Simulation modelling of potato virus Y spread in relation to initial inoculum and vector activity

Potato virus Y(PVY)is a non-persistent virus that is transmitted by many aphid species and causes significant damage to potato production.We constructed a spatially-explicit model simulating PVY spread in a potato field and used it to investigate possible effects of transmission efficiency,initial inoculum levels,vector behavior,vector abundance,and timing of peak vector activity on PVY incidence at the end of a simulated growing season.Lower PVY incidence in planted seed resulted in lower virus infection at the end of the season.However,when populations of efficient PVY vectors were high,significant PVY spread occurred even when initial virus inoculum was low.Non-colonizing aphids were more important for PVY spread compared to colonizing aphids,particularly at high densities.An early-season peak in the numbers of noncolonizing aphids resulted in the highest number of infected plants in the end of the season,while mid-and late-season peaks caused relatively little virus spread.Our results highlight the importance of integrating different techniques to prevent the number of PVY-infected plants from exceeding economically acceptable levels instead of trying to control aphids within potato fields.Such management plans should be implemented very early in a growing season.

Potato Virus Y mRNA Expression Knockdown Mediated by siRNAs in Cultured Mammalian Cell Line

RNA interference(RNAi) is a powerful tool for functional gene analysis which has been successfully used to downregulate the expression levels of target genes.The goal of this research was to provide a highly robust and concise methodology for in-vitro screening of efficient siRNAs from a bulk to be used as a tool to protect potato plants against PVY invasion.In our study,a 480bp fragment of the capsid protein gene of potato virus Y(CP-PVY) was used as a target to downregulate PVY mRNA expression in-vitro,as the CP gene interferes with viral uncoating,translation and replication.A total of six siRNAs were designed and screened through transient transfection assay and knockdown in expression of CP-PVY mRNA was calculated in CHO-k cells.CP-PVY mRNA knockdown efficiency was analyzed by RT-PCR and real-time PCR of CHO-k cells co-transfected with a CP gene construct and siRNAs.Six biological replicates were performed in this study.In our findings,one CP gene specific siRNA out of a total of six was found to be the most effective for knockdown of CP-PVY mRNA in transfected CHO-k cells by up to 80%-90%.

Screening and Identification of Tobacco Mutants Resistant to Potato Virus Y( PVY)

[ Objective] This study aimed to screen and identify tobacco mutants resistant to potato virus Y （PVY）, thus laying the foundation for obtaining PVY resistance genes. [ Method ] At seedling stage, tobacco mutant materials were inoculated with PVY virus and preliminarily screened by naked-eye observation. Enzyme-linked immunosorbent assay （ELISA）, real-time fluorescence quantitative PCR and test strip assay were performed to further identify the pre-screened PVY- resistant seedlings. [ Result ] In 2011, two highly PVY-resistant tobacco mutants （MZE2-15 and MZE2-16） and three PVY-tolerant mutants （MZE2-70, MZE2- 207 and MZE2-228） were obtained, which were further screened and identified in 2012. According to the results, tobacco mutant materials MZE2-407 and MZE2- 428 were susceptible to PVY; mutant materials MZE2-16 and MZE2-15 were resistant to PVY. [ Conclusion] This study provide theoretical basis for the control of tobacco PVY disease.

Cloning and Sequencing of Kappa Light Chain Gene of a Mouse Monoclonal Antibody Directed Against Potato Virus Y

A cDNA library was constructed in λgt11 vectors, complementary to the mRNA isolated from a mouse hybridoma raised against potato virus Y(PVY). Thirty cDNA clones were selected from the cDNA library by in situ immunohybridization with goat anti-mouse kappa-chain-specific antibody conjugated to alkaline phosphatase, from which one clone, k6, having the largest insert was characterized by sequence analysis. The result shows that the immunoglobulin messenger RNA corresponding to k6 is 956 nucleotides in length excluding the poly(A) region, among which 31 bases code for the 5’ non-coding region, 57 for the leader sequence of the protein, 657 for the mature protein and 211 for the 3’ non-coding region. Comparison of deduced amino acid sequences of the protein and other kappa light chains shows that they share a 100% identity in their constant regions(CL) and 93.7% identity in their variable regions(VL). The kappa light chain encoded by k6 is considered to be specific to PVY since only one type of light chain is expressed in the hybridoma.

Establishment of Multiplex PCR for Three Virus of Potato

[Objective]The aim was to establish the multiplex PCR method for three virus of potato：PVA（potato virus A）,TMV（Tobacco mosaic virus）and PVY（potato virus Y）.[Method]According to the PVA,TMV and PVY sequences available in GenBank,pairs of primer were designed for establishing a multiplex PCR method,and constructing recombinant plasmid of target genes by PCR amplified of three viruses as reference standard simple to be used in sensitivity test;PVX（Potato virus X）,PVM（Potato virus M）,PVS（Potato virus S）,PVV（Potato virus V）and CMV（Cucumber mosaic virus）were used to carry out the specificity test and detection of 11 samples which were suspected of virus infected.[Result]The detection limit for PVA,TMV and PVY was 14,14 and 14 copies/ml,respectively.No cross-reactivity was observed with other viruses.Seven of 11 samples were infected by three viruses.[Conclusion]The multiplex PCR for PVA,TMV,PVY three viruses of potato was established successfully,which had provided basis for the detection technology of potato virus.

河北保定地区黄瓜花叶病毒与马铃薯Y病毒复合侵染叶用莴苣分子鉴定

利用RT-PCR方法对采集自河北保定地区的疑似叶用莴苣病毒病样品进行分子生物学鉴定,并构建系统发育进化树。结果表明,特异性引物CMV和PVY分别扩增得到大小为260、420 bp的单一条带;通过核苷酸序列Blast比对及系统进化树分析,河北保定地区叶用莴苣病毒分离物分别与印度番茄CMV分离物(MN514839.1)、印度马铃薯PVY分离物(JX945850.1)聚在同一分支上,同源性分别为95%、92%。本研究首次检测到河北保定地区叶用莴苣病毒病是由CMV与PVY复合侵染所致。

Effects of Synergism Between PVY and PVX on Virus Titer and Cell Ultrastructure in Tobacco Plants

The viruses titer and the ultrastructure of infected cells in tobacco host (Nicotiana tabacum cv. Samsun), which doubly infected with potato virus Y necrosis strain (PVYN) and potato virus X (PVX), were studied under greenhouse conditions. The results indicated that PVYN and PVX interacted synergistically. and tobacco plants which doubly infected with PVX and PVYN could greatly increase symptom severity as compared with that induced by the single virus. As determined by triple antibody sandwich enzyme-linked immunosor-bent assay (TAS-ELISA), the titer of PVX in the tobacco leaves infected with both PVYN and PVX was up to 9.10 times higher than the plants infected with PVX only. No significant differences in PVYN titer were detected between singly and doubly infected plants. The enhancement of PVX titer in doubly infected plants was evident in greenhouse and was independent of the virus strains, tested seasons, intervals between PVYN and PVX inoculation. When sections of doubly infected leaves were examined with an electron microscope, it could be frequently found that cells contained pinwheels and large masses of PVX-like particles, pinwheels and laminate inclusions, or all three structures, most of them were swollen, and their chloroplast and other organella were destructed heavily. This suggested that doubly infected cells were involved in the enhancement phenomenon, which seemed to be the result of an increase in the amount of PVX synthesized in them.

马铃薯野生近缘种抗PVY种质资源分子标记辅助筛选

为拓宽四倍体(2n=4x=48)马铃薯栽培种抗马铃薯Y病毒(PVY)的遗传背景,对56份马铃薯野生近缘种进行了PVY抗性分子标记(RYSC3、YES3-3A和Ry364)辅助筛选。PCR检测结果显示,含有Ry_(adg)抗性基因(源自Solanum tuberosum ssp.andigena)分子标记RYSC3的材料有13份,其中二倍体(2n=2x=24)3份,四倍体6份,六倍体(2n=6x=72)4份;含有Ry_(sto)抗性基因(源自S.stoloniferum Schlechtdal)分子标记YES3-3A的材料有4份,其中二倍体1份,四倍体2份,染色体倍性未确定材料1份;含有Ry_(chc)抗性基因(源自S.chacoense Bitter)分子标记Ry364的材料有23份,其中二倍体6份,四倍体4份,六倍体13份。含有RYSC3、YES3-3A和Ry364中任意2种标记的材料有7份,同时含有3种标记的材料仅有OCH 14180a(S.stoloniferum Schlechtdal)。这些种质资源可用于马铃薯抗病毒品种选育、种质创新与基因挖掘。

含氟异喹啉二酮衍生物的合成及其抗马铃薯Y病毒活性分析

为了探索更高抗植物病毒活性的新药物分子,采用较廉价的原料、较温和的反应条件合成了12个含氟基团异喹啉二酮衍生物,并采用半叶枯斑法对合成的目标化合物进行抗马铃薯Y病毒(PVY)活性测定。结果表明:含氟异喹啉二酮衍生物对马铃薯Y病毒(PVY)具有较好的抑制活性,其中化合物3e的治疗活性(43.5%)、保护活性(47.1%)、钝化活性(51.9%)都表现出较好的效果,与阳性对照农用抗病毒药物病毒唑活性相当,在其结构基础上进行一定的结构修饰,有望得到具有更高抗病毒活性的化合物。

烟草PVYN辽宁分离物全序列测定与分析

利用引起烟草脉坏死病的马铃薯Y病毒脉坏死株系辽宁分离物(Potato virus Y—vein necrosis strain Liaoning isolate,PVYN-LN),以GenBank中已有的PVY全序列为基础,设计特异引物。通过总RNA提取、RT-PCR、3’RACE和5’RACE扩增及序列测定,测得PVYN-LN全长基因组序列(NCBI登录号为JQ971975)包括9714个碱基(含PolyA尾),整条序列仅包含一个由9186个碱基组成的开放读码框(ORF),编码一条包含3061个氨基酸的多聚蛋白。对所得序列进行BLAST,利用MEGA软件对所测得的PVYN-LN全序列与GenBank中已有的PVY全序列及氨基酸进行系统进化分析,发现PVYN-LN分离物与已报道的PVYN株系具有较高的进化亲缘关系,该分离物属于PVYN株系。序列重组分析软件RDP4分析,该序列无重组。

转录因子NbNAC062及其纳米药物对PVY侵染的抑制作用

前期研究表明NbNAC062能够抑制PVY早期侵染,本研究通过构建NbNAC062敲除突变体和过表达植株进一步明确NbNAC062的抗病毒功能,并利用异硫氰酸荧光素(fluorescein-5-isothiocyanate,FITC)标记的壳聚糖季铵盐(chitosan quaternary ammonium salt,HACC)包被NbNAC062质粒,制备HACC-NbNAC062纳米药物。激光共聚焦显微镜对纳米药物进行示踪;透射电镜和激光粒子分析仪对其表征进行分析。通过GFP荧光差异、qRT-PCR和蛋白免疫印迹检测病毒含量来探明纳米药物对PVY侵染的影响。结果显示,敲除组病毒GFP荧光增强,而过表达组病毒GFP荧光减弱,PVY CP含量与上述结果一致。纳米药物粒径集中分布在18~32 nm之间;Zeta电位为+41.8 mV。浸润纳米药物HACC-NbNAC062后48 h,在细胞内观察到FITC-HACC(绿色荧光)与RFP-NbNAC062(红色荧光);接种PVY-GFP后5、7、9 d,NbNAC062-HACC施药组的PVY CP mRNA水平较对照组分别下调17.41%、47.81%、13.03%;第7天施药组PVY CP蛋白水平明显低于对照组,病毒荧光强度显著暗于对照组。上述研究结果说明HACC-NbNAC062纳米药物成功递送了NbNAC062,并发挥了其对PVY初期侵染的抑制作用。

不同品种(系)马铃薯休眠块茎顶端和茎端芽眼组织马铃薯Y病毒含量分析

马铃薯Y病毒(Potato virus Y,PVY)是马铃薯生产中较常见的病毒之一,马铃薯病毒的检测是生产中保障马铃薯品质和产量的重要基础,收获后批量检测是进行种薯质量评价的主要依据之一。研究针对‘56-2’‘Ivory Russet’‘Clearwater Russet’‘龙薯14号’‘龙薯3号’‘龙薯15号’‘龙育201401-70’‘龙薯7号’‘克新23号’和‘克新28号’马铃薯品种(系)休眠块茎样品,采用TRIzol法提取马铃薯休眠块茎顶端和茎端芽眼组织的总RNA,经qRT-PCR和RT-PCR检测分析,比较块茎的顶端与茎端芽眼组织PVY含量分布的情况。结果表明,上述供试材料的休眠块茎茎端芽眼组织PVY浓度均高于顶端芽眼组织,能够精准的检测到病毒的存在;对‘Ivory Russet’品种的休眠块茎选取100个带病样品通过TRIzol法提取顶端与茎端的总RNA,采用4合1的方法合样后进行PVY RT-PCR检测,所有处理的顶端芽眼组织检测条带亮度低于茎端芽眼组织。可见,马铃薯休眠块茎茎端芽眼组织取样能够更加精准的检测出PVY。研究结果为马铃薯种薯收获后PVY的检测及合理取样提供了科学依据。

青岛烟区马铃薯Y病毒株系鉴定及系统传导特性

为明确引起青岛试验田烟草脉坏死及花叶的PVY的发生规律、分子进化和系统传导特性,通过病毒病害表型,发病率和病情指数明确青岛试验田病毒病害流行规律;利用MEGA7构建系统发育树鉴定PVY青岛分离物的株系;通过q RT-PCR,western blotting和PVY-GFP荧光明确PVY侵染烟株的传导路径;通过不同叶位、不同症状病叶取样,利用q RT-PCR检测PVYCPm RNA相对含量,明确显症和隐症叶片的病毒含量差异,以及TMV、CMV、PVY单独、两者混合、三者混合侵染时的干扰或协生作用。结果显示:烟株成熟期,PVY与TMV和CMV混合发生严重,PVY分离物为N:O株系,未突破va基因抗性。在侵染早期,病毒从接种叶沿叶脉进入茎,开始双向运输时,先向根部移动,进而到达苗端;再扩散至上部叶,较慢移动至下部叶;最后伴随烟株生长持续向两端新生部位运输。侵染中期病株上部叶隐症现象显著,病叶症状与病毒浓度呈正相关。烟田中后期,PVY与TMV和CMV混合侵染,病毒间的干扰和协生作用导致症状复杂多变。研究结果有助于提高品种抗性鉴定试验的准确性和药效试验的靶标性。

马铃薯应对马铃薯Y病毒与非介体昆虫胁迫的植物激素水平和基因表达变化

马铃薯Y病毒(potato virus Y,PVY)及其非介体昆虫马铃薯块茎蛾(Phthorimaea operculella)是世界马铃薯产业的重要病虫害,为探究PVY是否影响马铃薯对马铃薯块茎蛾的生理响应,本研究分析了马铃薯块茎蛾在PVY侵染和健康对照植株上的生长表现,并对无病虫害、PVY侵染、模拟虫害处理(用马铃薯块茎蛾口腔分泌物涂抹),以及PVY侵染和模拟虫害协同处理的植株叶片进行了植物激素测定和比较转录组分析。结果显示:马铃薯感染PVY后对马铃薯块茎蛾的抗性显著提高;PVY侵染可抑制模拟虫害造成的脱落酸含量上升;与健康对照组相比,模拟虫害和PVY侵染处理分别诱导产生3998个和104个差异表达基因,而两者协同处理可诱导产生9178个差异表达基因,说明这2种胁迫共存对马铃薯产生了极大的生理影响。与模拟虫害处理相比,PVY侵染和模拟虫害协同处理诱导产生743个差异表达基因,而这些基因主要富集在转移酶活性、内质网中蛋白质加工、苯丙素生物合成等通路中,而脱落酸合成通路中众多基因表达下调,与该植物激素变化情况一致。综上所述,本研究系统分析了马铃薯应对PVY侵染、马铃薯块茎蛾模拟虫害以及两者协同处理的生理反应,为探究“植物-病毒-非介体昆虫”三者互作提供了科学依据。

青岛及周边地区马铃薯Y病毒株系类型分析

马铃薯Y病毒(potato virus Y,PVY)是目前马铃薯生产中的重要病毒,PVY侵染马铃薯会造成产量、质量的严重下降。为了探明青岛及周边地区PVY株系类型,本次共采集青岛及周边地区485份马铃薯疑似PVY样本,共检测出298份PVY阳性样本。对PVY样本进行RT-PCR扩增,结果显示:本地区的主要株系为PVY^(NTN-NW)(SYR-Ⅱ型),占比为62.4%;PVY^(N-Wi)株系占比为31.6%;复合侵染株系占比为6.0%。对复合侵染株系的单株块茎(编号ShouGuang)进行测序、BLSAT比对及Simplot和RDP软件分析,显示PVY复合侵染的马铃薯植株体内存在两种重组类型(ShouGuang-Y1和ShouGuang-Y2);发生重组的位点主要集中在P1-1、HC-Pro/P3、6K2/VPg 3个区域。通过对PVY的不同变异株系分析,可为PVY株系的遗传多样性提供理论基础,为青岛及周边地区PVY防控提供理论依据。

PVY/PVX协生作用对病毒浓度及寄主细胞超微结构的影响

以烟草品种三生烟 (N .tabacumcv .Samsun)为测试寄主 ,采用酶联免疫检测实验 (TAS ELISA)和电镜观察的方法 ,在温室条件下研究了马铃薯Y病毒 (PVY)和马铃薯X病毒 (PVX)复合侵染所引起的寄主症状和病毒浓度变化的特点、不同条件下复合侵染时病毒浓度的变化规律以及复合侵染对寄主细胞超微结构的影响。结果表明 ,PVY/PVX在烟草植株内发生了协生作用 ,PVY是协生病毒 ,PVX是被协生病毒。与单独侵染相比 ,PVY和PVX的复合侵染使烟草植株症状明显加重。PVY在复合侵染植株中的浓度与在单独侵染植株中相比 ,没有明显的变化 ,而PVX在复合侵染植株中的浓度明显高于在单独侵染植株中的浓度。这种现象不受PVY株系、处理季节和接种次序的影响。但是 ,不同PVY株系、不同处理季节或不同接种次序对PVY/PVX协生作用中PVX浓度的影响程度存在着一定的差异。电镜观察表明 ,与不接种病毒或单独侵染的植株相比 ,受复合侵染的烟草叶片细胞超微结构发生了明显的病理学变化。细胞肿胀 ,叶绿体、线粒体等细胞器受到严重损伤 ,细胞质内有风轮状、薄片状的内含体 ,由于在细胞质中常常有大量纤维状的PVX病毒粒子聚集体存在 ,这意味着PVX浓度的增加可能是在复合侵染的细胞中病毒大量繁殖的结果。

马铃薯Y病毒两分离物特性及其侵染寄主的超微结构比较研究

报道了马铃薯 Y病毒两分离物的生物学和血清学特性、病毒粒体形态大小以及它们引起的寄主细胞病变特征等方面的差异。从山东省主要烟草和马铃薯种植区病毒样品中分离到两个马铃薯 Y病毒分离物 ,分别为 PVY- T和 PVY- P。两分离物在寄主植物上的症状表现、体外抗性、蚜传特性、血清学以及病毒粒体大小等方面存在着明显的差异。同时 ,这些结果与作对照的 PVY标准株系 PVYN和PVYO相比较 ,初步推测分离物 PVY- T属于 PVYO 株系 ,而 PVY- P则属于 PVYN。通过对受侵染寄主的细胞超微结构观察比较发现 ,这两种 PVY分离物在寄主细胞内的分布特征、内含体以及与寄主互作后所引起的细胞病变也明显不同 ,这些可能成为区别 PVY不同株系的依据之一。

翻译和非翻译马铃薯Y病毒外壳蛋白基因介导的抗病性比较

利用RT PCR方法克隆获得马铃薯Y病毒烟草叶脉坏死株系 (PVYN)的可翻译和不可翻译外壳蛋白 (CP)基因 ,并分别插入 pROKⅡ质粒中获得重组双元表达载体。通过根癌农杆菌(Agrobacteriumtumefaciens) 介导的基因转化方法 ,将可翻译和不可翻译的PVYN CP基因分别导入烟草栽培品种NC89叶片组织中 ,得到抗卡那霉素的再生植株。对所得到的抗卡那霉素的再生苗进行PCR检测表明 ,被导入可翻译和不可翻译CP基因的植株分别占卡那霉素抗性植株的 95 %和 98%。攻毒实验表明 ,两种类型的转基因烟草对PVYN 的抗病性具有相似性 ,其表现型为 :免疫、抗病和感病。免疫型转基因植株的抗病性不受接种物类型及其剂量的影响。Southern印迹杂交结果显示 ,目的基因已经整合到烟草基因组中。Northern印迹杂交证明 ,两种类型的CP基因都已在RNA水平上得到了表达 ,但细胞内RNA的积累量与转基因植株的抗病强度成负相关。Western印迹杂交表明 ,在表达不可翻译PVYN CP基因的转基因植株内未检测到CP蛋白 ,而在导入可翻译的PVYN CP基因的植株内检测到了CP蛋白 ,且CP蛋白含量与抗病性不存在正相关。本研究结果证明 ,表达可翻译与不可翻译PVYN CP基因的转基因烟草对PVYN 的抗病性均为RNA介导的抗病性。

利用RNA介导的抗病性获得高度抗马铃薯Y病毒的转基因烟草

以马铃薯 Y病毒坏死株系 (PVYN)的 RNA为模板 ,应用反转录 -聚合酶链式反应 (RT- PCR)方法 ,扩增出长度为 80 1bp的非翻译的马铃薯 Y病毒外壳蛋白基因。将扩增的片段克隆到 p BSK的Bam HI和 Kpn I之间并进行了序列测定。用 Bam HI和 Kpn I从重组克隆载体上切下该基因并插入到质粒 p ROKII内得到植物表达载体 p PVYCP。通过根癌农杆菌 (LBA4 40 4 )介导的方法转化烟草NC89,经卡那霉素抗性筛选、PCR和 Southern blot检测 ,获得 82株转基因植株。 Northern blot和Western blot分析表明 ,转基因植株只在 RNA水平上得到了表达。抗病性试验表明转基因植株之间抗性水平存在着差异 ,其中有 7株是对 PVYN高度抗病性的植株。转基因植株抗病特异性试验初步表明 ,对 PVYN 表现高度抗病的植株对 PVYO 也具有高度抗病性。

一个马铃薯Y病毒山东分离物的分离与鉴定

从具有典型花叶症状的马铃薯叶片中分离到马铃薯Y病毒 (PotatovirusY ,PVY) (本文称PVY SD TA分离物 ) ,扩繁后 ,提纯病毒 ,电镜下可观察到 70 0～ 90 0nm× 11nm的病毒粒体 ,病组织超薄切片观察可见风轮状的内含体结构 ,寄主反应特性研究表明其能侵染 2科 13种植物。SDS PAGE电泳检测病毒编码的外壳蛋白亚基的分子量为 33kDa。以PVY SD TA基因组RNA为模板 ,应用RT PCR方法和特异引物合成了外壳蛋白基因。对cDNA全序列分析表明 ,PVY SD TACP基因核苷酸序列与N株系的同源性为 96 % ,与GenBank中登录序列号为AJ390 30 6的O株系分离物的同源性最高 ,为 99% ;与国内不同学者报道的PVY中国流行株的同源性分别为 96 % ,97%和 98%。通过以上生物学特性和分子水平的研究将PVY SD TA鉴定为普通株系 (PVYO 株系 )。