马铃薯A病毒CP基因的克隆与序列分析

利用根据马铃薯A病毒 (PVA)外壳蛋白 (CP)基因序列设计合成的一对引物 ,以带毒植物总RNA为模板 ,RT-PCR扩增得到长 0.8kb的目的片段。将目的片段转入大肠杆菌并进行了序列测定。测序结果与PVA其他分离物CP基因序列比较 ,发现其核苷酸同源性最高可达 99%。依据CP序列建立了PVA病毒的系统进化树并对PVA不同分离物CP氨基酸序列差异性做了分析     

Biological, serological and molecular characterization of a cucumber mosaic virus isolate from India

A. virus causing mosaic and leaf deformation of Physalis minima has been identified as an isolate of cucumber mosaic virus (CMV) on the basis of its transmission by aphids in a non-persistent manner, polyhedral particles of 29 nm diameter, molecular weight of coat protein subunits us 24-5 kDa. serological relationship with a CMV isolate and a tripartite single-stranded RNA genome with a subgenomic RNA4- Furthermore. cDNA representing coat protein gene was synthesized and cloned. Complete nucleotide sequences (890 nt) were obtained which showed a coat protein gene open reading frame of 657 residues. THE nucleotide sequences provided the 218 amino ACID sequences of the coat protein. Nucleotide as well as amino acid sequences revealed more than 90% identity with the CMV subgroup I strains.     

Optimized loop-mediated isothermal amplification assay for <Emphasis Type="Italic">Tomato leaf curl New Delhi virus-[potato]</Emphasis> detection in potato leaves and tubers

Apical leaf curl disease of potato is caused by a whitefly transmitted begomovirus, Tomato leaf curl New Delhi virus-[potato] (ToLCNDV-[potato]) in India. Detection of this virus is essential to manage the disease, particularly in healthy potato seed production systems. Large scale testing of micro-plants demands a simple, rapid and sensitive assay. Hence, loop-mediated isothermal amplification (LAMP) method was developed for specific detection of ToLCNDV-[potato]. Six primers that recognize the coat protein gene sequence of ToLCNDV-[potato] were designed and LAMP assay was optimized using different concentrations of magnesium sulphate, betaine, dNTPs, Bst DNA polymerase and temperature. The results were assessed by visual observation of turbidity, colour change using SYBR green dye and also by gel electrophoresis. The assay successfully detected the virus in infected plants collected from potato fields whereas no cross-reactions were observed with healthy plants and other potato viruses. The optimized assay was as sensitive as PCR assay and could detect up to 0.002 pg of total DNA. The assay could detect the virus in infected potato tubers and also in asymptomatic plants. Print-capture LAMP assay was developed and its application could reduce the cost and time of the assay in large scale testing under seed production.     

一个马铃薯X病毒分离物的外壳蛋白基因序列分析与株系鉴定

对山东省侵染马铃薯的一个马铃薯X病毒(PVX)分离物PVX—SD1的外壳蛋白(CP)基因进行了克隆和序列分析。以提纯的病毒RNA为模板，应用RT-PCR扩增目的基因，通过常规的基因克隆法将扩增的CP基因导入pUC19载体，测序。结果表明，PVX—SD1的CP基因长719bp，可编码248个氨基酸；与Gen—Bank中报道的15个有代表性的株系或分离物相比较，核苷酸同源性在80．1％-99．7％，氨基酸同源性在89．8％-100％；与欧洲株系UK3仅1个核苷酸不同，同源性为99．7％，氨基酸同源性达100％，表明它们可能为同一株系，属于X^3组．     

烟草坏死病毒A大豆分离物的分子鉴定

 对曹琦和濮祖芹早期分离到的烟草坏死病毒大豆分离物的生物学、血清学和外壳蛋白的序列进行了进一步研究。该分离物能侵染8科29种植物, 除系统侵染大豆和本生烟外, 其余寄主均为局部侵染。电镜下病毒粒子呈球状, 直径约28nm。基因组为单组分RNA, 大小约为3.7 kb, 具有2条亚基因组, 分别约为1.6 kb和1.3 kb。外壳蛋白亚基的分子量约为30 kDa。血清学试验表明, 该分离物与TNV柳树分离物的抗血清呈特异反应, 与同属坏死病毒属(Necrovirus)的烟草坏死病毒D(TNV-D)和甜菜黑色焦枯病毒(BBSV)无血清学关系。利用简并引物通过RT-PCR克隆了该分离物的外壳蛋白基因。序列分析表明, 该分离物与烟草坏死病毒A(TNV-A)、TNV-D和TNV-D^H的外壳蛋白分别具有88.77%、45.13%和45.49%的氨基酸序列一致性。因此, 该大豆分离物属于TNV-A的一个新株系, 命名为TNV-A^C。     

Characteristics of a resistance-breaking isolate of potato virus Y causing potato tuber necrotic ringspot disease

An Austrian isolate of potato virus Y^NTN, the causal agent of potato tuber necrotic ringspot disease (PTNRD), was serologically compared with seven Dutch PVY^N isolates. Using polyclonal and monoclonal antibodies, it was found indistinguishable from PVY^N. Determination of the nucleotide sequence of the coat protein cistron and comparison of the deduced amino acid sequence with coat protein sequences of other potyviruses revealed a high level of homology with PVY^N coat protein sequences. This confirmed the close taxonomic relationship of PVY^NTN with the PVY^N subgroup of potato virus Y. PVY^NTN is able to overcome all resistance genes known so far in commercial potato cultivars. Remarkably, transgenic PVY-protected tobacco plants are also resistant to PVY^NTN infection upon mechanical and aphid-mediated inoculation. These experiments indicate that genetically engineered resistance offers great potential in protection of potato to new aggressive strains of PVY^N.     

福建马铃薯S病毒的分子鉴定及发生情况

为明确福建省马铃薯S病毒(PVS)的发生与分布情况,对福建省马铃薯主要种植区的PVS进行了鉴定和普查.在利用电镜技术和传统生物学方法鉴定的基础上,克隆了PVS外壳蛋白(cp)基因,依据PVS外壳蛋白氨基酸序列建立了PVS不同分离物的系统进化树.研究表明,利用PVS 外壳蛋白氨基酸序列分析可准确鉴定PVS,同时可分析不同分离物间的分子差异.利用病毒特异性引物和DIG标记的PVS cp基因为探针,分别利用RT-PCR技术和核酸斑点杂交技术(NASH)对PVS进行了检测,并对检测技术进行了改进.调查结果表明,PVS在福建省广泛分布,发病率最高可达80%以上,当地农家自留种可能是田间PVS的主要来源.     

甘薯潜隐病毒外壳蛋白基因的克隆、表达及其抗血清的制备

 根据已报道的甘薯潜隐病毒(Sweet potato latent virus,SPLV)外壳蛋白(CP)基因的核苷酸序列合成引物,利用RT-PCR方法克隆了SPLV河南分离物(SPLV-HN)的CP基因及部分3'端非编码区序列,序列分析表明,SPLV-HN CP基因由879个核苷酸组成(GenBank登录号为DQ399862),编码293个氨基酸残基。与GenBank中SPLV-CH(X84011)和SPLV-T(X84012)分离物的核苷酸序列相似性分别为96.8%和93.0%;与日本分离物(E15420)的核苷酸序列相似性为83.6%。将CP基因克隆到原核表达载体pET-30a(+)上,SDS-PAGE分析表明,经IPTG诱导,CP基因在大肠杆菌BL21(DE3)pLysS中得到了高效表达。以表达的蛋白为抗原,免疫家兔,制备了SPLV外壳蛋白的特异性抗血清。ACP-ELISA检测结果表明,制备的抗血清可用于田间甘薯样品的检测。     

Role of sponge gourd in apical leaf curl disease of potato in Northern India

Potato (Solanum tuberosum) is one of the important vegetable crops in the world and its production is seriously affected by apical leaf curl disease in northern India. This paper reveals the role of cucurbits in maintaining Tomato leaf curl New Delhi virus (ToLCNDV) and Potato apical leaf curl (PALCD) disease in that region. The affected plants showed severe leaf curling and stunted growth. The begomovirus causing leaf curling and mosaic disease in cucurbits could be easily transmitted by the whitefly to potato crops and develop apical leaf curl disease in northern India. The movement of the virus by whiteflies from cucurbits to potato and tomato is possible because of overlapping of planting and harvesting dates of these crops. The causal virus was identified as a begomovirus on the basis of whitefly transmission, PCR, dot blot hybridization, cloning and sequencing of the coat protein gene. The comparison of full length coat protein gene sequence homology revealed that 90% identity with the coat protein gene of ToLCNDV- [Luffa] isolate and the phylogenetic tree derived from these sequences with other selected begomoviruses formed a close cluster with ToLCNDV isolates. The findings proved that the virus causing disease in cucurbits could easily move to tomato and potato and cause leaf curl disease naturally. This is the first observation on the role of sponge gourd for maintenance of ToLCNDV and serving as a host for PALCD in northern India. The findings indicate that the causal organism is a strain of ToLCNDV.     

小西葫芦黄花叶病毒外壳蛋白基因的克隆及序列分析

 以小西葫芦黄花叶病毒(Zucchini yellow mosaic virus,ZYMV)的中国分离物(CH-87)接种发病的叶片中提取的总RNA为模板,经RT-PCR扩增获得ZYMV CP基因,将其克隆到pUCm-T质粒上进行序列分析。结果表明该CP基因由837个核苷酸组成,编码279个氨基酸。与已发表序列相比较,该CP基因与国际上已报道的4个基因型不同,应属于新的基因型,暂命名为基因型Ⅴ。     

Spread of potato virus Y in potato cultivars (Solanum tuberosum L.) with different levels of sensitivity

The aim of this work was to correlate the appearance of the symptoms, multiplication and spread of virus after mechanical inoculation of potato (Solanum tuberosum L.) cultivars showing different levels of susceptibility and sensitivity to Potato virus Y^NTN (PVY^NTN). The potato cultivars used were the resistant cultivar Sante and susceptible cultivars Igor, Pentland squire and Désirée. The spread of the virus PVY^NTN in infected plants was monitored using different methods: DAS-ELISA, tissue printing, immuno-serological electron microscopy and real-time PCR. In all three susceptible cultivars, the virus was detected in the inoculated leaves 4–5 days after inoculation. From there virus spread rapidly, first into the stem, then more or less simultaneously to the upper leaves and roots. Real-time PCR was shown to be very sensitive and enabled viral RNA to be detected in non-inoculated leaves of susceptible cultivar Igor earlier than other methods. Therefore, for exact studies of plant–virus interaction, a combination of methods which detect viruses on the basis of their different properties (coat protein, morphology or RNA) should be used to monitor the spread of viruses.     

Analysis of the triple gene block sequence in an important melon pathogen,Melon yellowing-associated virus

A novel viral disease of melon, caused by Melon yellowing-associated virus (MYaV), has become one of the most serious problems for melon production in Brazil. Despite its importance, little is known about the genome sequence of the virus. In this study, the triple gene block genomic region including the 3′-end region of an isolate of MYaV was elucidated (ca. 3.1 kb). Sweet potato chlorotic fleck virus, a newly suggested carlavirus species, was the most closely related virus with 62% nucleotide identity. The presence of two heptanucleotide-motifs for subgenomic RNA synthesis was confirmed in this sequence.     

Molecular breeding for virus resistant potato plants

To engineer resistance against potato virus X (PVX), the viral coat protein (CP) gene has been introduced into two potato cultivars. Stable expression of the gene in transgenic clones throughout the growing season has been obtained and resulted in considerably increased virus resistance. With varying frequencies depending on the original cultivar used, true-to-type PVX resistant transgenic clones have been obtained. Since deviant light sprout characteristics were invariably associated with aberrations in plant phenotype, they can be used in procedures to early screen for deviations. Furthermore, it has been possible to unequivocally discriminate between the original untransformed and independent transgenic cultivars. Although no relation has been found between the presence, if any, of the CP of potato virus Y (PVY) or potato leafroll virus (PLRV) in CP gene transgenic potato, appreciable levels of resistance to these viruses has been obtained. This suggests that the mechanism by which a viral CP gene in the potato genome evokes resistance, differs amongst various viruses.     

Molecular breeding for virus resistant potato plants

To engineer resistance against potato virus X (PVX), the viral coat protein (CP) gene has been introduced into two potato cultivars. Stable expression of the gene in transgenic clones throughout the growing season has been obtained and resulted in considerably increased virus resistance. With varying frequencies depending on the original cultivar used, true-to-type PVX resistant transgenic clones have been obtained. Since deviant light sprout characteristics were invariably associated with aberrations in plant phenotype, they can be used in procedures to early screen for deviations. Furthermore, it has been possible to unequivocally discriminate between the original untransformed and independent transgenic cultivars. Although no relation has been found between the presence, if any, of the CP of potato virus Y (PVY) or potato leafroll virus (PLRV) in CP gene transgenic potato, appreciable levels of resistance to these viruses has been obtained. This suggests that the mechanism by which a viral CP gene in the potato genome evokes resistance, differs amongst various viruses.     

甘薯褪绿斑病毒外壳蛋白的分子变异及其特异抗血清制备

 甘薯褪绿斑病毒(Sweet potato chlorotic fleck virus,SPCFV)是侵染甘薯的主要病毒之一。本研究利用RT-PCR方法克隆了SPCFV中国4个分离物的外壳蛋白(CP)基因。序列分析表明,cp基因全长900 bp,编码299个氨基酸残基。4个分离物cp基因的核苷酸序列一致性为78.3%～89.9%,推导的氨基酸序列一致性为91.3%～95.7%,存在较大的分子变异。不同分离物CP氨基酸序列N末端的第3-32位氨基酸为多变区。将四川分离物的cp基因克隆到原核表达载体pET-28a(+)上,SDS-PAGE分析表明,经IPTG诱导,cp基因在大肠杆菌BL21(DE3)中得到了高效表达。以表达的蛋白为抗原免疫家兔,制备了SPCFV CP的特异性抗血清。ACP-ELISA检测结果表明,制备的抗血清效价达1∶128 000,可用于田间甘薯样品的检测。