato anastomosed with AG 4 subgroup HG-I, as well as with subgroups HG-II and HG-III. DNA sequence analyses of ribosomal internal transcribed spacers showed that isolates from lettuce were AG 1-IB, isolates from tomato and melon were AG 4 HG-I, and isolates from broccoli and spinach were AG 4 HG-III. The tomato isolates caused stem rot symptoms, the spinach, broccoli and melon isolates caused hypocotyl and root rot symptoms on the respective host plants and the lettuce isolates caused bottom rot. This is the first report on the occurrence in Brazil of R. solani AG 4 HG-I in tomato and melon, of AG 4 HG-III in broccoli and spinach and of AG 1-IB in lettuce.     

Characterization of Rhizoctonia Species Associated with Foliar Necrosis and Leaf Scorch of Clonally-propagated Eucalyptus in Brazil

The objective was to identify and characterize the causal agent of foliar necrosis and leaf scorch of Eucalyptus spp. in Brazil. Nineteen putative isolates of Rhizoctonia obtained from Eucalyptus plants during clonal propagation were compared with isolates from other hosts and with tester strains of anastomosis groups of Rhizoctonia solani. Features compared were morphological characteristics of anamorphs and teleomorphs, numbers of nuclei per cell in the vegetative hyphae, anastomosis of hyphae, and ability to produce necrotic lesions on cuttings and damping-off of E. grandis×E. urophylla hybrid seedlings. Rhizoctonia solani AG1 (AG1-IB like) was the most frequent causal agent isolated from Eucalyptus plants and cuttings with symptoms of leaf scorch and foliar necrosis respectively. These isolates were highly virulent on Eucalyptus cuttings and presented naturally epiphytic growth on Eucalyptus shoots. Binucleate isolates and isolates of R. solani AG4 were also virulent on cuttings and were most virulent on Eucalyptus seedlings causing pre- and post-emergence damping-off. Virulence on Eucalyptus cuttings and seedlings was not restricted to a single species or anastomosis group of Rhizoctonia.     

Rhizoctonia solani Kühn AG 2-1 on kohlrabi in Italy

Rhizoctonia solani AG 2-1 was recorded in Central Italy on kohlrabi plants showing root and stem rot. After artificial inoculation the fungus caused damping-off of 7-day-old seedlings and root and stem rot of 4-month-old plants developed after 15 days of incubation. This seems to be the first record ofR. solani AG 2-1 on kohlrabi.