人工接种对新月弯孢菌侵染玉米籽粒的影响

研究了人工接种不同接种时期和方法对新月弯孢菌侵染玉米籽粒的影响,结果表明:玉米弯孢叶斑病菌可以侵染玉米果穗籽粒,使玉米籽粒产生褐色病斑。伤口接种法能使玉米果穗100%发病;花丝通道接种也可导致果穗发病,但其发病频率很低;而花丝喷雾接种和苞叶喷雾接种病菌不能成功侵染玉米果穗籽粒;吐丝后10 d和乳熟期接种只能引起接种点籽粒发病,病菌扩展不好;但籽粒形成期接种的玉米果穗籽粒不仅接种点发病,而且其周围的籽粒也感染了病菌,病菌扩展情况较好。试验明确,玉米籽粒形成期采用伤口接种是使玉米籽粒发生弯孢叶斑病的一种较为理想的人工接种方法。     

玉米新病害──弯孢菌叶斑病

玉米新病害──弯孢菌叶斑病戴法超，高卫东，吴仁杰，金晓华（中国农科院品资所，１０００８１））（北京市植物保护站）玉米弯孢菌叶斑病，俗名拟眼斑病，１９９４年秋在北京郊区县夏玉米上有较大面积发生。该病害是继玉米大斑病、小斑病之后，在北京地区新发生的一种重...     

生防细菌BMY-1对几种植物病原真菌的抑制作用

采用平板对峙培养法和滤纸片培养法测定细菌BMY-1菌株对番茄灰霉病菌(Botrytis cinerea)、辣椒疫霉病菌(Phytophthora capsici)、玉米小斑病菌(Bipolaria maydis)、玉米弯孢霉叶斑病菌(Curvularia lunata)等11种植物病原真菌生长的抑制作用。结果表明,BMY-1菌株对供试病原菌生长具有很好的抑制效果。平板对峙培养法中,BMY-1菌株对番茄灰霉病菌、玉米弯孢霉叶斑病菌、玉米小斑病菌的抑制效果最好,抑菌宽度分别达到15.0 mm,14.0 mm,13.0mm。滤纸片培养法中,BMY-1菌液对番茄灰霉病菌抑制效果最好,抑菌带宽度为8.0 mm。BMY-1菌液及其无菌发酵液对病原菌孢子萌发也有很强的抑制作用。其中对辣椒疫霉病菌和玉米小斑病菌孢子萌发的抑制效果最好。BMY-1菌液处理后,孢子萌发率分别为0.97%和1.00%,而对照萌发率为分别为96!29%和93.04%。     

玉米弯孢菌叶斑病在豫南发生危害

近年来,玉米弯孢菌叶斑病在河南驻马店、周口、漯河、南阳等地市发生日趋严重,已严重阻碍了当地玉米生产发展,一般减产15%~20%,发生严重的减产50%以上。1玉米弯孢菌叶斑病发病特点与危害状1.1发病晚,蔓延迅速据在驻马店、周口、漯河等市农业科学研究所玉米试验地和玉米大田的调查,玉米弯孢菌叶斑病在玉米抽雄散粉后的8月初开始发病,然后迅速蔓延,到8月中下旬达到高峰,许多感病品种叶片布满病斑,严重的到8月下旬即枯死。1.2病害相互交织发生在玉米成株中后期的两大病害—玉米弯孢菌叶斑病和玉米锈病几乎同时发病,相互交织在一起,在玉米试验田…     

玉米弯孢叶斑病菌Clm1 基因的克隆及其功能验证

 从玉米弯孢叶斑病菌中克隆到MAPK 基因之一的Clm1,其与玉米小斑病菌中的ChMps1 基因同源。采用InversePCR 和RACE 技术获得了该基因的全序列及其所在区域的旁侧序列。该基因cDNA 全长1. 251 kb,编码416 个氨基酸。通过农杆菌介导的转化方法对其进行了敲除。Clm1 敲除突变体在细胞壁完整性,分生孢子产量及形态方面发生明显变化,其侵染离体叶片的能力明显下降,纤维素酶活性有所下降,说明该基因与弯孢叶斑病菌细胞壁完整性及致病性有着密切的联系。     

玉米弯孢叶斑病菌生理分化及鉴定技术

 从我国20余个主栽玉米品种和20个骨干自交系中筛选出沈135、78599-1、Mo17、477、C8605、E28、7922和黄早4等8个自交系,作为鉴别寄主来研究弯孢叶斑病菌的生理分化。研究表明,弯孢叶斑病菌[Curvularia lunata(Wakker) Boed.]在温室进行的苗期鉴定与田间成株期鉴定的生理分化结果一致。苗期鉴定具有操作简单、鉴定环境条件易控制等特点。通过8个鉴别寄主将采自我国玉米产区的20株弯孢叶斑病菌分为6个致病类型,其中类型A致病性强、分布广,为优势致病类群;类型D主要分布在我国零星发生的地区,为弱致病类群。同时研究了影响病菌生理分化鉴定的主要环境因子,其中湿度、温度和植株营养状况对病菌生理分化鉴定结果有明显影响。本研究结果为我国玉米品种抗性鉴定、弯孢菌叶斑病流行监测和品种合理布局提供了理论依据。     

53份玉米品种(组合)对4种玉米病害的抗性评价

１９９３～１９９６年对北京玉米区试５３份品种（组合）进行抗玉米大斑病、小斑病、弯孢菌叶斑病和玉米矮花叶病的抗性鉴定，其中抗大斑病有１９份，抗小斑病有３９份，抗弯孢菌叶斑病有２３份，抗矮花叶病有２６份，兼抗２种病害以上有３６份，兼抗３种病害以上有１９份，兼抗４种病害有３份。     

53份玉米品种(组合)对4种玉米病害的抗性评价

１９９３～１９９６年对北京玉米区试５３份品种（组合）进行抗玉米大斑病、小斑病、弯孢菌叶斑病和玉米矮花叶病的抗性鉴定，其中抗大斑病有１９份，抗小斑病有３９份，抗弯孢菌叶斑病有２３份，抗矮花叶病有２６份，兼抗２种病害以上有３６份，兼抗３种病害以上有１９份，兼抗４种病害有３份。     

玉米弯孢菌叶斑病传播梯度模型

 根据植物病害流行学原理,采用人工接种方法,在田间造成玉米弯孢菌叶斑病不同的发病梯度,分析连续2年玉米弯孢菌叶斑病传播动态。利用SPSS统计软件构建了此病害的传播梯度模型,结果表明指数模型是沈阳地区玉米弯孢菌叶斑病传播梯度的最佳模型。接种2个月,掖单13玉米弯孢菌叶斑病传播梯度最佳模型是x=9.606×EXP (-0.2829×d),海试16最佳模型是x=7.154×EXP (-0.2351×d)(x:病情指数,d:距菌源中心的距离)。预测玉米弯孢菌叶斑病在2个月最远传播距离为28 m;传播速度为0.4~0.5 m/d。     

四川部分地区发生玉米弯孢菌叶斑病

20世纪 80年代末、90年代初 ,我国华北和东北主要玉米产区 ,普遍发生一种玉米新病害弯孢菌叶斑病 ,造成玉米损失 10 %～ 30 % ,引起植保部门、玉米育种单位和种子部门的高度重视。近年本所在进行玉米抗病性鉴定同时 ,调查了该病在四川省的发生情况。1　弯孢菌叶斑病在四川省的发展趋势1999年 7月全国玉米综防攻关专题组考察西南片区时 ,在雅安市草坝镇的川单 15号品种上发现拟似弯孢菌叶斑病病叶 ,经分离鉴定为玉米弯菌菌[Ｃｕｒｖｕｌａｒｉａｌｕｍａｔａ (Ｗａｋｋｅｒ)Ｂｏｅｄｉｊｎ],沈阳农业大学对此病样的分离结果 ,也证实为弯孢菌…     

李属坏死环斑病毒怀柔分离物CP基因的克隆、原核表达及其抗血清制备

本研究通过RT-PCR技术获得了包含李属坏死环斑病毒怀柔分离物CP蛋白基因的DNA片段,构建了针对pET29a载体的两种表达质粒;〖JP2〗转化大肠杆菌BL21(DE3),并经IPTG诱导表达了带不同融合肽段的PNRSV1（25 ku）〖JP〗和PNRSV2（29 ku）融合蛋白。经过Ni NTA亲和柱与SDS PAGE分离纯化,获得大量表达融合蛋白,并免疫家兔制备了融合表达蛋白的特异性抗体。间接ELISA测定其效价分别为8×103和3.2×104。     

应用间接酶联免疫吸附技术对芜菁花叶病毒血清学关系的研究

 本试验收集了来自不同国家和地区的10个芜菁花叶病毒株系或分离物(TuMV)。应用直接ELISA和间接ELISA对其各株系间血清学关系进行了比较试验。直接ELISA双抗体夹心法专化性较强。由病毒抗血清所制备的结合体只与同宗抗原起反应,不与TuMV其它株系异宗抗原起反应。应用病毒抗血清所制备的F (ab')₂包被处理的间接ELISA技术,鉴定病毒不同株系血清学亲缘关系时,只要用1个病毒株系抗血清即可对不同株系进行鉴定。由6个TuMV株系分别制备的抗血清对10个毒株进行鉴定表明,各株系均能交互反应,说明株系间具有共同的抗原性,仅OM株系与其它株系较少一致性,表明血清学关系较疏远。因此认为,间接ELISA适用于广泛的病毒诊断及株系鉴定之用,比直接ELISA优越。     

水稻白叶枯病菌的血清学研究

 用戊二醛固定的5个水稻白叶枯菌株制备了5个抗血清,利用琼脂双扩散、试管凝集、免疫电泳和酶联免疫吸附试验研究了107个水稻白叶枯菌株血清学反应的差异,将它们分为三个血清型。属于Ⅰ型的菌株(OS-225、F₄等)占供试菌株的95%,分布于全国各稻区;归属于Ⅱ型的菌株(OS 209、OS-109等)占5.6%,主要来自南方边远地区;Ⅱ型仅1个菌株(G₈),占0.9%,来自广西东部;其中还有两个菌株和上述抗血清均不能反应,暂不能归型,来自福建。血清型和致病型之间的相关性不用戊二醛固定、热处理等5种不同方法处理菌体后制备的抗血清之间,表现出一致的反应特异性和相似的"型"专化性。免疫电泳结果表明,不同血清型的免疫源组成是不同的,Ⅰ型仅具中性免疫源,Ⅱ型具中性及偏碱性免疫源,而Ⅱ型则具中性及偏酸性两种免疫源。
比较了反向间接血凝、酶联免疫吸附和免疫荧光反应等方法检测病菌的灵敏度,以免疫荧光试验(IF)为最灵敏,可检测到每毫升10³细胞,ELISA其次(10^4-5cell/ml),反向间接血凝法为10^6-7cells/ml,双扩散法最差,只有在高达10⁸ cells/ml时才有阳性反应。     

Problems of detecting phytopathogenic bacteria by ELISA1

Xanthomonas ampelina can be detected with the same sensitivity by ELISA double-antibody sandwich (ELISA-DAS) or indirect ELISA (ELISA-I) but the latter is preferred for its greater simplicity. The two methods also gave similar sensitivity results for soft-rot erwinias, but their application is complicated by the large number of erwinia serotypes. ELISA-I was unable to distinguish strains of Agrobacterium tumefaciens from A. radiobacter. The cross reactions with other bacteria of antisera against X. fragariae were tested by ELISA-I. The problems of applying these methods are discussed.     

香蕉花叶病的酶联免疫检测技术研究

 用分离自香蕉病株的黄瓜花叶病毒香蕉毒株(CMV-B)和烟草花叶病毒香蕉毒株(TMV-B)制备抗血清,其效价As-CMV-B为1:5000,As-TMV-B为1:8000。用这两种抗血清检测香蕉花叶病,间接ELISA和PAS-ELISA法可检测香蕉病叶汁液的最大稀释度均为1:1280,健叶汁液无非特异性反应,Dot-ELISA可检测病叶汁液的最大稀释度为1:640,健叶汁液在稀释度为1:20时有轻度非特异性反应。用间接ELISA法检测了田间香蕉病株和香蕉试管苗标样共158份,其中CMV的带毒率为58%,TMV的带毒率为19%,二者复合感染率为8.5%。     

新月弯孢菌及其近似菌菌落形态和可溶性蛋白电泳图谱比较分析

通过对分离自玉米及其他寄主的 12个新月弯孢菌菌株和 5个近似菌株菌落形态及可溶性蛋白电泳谱比较分析 ,表明菌落形态在不同种之间存在明显的差异 ,同种之间也存在一定差异 ,但不稳定和存在变异。 17个菌株可溶性蛋白SDS聚丙烯酰胺凝胶电泳显示 ,Curvularia属在Rf值为 0.177处有一条该属的特征蛋白带 ,新月弯孢菌在Rf值为0.225处有一条该种的特征蛋白带 ,但新月弯孢菌蛋白带存在多样性 ,聚类分析将未能确定的 13号菌株定为不等弯孢菌     

Antibody production and identity of MLOs associated with sugar-cane whiteleaf disease and bermuda-grass whiteleaf disease from Thailand

Cuttings from sugar-cane plants with symptoms of whiteleaf disease and bermuda-grass plants also showing whiteleaf symptoms were collected in Thailand and transferred to a glasshouse at East Mailing. Using these plants as source material, procedures were devised for the partial purification of MLO-associated immunogens. Antisera were raised separately to the sugar-cane whiteleaf and bermuda-grass whiteleaf immunogens. These antisera exhibited specificity for their homologous MLO antigens in F(ab')₂ indirect enzyme immunosorbent assays (ELISA). Detection of MLO infection was possible in crude tissue extracts diluted several hundredfold. No cross-reactions were observed in reciprocal tests between these two MLO sources and their antisera, nor were there reactions between either antiserum and extracts of other graminaceous hosts showing symptoms of natural whiteleaf infection. No cross-reactions were obtained in reciprocal tests with Spiroplasma citri or aster yellows MLO and their homologous antibodies.     

Detection of quarantine viruses of potato by ELISA

According to EC regulations, imported material of tuber-forming Solarium spp. has to be tested for the absence of defined quarantine viruses. In order to allow an efficient and timesaving application of the quarantine inspection procedure, antisera have been developed and scrutinized for their use by the ELISA technique. The viruses concerned were Andean potato latent virus (APLV), Andean potato mottle virus (APMV), arracacha virus B oca strain (AVB-O), potato virus T (PVT) and tobacco ringspot virus Andean potato calico strain (TRSV-Ca). The results show that all viruses can be reliably detected by double-antibody sandwich (DAS) ELISA. The detection limits were in the range ≤ 1–32 ng ml⁻¹. The strain specificity by DAS-ELISA of the antisera for APLV and APMV was overcome by mixing antisera from the different strains and strain groups, respectively. Strains C and Lm of APMV seemed to be serologically identical. A comparison of the suceptibility of several wild species of tuber-forming Solanum with that of several cultivars of Solanum tuberosum showed a higher frequency of infection in the wild species.     

A detection method for Pseudomonas solanacearum in symptomless potato tubers and some data on its sensitivity and specificity

A detection method is described for latent infections of Pseudomonas solanacearum race 3 in potato. This method is based on extraction of 200 heel ends of potato, followed by screening with an indirect antibody stain (IFAS) and (in IFAS-positive cases) a pathogenicity test on tomato (PT). Using the method in some sensitivity and specificity tests with more than 600 samples it appears that: (a) its detection level is 10⁴ cells ml^-1 in IFAS and 10²— 10⁴ cells ml^-1 in PT; (b) per cent recovery is 0.1–10% (10% at lower contamination levels); (c) false-positive samples due to cross-reacting bacteria in IFAS were limited to only 2–3%, using two polyclonal antisera against whole cells of P. solanacearum. The merits of the method in comparison with others (ELISA, selective media) are discussed.     

Significance of ABC transporters in fungicide sensitivity and resistance

ATP-binding cassette (ABC) transporters are members of a protein superfamily which can be responsible for efflux of drugs from cells of target organisms. In this way, the transporters may provide a mechanism of protection against cytotoxic drugs. In laboratory-generated mutants of fungi, overproduction of ABC transporters can cause multi-drug resistance to azoles and other non-related toxicants. The impact of this mechanism of resistance in field populations with decreased sensitivity to azoles remains to be established. Inhibitors of ABC transporter activity may synergize activity of azoles to populations of both sensitive and azole-resistant pathogens. The natural function of ABC transporters in plant pathogenic fungi may relate to transport of plant-defence compounds or fungal pathogenicity factors. Therefore, inhibitors of ABC transporter activity may act as disease control agents with an indirect mode of action. ©1997 SCI