Diversity of the coat protein-coding region among Ilarvirus isolates infecting hop in Australia

Coat protein (CP) sequences of 17 Ilarvirus isolates were obtained from hops at three farms in Tasmania, Australia. Phylogenetic analysis of these sequences and additional database sequences indicated several Apple mosaic virus (ApMV) isolate clusters distinct from Prunus necrotic ringspot virus (PNRSV): one containing isolates from apple; one containing a single isolate from almond; a third containing Australian hop isolates of the 'apple' serotype and a German isolate of unknown origin; and a fourth containing Australian hop isolates of the 'intermediate' serotype. Isolates from hop, pear and prune from the Czech Republic either formed a fifth grouping, or were divergent members of the 'intermediate' serotype group. Deduced amino acid (aa) residue differences between the coat proteins of the two hop isolate serotype groups were highlighted as possible regions of serological differentiation. No evidence for coinfection of plants with both serotypes was found. Tests of ApMV-infected hop buds using the Shirofugen flowering cherry assay revealed a possible differentiation of the two strains based on hypersensitivity. Because of serological similarities to PNRSV, these viruses have commonly been reported as strains of PNRSV. However, this study shows ilarviruses from Australian hops are strains of ApMV, but distinct from those infecting Malus spp.     

深度测序发现贵阳发生的辣椒病毒病由多种病毒复合侵染所致

2016年9月贵州省贵阳市发生严重的辣椒病毒病,症状复杂,主要表现为植株矮化,叶片黄化、花叶、皱缩、畸形以及枯死斑,果实有坏死斑等,根据症状难以判断病毒种类。本文采用小RNA深度测序技术对田间自然发病的2株辣椒标样进行了毒源鉴定,发现样品1由蚕豆萎蔫病毒2号(Broad bean wilt virus2,BBWV2)、辣椒脉斑驳病毒(Chilli veinal mottle virus,ChiVMV)、黄瓜花叶病毒(Cucumber mosaic virus,CMV)和辣椒内源RNA病毒(Bell pepper endornavirus,BPEV)4种病原复合侵染;样品2中除鉴定到上述4种病毒外,还检测到马铃薯Y病毒(Potato virusY,PVY)。进一步通过反转录PCR(RT-PCR)对深度测序结果进行了验证,证明其准确可靠。其中4个辣椒标样中均有的辣椒内源RNA病毒(BPEV)为贵州省首次报道。多种病毒复合侵染是辣椒产量和品质的重要限制因素之一,是辣椒生产的主要威胁。     

基于小RNA深度测序技术鉴定侵染我国部分省市草莓种苗的病毒种类

随着草莓保护地栽培面积的增加和无性繁殖种苗的繁殖与调运,草莓病毒病的发生与流行日益严重。为明确侵染我国部分省市草莓种苗的病毒种类,应用小RNA深度测序技术进行检测,并利用RT-PCR技术对结果进行验证及序列分析。结果表明,从来自我国7省市的41株具有典型病毒病症状的草莓种苗样品中检测到草莓斑驳病毒strawberry mottle virus (SMoV)、草莓镶脉病毒strawberry vein banding virus(SVBV)和草莓轻型黄边病毒strawberry mild yellow edge virus (SMYEV)3种。SMoV、SVBV和SMYEV的检出率分别为34.1%、24.4%和2.4%。选取不同产地草莓种苗上检出的不同病毒进行部分序列测定和分析,获得了3个SMoV分离物(四川分离物schhy13、辽宁分离物lnhy23和河北分离物hbhy28)的部分RNA1 3′端非编码区606 bp核苷酸序列,其一致性为98.12%～99.34%。测定并获得了5个SVBV分离物(辽宁分离物lnhy15、lnhy17、lnhy24、河北分离物hbhy28和陕西分离物sh...     

典型草原三种蝗虫种群竞争关系的研究

为探讨典型草原优势蝗虫种内、种间竞争模式,以及栖境对蝗虫种间竞争的影响,设计田间罩笼及正交试验分析研究了内蒙古典型草原3种优势蝗虫-亚洲小车蝗(Oedaleus asiaticus)、毛足棒角蝗(Dasyhippus barbipes)和鼓翅皱膝蝗(Angaracris barabensis)的种群竞争关系。结果表明,亚洲小车蝗和毛足棒角蝗的种内竞争随着密度的增加而加大,并随着栖境食物量的减少而加大;鼓翅皱膝蝗由于栖境不适,种内竞争与密度没有相关性;混合种群正交试验结果显示,亚洲小车蝗有较强的种间竞争能力,而栖境对毛足棒角蝗竞争能力的影响较大。表明栖境和种群密度影响蝗虫群落动态。栖境适合时,亚洲小车蝗种间竞争力大于其他两种蝗虫。     

高通量测序发现河南开封、中牟西瓜病毒病由多种病毒复合侵染导致

调查发现河南省开封市祥符区和郑州市中牟县西瓜田病毒病严重发生,症状表现为叶片黄化、蕨叶、皱缩、卷曲,枝梢翘起,果实变小和瓜纹不清。为明确其病毒种类,通过小RNA测序及生物信息学分析发现采集的西瓜样本中存在8种病毒。其中包括5种已知病毒:小西葫芦黄花叶病毒(Zucchini yellow mosaic virus, ZYMV)、甜瓜蚜传黄化病毒(Melon aphid-borne yellows virus, MABYV)、西瓜花叶病毒(Watermelon mosaic virus, WMV)、黄瓜绿斑驳花叶病毒(Cucumber green mottle mo-saic virus, CGMMV)和西瓜隐潜病毒(Citrullus lanatus cryptic virus, CiLCV);3种为新检出的RNA病毒:西瓜病毒A(Watermelon virus A, WVA)、西瓜皱叶相关病毒1号(Watermelon crinkle leaf-associated virus 1, WCLaV-1)和西瓜皱叶相关病毒2号(Watermelon crinkle leaf-associ...     

Identification of the principal viruses infecting tomato crops in Tunisia

Serological tests have been used to detect viruses associated with tomato in 257 samples collected in different regions in Tunisia, Cap-Bon, Sahel and South during successive seasons. The viruses detected were cucumber mosaic cucumovirus (CMV) and tomato aspermy cucumovirus (TAV), potato Y potyvirus (PVY), tobacco etch potyvirus (TEV) and pepper veinal mottle potyvirus (PVMV), tomato mosaic tobamovirus (ToMV) and tobacco mosaic tobamovirus (TMV), tobacco rattle tobravirus (TRV), alfalfa mosaic alfamovirus (AMV), tomato spotted wilt tospovirus (TSWV), tomato ringspot nepovirus (TomRSV) and potato X potexvirus (PVX). Some were detected in all three regions surveyed, at variable frequencies: TMV, CMV, TEV, PVY, ToMV, AMV, TAV, TSWV and TRV. Others were only detected in two regions (PVMV in Cap-Bon and Sahel and PVX in Sahel and in the south) or one region (TomRSV in Cap-Bon). Movement of individual viruses from one region to another may be due to movement of specific vectors, as in the case of the thrips-transmitted TSWV moving from the south to the north. Some of these viruses were found for the first time in Tunisia.     

潍坊萝卜红心病病原鉴定

 本文用生物学、血清学和分子生物学证据证明,引起潍坊萝卜红心病的病原为芜菁花叶病毒(Turnip mosaic virus,TuMV).该病毒可系统侵染曼陀罗、油菜、咸阳黄瓜、丝瓜、大白菜和普通烟,局部侵染苋色藜和假酸浆,不侵染豌豆.病毒粒体弯曲线状,长约700 nm,可由蚜虫传播,在红心病组织内形成风轮状和片层凝集状内含体,它在SDS-琼脂糖凝胶免疫双扩散试验中可与TuMV的抗血清形成明显的沉淀线.该病毒的CP基因共867个核苷酸,编码288个氨基酸,分子量为32.98 kD.该序列与国内外20个TuMV分离物的CP氨基酸序列比较结果表明,这些分离物可以分为5组,其中引起萝卜红心病的病毒与日本的H1J、KYD8lJ、意大利的ITA7同属一组.     

Detection and elimination of viruses infecting sweet potatoes in Hungary

Sweet potato has been grown in Hungary for the last three decades, and its popularity is increasing among farmers and consumers. Its production is hampered by pests and diseases due to poor agricultural practices, such as the use of virus-infected propagation materials. We tested the presence of 15 viruses by PCR and quantitative PCR in 110 sweet potato plants collected from seven regions in Hungary. Seven viruses in single or multiple infections associated with a wide range of foliar symptoms were detected: sweet potato chlorotic stunt virus (SPCSV), sweet potato virus G (SPVG), sweet potato virus C (SPVC), sweet potato feathery mottle virus (SPFMV), sweet potato virus 2 (SPV2), sweet potato leaf curl virus (SPLCV), and sweet potato pakakuy virus (SPPV). This is the first report on the occurrence of the begomovirus SPLCV in sweet potatoes in Hungary. The infectivity and identity of these viruses were confirmed through bioassays (grafting to Ipomoea setosa) and sequencing of the PCR-amplified sections of their genomes, respectively. Due to the necessity for virus-free sweet potato propagation material in Hungary, virus elimination was carried out successfully in five out of six genotypes important for Hungarian farmers using heat treatment and meristem tip culture. All five viruses detected in the plants before heat treatment were removed except SPPV, which persists after heat treatment. Production and strict regulation of virus-free sweet potato propagation materials are recommended to avoid exacerbating the virus situation and protect Hungarian farmers from further losses.     

观赏百合病毒病原形态及内含体研究

通过带病组织汁液和带病组织超薄切片负染电镜技术对侵染观赏百合的病毒粒子和内含体进行观察,证明在表现不同症状的5个品种中存在球状、短线状、长线状、短杆状4种病毒粒子和晶体状、风轮状、束状、卷筒状、正六边形5种内含体,通过ELISA检测及病毒粒子形态、大小及内含体形态分析,确定球状病毒粒子(直径29.5 nm)为黄瓜花叶病毒,短线状病毒粒子(593.29～639.97 nm×12.15～14.12 nm)为百合无症病毒,长线状病毒粒子(757.58～846.25 nm×12.12～12.75 nm)为马铃薯Y病毒,短杆状病毒粒子(500～807.69 nm×153.85～192.31 nm)为烟草脆裂病毒。     

新疆艾比湖湿地自然保护区主要植物的种间关系

采用2×2列联表的χ2检验、方差比率(VR)法、Ochiai关联指数、Pearson相关系数和Spearman相关系数,对艾比湖湿地自然保护区典型群落的25个主要植物种进行种间关联和种间相关性分析。结果表明:①胡杨(Populus euphratica)、盐穗木(Halostachys caspica)、甘草(Glycyrrhiza uralensis)分别为该地区乔、灌、草本层的优势种。②艾比湖湿地自然保护区内物种的总体联结性为不显著的负联结,大多数种对间呈不显著关联和无关联,物种趋向于独立分布。③相关性分析表明草本与其他物种的相关对数值高于乔灌木,结合Spearman相关系数、列联表的χ2检验值,可将研究区25种主要植物分为4个生态种组。     

Incidence of five viruses infecting sweetpotatoes in Uganda; the first evidence of Sweet potato caulimo-like virus in Africa

In a survey of most sweetpotato-growing areas of Uganda, virus-like diseases were observed in all districts surveyed. Out of 338 fields sampled in 35 of the then 42 districts, 219 (65%) had some plants with symptoms. The most common symptoms included vein clearing, mottling, leaf distortion, yellowing, stunting and leaf strapping. Particularly high virus-like disease incidences (means of 34–86%) were encountered in districts around Lake Victoria and in the Rift Valley in southern and western parts of Uganda; particularly low incidences were encountered in the east and north of Uganda. Using four formats of enzyme-linked immunosorbent assay in combination with immunoelectron microscopy and polymerase chain reaction assays, five viruses were identified. Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV) were most commonly detected, being found in about 90% of samples. Sweet potato mild mottle virus at 10%, Sweet potato chlorotic fleck virus (SPCFV) at 8% and Sweet potato caulimo-like virus (SPCaLV) at 0·07% were more rarely detected. Most infections were multiple, SPCSV + SPFMV constituting > 90% of all double infections. Triple infections, involving mainly SPFMV, SPCSV and either SPMMV or SPCFV, and quadruple infections of SPFMV + SPCSV + SPMMV + SPCFV were observed in < 10% of the diseased samples. The identification of SPCaLV is the first evidence of its occurrence in Africa.     

Effects of temperature increase on the epidemiology of three major vector-borne viruses

The epidemiologies of Maize streak virus (MSV), Maize stripe virus (MSpV), and Maize mosaic virus (MMV) were compared in La Réunion over a three year-period. Disease incidence caused by each virus was assessed, and the leaf and planthopper vector populations (Cicadulina mbila and Peregrinus maidis) were estimated in weekly sowings of the temperate, virus-susceptible maize hybrid INRA 508 and of the composite resistant cv. IRAT 297. MSV caused the most prevalent disease and MMV the least, with lower incidences in cv. IRAT 297 than in INRA 508. For each plant–virus–vector combination, (a) disease incidence was positively correlated to vector abundance, often with 1 month of time lag; (b) annual periodicity of disease incidence and of vector numbers was consistent with highest autocorrelations and a time lag of 12 months, (c) vector numbers and disease incidence were closely associated with temperature fluctuations, both remaining relatively constant below 24°C and increasing rapidly above this threshold temperature. By contrast, relationships with rainfall and relative humidity (RH) were less consistent. Overall, 63 to 80% of the variance of disease incidence was explained through stepwise regression with vector number, temperature, and sometimes also rainfall or RH. The simple epidemiological model proposed underlines the close link between increased temperature and possible (re-) emergence of these three diseases in a maize cropping area.     

沙漠化过程土壤种子库特征的研究

采用野外定点取样与室内萌发实验相结合的方法 ,研究了 4种不同类型退化沙地土壤种子库特征 ,主要结论是 :(1)土壤种子库密度随沙漠化程度的增加而下降 ,不同沙漠化发展阶段下降速率不同 ,从固定到半固定沙地是种子库密度衰减最快的时期 ;(2 )土壤种子库植物种数从固定到半流动沙地变化很小 ,半流动到流动沙地衰减速度明显加快 ,是种子库植物种数衰减最快的时期 ;(3) 4种类型退化沙地土壤种子库的种类组成以 1、2年生草本植物为主 ,所占比例 79%～ 88% ,多年生草本和灌木所占比例很小 ;(4 )土壤种子库物种多样性指数并非随着沙漠化程度的增加而下降 ,其中半流动沙地的物种多样性指数最小 ;(5 ) 4种类型退化沙地土壤种子库组成上的相似性系数变化范围为 0 .82 9～ 1.0 0 0 ,表现出较小的空间异质性。     

陕西省旅游资源群落多样性研究

本文结合生物群落的定义首次尝试性提出旅游资源群落这一新的概念,总结了旅游资源群落的基本特征,并以陕西省旅游资源为例,计算了旅游资源群落的物种多样性指数,从而实现对旅游资源群落的物种多样性研究。研究发现,在空间分布上,陕西旅游资源群落中各子群落物种多样性的梯度变化在经度和纬度上都基本上遵循由南到北逐步减小的规律,并可根据各群落的相似性初步确立陕西境内旅游资源群落的区划方案。结果表明:旅游资源群落这一概念对于旅游资源的研究具有较大的意义,为旅游资源科学提供了新的思路,即从群落及其物种多样性的角度来认识和分析旅游资源。     

Characterization of the first two viruses described from wild populations of hammer orchids (Drakaea spp.) in Australia

Sequences representing the genomes of two distinct virus isolates infecting wild plants of two members of the genus Drakaea (hammer orchids) in Western Australia are described. The virus isolated from Drakaea livida has a bipartite genome of 4490 nt (RNA1) and 2905 nt (RNA2) that shares closest sequence and structural similarity to members of the genus Pecluvirus, family Virgaviridae, described from legumes in the Indian subcontinent and West Africa. However, it differs from pecluviruses by lacking a P39 protein on RNA2 and having a cysteine‐rich protein gene located 3′ of the triple gene block protein genes. It is the first peclu‐like virus to be described from Australia. The name Drakaea virus A is proposed (DVA; proposed member of the family Virgaviridae, genus unassigned). The second virus isolate was identified from Drakaea elastica, a species classed as endangered under conservation legislation. The genome sequence of this virus shares closest identity with isolates of Donkey orchid symptomless virus (DOSV; proposed member of the order Tymovirales, family and genus unassigned), a species described previously from wild Caladenia and Diuris orchids in the same region. These viruses are the first to be isolated from wild Drakaea populations and are proposed to have an ancient association with their orchid hosts.     

侵染云南鸡蛋果的病毒种类鉴定及CMV cp 基因序列分析

Viral diseased Passiflora edulis samples showing mosaic, shrinking, chlorosis, and malformation were collected from Yuxi, Wenshan, Dehong, and Xishuangbanna in Yunnan Province. Forty diseased samples were detected by RT-PCR/PCR using degenerate primers of members in genera of Umbravirus, Tobamovirus, Luteovirus, Orthotospovirus, Begomovirus, Badnavirus, Potyvirus and specific primers of cucumber mosaic virus (CMV). Results showed that CMV, telosma mosaic virus (TeMV) and papaya leaf curl Guangdong virus (PaLCuGdV) were detected in the diseased P. edulis samples. CMV showed the highest detection rate of 27.5 %, while TeMV and PaLCuGdV had the rates of 20.0% and 7.5% respectively among the P. edulis samples. Mixed infections of PaLCuGdV+CMV, PaLCuGdV+TeMV and CMV+TeMV were also found in these samples. The 657 nucleotide (nt) CMV full-length coat protein (CP) gene was cloned and sequenced from two diseased samples in Yuxi (YYXi-JDG, Acc. No. MW495062) and Xishuangbanna (YXSBN-JDG, Acc. No. MW495063), respectively. These two CMV isolates shared 97.3% identity of nt sequence with each other, while had 76.9%-97.7% and 77.0%-98.2% nt identity with other CMV isolates, respectively. Phylogenetic tree showed that the two CMV isolates from P. edulis belonged to CMV subgroup Ⅰ, and no obvious geographic differentiation and host specificity relationship was found among the selected 33 CMV isolates worldwide.     

塔克拉玛干沙漠土壤种子库特征初探

通过野外采样和室外萌发的方法,研究了塔克拉玛干沙漠公路沿线6种立地类型的土壤种子库特点.其主要结论:①所有立地类型的土壤种子库密度都很小.立地类型I,Ⅱ,Ⅲ,Ⅳ,V,Ⅵ的土壤种子库密度分别为:(46.20±4.45)粒/m2,(27.50±5.58)粒/m2,(15.00±3.37)粒/m2,(6.52±0.87)/m2,(10.00±2.42)粒/m2和(50.00±5.50)粒/m2.②所有立地类型土壤种子库中所出现的物种数量都很少.③所有立地类型土壤种子库中出现的物种生活型,一年生草本并不占优势.④在塔克拉玛干沙漠空间分布上,沙漠南缘和北缘的土壤种子库密度和物种多样性较大,而中部的密度和物种多样性较小.     

大白菜抗感品种间作提高感病品种抗病毒病能力研究

为了探讨通过抗感品种间作栽培方式来提高大白菜品种抗病毒病的能力,采用小区试验和对黑龙江大白菜区试与生试结果分析。结果表明,抗感品种间作可提高感病大白菜品种抗病毒病能力;抗性不同的品种间作使同一品种在区试、生试中表现出不同的抗性,与对照相比表现出不同增产幅度。