番茄青枯病内生拮抗细菌的筛选

 从广西一些市县采集番茄茎标本分离得到55个细菌菌株,分属为芽孢杆菌(Bacillus spp.)、黄单胞菌(Xanthomonas spp.)、假单胞菌(Pseudomonas spp.)和欧文氏菌(Erwinia spp.),其中芽孢杆菌为优势种群。经回接测试,有36个菌株为番茄植株内生菌。这些内生菌只有7个菌株对番茄青枯病菌有拮抗作用,芽孢杆菌B₄₇菌株对番茄青枯病菌拮抗作用较强,经室内和田间初步防治测定,它对番茄青枯病有较好的防治效果。     

内生细菌B47菌株的鉴定及其对番茄青枯病的防效测定

通过形态特征、生理生化特征和16S rDNA序列分析，对分离于番茄茎部能较强抑制茄青枯病菌生长的内生细菌B47菌株进行了鉴定。结果表明，该菌为枯草芽孢杆菌，其最适长pH5～6，最适生长温度为35℃。室内防治试验结果表明，用淋根法先接种B47后接种病菌和用注射法先接种B47菌后接种病原菌的处理可取得81．25％和92．10％的防效，而用淋法、注射法同时接种B47菌与病原菌的处理防效较低。     

番茄内生细菌的分离及拮抗菌株的筛选

生物防治以其安全、高效及无污染等特点已经成为植物病害防治的重要途径。植物内生细菌在植物体内具有稳定的生存空间、不易受外界环境的影响等特点,近年来受到广泛关注[1]。番茄灰霉病和叶霉病是番茄重要病害,多年来一直依赖化学药剂防治。据报道,这两种病害的生防菌株主要是从土壤中分离的,与植物内生细菌相比,这些“外来”微生物在与植物根际土壤中大量习居微生物的竞争中难以占居优势,田间防治效果大多不明显甚至无效。作者从健康番茄植株体内分离内生细菌,筛选出对灰霉病菌和叶霉病菌有拮抗作用的菌株,以期探索新的生物防治途径。1材料…     

内生细菌B_(47)菌株的鉴定及其对番茄青枯病的防效测定

通过形态特征、生理生化特征和16SrDNA序列分析,对分离于番茄茎部能较强抑制番茄青枯病菌生长的内生细菌B47菌株进行了鉴定。结果表明,该菌为枯草芽孢杆菌,其最适生长pH5~6,最适生长温度为35℃。室内防治试验结果表明,用淋根法先接种B47菌后接种病原菌和用注射法先接种B47菌后接种病原菌的处理可取得81.25%和92.10%的防效,而用淋根法、注射法同时接种B47菌与病原菌的处理防效较低。     

银杏内生细菌防治辣椒疫病研究

从健康银杏植株叶片中分离到108 株内生细菌,通过平板测试从中筛选获得35 株对辣椒疫霉菌Phytophthora capsici具有拮抗作用的菌株.温室盆栽试验证明,菌株 Zy44、Fy11、Hy7、Hy14 和 Zy25 对辣椒疫病防效显著,其中Zy44 和 Fy11 发酵液在辣椒疫霉菌接种 20 d 后防效分别为 62%和 52.33%;经形态观察、生理生化特征测试、16S rDNA序列和gyrB基因序列分析,鉴定这两个菌株为解淀粉芽胞杆菌Bacillus amyloliquefaciens;其发酵滤液及酸沉淀获得的脂肽类抑菌物质对盆栽辣椒苗疫病的防治试验结果表明,菌株 Zy44 的防效高于 Fy11,且脂肽类物质的防效高于发酵滤液;显微镜观察发现菌株 Zy44的脂肽类抑菌物质可导致辣椒疫霉菌菌丝体膨大, 分枝增多, 成簇状,并显著抑制孢子囊的形成.     

稻瘟病抗性分子机制及抗病育种策略研究进展

由稻瘟菌侵染引起的稻瘟病是威胁水稻安全生产最严重的真菌病害之一。鉴定克隆水稻抗稻瘟病基因, 系统深入研究稻瘟菌与水稻的相互作用, 揭示水稻的抗病机制, 进而创制推广抗稻瘟病新材料, 对确保粮食安全具有重要意义。本文总结了近10年来稻瘟病抗病基因和感病基因的鉴定、分子机理解析和应用等进展, 总结归纳了抗病基因聚合、分子设计育种、感病基因编辑、抗病基因的病原诱导表达等抗病育种主要策略。最后提出充分利用种质资源, 利用新技术挖掘新基因及创制新材料, 深入研究叶瘟和穗瘟抗病机制差异等是稻瘟病抗病育种下一步重点研究方向和新挑战。     

内生细菌EBS05对烟草诱导抗性的信号转导途径研究

 樟树内生枯草芽胞杆菌EBS05是一株对多种植物病原菌具有较强拮抗活性,并能诱导烟草系统抗性的生防菌株。本文以缺失Surfactin A合成相关基因的突变菌株EBS05^T为材料,研究了内生细菌EBS05对烟草诱导系统抗性的激发子及其信号转导途径。结果表明,菌株EBS05产生的Surfactin A是诱导烟草对TMV系统抗性的有效激发子;Surfactin A诱导处理后,SA信号转导途径下游的关键调节基因NPR1首先被激活,并持续超量表达,进而触发PR1b和PR1a基因持续超量表达,表明Surfactin A诱导烟草对TMV的系统抗性是通过激活SA信号转导途径实现的。同时,Surfactin A诱导处理后24~72 h,JA/ET信号转导途径调节基因PDF1.2被激活,且超量表达,表明在Surfactin A诱导烟草对TMV系统抗性的信号转导过程中,可能存在SA信号途径和JA/ET信号途径的交叉协同作用。     

小麦内生有害细菌的发现和作用研究

 本文对小麦内生有害细菌的存在、作用和定殖进行探索性研究,发现它们接种植物引起出苗不齐,生长缓慢、发育不良、叶尖易变黄,并有扭曲苗出现。其致害作用因接种时间和温度而不同,菌本身和其代谢物共同作用,对植株的作用表现为与促生菌种群数量的竞争结果。细菌学鉴定其为蜡质芽孢杆菌(Bacillus cereus)。菌本身及其代谢物中生长激素(赤霉素GA₃,玉米素Z)含量和超氧化物歧化酶活性均低于促生菌。采用抗药双标记法从灭菌土栽培小麦苗上回收标记菌,只在根部大量回收到,茎、叶部位没有回收到。     

苦参内生枯草芽孢杆菌B_（36）抗菌物质对番茄叶霉病菌的作用机制

采用大孔树脂吸附法提取苦参内生细菌B36的抗菌物质,研究其对番茄叶霉病菌的作用机制。结果表明,菌株B36抗菌物质粗提物对番茄叶霉病菌抑菌圈直径达20.5mm;引起菌丝畸形,产生囊泡;抑制分生孢子萌发。当抗菌物质浓度为10.6×10^2μg/ml时,对孢子萌发的抑制率达86.56%;果胶酶和羧甲基纤维素酶的酶活分别为0.5911和0.01757U/ml,显著低于对照。说明B36抗菌物质抑制两种菌丝胞外细胞壁水解酶的合成,通过破坏细胞膜结构产生抑菌作用,而抗菌物质对病菌菌丝细胞壁组成物质几丁质和菌丝蛋白质的浓度没有影响。     

拮抗芒果炭疽病菌的红树内生细菌筛选及AiL3菌株抗菌物质研究

采用对峙生长法测定了24株红树内生细菌对芒果炭疽菌Colletotrichum gloeosporioides不同菌株的拮抗作用,其中来自老鼠簕Acanthus ilicifolius叶片的菌株AiL3拮抗效果较好,对芒果炭疽菌3个菌株的抑菌带均大于10mm。该菌株对辣椒疫霉Phytophthora capsici、黄瓜枯萎病菌Fusarium oxysporum f.sp.cucumerinum等8种植物病原菌亦有较强的拮抗作用。菌株培养滤液经有机溶剂萃取和硫酸铵沉淀分析发现,硫酸铵沉淀物具有抑菌活性;沉淀物经蛋白酶K和胃蛋白酶作用后,拮抗作用消失,说明菌株AiL3产生的抗菌物质是蛋白类物质。该蛋白对热和酸碱稳定、对紫外线不敏感。     

内生细菌与木霉复合处理诱导甜瓜对枯萎病的抗性

在对甜瓜枯萎病温室防效试验的研究中发现，内生枯草芽孢杆菌B6菌株与绿色木霉T23菌株复合处理的相对防效达82．22％，比B6和T23的单独处理分别提高32．8％和146．7％。分析比较了B6和T23单独和复合处理甜瓜幼苗后，甜瓜根部防御反应相关酶系苯丙氨酸解氨酶、过氧化物酶、多酚氧化酶、β-1，3-葡聚糖酶比活性的变化趋势。结果表明：内生细菌B6和木霉T23复合接种，其苯丙氨酸解氨酶、过氧化物酶、多酚氧化酶和β-1，3-葡聚糖酶比活性比单独接种有不同程度的增强，这种变化在挑战接种甜瓜枯萎病菌之后更加明显。     

转hrf1基因水稻对稻曲病抗性分析

用注射接种法测定9个转hrf1基因水稻品系对稻曲病的抗性,结果表明B12-2m、B12、HTRP2和NJH12转基因系对稻曲病的抗性有显著提高,其中NJH12对稻曲病的抗性表现最突出。在江苏南京和安徽潜山两地的田间测定结果显示NJH12对稻曲病的抗性表现明显,与对照相比防效提高65%以上。用RT-PCR测定抗病转基因系中防卫基因的表达,在抗病转基因系中,Ospr1a、Ospr1b和PAL等防卫反应基因的表达明显增强。转hrf1基因水稻可能通过诱导防卫反应基因的表达提高水稻对稻曲病的抗性。     

蜡质芽孢杆菌AR156防治水稻纹枯病机理初探

蜡质芽孢杆菌AR156是一种防治多种土传病害的生物制剂,对水稻纹枯病具有较好的防治效果。本研究通过温室试验方面验证菌株 AR156的防病效果和促生作用,从细胞水平和基因水平初步揭示了菌株AR156防治水稻纹枯病的机理。结果表明,菌株AR156对水稻纹枯病的温室防效达73.06%,同时促进水稻生物量增加14.45%。菌株AR156处理提高了水稻植株SOD、PAL、POD和CAT等防御酶活性,增强了OsPR1b、OsPR10、OsNPR1和ZB8等防卫相关基因的表达。接种立枯丝核菌Rhizoctonia solani HNW-21之前用菌株AR156预处理的水稻植株,SOD和PAL分别提前4、2 d出现活性峰;防卫相关基因均提前表达,且表达时间延长,从而提高水稻对纹枯病的抗性。     

Induced Resistance to Rice Blast by Antagonistic Bacterium, <Emphasis Type="Italic">Serratia marcescens </Emphasis>Strain B2

An antagonistic bacterium, Serratia marcescens strain B2, controlled rice blast after being sprayed onto rice phylloplane, as did the bacterial suspension when poured into rhizosphere soil of rice plants. Three days after root treatment, rice blast conidia were sprayed onto rice foliage. A week after pathogen inoculation, rice blast was suppressed and lesions caused by the pathogen decreased in size. Brown deposits were observed around sites of pathogen infection after root treatment. Induced resistance was not associated with an increase in the activitiy of peroxidase, phenylalanine ammonia lyase, tyrosine ammonia lyase, β-1,3-glucanase, β-1,4-glycosidase, N-acetylhexosaminidase or chitinase. However, lipoxygenase levels were elevated after the root treatment with strain B2 following inoculation with the pathogen. Strain B2 was not detected in rice foliage after root treatment. These data suggest that strain B2 induced resistance against rice blast caused by Pyricularia oryzae. Received 1 November 2001/ Accepted in revised form 25 January 2002     

Implication of Systemic Induced Resistance in the Suppression of Fusarium Wilt of Tomato by Pseudomonas fluorescens WCS417r and by Nonpathogenic Fusarium oxysporum Fo47

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.     

真核表达产物Y3诱导烟草对烟草花叶病毒的抗性研究

从毛头鬼伞Coprinus comatus中提取的碱性糖蛋白Y3可以降低烟草花叶病毒(TMV)的侵染.克隆获得Y3蛋白cDNA后与真核表达载体pPIC-9k连接,重组载体pPIC-9k-Y3成功电转化入毕赤酵母Pichia pastoris后,转化子在28℃、250 r/min培养条件下,使用1.0％甲醇诱导表达6d,...     

玫瑰黄链霉菌Men-myco-93-63诱抗粗蛋白对黄瓜的诱抗作用

玫瑰黄链霉菌Strempomyces roseoflavus Men-myco-93-63是分离自马铃薯疮痂病自然衰退土壤中的一株拮抗链霉菌,该菌株及其代谢产物对多种重要的植物病原菌都具有较强的抑制作用,为了探明该生防菌产生的诱抗粗蛋白对黄瓜抗病性的诱导作用,采用离体叶片接种的方法,发现诱抗粗蛋白诱导黄瓜叶片灰霉病发病直径显著小于对照;经组织染色法和紫外分光光度计法测定,发现诱抗粗蛋白可以诱导黄瓜叶片中活性氧（ROS）的积累和超氧化物歧化酶（SOD）、过氧化物酶（POD）和多酚氧化酶（PPO）等抗病相关酶活性的显著提高;通过实时荧光定量PCR（qRT-PCR）测定,发现诱抗粗蛋白还可以诱导黄瓜叶片中PR-1a、PR-3、PR-9和NPR1等抗病相关基因表达的上调,试验结果表明Men-myco-93-63产生的诱抗粗蛋白能够诱导黄瓜抗病性的提升。     

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.