First occurrence of <Emphasis Type="Italic">Sugarcane streak mosaic virus</Emphasis> infecting sugarcane in Indonesia

On plants at 59 sugarcane plantations in Central and East Java, Indonesia, we found virus-like symptoms such as streak mosaic. The virus was transmitted mechanically and was sett-borne. The nucleotide sequence of the coat protein gene had the highest identity with that of Sugarcane streak mosaic virus (SCSMV) isolate Pakistani. We tentatively designate this isolate as SCSMV-Idn (Indonesia).     

Identification and characterization of a potyvirus causing chlorotic spots on <Emphasis Type="Italic">Phalaenopsis</Emphasis> orchids

A putative virus-induced disease showing chlorotic spots on leaves of Phalaenopsis orchids was observed in central Taiwan. A virus culture, phalaenopsis isolate 7-2, was isolated from a diseased Phalaenopsis orchid and established in Chenopodium quinoa and Nicotiana benthamiana. The virus reacted with the monoclonal antibody (POTY) against the potyvirus group. Potyvirus-like long flexuous filament particles around 12–15 × 750–800 nm were observed in the crude sap and purified virus preparations, and pinwheel inclusion bodies were observed in the infected cells. The conserved region of the viral RNA was amplified using the degenerate primers for the potyviruses and sequence analysis of the virus isolate 7-2 showed 56.6–63.1% nucleotide and 44.8–65.1% amino acid identities with those of Bean yellow mosaic virus (BYMV), Beet mosaic virus (BtMV), Turnip mosaic virus (TuMV) and Bean common mosaic virus (BCMV). The coat protein (CP) gene of isolate 7-2 was amplified, sequenced and found to have 280 amino acids. A homology search in GenBank indicated that the virus is a potyvirus but no highly homologous sequence was found. The virus was designated as Phalaenopsis chlorotic spot virus (PhCSV) in early 2006. Subsequently, a potyvirus, named Basella rugose mosaic virus isolated from malabar spinach was reported in December 2006. It was found to share 96.8% amino acid identity with the CP of PhCSV. Back-inoculation with the isolated virus was conducted to confirm that PhCSV is the causal agent of chlorotic spot disease of Phalaenopsis orchids in Taiwan. This is the first report of a potyvirus causing a disease on Phalaenopsis orchids.     

Molecular identification of a new isolate of <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> subgroup II from basil (<Emphasis Type="Italic">Ocimum sanctum</Emphasis>) in India

Natural occurrence of mosaic disease was observed on basil (Ocimum sanctum L.) in Aligarh, U. P., India, during 2008. The disease could be transmitted by sap inoculations from naturally infected O. sanctum to O. sanctum and some test plant species. Cucumber mosaic virus (CMV) was detected by RT-PCR using coat protein gene specific primers of CMV (Acc. AM180922 & AM180923), which resulted in the expected size ~650 bp amplicon in infected samples. The amplicon was cloned, sequenced and data were deposited in GenBank Acc. EU600216. The sequence data analysis revealed 97–99% identities at both nucleotide and amino acid levels with the CMV strains of subgroup II reported worldwide. Based on the high sequence identities and close phylogenetic relationships with CMV subgroup II strains, the virus under study has been identified as a new isolate of CMV subgroup II and designated as CMV-Basil.     

Partial characterisation of a novel <Emphasis Type="Italic">Tobamovirus</Emphasis> infecting <Emphasis Type="Italic">Actinidia chinensis</Emphasis> and <Emphasis Type="Italic">A. deliciosa</Emphasis> (Actinidiaceae) from China

Actinidia chinensis and A. deliciosa plants from China, showing a range of symptoms, including vein clearing, interveinal mottling, mosaics and chlorotic ring spots, were found to contain ~300 nm rod-shaped virus particles. The virus was mechanically transmitted to several herbaceous indicators causing systemic infections in Nicotiana benthamiana, N. clevelandii, and N. occidentalis, and local lesions in Chenopodium quinoa. Systemically- infected leaves reacted with a Tobacco mosaic virus polyclonal antibody in indirect ELISA. PCR using generic and specific Tobamovirus primers produced a 1,526 bp sequence spanning the coat protein (CP), movement protein (MP), and partial RNA replicase genes which showed a maximum nucleotide identity (88%) with Turnip vein clearing virus and Penstemon ringspot virus. However, when the CP sequence alone was considered the highest CP sequence identity (96% nt and 98% aa) was to Ribgrass mosaic virus strain Kons 1105. The morphological, transmission, serological and molecular properties indicate that the virus is a member of subgroup 3 of the genus Tobamovirus.     

Production of discernible disease phenotypes in Canna by five plant viruses belonging to the genera Potyvirus,Cucumovirus and Badnavirus

Cannas are tropical and subtropical flowering perennial plants. The genus contains many species but most commercially grown cultivars are interspecific hybrids selected for their attractive foliage and flowers. Canna production is so lucrative that there are farmers and nurseries dedicated solely to its production. The specific issue that the canna industry faces is virus diseases. In this study, rhizomes of 24 canna cultivars were gathered and diagnostics conducted to detect Bean yellow mosaic virus (BYMV, Potyvirus), Canna yellow mottle virus (CaYMV, Badnavirus), Canna yellow streak virus (CaYSV, Potyvirus), Cucumber mosaic virus (CMV, Cucumovirus) and Tomato aspermy virus (TAV, Cucumovirus). Visual assessment of disease symptoms and diagnostic tests were carried out to identify the prevalent diseases and describe the symptoms that are associated with virus infection. BYMV, CaYMV and CaYSV caused severe mosaic and necrosis either in the leaf lamina or veins of infected leaves. Potyvirus infection suppressed red colouration in the foliage of some varieties. CaYMV and CaYSV often appeared in the same plant, suggesting they might represent a viral complex. CMV and TAV were rarely seen in these populations. Interestingly, CaYMV but not CaYSV could be mechanically inoculated to Phaseolus vulgaris plants.     

A generic RT‐PCR assay for the detection of Luteoviridae

This study, using RT‐PCR, is the first comprehensive assessment since 1991 of a generic detection method for the Luteoviridae. Thirteen Luteoviridae species were detected using three separate sets of low‐degeneracy generic primers with RT‐PCR to amplify 68‐, 75‐ and 129/156‐bp regions of the Luteoviridae coat‐protein gene. Species detected include all members of the genus Luteovirus [Barley yellow dwarf virus (BYDV)‐PAV, BYDV‐PAS, BYDV‐MAV (129 and/or 156 bp amplicons), Soybean dwarf virus, Bean leafroll virus (68 bp amplicon)] and eight of nine species from the genus Polerovirus [Beet western yellows virus, Beet chlorosis virus, Beet mild yellowing virus, Turnip yellows virus, Potato leafroll virus, Cucurbit aphid‐borne yellows virus, Cereal yellow dwarf virus‐RPV (68‐bp amplicon) and Sugarcane yellow leaf virus (75‐bp amplicon)]. These primers were not able to detect Carrot red leaf virus, Sweet potato leaf speckling virus (both belong to unassigned Luteoviridae) and Pea enation mosaic virus‐1 (genus Enamovirus). A synthetic positive control containing all primer sequence priming sites was designed to facilitate this method as a generic tool for use with a variety of host plants. The Luteoviridae primers described in this study present a simple infection‐detection tool of benefit to biosecurity authorities in nursery‐stock surveillance, disease management or outbreak prevention, and may also be useful in detection of as‐yet undiscovered species within the Luteovirus and Polerovirus genera.     

玉米褪绿斑驳病毒实时荧光RT-PCR检测方法研究

玉米褪绿斑驳病毒(Maize chlorotic mottle virus,MCMV)是我国对外公布的检疫性有害生物。本研究根据该病毒外壳蛋白基因的保守序列,设计得到特异性引物及Taqman荧光探针,建立了MCMV的实时荧光RT-PCR方法,并对其灵敏度与特异性进行了研究。该方法针对2个不同来源的毒株均能得到典型扩增曲线,而没有从小麦线条花叶病毒、玉米粗缩病毒和玉米矮花叶病毒的RNA得到扩增曲线,表明引物与荧光探针具有良好的特异性。针对玉米褪绿斑驳病毒RNA不同稀释度样品,实时荧光RT-PCR检测低限达到10-5稀释度,检测灵敏度要比普通RT-PCR高出100倍。因此,本研究建立的MCMV实时荧光方法具有特异性强、灵敏度高和快速有效的优点。     

Incidence of viruses in <Emphasis Type="Italic">Alstroemeria</Emphasis> plants cultivated in Japan and characterization of <Emphasis Type="Italic">Broad bean wilt virus-2, Cucumber mosaic virus</Emphasis> and <Emphasis Type="Italic">Youcai mosaic virus</Emphasis>

Alstroemeria plants were surveyed for viruses in Japan from 2002 to 2004. Seventy-two Alstroemeria plants were collected from Aichi, Nagano, and Hokkaido prefectures and 54.2% were infected with some species of virus. The predominant virus was Alstroemeria mosaic virus, followed by Tomato spotted wilt virus, Youcai mosaic virus (YoMV), Cucumber mosaic virus (CMV), Alstroemeria virus X and Broad bean wilt virus-2 (BBWV-2). On the basis of nucleotide sequence of the coat protein genes, all four CMV isolates belong to subgroup IA. CMV isolates induced mosaic and/or necrosis on Alstroemeria. YoMV and BBWV-2 were newly identified by traits such as host range, particle morphology, and nucleotide sequence as viruses infecting Alstroemeria. A BBWV-2 isolate also induced mosaic symptoms on Alstroemeria seedlings.     

Molecular characterization of Cucumber mosaic virus strain causing severe mosaic disease on petunia in India

Severe mosaic, yellowing and stunting symptoms were observed on petunia (Petunia hybrida L.) growing in pots at NBRI and in various gardens of Lucknow, India. The association of Cucumber mosaic virus (CMV) with the mosaic disease was detected based on positive bioassay on susceptible hosts, isometric cored virus particles of ~28?nm during electron microscopic observations in leaf dip preparations and positive amplification of expected size (~650?bp) during RT-PCR using coat protein gene specific primers. Further, the complete RNA 3 genomic fragment of virus isolate was amplified by RT-PCR using RNA 3 specific primers. The obtained amplicons of ~2.2 Kb were cloned and sequenced. The analysis of sequence data of RNA 3 revealed highest sequence identities (96%) with several CMV strains which belong to subgroup IB. The virus isolate also showed closest phylogenetic relationships with banana strain of CMV of subgroup IB (Acc. EF178298) reported from India. To the best of our knowledge, we report the first molecular characterization of CMV strain of subgroup IB causing severe mosaic disease on petunia in India.     

First report of <Emphasis Type="Italic">Bean common mosaic virus</Emphasis> in yam bean [<Emphasis Type="Italic">Pachyrhizus erosus</Emphasis> (L.) Urban] in Indonesia

Severe mosaic with leaf malformation and green vein banding was observed on yam bean in West and Central Java, Indonesia. Virions of the causal virus were flexuous filaments, about 700 nm in length, with a coat protein of 30 kDa. The virus was transmitted by mechanical inoculation and by aphids in a nonpersistent manner. The nucleotide sequence of the coat protein gene had the highest identity with that of Bean common mosaic virus (BCMV, genus Potyvirus) isolate VN/BB2-5. Based on demarcation criteria, including the genome sequence and host range, we tentatively designate this isolate as BCMV-IYbn (Indonesian yam bean). The nucleotide sequence reported is available in the DDBJ/EMBL/GenBank databases under accession number AB289438.     

An isolate of Wheat streak mosaic virus from foxtail overcomes Wsm2 resistance in wheat

Wheat streak mosaic virus (WSMV) is an economically important pathogen of wheat (Triticum aestivum) causing major yield losses in regions where severe infection occurs. To detect the presence of any new virus or new WSMV isolates, green foxtail (Setaria viridis) plants exhibiting virus-like symptoms were sampled in a summer-fallowed wheat field at the Agricultural Research Center-Hays, Kansas State University, Hays, Kansas. These plants were tested serologically for four wheat viruses: WSMV, Triticum mosaic virus (TriMV), High Plains wheat mosaic virus (HPWMoV) and Foxtail mosaic virus (FoMV). Among 38 plant samples exhibiting virus-like symptoms, 29 contained WSMV as indicated by ELISA. Four isolates from samples with relatively strong reactions were transferred to healthy wheat seedlings by mechanical inoculation in a growth chamber for pathogenicity testing. Three isolates were avirulent to a wheat variety RonL, which contains Wsm2, a gene providing temperature-sensitive resistance to currently prevalent isolates of WSMV. However, one isolate, KSH294, was able to infect RonL and showed more virulence on two other varieties/lines containing Wsm2. Further sequence and phylogenetic analysis of KSH294 confirmed that this isolate displays a sequence homology with WSMV, but has sequence differences making it distinct from previously identified WSMV isolates included in the phylogenetic analysis.     

First report of a <Emphasis Type="Italic">Grapevine Algerian latent virus</Emphasis> disease on statice plants (<Emphasis Type="Italic">Limonium sinuatum</Emphasis>) in Japan

A viral disease was found in Nagano Prefecture, Japan, on statice (Limonium sinuatum) with chlorotic leaf spot, necrotic stunt, and dwarfing. Spherical virus particles 30 nm in diameter were isolated from infected plants and statice seedlings and caused identical symptoms 4 weeks after mechanical inoculation. Nucleotide and deduced amino acid sequences of the coat protein showed 98% and 98.7% identities with those of Grapevine Algerian latent virus (GALV) nipplefruit strain. This is the first report in Japan of a viral disease on statice caused by GALV. The nucleotide sequence data reported here are available in the DDBJ/EMBL/GenBank databases under accession AB461854.