Viruses infecting almond trees in the region of Valencia (Spain) 1

In the last 10 years, more than a thousand almond trees have been analysed by the DAS-ELISA method in the Valencia region. The most frequent virus infecting unselected almond trees was prune dwarf ilarvirus (PDV) (62%), followed by prunus necrotic ringspot ilarvirus (PNRSV) (36%), apple mosaic ilarvirus (ApMV) (14%) and apple chlorotic leafspot trichovirus (ACLSV) (2%). Infection levels of selected trees were 26% for PDV, 15% for PRSV, 0% for ApMV and 5% for ACLSV.     

A survey of peach viruses in Lebanon

Field surveys were carried out in the main peach-growing areas of Lebanon to assess the presence and distribution of viruses and viroids in commercial orchards. Field inspections were made in spring and summer 2000 to observe symptoms of virus and viroid diseases respectively. In total, 950 trees in 95 commercial plantings from three different regions of Lebanon (Bekaa Valley, Mount Lebanon and north Lebanon) were surveyed and sampled. Immunoenzymatic tests (DAS-ELISA) were used to ascertain the presence of the following: Prunus necrotic ring spot ilarvirus (PNRSV), Prune dwarf ilarvirus (PDV), Apple mosaic ilarvirus (ApMV), Apple chlorotic leaf spot trichovirus (ACLSV), Plum pox potyvirus (PPV), Tomato ringspot nepovirus (ToRSV) and Strawberry latent ringspot nepovirus (SLRSV). Peach latent mosaic pelamoviroid (PLMVd) and Hop stunt hostuviroid (HSVd) were identified by molecular hybridization. About 25% of the tested samples were infected by one or more viruses. In particular, the prevailing virus was PNRSV (61.2% of infection), followed by ACLSV (27.1%), PDV (22.4%) and ApMV (2.1%). Mixed infections were about 13%. ToRSV, SLRSV and PPV were not found. HSVd was apparently absent, whereas PLMVd was identified in 34% of the samples examined. This viroid prevailed in certain areas of Mount Lebanon in both native and foreign cultivars.     

Rose mosaic disease: symptoms induced in roses by graft inoculation with both prunus necrotic ringspot and apple mosaic viruses

Symptoms induced in rose by single isolates of the cherry serotype of prunus necrotic ringspot virus (PNRSV) and an apple serotype (apple mosaic virus; ApMV) were characteristically different, and appeared at different times throughout the growing season according to the ambient temperature. These features remained discrete, even in roses infected by both viruses and were shown by immunospecific electron microscopy to be a reliable indication of infection by either virus.
However, cross-protection between the two isolates was not reciprocal; mixed infections were established only when roses were simultaneously graft-inoculated with ApMV and PNRSV, or when PNRSV-infected roses were supei-infected with ApMV. The significance of these results in relation to the possible natural occurrence of mixed infections in rose or of isolates of intermediate serotype is discussed.     

The coat proteins and putative movement proteins of isolates of Prunus necrotic ringspot virus from different host species and geographic origins are extensively conserved

A complete sequence for the RNA 3 of Prunus necrotic ringspot virus (PNRSV) is described (Genbank Accession U57046). Primers from this sequence were used to amplify both the movement protein and coat protein genes of 3 other isolates of PNRSV originating from different host species and geographic locations. Comparisons of these sequences with those of other published sequences for PNRSV and the closely related apple mosaic virus (ApMV) showed that both the movement proteins and coat proteins of isolates of PNRSV are extensively conserved irrespective of either the original host or the geographic origin. The movement protein and coat protein of ApMV and PNRSV are sufficiently conserved to suggest that these two viruses may have evolved from a common ancestor. The amino acid sequence of the two coat proteins shows areas of similarity and difference that would explain the serological continuum reported to occur among isolates of these two viruses. Nevertheless, the movement protein and coat protein of the two viruses are sufficiently different so that ApMV and PNRSV should be considered to be distinct viruses.     

Sanitary status of stone-fruit trees in East Anatolia (Turkey) with particular reference to apricot

Field surveys were carried out in the main stone-fruit-growing areas of East Anatolia (Turkey) to assess the sanitary status of varietal collections, mother blocks and commercial orchards. The presence of virus and virus-like diseases was ascertained by enzyme-linked immunosorbent assay (ELISA), sap transmission to herbaceous hosts, graft transmission to peach cv. GF305 and molecular hybridization tests. A total of 1019 samples was tested by ELISA (859 apricot, 120 cherry, 21 almond and 19 peach). The sanitary status of apricot was extremely satisfactory, as the infection level was less than 0.3%. Cherry and almond, however, showed 21% and 33% infection respectively. The viruses identified were apple chlorotic leaf spot trichovirus (ACLSV), prune dwarf ilarvirus (PDV) and prunus necrotic ringspot ilarvirus (PNRSV). The commonest virus was PDV. Plum pox potyvirus (PPV), apple mosaic ilarvirus (ApMV) and the nepoviruses tomato black ring (TBRV), raspberry ringspot (RpRSV), strawberry latent ringspot (SLRV), cherry leaf roll (CLRV), arabis mosaic (ArMV) and tomato ringspot (ToRSV) were not encountered. Peach latent mosaic viroid (PLMVd) and hop stunt viroid (HSVd) were not detected either.     

Viruses and viroids of stone fruits in Jordan

Field surveys were carried out in the main stonefruit-growing areas of Jordan to assess the sanitary status of varietal collections, mother plant blocks and commercial orchards. The presence of virus and virus-like diseases was determined by ELISA, sap transmission to herbaceous hosts, graft transmission to Prunus persica cv. GF 305 and P. serrulata cv. Kwanzan, and molecular hybridization tests. A total of 1312 samples was tested by ELISA (531 peach, 361 plum, 218 apricot, 135 almond and 67 cherry trees). The overall mean level of infection was about 14%, indicating an acceptable sanitary status as a whole, considering that no sanitary selection has ever been carried out in Jordan. The infection level of different species was: peach (18%), cherry (15%), almond (14%), apricot (11%) and plum (10%). The following viruses and viroids were identified: Plum pox potyvirus (PPV), Prunus necrotic ringspot ilarvirus (PNRSV), Prune dwarf ilarvirus (PDV), Apple mosaic ilarvirus (ApMV), Apple chlorotic leaf spot trichovirus (ACLSV), Hop stunt viroid (HSVd) and Peach latent mosaic viroid (PLMVd). Most of these agents (ApMV, ACLSV, PLMVd and HSVd) are reported for the first time from Jordan.     

Preliminary account of the phytosanitary status of stone-fruit trees in Lebanon

Investigations were carried out in the main stone-fruit growing areas of Lebanon to assess the phytosanitary condition of commercial orchards. The presence of virus and virus-like diseases and their identification was ascertained through: (i) field surveys, (ii) sap transmission to herbaceous hosts, (iii) graft transmission to woody indicators; and (iv) ELISA and IEM tests. The mean infection level was 25%. ranging from 5% in apricot to 45% in cherry. The following viruses were identified: apple chlorotic leaf spot trichovirus (ACLSV), prunus necrotic ringspot (PNRSV) and prune dwarf (PDV) ilarviruses. Plum pox potyvirus (PPV), apple mosaic ilarvirus (ApMV), and six nepoviruses tested for (SLRV, TBRV, RRV, CLRV, ArMV and ToRSV) were not encountered.     

Detection of virus diseases affecting almond nursery trees in western Anatolia (Turkey)

The purpose of this study was a comprehensive survey on the occurrence and distribution of the viruses affecting almond nursery trees in western Anatolia (Turkey). Three provinces (Aydýn, Balýkesir and Ýzmir) which are well known for their state and commercial nursery plantations of almond (mixed with other stone fruits) were visited and 19 300 and 19 000 almond nursery trees were surveyed in 1992 and 1993, and 56 and 40 leaf samples collected, respectively. The main viral symptoms were chlorotic and necrotic spots, calico, mosaic, narrowing and deformation of the leaves; gummosis, weak growth, dwarfing and short internodes of the trees. DAS-ELISA was used to detect prunus necrotic ringspot ilarvirus (PNRSV), prune dwarf ilarvirus (PDV), raspberry ringspot nepovirus (RRV), peach rosette mosaic nepovirus (PRMV) and tomato ringspot nepovirus (ToRSV) in almond nursery trees in west Anatolia. PNRSV was found to be the most widespread according to ELISA. PDV was the second most important virus, and some samples were infected with both ilarviruses. Fewer samples were found infected with PRMV, RRV and only a few samples were infected with ToRSV.     

A preliminary account of the sanitary status of stone-fruit trees in Morocco

Field surveys were carried out in the main stone-fruit growing areas of Morocco to evaluate the sanitary status of commercial orchards, varietal collections and nurseries. The presence of virus and virus-like diseases was checked by ELISA, sap transmission to herbaceous hosts, testing on woody indicators and molecular hybridization (dot-blot and tissue-printing). 1211 samples (382 almond, 339 peach, 291 plum, 150 apricot and 49 cherry) were tested by ELISA for the presence of Prunus necrotic ring spot virus (PNRSV), Prune dwarf virus (PDV), Apple chlorotic leaf spot virus (ACLSV), Apple mosaic virus (ApMV) and Plum pox virus (PPV). The overall average of virus infection rate was 16.4%, whereas that of single species was: 22.6% for almond, 17.8% for plum, 15% for peach, 10.2% for cherry, and 2.7% for apricot. The following viruses were detected: PNRSV, PDV, ACLSV and ApMV. 565 samples were tested by dot-blot and tissue-printing hybridization for the presence of Peach latent mosaic viroid (PLMVd) and Hop stunt viroid (HSVd). 48 samples were infected, 41 by PLMVd and 7 by HSVd. In addition, nested-PCR tests identified Plum bark necrosis and stem-pitting associated virus (PBNSPaV) in a few almond trees affected by stem pitting.     

Viruses of stone fruits in Albania

Surveys were carried out in the main stone-fruit growing areas of Albania to assess the phytosanitary status of Prunus in conimercial orchards and varietal collections. The presence of virus and virus-like diseases and their identification was ascertained through field observations, sap transmission to herbaceous hosts, graft transmission to woody indicators, ELISA and IEM tests. The mean infection level was 42%. In particular, infections in apricot and almond were 12 and 16%, respectively, i.e. lower than in plum and cherry (47 and 56%, respectively). The following viruses were identified: plum pox potyvirus (PPV). apple chlorotic leaf spot trichovirus (ACLSV). prunus necrotic ringspot (PNRSV) and prune dwarf (PDV) ilarviruses. PPV infection was very severe in plum, and limited in apricot and peach. Apple mosaic ilarvirus (ApMV), and six nepoviruses tested for (SLRV, TBRV, RRV, CLRV, ArMV and ToRSV) were not encountered in Primus.     

侵染肥城桃的病毒和类病毒的分子检测与鉴定

为明确山东肥城桃种植区桃树上主要存在的病毒和类病毒及其发生情况,采集具有花叶、斑驳和皱缩典型症状的肥城桃样品,提取叶片总RNA后,分别选用桃树上已报道的啤酒花矮化类病毒Hopstuntviroid(HSVd)、桃潜隐花叶类病毒Peach latent mosaic viroid(PLMVd)、苹果褪绿叶斑病毒Apple chlorotic leaf spot virus(ACLSV)、樱桃锉叶病毒Cherry rasp leaf virus(CRLV)、桃花叶病毒Peach mosaic virus(PMV)、李属坏死环斑病毒Prunus necrotic ringspot virus(PNRSV)、李痘病毒Plum pox virus(PPV)、李矮缩病毒Prunus dwarf virus(PDV)、樱桃绿环斑驳病毒Cherry green ring mottle virus(CGRMV)、杏假褪绿叶斑病毒Apricot pseudo-chlorotic leaf spot virus(APCLSV)、李树皮坏死茎纹孔伴随病毒Plum bark necrosis stem pitting-associated virus(PBNSPaV)和小樱桃病毒1号Little cherry virus 1(LchV1)的特异性引物进行RT-PCR检测。PCR结果显示仅HSVd、PLMVd、ACLSV、PNRSV和PBNSPaV的扩增产物中得到了预期大小的目的片段,将目的片段克隆测序后,经NCBI BLAST比对发现,山东肥城桃分离物HSVd、PLMVd、ACLSV、PNRSV和PBNSPaV与GenBank已报道分离物序列一致性均达90%以上。表明山东肥城桃已感染HSVd、PLMVd 2种类病毒和ACLSV、PNRSV、PBNSPaV 3种病毒。     

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.     

我国梅树上病毒及类病毒的检测和鉴定

目前, 我国梅树上的病毒种类及发生情况仍不完全清楚。本研究从北京、武汉、南京和无锡的梅园中采集了64份疑似感染病毒的叶片样品, 通过RT-PCR和斑点杂交, 对7种病毒和2种类病毒进行了检测。共检测到6种病毒和1种类病毒。其中, 李属坏死环斑病毒(prunus necrotic ringspot virus, PNRSV)和桃潜隐花叶类病毒(peach latent mosaic viroid, PLMVd)为我国梅树上的首次检出。PNRSV、亚洲李属病毒2号(Asian prunus virus 2, APV2)、桃叶痘伴随病毒(peach leaf pitting-associated virus, PLPaV)的检出率高于30%。综合考虑病毒的分布及检出率, PLPaV、APV2、PNRSV和李树皮坏死茎痘伴随病毒(plum bark necrosis stem pitting-associated virus, PBNSPaV)是武汉、南京和无锡梅树上的主要病毒。此外, 通过克隆和测序, 获得了PLMVd和梅树病毒A(mume virus A, MuVA)的基因组, PLPaV的RNA1组分和PNRSV外壳蛋白(CP)基因序列。序列比较分析显示, 我国PLMVd梅分离物和PNRSV梅分离物与我国桃分离物亲缘关系最近, 表明PLMVd和PNRSV可能在梅和桃树间交互侵染;我国MuVA梅分离物序列与日本梅分离物序列的相似性高达98.56%;PLPaV梅分离物与我国桃分离物之间序列变异较大。上述结果不仅进一步明确了我国梅树上的病毒及类病毒种类和分布情况, 而且有助于深入了解它们的流行与传播。     

Viruses of pome fruit trees in Syria

A survey was conducted to evaluate the sanitary status of pome fruit trees in Syria during spring 2003 and 2004 in 6 governorates: Damascus, Al-Qunaitara and Al-Sweida (Southern region), Homs and Hama (Central region) and Latakia (Costal Western region), as the main production areas of pome fruits. Leaf samples from 1077 apples, 54 pears and 14 quince were collected and tested for the presence of Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASGV) and Apple mosaic virus (ApMV) in 70 commercial orchards and 3 varietal collections by ELISA. Results showed that the virus infection rates were 34 and 2% in apple and pear, respectively. Quince trees were found to be virus tested free. ACLSV was prevailing on apple with 34%, whereas ASGV and ApMV were found in 2 and 0.2% of tested trees, respectively. Pear trees were infected only with ACLSV (2%). 21 apples and 15 pears representative budwood samples were indexed by grafting on the following indicators: (i) Malus pumila cvs. Virginia Crab and Radiant for apple and (ii) M. pumila cv. V. Crab and Pyrus communis cv. Nouveau Poiteau for pear. The virus infection rates by woody indexing were much higher than ELISA, Apple stem pitting virus (ASPV) and ASGV were found in 86 and 82% of apple tested samples, whereas they were 80 and 60% of pear tested samples, respectively. Additional RT-PCR testing carried out for a limited number of samples confirmed the high incidence of ACLSV ASPV, ASGV and the presence of ApMV. This is the first report on pome fruit viruses in Syria, indicating an unsatisfactory sanitary status of the industry. As a consequence, a certification program is recommended for producing locally healthy propagating material.     

Infectious diseases of almond with special reference to the Mediterranean area 1

The major and most widespread virus-induced disorder of almond is a complex disease called mosaic. The disease is characterized by a variety of symptoms ranging from bright chrome-yellow (calico) to chlorotic discolorations, localized necrosis of the leaf blade, leaf curling, bud failure, fasciations, rosetting, stunting and bushy growth. Three ilarviruses, apple mosaic (ApMV), prune dwarf (PDV) and prunus necrotic ringspot (PNRSV), are associated with almond mosaic throughout the Mediterranean, and are involved to different extents in its aetiology. Apple chlorotic leaf spot trichovirus (ACLSV) may also be present in mosaic-affected plants, and is sometimes associated with a chlorotic leafroll condition. Two epoviruses, tomato ringspot (ToRSV) and tomato black ring (TBRV), have been reported from the USA and Europe as the agents of diseases called yellow bud mosaic and enations, respectively. Plum pox potyvirus (PPV) and another filamentous virus, prunus latent virus (PLV), can also infect almond. Brown line and decline, a putative phytoplasma disease, occurs in California, together with the leaf scorch induced by the xylem-limited bacterium Xylella fastidiosa. A stem pitting lot associated with nepovirus infection and a graft-union necrosis apparently not caused by phytoplasmas have been reported from Italy. Infections by hop stunt viroid (HSVd) were recently reported from Spain.     

Phytosanitary status of almond and apricot in Tunisia

Surveys were carried out in the traditional areas of almond and apricot cultivation in Tunisia to assess the phytosanitary status of these species in varietal collections, mother block stands and commercial orchards. The presence of virus and virus-like diseases was ascertained through field surveys, sap transmission to herbaceous hosts, and ELISA and IEM tests. The mean infection level in almond was 34%. compared with only 4.7% in apricot. The following viruses were identified: apple chlorotic leaf spot trichovirus (ACLSV), apple mosaic (ApMV), prune dwarf (PDV) and prunus necrotic ringspot (PNRSV) ilarviruses. Plum pox potyvirus (PPV) was not detected. Likewise, none of the six nepoviruses tested for (SLRV, TBRV, RRV. CLRV. ArMV and ToRSV) was encountered.     

Incidence and natural spread of apple mosaic ilarvirus in hazel in north-east Spain

Apple mosaic ilarvirus (ApMV) was detected in all (160) hazel ( Corylus avellana ) cv. Negret orchards assayed in Catalonia, north-east Spain, during 1997 and 1998. In a preliminary survey, using enzyme-linked immunosorbent assay (ELISA), only 9 of the 320 samples collected appeared free from ApMV and three of these individuals indexed ELISA positives when re-tested. The spread of ApMV was studied in a plantation of Negret hazel in which virus-free trees were randomly interspersed with graft-inoculated individuals. When tested by ELISA 10 years after planting, 15% of the ungrafted trees contained ApMV. At that time, 8% of seeds on ungrafted and virus-free trees and 54% of seeds on ApMV-inoculated trees indexed ApMV-positive. These results are discussed in terms of pollen-mediated inoculation.     

北京月季病原病毒的高通量测序鉴定和RT-PCR检测

本研究利用高通量测序技术对北京地区的月季染病样品进行了病毒鉴定,通过序列比对和拼接获得了李属坏死环斑病毒(prunus necrotic ringspot virus,PNRSV)、苹果茎沟病毒(apple stem grooving virus,ASGV)、柑橘碎叶病毒(citrus tatter leaf viru...     

Capsid protein sequence gene analysis of <Emphasis Type="Italic">Apple mosaic virus</Emphasis> infecting pears

Apple mosaic virus (ApMV, genus Ilarvirus) was detected in pears, a previously non-reported virus host. No symptoms were visible on the hosts leaves. Seventeen out of 22 randomly selected pear trees in Italy (Lombardy) and in three regions in the Czech Republic were ApMV-infected. All nine newly sequenced ApMV isolates from pears had a 15-nucleotide insertion in the capsid protein gene in identical position of that of apple isolates compared with isolates from hop and prunes. The insertion is the most prominent (but not essential) modification of the capsid protein gene, which results in a phylogenetic separation of ApMV isolates into three clusters. Sequence analysis data of an additional 15 isolates revealed a sequence correlation with kernelled fruit trees (apple and pear).