Potato Virus Y from Petunia can cause Symptoms of Potato Tuber Necrotic Ringspot Disease (PTNRD)

A potyvirus known to be an important agent involved in causing a disease of trailing petunias, was identified as being a member of the necrotic strain of potato virus Y (PVY) using a number of monoclonal antibodies. The sequence of the coat protein gene for the PVY isolate was determined and when compared with sequences for other PVY strains it was shown to cluster closely with isolates of PVY^NTN and to have a recombination point present within the coat protein common with other isolates of PVY^NTN. When inoculated onto potato tuber necrotic ringspot disease (PTNRD) susceptible potato cultivars the petunia isolate was found to be capable of causing necrotic tuber symptoms, consistent with those caused by other isolates of PVY^NTN. Due to the number of similarities it is thought the petunia isolate belongs to the PVY^NTN group of isolates. Out of 24 species of bedding and pot plant crops tested, 19 were shown by mechanical inoculation to be susceptible to PVY, highlighting not only a clear risk to a number of commercially important plant species from PVY^NTN infected trailing petunias, but also other susceptible crops grown in these areas.     

Characterization of potato potyvirus Y (PVY) isolates from seed potato batches. Situation of the NTN, Wilga and Z isolates

A collection of 38 PVY isolates from seed potato batches, originating from several Western European countries, was characterized by using current biological, serological and molecular tools differentiating PVY strains and groups. The correlation between the three kinds of tests was good but not absolute. No single serological or PCR method was able to discriminate among the five isolate groups found. Twenty-nine isolates belonged to the PVY^N strain and six to the PVY^O strain. No PVY^C was found. Two other isolates reacted serologically like PVY^O, but were unable to elicit a hypersensitive response from the Ny_tbr gene and probably represent the PVY^Z group. At the molecular level, these two isolates showed a combination of both PVY^O and PVY^N and could be recombinants of these strains. Another isolate reacted serologically like PVY^O, but induced vein necrosis in tobacco, like PVY^N-Wilga. Some PVY^N isolates caused tuber ring necrosis in glasshouse conditions. These might belong to the PVY^NTN group. The PVY^NTN, PVY^N-Wilga and PVY^Z groups probably represent pathotypes within strains PVY^N and PVY^O, respectively. The present study also confirms previous reports showing a high genetic variation at the 5 end within the PVYN strain.     

New aphid vectors of potato virus YN

During three successive years, 1983, 1984 and 1985, winged aphids were caught alive in a potato field with a conical net and with transportable suction traps.One hundred and one aphid species or species groups were checked for their ability and efficiency in transmitting potato virus Y^N (PVY^N) from potato to potato. Seventy-eight species or species groups were found unable to transmit PVY^N, whereas twenty-three species did transmit, among them beingAphis nasturtii, Brachycaudus helichrysi, Cryptomyzus galeopsidis, Cryptomyzus ribis, Hyadaphis foeniculi, Hyalopterus pruni, Hyperomyzus lactucae, Sitobion avenae andSitobion fragariae. All species, with the exception ofA. nasturtii, are recorded the first time as vectors for PVY^N.In transmission experiments alatae caught with a conical net yielded better results than did those caught with a suction trap.Samenvatting Gedurende drie opeenvolgende jaren (1983, 1984, 1985) werden gevleugelde exemplaren van 101 bladluissoorten levend gevangen met een fuik en met verplaatsbare zuigvallen, en in een kas getoetst op hun vermogen om aardappelvirus Y^N (PVY^N) van aardappel naar aardappel over te brengen.Achtenzeventig soorten brachten het PVY^N niet over. Naast de reeds algemeen bekende vectorsoorten werden nog enkele soorten gevangen die in staat bleken PVY^N over te brengen in het laboratorium, te weten:Aphis nasturtii, Brachycaudus helichrysi, Cryptomyzus galeopsidis, Cryptomyzus ribis, Hyadaphis foeniculi, Hyalopterus pruni, Hyperomyzus lactucae, Sitobion avenae enSitobion fragariae.Met bladluizen gevangen in de fuik werden betere overdrachtsresultaten behaald dan met de bladluizen gevangen in de zuigvallen.     

Biological and sequence comparisons of Potato virus Y isolates associated with potato tuber necrotic ringspot disease

The biological and molecular relationships between a large number of Potato virus Y (PVY) isolates were examined, concentrating mainly on isolates associated with potato tuber necrotic ringspot disease (PTNRD). Following detailed analysis of the coat-protein gene, four main groups were identified which broadly corresponded to the phenotype of the different isolates. The groups comprised the ordinary strain (PVY^O), the necrotic strain (PVY^N), the C strain (PVY^C) and a group of recombinant (between ordinary and necrotic) isolates. In the latter group, all members were associated with PTNRD. However, four nonrecombinant isolates were also identified which were associated with PTNRD or tuber necrosis. Three were from tubers showing PTNRD symptoms in the field, while the fourth originated from symptomless tubers, but could cause necrotic rings on tubers under glasshouse conditions. The results show that although coat-protein recombination is always found associated with the PTNRD phenotype, some nonrecombinant isolates have very similar biological properties.     

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.     

马铃薯Y病毒中国分离物的分子株系组成

 马铃薯Y病毒(potato virus Y,PVY)主要侵染马铃薯和烟草等茄科作物,给世界农业造成巨大经济损失。本文对测定的23个及GenBank中注册的52个中国PVY分离物ORF序列进行了系统发育、重组和选择压等分析。系统发育分析表明,根据ORF序列可把我国75个PVY分离物和国外30个参比分离物分成O、C、E、NTN-NW(SYR-I型)、NTN-NW(SYR-II型)、NTN(NTN-a型)、NTN(NTN-b型)、NA-N/NTN、Eu-N、N-Wi(N:O型)和N-Wi(N-Wi型)等11个分子株系,其中中国PVY分离物属于除E和C株系外的9个分子株系。除ME162、guiyang、PVYzu、SD-G、WA-13和CN:JL-1:17等 6个分离物基因组中未检测到重组,其余69个分离物均存在明显重组。根据重组位点的不同,中国PVY可分为11种重组类型,其中5种为新的重组类型。选择压分析表明,中国PVY分离物的11个基因均处于负选择,其中核内含体b基因受到的选择压最大,PIPO受到的选择压最小。基因流分析表明,黑龙江、河南和山东PVY分离物间基因交流频繁,马铃薯与烟草PVY分离物之间基因交流频繁。本研究的结果明确了中国PVY分离物的分子株系组成,对指导PVY的检测和防控具有积极作用。     

Aphid vectors of potato virus YN

BesideMyzus persicae a dozen other species were found to be vectors of potato virus Y^N. Eleven other species did not transmit the virus.White Burley tobacco and A6 potato are equally suitable as test plant to monitor the efficency ofRhopalosiphum padi as vector of PVY^N, but as PVY^N source tobacco is not suitable for this aphid species.Between some aphid species rather large differences exist in retention periods of PVY^N. WithR. insertum andAphis fabae transmission after a 1 h starvation period was still 50% of that without starvation. WithPhorodon humuli, M. certus andM. persicae this value was only 15, 30 and 30%, respectively.Samenvatting Van 12 bladluissoorten werd vastgesteld dat zij, evenalsMyzus persicae, vectoren van het aardappelvirus Y^N (PVY^N) zijn. Van 11 andere soorten kon dit niet worden vastgesteld. Nicotiana tabacum cv. White Burley enSolanum tuberosum cv. A6 bleken beide goed bruikbaar als toetsplant voor het vaststellen van de efficiëntie vanRhopalosiphum padi als vector van het PVY^N; voor deze bladluissoort is tabak ongeschikt als bron van PVY^N.De retentieperiode van het PVY^N lijkt bij verschillende bladluissoorten aanzienlijk te variëren. BijRhopalosiphum insertum enAphis fabae bracht één uur vasten na de acquisitie de overbrenging terug tot 50% van die welke zonder vasten werd verkregen. BijPhorodon humuli was de reductie in overbrenging na één uur vasten 85%, bijMyzus certus enM. persicae was deze 70%.     

Characterisation of a Tobamovirus from Trailing Petunias

A tobamovirus has been identified as being involved in a devastating disease of trailing petunia. Results from indicator plants and ELISA suggested that the tobamovirus was a strain of Tobacco mosaic virus (TMV). This was confirmed from the full sequence of the coat protein gene and a partial sequence of the replicase gene. Sequence analysis revealed that TMV isolated from diseased petunia had high identity (ca. 98–99) with TMV vulgare type sequences reported from Korea and Japan. Mechanical inoculation of 23 varieties, representing 21 species of pot and bedding plants with the petunia isolate of TMV confirmed that 11 were infected by the petunia isolate of TMV, although several species remained symptomless after three weeks. This highlights a clear risk to a number of commercially important pot and bedding plant species from TMV infected trailing petunias.     

Infection pressure of potato virus YN

Potato virus Y^N (PVY^N) infection was determined by the tobacco test in Swifterbant (Eastern Flevoland). In plots with beet, wheat and seed potatoes the infection exhibited an identical course. No differences were found either between PVY^N infection in the border and that in the middle of a field planted with ware potatoes, although infection pressure was clearly higher here than in the plot with seed potatoes. A barrier crop of 10 rows of wheat did not decrease the infection pressure of the virus.From August onwards, the spread of PVY^N in Lienden (Betuwe) was followed. Here virus transmission was found continuously, even until mid-November.Potato volunteers outside as well as in potato fields are serious infection sources. In 1976 and in 1977 virus spread was detected before the flight ofMyzus persicae, as determined with yellow Moericke traps. Infection pressure can be measured more efficiently by the tobacco test than by aphid trapping. The effect of rogueing at the time of virus spread should be reconsidered.If infection pressures in different areas or successive years are to be compared, the tobacco test should be standardized. A proposal to this effect is made.Samenvatting In Swifterbant (Oostelijk Flevoland) werd de infectie met het aardappel-Y^N-virus (PVY^N) bepaald met behulp van de tabakstoests. In percelen met bieten, tarwe en pootaardappelen bleek de infectie hetzelfde verloop te hebben. Tussen het infectieverloop van PVY^N in de rand en in het midden van een veld consumptieaardappelen werd eveneens geen verschil gevonden. Wel was de infectiedruk hier duidelijk hoger dan in het pootgoedperceel. Een barrier crop van 10 rijen tarwe verminderde de infectiedruk niet.De volgende conclusies kunnen worden getrokken. Aardappelopslag buiten en in aardappelvelden vormt een zeer belangrijke infectiebron. Zowel in 1976 als in 1977 vond de virusverspreiding plaats vóór de vlucht vanMyzus persicae begon, zoals deze werd bepaald met behulp van de gele Moericke vangbakken. Het effect van opzuiveren ten tijde van de virusverspreiding dient aan een nader onderzoek te worden onderworpen. De infectiedruk kan met de tabakstoets op meer directe wijze worden vastgesteld dan met bladluisvangsten mogelijk is.Wil men overgaan tot het vergelijken van de infectiedruk in verschillende gebieden of in verschillende jaren, dan dient de tabakstoets te worden gestandaardiseerd. Een voorstel hiertoe wordt gedaan.     

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.     

Acquisition of potato virus YN by Myzus persicae from primarily infected ‘Bintje’ potato plants

When ‘Bintje’ potato plants were inoculated mechanically with potato virus Y^N (PVY^N),Myzus persicae acquired PVY^N from both the inoculated and non-inoculated leaves about one week earlier than when plants were inoculated byM. persicae. Only when young plants of about four weeks after planting were inoculated byM. persicae, this aphid acquired PVY^N from the non-inoculated top leaves within a fortnight. When plants later than four weeks after planting were inoculated byM. persicae it generally took at least four weeks for this aphid to acquire PVY^N from non-inoculated top and other leaves of such plants. A number of leaves situated on the potato stems near to the inoculated ones did not serve as a PVY^N-source forM. persicae within the experimental period of 38 days. The results indicate that it is possible that in seed potato growing areas primarily infected PVY^N-infected plants, not yet showing symptoms, can act as virus sources for further spread. This is especially true in the beginning of the season.     

油桃茎痘相关病毒中国分离物基因组的分子特征分析

为明确我国油桃茎痘相关病毒(nectarine stem-pitting-associated virus,NSPaV)基因组的分子特征,利用RT-PCR和RACE技术对NSPaV中国分离物NSPaV-T04基因组进行克隆,采用最大似然法对得到的NSPaV基因组序列和GenBank中的5条NSPaV基因组序列构建系统发育树,应用RDP软件对NSPaV基因组序列进行重组分析。结果表明:中国分离物NSPaV-T04基因组序列全长为4 991 nt,包括4个开放阅读框(open reading frame,ORF),其中ORF1与ORF2共同编码1个RdRp P1-P2融合蛋白,ORF3编码1个CP,ORF5与ORF3共同编码CP通读蛋白。系统发育树和序列比较分析结果显示,中国分离物NSPaV-T04(MN095353)与美国分离物NSPaV/12P42(KT273410)的亲缘关系最近,核苷酸序列同源性最高,为96.4%;NSPaV-T04的RdRp P1变异较大,与GenBank中5条NSPaV基因组核苷酸序列的同源性为90.5%~96.1%,CP较为保守,核苷酸序列的同源性为96.6%~98.7%。重组分析结果显示,中国分离物NSPaV-T04为鉴定的一个重组体(韩国分离物SK)的亲本序列,表明中国分离物NSPaV-T04可能是一个实际的重组体。     

甘薯杆状病毒湖南分离物基因组全序列测定及比较分析

 利用Small RNA测序技术对采自湖南的甘薯杆状病毒进行鉴定,获得与SPBV-B序列具有相似性的contigs 161个。首先设计小片段引物,PCR扩增分离出706 bp的目的片段,与SPBV-B (FJ560944)相似性为78%。分段设计引物,进行基因全序列PCR扩增。引物组合SPBV-BF1/R1、SPBV-BF2/R4和SPBV-BF5/R5分别扩增出3 150、2 900和3 500 bp目的条带。序列拼接获得2个SPBV-B基因组全序列,大小分别为7 894 bp(MK052980)和7 981 bp(MK052981),包含完整编码阅读框。进化分析表明MK052980和MK052981与SPPV聚为同一分支,与SPPV相似性分别为81%和83%,与SPBV-B相似性分别为86%和94%。MK052980和MK052981具有89.5%的相似性。经编码阅读框氨基酸序列比对,MK052980序列的ORF3a氨基酸序列存在变异。这是国内首次报道SPBV-B全基因序列。     

甘薯杆状病毒湖南分离物基因组全序列测定及比较分析

 利用Small RNA测序技术对采自湖南的甘薯杆状病毒进行鉴定,获得与SPBV-B序列具有相似性的contigs 161个。首先设计小片段引物,PCR扩增分离出706 bp的目的片段,与SPBV-B (FJ560944)相似性为78%。分段设计引物,进行基因全序列PCR扩增。引物组合SPBV-BF1/R1、SPBV-BF2/R4和SPBV-BF5/R5分别扩增出3 150、2 900和3 500 bp目的条带。序列拼接获得2个SPBV-B基因组全序列,大小分别为7 894 bp(MK052980)和7 981 bp(MK052981),包含完整编码阅读框。进化分析表明MK052980和MK052981与SPPV聚为同一分支,与SPPV相似性分别为81%和83%,与SPBV-B相似性分别为86%和94%。MK052980和MK052981具有89.5%的相似性。经编码阅读框氨基酸序列比对,MK052980序列的ORF3a氨基酸序列存在变异。这是国内首次报道SPBV-B全基因序列。     

Molecular variability of Spanish and Hungarian isolates of Tomato torrado virus

The population structure and genetic variation of Tomato torrado virus (ToTV) were estimated from 19 Spanish isolates collected from 2001 to 2009 in different tomato‐production areas by analyses of the partial nucleotide sequences of five regions of the virus genome: the protease cofactor (Pro‐Co) and the RNA‐dependent RNA polymerase (RdRp) in RNA1, and the movement protein (MP) and two subunits of the coat protein (CP; viz. Vp35 and Vp23) in RNA2. Three Hungarian isolates of the virus were also included in the analyses. All the ToTV isolates clustered together in the phylogenetic analysis of the nucleotide sequences of the different regions. However, some genetic diversity was observed in the case of the two CP subunits among the Gran Canaria isolates and the remaining ToTV‐isolates analysed, which grouped together. A high similarity was observed among all the isolates and the two published ToTV isolates: the ToTV type isolate (PRI‐ToTV0301) and the Polish isolate Wal03. The most variable encoding regions studied were those on RNA2. In general, no correlation was found between genetic diversity and collection date. Studying the genetic distances between pairs of sequences, the ratio between nonsynonymous (amino‐acid‐replacing) and synonymous (silent mutational) substitutions was low, indicating a strong negative selective pressure in the studied regions. Nine negatively selected sites (distributed in Pro‐Co, MP, Vp23 and Vp35) and just one positively selected one (in Pro‐Co) were found for all the genome regions studied.     

马铃薯Y病毒云南昭通烟草分离物的检测及年度间差异比较

利用DAS-ELISA检测试剂盒检测昭通烟草脉斑病样品,结果表明存在马铃薯Y病毒O株系和马铃薯Y病毒N株系两个不同株系病毒。利用Sprimer和M4引物扩增、克隆、测序,得到长度为1 771 bp目的片段,该片段包含病毒的外壳蛋白基因序列、3′ UTR序列以及部分Nib基因序列;序列分析表明与湖南HN 2分离物（GenBank No. GQ200836）和美国NE 11分离物（GenBank No. DQ157180）核苷酸序列相似性均为98%,系统进化分析表明其具有较近的亲缘关系。     

Molecular characterization ofPseudomonas syringae pv.tomato isolates from Tanzania

Bacterial speck caused byPseudomonas syringae pv.tomato is an emerging disease of tomato in Tanzania. Following reports of outbreaks of the disease in many locations in Tanzania, 56 isolates ofP. syringae pv.tomato were collected from four tomato- producing areas and characterized using pathogenicity assays on tomato, carbon source utilization by the Biolog Microplate system, polymerase chain reaction and restriction fragment length polymorphism (RFLP) analysis. All theP. syringae pv.tomato isolates produced bacterial speck symptoms on susceptible tomato (cv. ‘Tanya’) seedlings. Metabolic fingerprinting profiles revealed diversity among the isolates, forming several clusters. Some geographic differentiation was observed in principal component analysis, with isolates from Arusha region being more diverse than those from Iringa and Morogoro regions. The Biolog system was efficient in the identification of the isolates to the species level, as 53 of the 56 (94.6%) isolates ofP. syringae pv.tomato were identified asPseudomonas syringae. However, only 23 isolates out of the 56 (41.1%) were identified asPseudomonas syringae pv.tomato. The results of this work indicate the existence ofP. syringae pv.tomato isolates in Tanzania that differ significantly from those used to create the Biolog database. RFLP analysis showed that the isolates were highly conserved in theirhrpZ gene. The low level of genomic diversity within the pathogen in Tanzania shows that there is a possibility to use resistant tomato varieties as part of an effective integrated bacterial speck management plan. http://www.phytoparasitica.org posting August 8, 2008.