Detection of Erwinia herbicola pv. gypsophilae in gypsophila plants by PCR

Three PCR primer pairs, based on the cytokinins (etz) or IAA biosynthetic genes, were used for detecting Erwinia herbicola pv. gypsophilae in Gypsophila paniculata plants. The primers were specific to all gall-forming E. herbicola strains and distinguished them from saprophytic strains associated with gypsophila plants or from other gall-forming bacteria. In pure culture of the pathogen, less than one bacterial cell was detected with nested PCR using the etz primers - an increase of 100-fold in sensitivity as compared with single-round PCR. In the presence of plant extract a reduction of tenfold in sensitivity was observed by nested PCR. When cells were grown on a semi-selective medium prior to PCR (Bio-PCR), five cells from pure culture of the pathogen were detected. The bacteria could be detected by nested-PCR or Bio-PCR in symptomless gypsophila cuttings after 7 days. The Bio-PCR procedure described in this study can be used to establish disease-free nuclear stock of mother plants of gypsophila.     

A strain of Erwinia herbicola pathogenic on Gypsophila paniculata

A yellow pigmented, rod-shaped, Gram negative, peritrichously flagellated, fermentative bacterium was isolated from galls on the stems of the ornamental plant,Gypsophila paniculata. The galls appeared to be similar to those described on the plant by Brown (1934). The isolate proved pathogenic when inoculated into healthy stems; it was identified as a strain ofErwinia herbicola (Lohnis) Dye. It is suggested that the organism should be namedE. herbicola f. sp.gypsophilae.Samenvatting Een geel gepigmenteerde, staafvormige, Gram-negatieve, fermentatieve bacterie met petritriche flagellen werd geïsoleerd uit gallen op de stengels van de sierplantGypsophila paniculata. De ziektesymptomen kwamen overeen met de door Brown in 1934 van deze plant beschreven gallen. Het isolaat bleek na inoculatie in gezonde stengels pathogeen te zijn en werd geïdentificeerd als een stam vanErwinia herbicola. Voorgesteld wordt dit organism aan te duiden alsE. herbicola f. sp.gypsophilae.     

长角扁谷盗触角感器的扫描电镜观察

利用扫描电镜对长角扁谷盗雌、雄成虫触角形态及感器进行观察,分析了雌、雄成虫触角感器的类型、形态与分布。结果表明,长角扁谷盗成虫触角由柄节、梗节和鞭节组成,其中鞭节由9个亚节组成。成虫触角上共有3类感受器,可将其分为8种,分别是:刺形感器(Ⅰ、Ⅱ、Ⅲ、Ⅳ)、毛形感器(Ⅰ、Ⅱ、Ⅲ)以及B9hm氏鬃毛。比较发现,雄虫触角每节的长度均显著长于雌虫,雌、雄虫触角感器的形态相似,类型基本相同。结合长角扁谷盗触角感器的形态、分布和已报道的锈赤扁谷盗的相关研究等,对长角扁谷盗成虫触角各类感器的功能进行了分析与推测。     

锈赤扁谷盗触角感器的扫描电镜观察

利用扫描电镜对锈赤扁谷盗触角感器进行观察,发现其触角由柄节、梗节和鞭节组成,鞭节分9个亚节。雄虫触角各节均显著长于雌虫,而直径除鞭节5、7、8、9四节外,其余各节均显著大于雌虫。成虫触角感器主要有刺形感器、毛形感器和Bhm氏鬃毛3种主要类型。其中,刺形感器具有4种形态,主要分布于鞭节第7、8、9节,毛形感器有2种形态,毛形感器Ⅰ各节都有分布,毛形感器Ⅱ仅有1根,位于柄节腹面,Bhm氏鬃毛主要分布于柄节与梗节连接处。雌、雄虫感器的类型、分布无明显差异,雄虫感器密度略大于雌虫。结合感受器的形态、分布和已报道的触角电位反应数据,对各感受器的功能进行了推测。     

轮纹异痂蝗触角感器的扫描电镜观察

利用扫描电镜观察了轮纹异痂蝗[Bryodemella tuberculatum dilutum(Stoll)]成虫触角感器的类型和分布。结果表明:轮纹异痂蝗触角为丝状,由柄节、梗节和鞭节组成,雄性个体鞭节包括24个亚节,雌性个体鞭节包括23个亚节。雌雄个体均具有12种感受器,即毛形感受器、刺形感受器(Ⅰ型和Ⅱ型)、锥形感受器(Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型和Ⅴ型)、腔锥形感受器、腔形感受器及Bhm氏鬃毛。根据各类感器的形态、分布和显微结构探讨了其可能承担的功能。     

Evaluation of a DNA probe for the detection of Erwinia herbicola strains pathogenic on Gypsophila paniculata

A 7.5-kb DNA fragment carrying genes for indole acetic acid biosynthesis in Erwinia herbicola pv. gypsophilae was used as a DNA probe to detect gall-forming E. herbicola strains. A quick colony hybridization procedure was developed to detect E. herbicola pv. gypsophilae in cuttings of gypsophila, and was compared with ELISA and pathogenicity tests. The sensitivity of the colony hybridization procedure was sufficient to detect less than 100 colony-forming units after enrichment culture. In mixed cultures, with saprophytes associated with the gypsophila plant, about 10⁴ CFU/ml of the pathogen were detectable. The colony hybridization is specific to gall-forming E. herbicola strains, and is relatively easy to perform. The advantages of using the colony hybridization procedure for practical purposes, compared with ELISA and pathogenicity tests, are discussed.     

Scanning electron microscopy of Setaria labiatopapillosa (Alessandrini, 1848) from cattle of Kazakhstan.

Surface structures of males and females of Setaria labiatopapillosa were studied by means of scanning electron microscopy at high magnification. It was found that the surface of buccal cavity, lateral appendages, vulva, anus and cloaca differs from the remaining cuticle. The shape of internal and external mouth papillae, amphids, deirids, postdeirid and phasmidial pore was studied. On the surface of the postdeirid are four small papillae arranged in a typical manner around the depression from which projects a needle-like formation. The ventral bands are formed by fine longitudinal parallel folds of the cuticle. Some anomalies in the localization of postcloacal papillae were observed.     

Scanning electron microscopy of early infection in the uredial stage of Puccinia sorghi in Zea mays

An SEM study was made of the infection process of Puccinia sorghi in Zea mays. A uredospore germ tube grows across epidermal cells and along their anticlinal walls, often branching and altering direction of growth. The fungus, on attaining a stoma, delimits an appressorium over it. Infection peg initials enlarge linearly and centripetally along the appressorium base, forcing open the stomatal slit. Having penetrated the stomatal aperture, the infection peg develops a substomatal vesicle. From the vesicle, two short primary infection hyphae develop synchronously, a septum later forming between the vesicle body and each hyphal base. A further septum divides the primary hypha into two cells. Secondary infection hyphae emerge later from the fully expanded vesicle on the proximal side of each vesicle/primary hypha septum. Secondary hyphae are narrower than primary hyphae, form their proximal septum some distance along the hypha, develop asynchronously, and proliferate to form the intercellular mycelium. Infection processes and epidermal stripping are discussed.     

Scanning electron microscopy study of infection structure formation of Puccinia graminis f.sp. tritici in host and non-host cereal species

The development of uredospore-derived infection structures of Puccinia graminis f.sp. tritici in wheat, barley, sorghum and maize was examined by scanning electron microscopy (SEM). Germ tubes grew over the leaf surface until a stoma was located. An appressorium formed over the stoma and the leaf was penetrated by an infection peg. Within the substomatal chamber of all species the infection peg developed a substomatal vesicle by 6 h post-inoculation (hpi). from which a primary infection hypha developed parallel to the long axis of the leaf. In wheat, barley and maize, when a primary infection hypha abutted onto a host cell, a septum was laid down between the tip of the hypha and the substomatal vesicle, delimiting a haustorial mother cell by 12 hpi; haustorial mother cells did not form in sorghum. Secondary infection hyphae arose on the substomatal vesicle side of the septum; infection did not progress further in maize, but in wheat and barley secondary infection hyphae branched, and proliferated intercellularly forming the fungal thallus. A haustorial mother cell was delimited when an intercellular hypha abutted onto a host cell. Infection sites with haustorial mother cells were observed at 12 hpi in barley and 24 hpi in wheat. In all four plant species, some atypical substomatal vesicle initials, substomatal vesicles and primary infection hyphae were observed.     

水稻与白叶枯病菌互作的功能基因组学研究

水稻白叶枯病是水稻生产上重要的细菌病害之一。随着水稻和白叶枯病菌(Xanthomonas oryzaepv.oryzae,Xoo)全基因组序列的完成,该病害己成为植物-病原物互作研究的模式。水稻-Xoo互作涉及到寄主与病原菌因子的时空表达和严密调控。因此,阐明互作基因的表达调控机理,对于全面解析水稻-Xoo互作机制具有重要的科学意义。本文介绍了近年相关工作的研究进展。1Xoo基因鉴别和功能分析1.1Xoo侵染的基因表达谱和分子量化根据Xoo基因组序列信息,自主研制了载有调控基因、致病基因、特有基因以及保守基因特异片段的基因芯片,成功地用于在离体培养、…     

Comparison of immunofluorescence microscopy and dilution-plating for the detection of Xanthomonas campestris pv. campestris in crucifer seeds

The correlation between immunofluorescence microscopy (IF) and dilution-plating on nutrient starch cycloheximide agar (NSCA) or NSCA with the addition of nitrofurantoin and vancomycin (NSCAA) was studied for the detection ofXanthomonas campestris pv.campestris (Xcc) in crucifer seeds. When checking 50 l of the seed extract in IF, IF and dilution-plating gave corresponding results (both positive or negative) for 45.4–56.4% of the samples tested. No differences were observed in this respect between tests using a polyclonal antiserum (PCA 94) and replicate tests using monoclonal antibodies (MCA 20H6). When 20 l of the seed extract was checked in IF, 67.3–71.3% of the samples tested were both positive or negative with dilutionplating and IF. IF negative and dilution-plating positive samples were found for 0.0–7.3% of all samples tested. The percentage of IF positive and dilution-plating negative samples ranged from 26.7–29.2 (20 l seed extract checked) to 41.8–47.3% (50 l seed extract checked). Generally, the probability of isolating Xcc increased with increasing numbers of fluorescent cells found in IF. Above 10 000 cells per ml the probability of isolating Xcc ranged from 57.1–81.8%. Increasing the extraction time from 5 min to 2.5 h shaking showed no significant increase of the number of samples found positive in IF and dilution-plating. However, when using both 5 min and 2.5 h shaking as compared to 5 min shaking only, more samples can be found positive in IF (1.0–14.5%) and dilution-plating (3.0–18.5%). Examining 1 l instead of 50 l of the sample smear, would increase the correspondence between IF and dilution-plating results up to minimally 69.1% (MCA 20H6). However, the risk of false-negative results in IF as compared to dilution-plating would also increase.     

Scanning electron microscopy of the establishment of compatible and incompatible Xanthomonas campestris pathovars on the leaf surface of Italian ryegrass and maize1

Scanning electron-microscopy observations made on the leaves of Italian ryegrass and maize, inoculated with Xanthomonas campestris pvs graminis, oryzae and oryzicola clearly showed a difference in the distribution pattern among the different pathovars tested. Pvs oryzae and oryzicola could be detected on the leaf trichomes of ryegrass, while pv. graminis was not. On maize leaves, the attachment of pvs oryzae and oryzicola to trichomes was much more pronounced than on ryegrass. In addition, pv. oryzae spread further into leaves of maize than did pvs graminis and oryzicola and could be detected in masses until at least the sixth day after inoculation. These observations suggest that non-host plants such as maize could function as alternate inoculum sources of pv. oryzae for nearby rice plants.     

油茶蓝翅天牛触角感器扫描电镜观察

蓝翅天牛是我国特有种,为油茶重要蛀干害虫之一,对油茶生产造成严重影响。为探明蓝翅天牛触角感器类型,为基于嗅觉和味觉的防控技术探索提供依据,本文利用扫描电镜对蓝翅天牛成虫触角上的感器进行观察和比对。结果表明：蓝翅天牛成虫触角存在雌雄二型现象,触角长度、感器类型及分布均有明显差异。雌雄成虫触角上共发现感器类型7类12种,其中刺形感器Ⅱ型在雄成虫触角特异分布,可能在雄虫的某些行为中发挥主导作用。     

Scanning electron microscopic studies on males of trichinella species

Ultrastructure of the cuticle and pseudobursa of adult males of four species of Trichinella has been studied by SEM. T. nativa differs markedly from T. spiralis, T. nelsoni and Trichinella sp. in the form of the pseudobursa. Trichinella sp. differs only slightly from T. spiralis and T. nelsoni. The ultrastructure of the cuticle revealed no characters suitable for the differentiation of the taxons under study.     

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.     

腰带长体茧蜂雌蜂触角的扫描电镜观察

采用扫描电镜技术对腰带长体茧蜂Microcentrus cingulum的触角感器进行了观察。结果表明,腰带长体茧蜂雌蜂触角上存在三种感器,分别为毛形感器、刚毛形感器、板形感器。对触角各种感器的形态和分布特点进行了描述,并就三类触角感器的功能进行了探讨。     

Description of the Bacterium Causing Blight of Leek as Pseudomonas syringae pv. porri (pv. nov.)

ABSTRACT Forty bacterial strains isolated from leek blight (Allium porrum) in France and other countries were studied by conventional biochemical methods, serological reactions, numerical taxonomy, DNA-DNA hybridization, and ice nucleation activity, as well as by pathogenicity on leek and other host plants. They were compared with reference strains of Pseudomonas, mainly pathotype strains of P. syringae pathovars and strains of P. syringae pv. syringae isolated from various host plants including onions. Leek strains sorted with P. syringae species (sensu lato) by LOPAT tests (production of levan-sucrase, oxidase, pectinase, arginine dihydrolase, and hypersensitive reaction on tobacco). Leek strains were pathogenic to leek and produced symptoms identical to those observed in the field. They were the only strains in our study that could cause blight of leek. Thus, our results justify the creation of a new pathovar. Leek strains constituted a highly homogeneous DNA group and a discrete phenon by numerical taxonomy, and they belonged to O-serogroup POR. The name of P. syringae pv. porri is proposed for the bacterium causing leek blight. Criteria for routine identification are presented and taxonomic status is discussed.