Apple necrotic mosaic virus,a novel ilarvirus from mosaic-diseased apple trees in Japan and China

The causal agent of apple mosaic disease has been previously thought to be solely caused by apple mosaic virus (ApMV). In this study, we report that a novel ilarvirus is also associated with apple mosaic disease. Next-generation sequencing analysis of an apple tree showing mosaic symptoms revealed that the tree was infected with three apple latent viruses (apple stem pitting virus, apple stem grooving virus, and apple chlorotic leaf spot virus) and a novel ilarvirus (given the name apple necrotic mosaic virus (ApNMV)) that is closely related to Prunus necrotic ringspot virus (PNRSV) and ApMV. The genome of ApNMV consists of RNA1 (3378 nt), RNA2 (2767 nt), and RNA3 (1956 nt). A phylogenetic analysis based on the coat protein amino acid sequences indicated that the novel virus belongs to the same subgroup 3 of the genus Ilarvirus as PNRSV and ApMV. The presence of mosaic leaves, which tend to be unevenly distributed in diseased apple trees, was correlated with the internal distribution of ApNMV. RT-PCR detection of mosaic-diseased apple trees in Japan indicated that ApNMV was detected in apple trees introduced from China, whereas ApMV was detected from cultivated apple trees in domestic orchards. Consistent with these findings, a survey of mosaic-diseased apple trees in major apple-producing provinces in China revealed that the majority of apple trees showing mosaic symptoms in China are infected with ApNMV.     

Identification and transmission of Piper yellow mottle virus and Cucumber mosaic virus infecting black pepper (Piper nigrum) in Sri Lanka

Sri Lankan black pepper with symptoms of yellow mottle disease contained a mixture of viruses: Piper yellow mottle virus (PYMV) particles (30 × 130 nm), Cucumber mosaic virus (CMV, 30 nm diameter isometric particles), and unidentified, isometric virus-like particles (30 nm diameter). An effective purification procedure is described for PYMV. Immunosorbent and conventional electron microscopy successfully detected badnavirus particles only when at least partially purified extracts were used. PYMV was confirmed as the cause of the disease, with the other two viruses apparently playing no part in producing symptoms. PYMV was transmitted by grafting, by the insect vectors citrus mealy bug ( Planococcus citri ) and black pepper lace bug ( Diconocoris distanti ), but not by mechanical inoculation or through seeds. The CMV isolate was transmitted to indicator plants by mechanical inoculation and by the vector Aphis gossypii , but not by Myzus persicae ; but neither mechanical nor insect transmission of CMV to black pepper was successful. A sensitive polymerase chain reaction assay was developed to detect PYMV in black pepper.     

Transmission and the role of honeybees in field spread of blueberry shock ilarvirus, a pollen-borne virus of highbush blueberry

ABSTRACT The rapid and random spread of blueberry shock ilarvirus (BlShV) in commercial plantings suggested that insects played a role in transmission. Transmission from infected field plants to trap plants only occurred during bloom, indicating that flowers were the avenue for infection and flower-visiting insects including pollinators were involved. Trap plants readily became infected during bloom when a honeybee hive was included in cages with diseased field plants and trap plants. There was limited transmission in cages without a hive and no transmission when healthy field bushes were caged with trap plants either with or without honeybees. Infective pollen survived within the hive for 1 but not 2 weeks. Western flower thrips did not transmit BlShV when they were allowed to feed on caged flowering trap plants in the presence of a source of infected pollen. Results of pollen washes, cell disruption, and electron microscopy show that particles of BlShV were on, in, and between the cells of the pollen tetrad. Pollen from infected plants germinated as readily as pollen from healthy plants. BlShV was seedborne, but at a low level. All 42 cultivars tested were susceptible to BlShV when inoculated by grafting. The primary mechanism of transmission appears to be the transfer of BlShV-contaminated pollen by honeybees from flowers on infected plants to flowers on healthy plants.     

江西甘蔗花叶病田间调查

2007年9-10月对江西甘蔗花叶病(sugarcane mosaic disease)进行了多点田间调查,结果表明江西甘蔗普遍发生花叶病,其中红皮甘蔗花叶病重于青皮甘蔗,两者病丛率分别为59.8%和19.2%,赣北、赣中、赣南3大地区之间的甘蔗花叶病发生轻重无明显差异。     

苹果经营代际传递意愿及其影响因素分析——基于山东和陕西1012个苹果户的调查数据

采用山东和陕西1012个苹果户调查数据,运用二元Logit模型分析影响苹果经营代际传递意愿的主要因素.结果 表明:苹果经营代际传递意愿总体较弱,18.68％的苹果户愿意代际传递;苹果种植决策者的年龄、苹果劳动力人数、苹果收入占比、苹果效益、苹果种植技术和果园装备投入对苹果经营代际传递意愿有显著正向影响;计划缩小苹果种植...     

甘蔗花叶病毒HC-Pro基因原核表达及表达产物抗血清制备

采用RT-PCR方法自甘蔗花叶病毒北京玉米分离物（SCMV-BJ）的基因组中分离出其HC-Pro基因，通过T4DNA聚合酶连接到原核表达载体pET-22b（＋）上，获得的重组子pETHC转化大肠杆菌B121（DE3），用IPTG在37℃进行诱导表达。SDS-PAGE和Western blot分析表明，HC-Pro基因在大肠杆菌中获得了高效表达，产生分子量约为52kDa的融合蛋白。将融合蛋白纯化后免疫兔子，获得了特异性的抗血清并提取了抗体IgG。ACP-ELISA测定抗血清的效价为1／8192。结果表明，该血清可用于SCMV-BJ的检测，并为进一步分析HC-Pro的功能奠定基础。     

The natural occurrence of bean yellow mosaic, cucumber mosaic and tobacco mosaic viruses in lisianthus in Israel

Mosaic on leaves, necrosis, stunting and flower symptoms were observed in lisianthus ( Eustoma russellianum ) raised from seed. Three viruses, bean yellow mosaic (BYMV), cucumber mosaic (CMV) and tobacco mosaic (TMV), were isolated. Virus identification was based on electron microscopy, host range, aphid transmission and serology.     

Analysis of natural populations and possible natural reassortment of Cucumber mosaic virus

Plants naturally infected with Cucumber mosaic virus (CMV) were collected and analyzed by electrophoresis of the replicative form of dsRNA and by Northern blot hybridization using CMV RNA-specific probes. Some of the CMV-infected plants, especially winter crops, contained two kinds of RNA 1 segments or RNA 2 segments (or both), suggesting that mixed infections of CMV occurred naturally. Single-aphid-transmitted isolates (SATIs) from the field isolate containing two RNA 1 segments were grouped into three types by the electrophoretic mobility of RNA 1 (i.e., those containing one slow segment, those containing one fast segment, and those containing both). Furthermore, SATIs and single-lesion isolates, generated from the plants inoculated with a mixture of two CMV isolates that could be differentiated by their electrophoretic dsRNA profiles, were analyzed by dsRNA, indicating that nonparental progenies were observed. These results suggested that genetic reassortment of CMV RNA may occur in nature and that this is an important mechanism in CMV evolution.     

National and local spread of barley yellow mosaic virus in the United Kingdom1

Barley yellow mosaic virus was first reported in the United Kingdom in 1980. Since then cumulative records of reports of disease, confirmed at the laboratory of the Agricultural Development and Advisory Service of the Ministry of Agriculture, Fisheries and Food, show how infection has spread from the east of England where it first occurred in quantity, to the west. Areas of concentrated infection appear to relate to areas of intensive winter-barley cultivation. Records suggest that infection may have occurred as early as 1976. Patterns of local spread in fields as defined in aerial photographs reflect the means by which the viruliferous vector may be passively moved in the soil. Other patterns reflect previous cropping. The higher frequency of infection on the sites of long-removed hedgerows is not explained.     

Stability of the aphid transmission phenotype in cucumber mosaic virus

The stability of the aphid transmission phenotype in seven field isolates of cucumber mosaic virus (CMV) was studied, using aphids Aphis gossypii and Myzus persicae . Field isolates, obtained from four vegetable crops, were propagated in squash and Nicotiana glutinosa , and passaged by either aphid transmission or mechanical transfer. All seven isolates were transmissible by both aphids and this aphid transmission phenotype was stable after 20–24 mechanical passages. Upon further mechanical passaging, one of the seven isolates, CMV-2 A1-MT 60x, lost its transmissibility by Myzus persicae but was still transmissible by Aphis gossypii , although at a reduced rate. Isolates maintained by both aphid transmission and mechanical transfer were transmitted more efficiently by Aphis gossypii than by Myzus persicae . A comparison of the RNA profiles showed no major differences among the CMV isolates before and after mechanical passage.     

Population Dynamics of Cucumber mosaic virus in Melon Crops and in Weeds in Central Spain

ABSTRACT Understanding epidemiology and evolution of plant viruses requires knowledge of their ecology: obtaining information about the dynamics and genetic structure of viral populations in their various hosts is necessary to analyze host specialization and to identify reservoirs and inoculum sources. We present here a 3-year analysis of the population dynamics of Cucumber mosaic virus (CMV) in Central Spain in weed hosts and melon. CMV infection in weed hosts was detected throughout the year and showed a clear seasonality, with maximum incidence of 20 to 30% in summer and autumn. The dynamics of CMV incidence were different in various weed habitats (i.e., fallow fields, edges, and wastelands), which differed in stability due to the degree of human intervention. CMV incidence in weed habitats was correlated with the amount of vegetation, estimated both as biomass and as soil cover by plants. CMV population dynamics in melon crops was unrelated to that in weed habitats. Genetic characterization by ribonuclease protection assays and biological characterization on differential hosts showed no significant differences in the frequency of genotypes or biotypes for CMV isolates from weeds or melon. Hence, different population dynamics in various hosts and habitats has not resulted in population differentiation, suggesting that migration between hosts and habitats prevents fragmentation of the population.     

Susceptibility of cider apple cultivars to the sooty blotch and flyspeck complex in Spain

Cultivar may be an important factor associated with the occurrence and severity of sooty blotch and flyspeck (SBFS) fungi in apple. The aim of the study was to analyse the influence of 28 cultivar features on the occurrence of the SBFS complex in apple and to categorize the importance of each using a multivariate approach. Features were classified as agronomic (related to fruiting and growing behaviour and to susceptibility to other diseases; 11 features), morphological (describing fruit morphology; 11) and technological (related to the chemical composition of the fruit juice; 6). Susceptibility to SBFS varied widely among cultivars. The predictive value of some features was not the same for the signs of SB and FS, possibly because each sign is produced by a different species complex which may behave differentially against environmental variables, including the cultivar. Our results showed that agronomic features as a whole were more significant than morphological or technological ones for explaining the cultivar variability in damage. Those related to fruit development phenology were the more explanatory among the agronomic features: late-maturing cultivars suffered higher damage. The intensity of colour was the most explanatory variable among the features describing fruit morphology, showing that SBFS severity was greater on light-coloured apples. Russeting level or skin texture, amongst other variables, were significant but less predictive. The technological features were least explanatory: FS damage was favoured by lower sugar content and higher phenol content at harvest, whereas variability in SB signs was not explained by any juice parameter. The multivariate approach allowed us to select the most important variables in relation to SBFS damage and to discard those without influence, which may be a valuable contribution to understand SBFS development. This research highlights the need of a proper choice of cultivar to reduce disease severity.     

苹果园杂草多样性及其对天敌昆虫的影响

陕西渭北的黄土高原是我国苹果的主要产区,该地区果园地形复杂,地面植被丰富,生产上往往需要投入大量的人力和物力清除杂草。果园植物的种类对果园昆虫多样性有明显影响,果园生物多样性指数维持较高水平时害虫不易成灾。严毓骅和段建军及王大平研究表明,在苹果园保留夏至草,或间作苜蓿、三叶草、白花草木犀、百脉根等可提高天敌昆虫的多样性,有助于发挥天敌昆虫的作用。果园地面杂草覆盖度较高时,捕食性蜘蛛的丰富度和多样性也较高,可有效控制果园中的主要害虫。目前,关于黄土高原苹果园杂草多样性以及不同杂草对天敌昆虫的影响尚未见报道。本试验对陕西省黄陵县不同地形的苹果园地面植被进行系统调查,明确杂草种类及优势种,并对杂草群落与果园天敌昆虫群落相似性进行了比较。     

南芥菜花叶病毒RT-PCR扩增产物胶体金层析和酶联检测方法的建立

南芥菜花叶病毒是我国进境植物检疫性有害生物,为建立快速灵敏的检疫检测方法,本研究用生物素标记一条引物,用荧光素(或地高辛)标记另一条引物,经RT-PCR扩增产生双标记的扩增产物,建立了PCR扩增产物的胶体金层析检测和ELISA检测方法。胶体金层析检测方法在15min即可获得检测结果,ELISA方法需20h,后者检测的灵敏度可比前者分别提高100倍和5000倍。所建立的2种方法都免去了普通PCR检测的溴化乙锭染色和电泳的过程。     

苜蓿花叶病毒ELISA检测方法的建立及其在大豆病毒调查和抗性资源鉴定中的应用

苜蓿花叶病毒(alfalfa mosaic virus, AMV)是一种世界性分布、宿主范围广、具有严重危害性的植物病毒,能引起大豆的严重病害。本研究利用原核表达的AMV CP蛋白制备的抗血清,建立了高效、准确的AMV间接ELISA检测方法,并应用于病害调查和抗性鉴定,结果表明制备的3份抗血清对重组蛋白和AMV感染的大豆植物粗提液的效价均达到256 000倍,血清特异性分析结果显示3份抗血清仅识别感染AMV的大豆叶片,不识别感染大豆花叶病毒(soybean mosaic virus, SMV)的大豆叶片。通过建立的AMV间接ELISA与常规RT-PCR同时对采集的50份疑似感染AMV的大豆样品进行检测,有46份样品检测结果一致,符合率达92%。利用建立的AMV ELISA方法和课题组已建立的SMV ELISA方法对吉林省大豆主产区的大豆样品进行病毒检测的结果表明,病毒检出率为38.30%,SMV的检出率达30.85%,AMV的检出率达17.06%,复合侵染率为9.61%。对接种AMV的40个大豆品种进行抗性鉴定,结果显示40份大豆全部感染AMV,但是病毒载量存在差异,部分品种表现出AM...     

134种植物害虫的寄主与扩散分析

随着国际贸易和全球旅游业的发展 ,植物害虫越来越迅速广泛地向新的地区扩散。本文主要依据EPPO(欧洲和地中海植物保护组织 )和CABI(国际农业与生物科学中心 )分别于 1 996年和 1 997～ 2 0 0 0年陆续新公布的 1 34种对农业、林业及农林产品有害的重要昆虫和蜱螨类植物害虫的全球分布图 ,收集其它相关资料 ,从寄主植物与食性、传播途径两个方面比较分析。得出如下结论 :作为木材来源的裸子乔木 ,作为水果来源的蔷薇科植物 ,蔬菜来源的茄科、葫芦科、豆科植物以及原产于热带、亚热带的观赏植物这些与人类的生活和生产活动息息相关的寄主植物易于受到各种不同害虫的侵袭。寄主的分布对昆虫的扩散影响巨大 ,但是昆虫的食性多寡和食性的改变也对昆虫分布有一定作用     

陕西苹果园天敌昆虫分布调查

对陕西不同地区苹果园天敌昆虫进行了调查研究,结果获得天敌昆虫17种,隶属于8目11科。天敌昆虫在陕西不同地区的苹果园的分布存在一定的差异。随着苹果园海拔高度的升高,果园天敌昆虫的种群及数量分布有逐渐减低的趋势。天敌昆虫的分布不仅与自然地理条件、植被等因素直接有关,而且与管理等人为影响有较大的关系。     

Two Hungarian isolates of cucumber mosaic virus from sweet pepper (Capsicum annuum) and melon (Cucumis melo): Identification and antiserum preparation

Two Hungarian virus isolates from sweet pepper (K8) and melon (S4) were identified as cucumber mosaic virus (CMV) on the basis of host plant reactions and serology. The isolates were purified and antisera prepared. Homologous antiserum titers in double-diffusion tests were 256 (K8) and 512 (S4). They were serologically closely related to each other and to other CMV isolates. On the basis of symptoms they belong to different symptomatological groups of CMV; this was supported by serological properties. Sedimentation coefficients were c. 93 S, at 2 mg ml^–1. Purified preparations, stained with 2% uranyl acetate, showed spherical particles. In ELISA purified preparations reacted with each other's antisera.Samenvatting Twee hongaarse virusisolaten uit paprika (K8) en meloen (S4) werden geïdentificeerd als komkommermozaïekvirus (CMV) met behulp van toetsplanten en serologie. Beide isolaten werden gezuiverd en er werden antisera tegen bereid. De homologe titers van de antisera in de agar-geldiffusietoets bedroegen 256 (K8) en 512 (S4). K8 en S4 waren serologisch nauw verwant aan elkaar, evenals aan andere CMV-isolaten. Op grond van hun symptomen op toetsplanten behoren ze tot verschillende symptomatologische groepen van CMV. Dit laatste werd gesteund door de serologische eigenschappen. Beide isolaten hebben een sedimentatiecoëfficiënt van ca 93 S, bij een concentratie van 2 mg ml^–1. Gezuiverde preparaten, gekleurd met 2% uranylacetaat, bleken bolvormige deeltjes te bevatten. In ELISA reageerden gezuiverde preparaten van K8 en S4 met elkaars antisera.