莱氏野村菌CQNr01对斜纹夜蛾幼虫的侵染研究

以莱氏野村菌Nomuraea riley CQNr01菌株接种斜纹夜蛾Spodoptera litura 2龄和4龄幼虫,观察感病率,并利用荧光染色观察菌株在幼虫离体表皮上的孢子萌发和附着胞产生情况。结果显示,菌株CQNr01孢子悬液浓度为1×10^8、1×10^9孢子·mL^-1时斜纹夜蛾2龄幼虫的累计死亡率分别为86.58%和89.91%,而4龄则只有13.33%和16.67%。菌株CQNr01的孢子能够成功附着在斜纹夜蛾幼虫的离体表皮上,但孢子在2龄幼虫表皮的粘附能力优于4龄幼虫;接种24 h起两个龄期的离体表皮上均开始有孢子萌发现象并有附着胞和芽管产生,并随着接种时间的增长芽管不断伸长,但相同接种时间下孢子在2龄幼虫表皮上的萌发率和附着胞产生数量明显多于4龄幼虫表皮。研究证明菌株CQNr01对斜纹夜蛾高龄和低龄幼虫的致病力差异显著,其差异主要源于斜纹夜蛾幼虫体壁的屏障作用。     

洋葱伯克氏菌群不同基因型菌株对几种重要植物病原真菌的抑制作用及其潜在致病性

从玉米和水稻根围分离到70株不同基因型的洋葱伯克氏菌,对这些菌株进行了拮抗植物病原菌的筛选,并对高拮抗菌株进行了潜在致病性和安全性分析。结果表明,有46株洋葱伯克氏菌对一种或多种病菌有较高的拮抗活性。在不同的洋葱伯克氏菌基因型内,以基因型Ⅴ内拮抗菌株占的比例最高,对所测5种病原真菌的平均拮抗菌株比率为80．0％,其中部分菌株表现出很强的拮抗活性。筛选出的4株高拮抗菌株对洋葱不具有致病性,同时也未检测到与人体致病相关的BCESM毒力基因。     

进境哈萨克斯坦向日葵种子中向日葵黑茎病菌的鉴定

自进境哈萨克斯坦向日葵种子中,采用常规平板分离法获得1株疑似向日葵黑茎病菌Plenodomus lindquistii菌株LL4,通过生物学性状、ITS序列测定和比对分析及致病性测定等方法对其进行了鉴定。结果表明,该病菌在PDA平板上培养初期菌丝无色,分隔分枝多,后期菌丝褐色或深褐色,常膨大;分生孢子器暗褐色,分散或聚集,球形、近球形或不规则形,大小为71.2~361.8μm;分生孢子形态变化较大,无色,单孢,肾形至椭圆形,大小为3.6~8.2μm×2.2~3.7μm,常含有2个油球;培养期间未见有性阶段。基于ITS序列分析比对发现,菌株LL4与Gen Bank中多个向日葵黑茎病菌分离物序列同源性达99%以上,系统进化树显示其与其它向日葵黑茎病菌分离物聚在同一个分支。菌株LL4可侵染向日葵根茎部,造成典型黑茎病症状。表明分离获得的菌株LL4为向日葵黑茎病菌P.lindquistii。     

陕西苹果树腐烂病菌(Cytospora spp.)不同分离株的生物学特性与致病性研究

 本研究从陕西分离得到61株苹果树腐烂病菌(Cytospora spp.),选取在PDA培养基上菌落特征差异明显的7个分离株,对其生物学特性及致病性进行研究。结果表明:各分离株在PDA、PSA、PMA和PEMA培养基上菌落生长较好,但在PDA上的菌落颜色和产孢情况差异很大。各分离株均能在5~32℃生长,但对35℃以上高温的适应性差异较大;所有分离株均能在pH4~9的条件下生长,最适pH为5~6;光照对各分离株的菌落生长有明显的促进作用。各分离株均可在Cza-pek培养基及供试的其它碳、氮源培养基上生长,其中以葡萄糖、麦芽糖和酵母膏为最佳碳、氮源。采用烫伤接种的方法,分别以菌饼和分生孢子悬浮液接种苹果离体枝条,两者均可侵染发病,但各分离株致病力差异显著,其中菌落颜色为黄褐色的菌株致病性强。因此,根据菌落颜色、致病性和生物学特性可将这7个分离株划分为3个类群:Ⅰ型为黄褐色强致病类群,但各分离株的产孢量有差异;Ⅱ型为乳白色不产孢的弱致病类群;Ⅲ型为灰褐色易产孢弱致病类群。其余54株分离物均属于Ⅰ型,这些结果说明陕西省苹果树腐烂病菌具有多样性和致病性分化现象。     

3株鸽源新城疫病毒的分子特征及对鸽的致病性

2011-2013年在新城疫流行病学调查中分离到3株鸽源新城疫病毒(SDS,SD01和SD02),为了进一步了解其生物学特性和遗传进化规律,对3株病毒进行了测序和生物活性分析,并对分离株SDS对鸽的致病性进行了评价.结果表明,毒株SDS基因组全长为15 192 bp,基因排列方式为3'-NP-P-M-F-HN-L-5'...     

云南、广西三七黑斑病病原链格孢菌的鉴定

正黑斑病是三七栽培生产中常见的一大病害,叶片受害产生近圆形或不规则水浸状病斑,常导致成株落叶、幼苗生长点及茎秆顶端腐烂枯死。其病原一般认为是链格孢属真菌人参链格Alternaria panax Whetzel~([1,2]),也有相关研究证明黑斑病病原为细链格孢Alternaria tenuis Nees~([3]),后定名为链格孢Alternaria alternata Keissl~([4])。本研究利用ITS序列和histone 3部分编码序列的PCR鉴定,结合形态学鉴定,分析三七主产区黑斑病菌的组成和分布情况及几种病原菌的致病力差异,以期为三七黑斑病防治提供理论依据。     

Application of polyclonal and monoclonal antibodies for the detection of Xanthomonas campestris pv. campestris in crucifer seeds using immunofluorescence microscopy

Polyclonal and monoclonal antibodies (PCAs and MCAs) were tested for the detection ofXanthomonas campestris pv.campestris (Xcc) in cabbage seeds using immunofluorescence microscopy (IF). It was concluded that PCA 94, MCAs 20H6, 2F4, 18G12 and a mixture of MCAs 20H6, 18G12, 2F4 and 16B5 could be used to detect Xcc in seed extracts when 5 min and 2.5 h shaking of seeds are used as extraction methods. The reliability of confirming suspect colonies with MCAs and PCA 94 in IF depended in part on the seed lot tested and the antibody used. Some virulent Xcc strains derived from seed lots, did not react with MCAs 10C5, 2F4, 18G12, 17C12 and 16B5. On the other hand, saprophytic isolates obtained from one seed lot cross-reacted with MCA 17C12 and to a lesser extent with MCAs 2F4, 18G12 and PCA 94. No relationship was found between IF-reactions of Xcc strains using MCAs and reactions of Xcc strains in pathogenicity testing. Xcc andX. c. pv.amoraciae (Xca) could in general not be distinguished on the basis of reactions with MCAs and PCAs. Also in pathogenicity tests Xcc and Xca were hard to distinguish.     

梨和苹果腐烂病菌不同培养表型菌株的致病性分析

The pathogenicity of three strains (F-SD-8, F-BJ-2c-2 and F-HN-2a-1) of Valsa mali var. pyri causing pear canker and one strain (F-SX-A6) of V. mali var. mali causing apple canker in China were comparatively tested by wound inoculation on in vitro twigs of pear, apple and some other woody plants, and in vivo twigs of pear. Significant pathogenicity differentiation was detected in V. mali var. pyri. Generally strains F-SD-8 and F-BJ-2c-2 were highly pathogenic on pear although their culturing characteristics differed greatly. The strain F-SX-A6 was more aggressive on apple than on pear, and the strain F-HN-2a-1 showed significant lower pathogenicity on ten pear cultivars and other seven species of woody plants. Our results confirmed that two variants of V. mali had host preference and were also aggressive to crabapple, apricot, and peach besides apple and pear. Meanwhile, strains F-SD-8 and F-BJ-2c-2 could induce the formation of pycnidia on in vivo twigs of pear, which was not observed on in vivo twigs inoculated with F-HN-2a-1 and F-SX-A6.     

Testing variability in pathogenicity ofPhytophthora cactorum, P. citrophthora andP. syringae to apple, pear, peach, cherry and plum rootstocks

The relative virulence ofPhytophthora cactorum andP. syringae originating from almond trees, and ofP. citrophthora originating from citrus, to apple, pear, peach, cherry and plum rootstocks, was studiedin vivo andin vitro. Results of the different experiments were in good agreement. All testedPhytophthora isolates showed little virulence to pear rootstocks-causing only minor crown rot symptoms - and no virulence at all to apple rootstocks. In contrast, they were highly virulent to stone fruit rootstocks, causing crown rot disease. The non-pathogenicity of these isolates to pome rootstocks could be interpreted as strict host specificity.     

Resistance of Capsicum species to tobacco,tomato and pepper strains of tobacco mosaic virus

A number ofCapsicum accessions including nine species were tested for resistance to TMV based on hypersensitivity. The tobacco strain MA and the tomato strain SPS, which were both isolated from tomato, and two pathogenically distinct pepper strains P 11 and P 8, were used. Of the 73Capsicum accessions tested 58 were resistant to MA and SPS, 31 were resistant to P 11 and five were resistant to P 8.Samenvatting Om verschillen in pathogeniteit tussen twee in Nederland voorkomende paprikastammen van het TMV nader vast te stellen, werd een aantalCapsicum-herkomsten, waaronder negen soorten, op resistentie getoetst. Hierbij werden de representatieve paprika-isolaten P 11 en P 8 vergeleken met de uit tomaat afkomstige isolaten MA en SPS als vertegenwoordigers van respectievelijk de tabaks- en tomatestam van het TMV. Bij het beoordelen van de symptomen duidden lokale, necrotische vlekken en afvallen van geïnoculeerde bladeren op resistentie, systemische necrosen of mozaïeksymptomen op vatbaarheid. In deze symptomen kwamen tussen de gebruikte stammen verschillen in virulentie tot uitdrukking. Er werden echter vooral verschillen in agressiviteit waargenomen met betrekking tot zowel afzonderlijke, voor resistentie uitsplitsende,Capsicum-herkomsten als het totale aantal getoetste herkomsten. Van de ruim 73 herkomsten waren er 58 resistent tegen MA en SPS, 31 daarvan tegen P 11, maar slechts vijf daarvan tegen P 8. Deze resistentie tegen P 8 werd gevonden inC. chinense.