Infection by the semi-persistently transmitted Tomato chlorosis virus alters the biology and behaviour of Bemisia tabaci on two potato clones

Insect-borne plant viruses usually alter the interactions between host plant and insect vector in ways conducive to their transmission ('host manipulation hypothesis'). Most studies have tested this hypothesis with persistently and non-persistently transmitted viruses, while few have examined semi-persistently transmitted viruses. The crinivirus Tomato chlorosis virus (ToCV) is semi-persistently transmitted virus by whiteflies, and has been recently reported infecting potato plants in Brazil, where Bemisia tabaci Middle East Asia Minor 1 (MEAM1) is a competent vector. We investigated how ToCV infection modifies the interaction between potato plants and B. tabaci in ways that increase the likelihood of ToCV transmission, in two clones, one susceptible ('Agata') and the other moderately resistant (Bach-4) to B. tabaci. Whiteflies alighted and laid more eggs on ToCV-infected plants than mock-inoculated plants of Bach-4. When non-viruliferous whiteflies were released on ToCV-infected plants near mock-inoculated plants, adults moved more intensely towards non-infected plants than in the reverse condition for both clones. Feeding on ToCV-infected plants reduced egg-incubation period in both clones, but the egg-adult cycle was similar for whiteflies fed on ToCV-infected and mock-inoculated plants. Our results demonstrated that ToCV infection in potato plants alters B. tabaci behaviour and development in distinct ways depending on the host clone, with potential implications for ToCV spread.

First Report of Beet necrotic yellow vein virus on Red Table Beet in Brazil

Beet necrotic yellow vein virus (BNYVV) is an economically important pathogen of sugar beet (Beta vulgaris var. saccharifera) in several European, and Asian countries and in the United States (3). The virus is transmitted by the soil-inhabiting plasmodiophorid Polymyxa betae and causes the rhizomania disease of sugar beet. In November 2012, plants of B. vulgaris subsp. vulgaris cv. Boro (red table beet) exhibiting mainly severe characteristic root symptom of rhizomania were found in a commercial field located in the municipality of São José do Rio Pardo, State of São Paulo, Brazil. No characteristic virus-inducing foliar symptom was observed on diseased plants. The incidence of diseased plants was around 70% in the two visited crops. As the hairy root symptom is indicative of infection by BNYVV, the present study aimed to detect and identify this virus associated with the diseased plants. Preliminary leaf dip analysis by transmission electron microscopy revealed the presence of very few benyvirus-like particles. Total RNA was extracted from roots of three symptomatic plants and one asymptomatic plant according to Toth et al. (3). One-step reverse-transcription-polymerase chain reaction (RT-PCR) was performed as described by Morris et al. (2) with primers that amplify part of the coat protein gene at RNA2. The initial assumption that the hairy root symptom was associated with BNYVV infection was confirmed by the amplification of a fragment of ~500 bp from all three symptomatic samples. No amplicon was obtained from the asymptomatic control plant. Amplicons were directly sequenced, and the consensus nucleotide and deduced amino acid sequences showed 100% identity. The nucleotide sequence for one amplicon (Accession No. KM433683) was compared with other sequences deposited in GenBank. The nucleotide (468 nt) and deduced amino acid (156 aa) sequences shared 93 to 100 and 97 to 99% identity, respectively with the corresponding nucleotide and amino acid sequences for other isolates of type A of BNYVV. The virus was transmitted to three of 10 red table beet plants inoculated with contaminated soil, and infection was confirmed by nested RT-PCR, as described by Morris et al. (1), and nucleotide sequencing. This is the first report on the occurrence of BNYVV in Brazil, which certainly will affect the yield of red table beet in the producing region. Therefore, mapping of the occurrence of BNYVV in red table beet-producing areas in Brazil for containment of the spread of the virus is urgent. In the meantime, precautions should be taken to control the movement of contaminated soil and beet roots, carrots, or any vegetable grown on infested land that might introduce the virus to still virus-free regions. References: (1) J. Morris et al. J. Virol. Methods 95:163, 2001. (2) D. D. Sutic et al. Handbook of Plant Virus Diseases. CRC Press, Boca Raton, Florida, 1999. (3) I. K. Toth et al. Methods for the Detection and Quantification of Erwinia carotovora subsp. atroseptica (Pectobacterium carotovorum subsb. atrosepticum) on Potatoes: A Laboratory Manual. Scottish Crop Research Institute, Dundee, Scotland, 2002.

First Report of Catharanthus mosaic virus in Mandevilla in the United States

Mandevilla (Apocynaceae) is an ornamental tropical vine popular for its bright and attractive flowers. During 2012 to 2013, 12 Mandevilla sp. samples from Minnesota and Florida nurseries were submitted for analysis at the University of Minnesota Plant Disease Clinic. Plants showed mosaic symptoms, leaf deformation, premature leaf senescence, and vine dieback. Filamentous virus particles with modal lengths 700 to 900 nm were observed by transmission electron microscopy (TEM) in partially purified preparations from symptomatic leaves. Partially purified virions were obtained using 30% sucrose cushion centrifuged at 109,000 g_max for 2 h at 10°C (5). No other virus particles were observed in these samples, nor were any observed in non-symptomatic samples. One sample was submitted as potted plant (Mandevilla 'Sunmandeho' Sun Parasol Giant White) and was kept under greenhouse conditions for subsequent analyses. Total RNA (Qiagen) was extracted from this sample, and Potyvirus was detected using the universal primers Poty S (5'-GGN AAY AAY AGY GGN CAR CC-3') and PV1 (5'-20(T)V-3') (1) by reverse transcription (RT)-PCR (3). The amplified product was the expected ~1.7-kb, corresponding to the partial nuclear inclusion body gene, the coat protein (CP) gene, and the 3' end untranslated region. The RT-PCR amplicon was cloned (NEB) and sequenced, and the 1,720-bp consensus sequence was deposited in GenBank (Accession No. KM243928). NCBI BLAST analysis at the nucleotide level revealed highest identity (83%) with an isolate of Catharanthus mosaic virus (CatMV) from Brazil (Accession No. DQ365928). Pairwise analysis of the predicted 256 amino acid CP revealed 91% identity with the CatMV Brazilian isolate (ABI94824) and 68% or less identity with other potyviruses. Two potyviruses are usually considered the same species if their CP amino acid sequences are greater than 80% identical (2). Serological analysis of the infected sample Mandevilla 'Sunmandeho' Sun Parasol Giant White using a CatMV specific antiserum (4) resulted in positive indirect ELISA reactions. CatMV has been previously reported in periwinkle (Catharanthus roseus) in Brazil (4). Based on the analyses by TEM, RT-PCR, nucleotide and amino acid sequence identities, and serological reactivity, we identify this virus as a U.S. Mandevilla isolate of CatMV. To our knowledge, this is the first report of Catharanthus mosaic virus both in the United States and in Mandevilla. References: (1) J. Chen et al. Arch Virol. 146:757, 2001. (2) A. Gibbs and K. Ohshima. Ann. Rev. Phytopathol. 48:205, 2010. (3) R. L. Jordan et al. Acta Hortic. 901:159, 2011. (4) S. C. Maciell et al. Sci. Agric. Piracicaba, Brazil. 68:687, 2011. (5) D. Mollov et al. Arch Virol. 158:1917, 2013.

Fevillea trilobata as a Natural Host of Zucchini yellow mosaic virus in Brazil

The antidote vines or nhandirobas (Fevillea trilobata L. [Cucurbitaceae]) are dioecious plant species native to the South American Neotropics (1). Genetic materials of these species are now being domesticated and evaluated as potential crops for seed-oil extraction aiming to produce biodiesel fuel (2). Plants of F. trilobata (Accession No. CNPH-001) were cultivated from seeds under open field conditions during the years 2008 through 2011 in Brasília-DF, Brazil. Approximately 200 plants exhibiting mosaic symptoms and severe leaf malformation (with typical bubble-like patches) were found in all fields every year. Apical mosaic was slightly more severe in female than in male plants. Electron microscopy examination of negatively stained extracts of symptomatic leaf tissue showed the presence of filamentous particles about 700 to 800 nm long. Analysis of ultra-thin sections of the same tissues revealed the presence of lamellar inclusions typical of a potyvirus infection. No aphid colonies were observed on field-grown F. trilobata plants. The virus was mechanically transmitted to healthy Cucurbita pepo cv. Caserta and Luffa cylindrica, causing systemic mosaic. Sap from these infected plants reacted in PTA-ELISA with polyclonal antiserum against Zucchini yellow mosaic virus (ZYMV), but not with antisera against Papaya ringspot virus - type W (PRSV-W), Cucumber mosaic virus (CMV), and Zucchini lethal chlorosis virus (ZLCV). Total RNA extracted from experimentally infected C. pepo was analyzed by RT-PCR using specific pairs of primers for the coat protein gene of ZYMV (3). A cDNA fragment of approximately 1,186 bp was amplified and the nucleotide sequence obtained by direct sequencing. Comparisons of the nucleotide (837 nt) and deduced amino acid (279 aa) sequences of the coat protein genomic segment (GenBank Accession No. JX502677) revealed 93 to 98% and 97 to 98% identity, respectively, with the corresponding nucleotide and amino acid sequences of a group of ZYMV isolates from distinct hosts (AY188994, AY279000, and NC_003224). The infection by ZYMV might cause fruit yield losses to F. trilobata. In addition, the infected F. trilobata crops might work as a reservoir of ZYMV providing inoculum to other cucurbit hosts since it has been managed as a semi-perennial crop. To our knowledge, this is the first report of the genus Fevillea as a natural host of ZYMV. References: (1) M. Nee et al. Syst. Bot. 34:704, 2009. (2) E. G. Shay. Biomass Bioenergy 4:227, 1993. (3) K. G. Thomson et al. J. Virol. Meth. 55:83, 1995.

First Report of Tomato yellow spot virus Infecting Leonurus sibiricus in Brazil

In Brazil, serious epidemics of begomovirus diseases have been successively reported since the mid-90s, among them those caused by Tomato yellow spot virus (ToYSV) (1). In July 2009 and October 2010, high incidences (40 to 60%) of plants of the weed Leonurus sibiricus (Lamiaceae) exhibiting symptoms of yellow leaf mosaic were found near soybean (Glycine max) crops within the municipalities of Marechal Cândido Rondon and Tapejara, in the states of Paraná and Rio Grande do Sul. Leaves from 21 symptomatic and seven asymptomatic L. sibiricus plants were collected from both localities and tested for the presence of begomovirus. Total DNA was extracted from each sample using Dneasy Plant Mini Kit (Qiagen) and submitted to PCR using begomovirus universal oligonucleotides PAL1v1978/PAR1c496 (3). One fragment of approximately 1,300 bp comprising the 5'-region of the replication-associated protein (Rep) gene, the entire intergenic region (IR), and the 5'-region of the coat protein (CP) gene was amplified from all symptomatic, but not from asymptomatic samples. Amplified fragments corresponding to all isolates were directly sequenced and nucleotide sequence comparisons indicated 98 to 99% nucleotide identity among themselves, and 93 to 94% identity with the corresponding nucleotide sequences for the DNA-A of the begomovirus ToYSV (GenBank Accession No. DQ336350). To confirm these results, the full genome of ToYSV Mc-7 isolated from Marechal Cândido Rondon was cloned and completely sequenced by primer walking (Macrogen Seoul, Korea). The DNA-A of ToYSV Mc-7 (JX513952) was 2,592 nt long and shared 92 and 91% identity with isolates of ToYSV from Argentina (FJ538207) and Brazil (DQ336350), respectively. The DNA-B of ToYSV Mc-7 (JX513952) was 2,568 nt long and shared 91% identity with DNA-B of a Brazilian isolate of ToYSV (DQ336351). The ToYSV Mc-7 isolate is a new strain named Tomato yellow spot virus (Brazil:Marechal Candido Rondon 7:Leonurus:2009) [ToYSV-(BR:MCR7:Le:09)]. To demonstrate pathogenicity, virus-free adults of Bemisia tabaci biotype B were confined on symptomatic L. sibiricus plants for a 48-h acquisition period. The whiteflies were then transferred to healthy L. sibiricus, bean (Phaseolus vulgaris), soybean, and tomato (Solanum lycopersicum) plants. L. sibiricus plants showed the original symptoms on the leaves (five symptomatic plants, seven inoculated plants), whereas bean (3/7), soybean (4/10), and tomato plants (5/10) exhibited mild yellow leaf mosaic. The infection in these symptomatic plants was confirmed by PCR with oligonucleotides PAL1v1978/PAR1c496 (3) and subsequent direct nucleotide sequencing of the 5'-region of the CP gene, which confirmed the identity of the transmitted virus as ToYSV. ToYSV was first reported infecting tomato plants in Minas Gerais state, Brazil (1). Recently, ToYSV was found infecting bean and soybean plants in northwestern Argentina (2). Because L. sibiricus is a weed widely distributed throughout Brazil, and the ToYSV vector B. tabaci is also common, this weed may become a potential source of inoculun of ToYSV to bean, soybean, and tomato crops. To our knowledge, this is the first report of L. sibiricus as a natural host of ToYSV. References: (1) R. F. Calegario et al. Pesq. Agropec. Bras. 42:1335, 2007. (2) P. E. Rodríguez-Pardina et al. Ann. Appl. Biol. 158:69, 2011. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993.

A distinct tymovirus infecting Cassia hoffmannseggii in Brazil

Leaves of Cassia hoffmannseggii, a wild fabaceous species found in the Atlantic Forest, with a severe mosaic symptom were collected in Pernambuco State, Brazil. By transmission electron microscopy, two types of virus particles were found: the first was recognized as particles of a potyvirus, which was later identified as Cowpea aphid-borne mosaic virus; and the second was isometric and present in high concentration. The observation of vesicles at the periphery of chloroplasts suggested a tymovirus infection, which was confirmed by subsequent assays. A serological assay against several tymovirus antisera resulted in positive reaction of this tymo-like virus with an antiserum of Passion fruit yellow mosaic virus. By means of RT-PCR and using degenerated primers for the conserved region of RNA-dependent RNA polymerase (RdRp) gene of tymoviruses, a specific DNA fragment was amplified and sequenced. Based on this sequence, a specific forward primer was synthesized and successfully used to amplify the 3' terminal genome region, containing the partial RdRp gene and the complete coat protein (CP) sequences. The CP was 188 amino acids (aa) long, and the highest CP aa identity was observed with Kennedya yellow mosaic virus (61 %). Based on the current ICTV demarcation criterion, this isolate was considered as a distinct tymovirus and tentatively named as Cassia yellow mosaic-associated virus.

First Report of Tomato chlorosis virus in Potato in Brazil

Potato plants (Solanum tuberosum cv. Ágata) exhibiting symptoms of leaf roll and interveinal chlorosis, especially on older leaves, were found in a commercial crop in the County of Cristalina, State of Goiás, Brazil in June 2011. The crop was severely infested by whitefly Bemisia tabaci biotype B. Four potato tubers from symptomatic plants were indexed for the presence of the following viruses: Tomato chlorosis virus (ToCV), Potato leaf roll virus (PLRV), Tomato severe rugose virus (ToSRV), and Potato virus Y (PVY). Total RNA was extracted separately from each tuber and used for reverse transcription (RT)-PCR using the HS-11/HS-12 primer pair, which amplifies a fragment of 587 bp from the highly conserved region of the heat shock protein (HSP-70) homolog gene reported for ToCV. The RT-PCR product was subsequently tested by nested-PCR for detection of ToCV with specific primers ToC-5/ToC-6 (2). Amplicons of 463 bp, amplified from total RNA separately extracted from three tubers, were purified and directly sequenced. Comparisons among the three consensus sequences of 448 bp (GenBank Accession Nos. JQ288896, JQ288897, and JQ288898) revealed respectively, 98, 100, and 100% identity with the reported sequence of a tomato isolate of ToCV from Brazil (GenBank Accession No. EU868927) (1). For ToSRV detection, total DNA was extracted from two tubers and a fragment of approximately 820 bp was amplified by PCR with specific primers (3). PLRV and PVY were indexed in two and three tubers, respectively, by double-antibody sandwich-ELISA (SASA, Edinburg, Scotland). Virus-free B. tabaci biotype B were separately transferred to potato and tomato leaves infected with ToCV for an acquisition access period of 24 h. Groups of 30 viruliferous whitefly were transferred to four, young, sprout-grown potato plants cv. Ágata (two plants per virus isolate) for 24-h inoculation access period. After 37 days of inoculation, one plant inoculated with the potato and tomato isolates of ToCV, respectively exhibited symptoms of leaf roll and interveinal chlorosis on order leaves, which were similar to that induced by PLRV. Experimental infection of potato plants with ToCV, which induced leaf roll symptoms resembling PLRV infection, was reported in the United States by Wisler et al. (4). The potato isolate of ToCV was also transmitted by B. tabaci to one of two inoculated tomato plants. The presence of ToCV in all inoculated plants was detected by nested-RT-PCR as described above. To our knowledge, this is the first report on detection of ToCV in field potato plants in the world. Considering that ToCV occurs in innumerous countries around the world, it is transmitted by a cosmopolitan insect, and it induces symptoms similar to PLRV, this finding triggers an alert to field dependent seed-potato multiplication, virus inspector, and certification system. References: (1) J. C. Barbosa et al. Plant Dis. 92:1709, 2008. (2) C. I. Dovas et al. Plant Dis. 86:1345, 2002. (3) F. R. Fernandes et al. Trop. Plant Pathol. 35:43, 2010. (4) G. C. Wisler et al. Plant Dis. 82:270, 1998.

First Report of Cowpea aphid-borne mosaic virus on Sesame in Paraguay

Sesame (Sesamum indicum L.) is cultivated mainly in the central region of the Departamento de San Pedro in Paraguay from October to February and the seed are exported to Asia. The crop is grown on 100,000 ha annually and Escoba blanca is the most common cultivar. The crop plays an important socioeconomical role since it is cultivated mostly by small growers. A disease characterized by yellowing and curling down leaves and shortening of the internodes has been observed in almost all sesame-growing areas. It is referred to locally as "ka'are" because the affected sesame plant resembles Chenopodium ambrosioides L. This disease occurred occasionally and was of marginal importance prior to 2005, but during the last five growing seasons the disease incidence has increased substantially, with some growers losing the entire crop. To determine the causal agent, symptomatic leaf samples were collected from five commercial fields near Colonia San Pedro and Choré, Departamento San Pedro in December 2009. Preliminary transmission electron microscopy (TEM; Zeiss EM900) of extracts from symptomatic leaves revealed the presence of elongated flexible particles resembling a potyvirus. Mechanical transmission assays resulted in chlorotic local lesions on C. quinoa and C. amaranticolor, mosaic on Vigna unguiculata and Nicotiana benthamiana, and symptoms on sesame that are similar to those observed in the field. The disease could also be reproduced in sesame by aphid (Myzus persicae) transmission in a nonpersistent manner. TEM examination of leaf sections of these naturally or experimentally infected plants showed the presence of the type I cylindrical inclusions and masses of filamentous particles. Leaf extracts of naturally or experimentally infected sesame and test plants were positive for Cowpea aphid-borne mosaic virus (CABMV) on the basis of plate-trapped antigen (PTA)-ELISA. CABMV as the causal agent of "ka'are" disease of sesame in Paraguay was further confirmed by analyzing part of the nucleotide sequence of CABMV coat protein and 3' nontranslated region that were obtained directly from reverse transcription-PCR product amplified with PV1-antisense primer (5'-gatttaggtgacactatagt₁₇-3') and WCIEN-sense primer (5'-atggtttggtgyatygaraat-3') (1,2). Comparisons of the 676-bp nucleotide sequence of two sesame virus isolates (GenBank Accession Nos. HQ336402 and HQ336403) revealed 92% identity with the corresponding nucleotide sequence of CABMV available in the GenBank (Accession No. AF348210). Thus, all the assays indicated that the "ka'are" disease of sesame in Paraguay is caused by an isolate of CABMV. Several cowpea fields, nearby sesame diseased crops, also contained plants exhibiting mosaic symptoms. Transmission assays, electron microscopy, PTA-ELISA, and nucleotide sequence analysis indicated that they were also infected by CABMV and may play an important role in the epidemiology of this disease on sesame. CABMV isolates from passion fruit and cowpea from Brazil were mechanically transmitted to sesame but induced milder symptoms. CABMV-infected sesame was described in the United States (3), but to our knowledge, this is the first report of a severe disease on sesame caused by this virus in Paraguay. References: (1) A. Gibbs and A. Mackenzie. J. Virol. Methods 63:9, 1997. (2) L. D. C. Mota et al. Plant Pathol. 53:368, 2004. (3) H. R. Pappu et al. Arch. Virol. 142:1919, 1997.

A Sida sp. Is a New Host for "Candidatus Phytoplasma brasiliense" in Brazil

Sida is a genus of flowering herbs in the family Malvaceae, which includes several species that are weeds in Brazil. Plants of a Sida sp. exhibiting symptoms characterized by stunting, chlorosis, small leaves, and witches'-broom, indicative of infection by phytoplasmas, were found in a field previously cultivated with tomato, located in the region of Campinas, State of São Paulo, in December 2008. To demonstrate the presence of phytoplasmas in diseased tissues, DNA was extracted from shoots and leaves from three symptomatic and eight asymptomatic plants. Nested PCR was performed using primers P1/Tint followed by primer pair R16F2n/R16R2 (1). DNA fragments of 1.2 kb, corresponding to 16S rDNA, were amplified only for DNA from two symptomatic samples. Phytoplasma identification was initially carried out by restriction fragment length polymorphism (RFLP) analysis through digesting the PCR products with the restriction enzymes AluI, HhaI, HaeIII, HpaII, MseI, and RsaI. The two phytoplasma isolates found to be infecting a Sida sp. showed identical RFLP patterns, which were indistinguishable from the phytoplasma previously reported in association with hibiscus (Hibiscus rosa-sinensis) witches'-broom in Brazil (2). Nucleotide sequence alignment revealed that 16S rDNA of both phytoplasma isolates found in a Sida sp. (GenBank Accession No. HQ230579) shared 99.9% sequence similarity with 16S rDNA from hibiscus witches'-broom phytoplasma (HibWB) (GenBank Accession No. AF147708). HibWB is the representative of the 16SrXV group and it was proposed as a putative species nominated "Candidatus Phytoplasma brasiliense" (2). The disease is frequently observed in hibiscus plants used as ornamentals in the states of São Paulo (4) and Rio de Janeiro (2). "Ca. Phytoplasma brasiliense" has only been reported in Brazil to be infecting hibiscus (2,4) and periwinkle (Catharanthus roseus) (3). The presence of a phytoplasma belonging to group 16SrXV in a Sida sp. expands its natural host range. The role of this weed as a potential source of inoculum for crops should be investigated. References: (1) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (2) H. G. Montano et al. Int. J. Syst. Evol. Microbiol. 51:1109, 2001. (3) H. G. Montano et al. Plant Dis. 85:1209, 2001. (4) E. G. Silva et al. Summa Phytopathol. 35:234, 2009.

First Report of Turnip mosaic virus on Watercress in Brazil

Watercress (Nasturtium officinale L.), a member of the family Brassicaceae, is consumed mainly as salad. Medicinal properties have also been attributed to this species. In Brazil, watercress is grown mainly by very small farmers. The crop is primarily seed propagated and growers can harvest several times per year in an established planting. Very few diseases have been reported in this crop worldwide. In Brazil, watercress infection by Cauliflower mosaic virus (CaMV) (3), Cucumber mosaic virus (CMV) (1), and an unidentified potyvirus (2) were previously reported. In January 2009, 80% of watercress plants, cv. Gigante Redondo, exhibiting severe mosaic, leaf size reduction, and plant stunting were observed in a crop in Marechal Floriano Municipality, State of Espírito Santo, Brazil. Preliminary leaf dip analysis by transmission electron microscopy revealed the presence of potyvirus-like particles. Sap from five infected plants reacted in plate-trapped antigen (PTA)-ELISA with polyclonal antiserum against Turnip mosaic virus (TuMV), but not with antiserum against CMV. Both antisera were produced in the Plant Virology Laboratory, ESALQ/USP. Mechanically inoculated watercress plants developed similar systemic mosaic symptoms. The virus was also transmitted to Nicotiana benthamiana, which exhibited severe mosaic and stunting. The presence of TuMV on these inoculated plants was confirmed by PTA-ELISA and reverse transcription (RT)-PCR. Total RNA extracted from infected and healthy watercress and infected N. benthamiana was analyzed by RT-PCR using specific pairs of primers flanking the coat protein gene of TuMV. Degenerated anti-sense (5'-t/caacccctt/gaacgcca/cagt/ca-3') and sense (5'-gcaggtgaa/gacg/acttgat/ca/gc-3') primers were designed after analysis to an alignment of the nucleotide sequences for five isolates of TuMV available in the GenBank (Accession Nos. NC_002509, D10927, EU680574, AB362513, and D88614). One fragment of 838 bp was amplified from samples in the infected plants, but not in the healthy controls. Two amplicons were purified and directly sequenced in both directions. Comparisons of the 731-bp consensus nucleotide sequence (Accession No. HM008961) to several other isolates of TuMV revealed 94 to 95% identity in the coat protein region. To our knowledge, this is the first report of TuMV in watercress in Brazil. Management of the disease should include propagation by seeds instead of vegetative parts of the plants and rouging of diseased plants to prevent mechanical transmission during successive harvestings. References: (1) A. J. Boari et al. Fitopatol. Bras. 25:438, 2000. (2) A. J. Boari et al. Fitopatol. Bras. 27:S200, 2002. (3) M. L. R. Z. C. Lima et al. Fitopatol. Bras. 9:403, 1984.

First Report of Papaya ringspot virus-Type W and Zucchini yellow mosaic virus Infecting Trichosanthes cucumerina in Brazil

Trichosanthes cucumerina L., known as snake gourd, is a cucurbitaceous plant that is probably native to and originally domesticated in India. It is cultivated in humid subtropical and tropical countries of Australia, Latin America, and Africa (2). Plants of this species exhibiting symptoms of mosaic and leaf malformation were found during November 2008 near an experimental field of the Departamento de Fitopatologia e Nematologia, Universidade de São Paulo, Piracicaba, State of São Paulo, Brazil. Electron microscopy examination of negatively stained extract of infected tissue showed the presence of filamentous potyvirus-like particles. Sap from these infected plants reacted in plate-trapped antigen (PTA)-ELISA with the antiserum against Papaya ringspot virus-type W (PRSV-W) or Zucchini yellow mosaic virus (ZYMV), but not with the antiserum against Cucumber mosaic virus (CMV) or Zucchini lethal chlorosis virus (ZLCV). PRSV-W and ZYMV were simultaneously transmitted by mechanical inoculation to four plants of Cucurbita pepo cv. Caserta and one plant of T. cucumerina, causing mosaic. In addition, PRSV-W and ZYMV isolates from our virus collection separately infected one plant of T. cucumerina after mechanical inoculation. Infections were confirmed by PTA-ELISA. Total RNA extracted from infected and healthy T. cucumerina was analyzed by reverse transcription (RT)-PCR using a primer pair specific to the coat protein (CP) gene of PRSV-W (4) or ZYMV (3). Fragments of 864 bp and 1,045 bp were amplified with each pair of primers, respectively. Nucleotide sequences directly obtained from purified PCR products were used for further identification of these potyviruses. The nucleotide and deduced amino acid sequences of part of the CP gene (792 nt) of PRSV-W (GenBank Accession No. GU586789) shared 99 and 98% identity, respectively, with that of the Brazilian isolate PRSV-W-C (GenBank Accession No. 4152). The nucleotide and deduced amino acid sequences of the entire CP gene (837 nt) of ZYMV (GenBank Accession No. 6790) shared 91 to 98% and 94 to 100% identity, respectively, with innumerous isolates of ZYMV deposited in the GenBank (e.g., Accession Nos. AB004640, D13914, AB004641, and AJ420019). Natural infection of T. cucumerina by PRSV-W was reported in Nepal (1). To our knowledge, this is the first report of T. cucumerina infected by PRSV-W and ZYMV in Brazil. References: (1) G. Dahal et al. Ann. Appl. Biol. 130:491, 1997. (2) R. W. Robinson and D. S. Decker-Walters. Cucurbits. CAB International, Wallingford, UK. 1997. (3) K. G. Thomson et al. J. Virol. Methods 55:83, 1995. (4) M. G. S. D. Vechia. Fitopatol. Bras. 28:678, 2003.

First Report on the Susceptibility of Sweet Pepper Crops to Tomato chlorosis virus in Brazil

In June of 2009, sweet pepper (Capsicum annuum cvs. Elisa and Prador) plants exhibiting interveinal chlorosis, some necrosis, and mild upward leaf curling on the intermediate leaves were found in three protected crops in the municipality of São Miguel Arcanjo, São Paulo state, Brazil. Incidence of symptomatic plants varied from 70 to 100%. Abundant whitefly adults were seen in all crops. Initially, total DNA was separately extracted from seven symptomatic plants and submitted to a PCR reaction using the universal primer pairs PAL1v1978/PAR1c496 and PBL1v2040/PCRc1 for begomovirus (3). The results were negative. The same samples were also analyzed for infection with Tomato infectious chlorosis virus (TICV) and Tomato chlorosis virus (ToCV) (genus Crinivirus, family Closteroviridae). Total RNA was extracted separately from leaves of each symptomatic plant and used for one-step reverse transcription (RT)-PCR using the HS-11/HS-12 primer pair, which amplifies a fragment of 587 bp from the highly conserved region of the heat shock protein (HSP-70) homolog gene reported for TICV and ToCV (1). The RT-PCR product was subsequently tested by nested-PCR for single detection of TICV and ToCV using primer pairs TIC-3/TIC-4 and ToC-5/ToC-6, respectively (1). Only one fragment of approximately 463 bp was amplified from the five plants with the primer pair specific for ToCV. No amplification was obtained with the primers specific for TICV. Four purified amplicons of 463 bp were directly sequenced in both directions. Sequence comparisons of the 419-bp consensus sequence, encompassing nucleotides 750 and 1,167 of the HSP-70 homolog gene, revealed 98% identity with the reported sequences of tomato infecting isolates of ToCV from Brazil (GenBank Accession No. EU868927) and the United States (GenBank Accession No. AY903448). Virus-free adults of Bemisia tabaci biotype B were confined on symptomatic pepper leaves for a 48-h acquisition access period. Twenty adults were transferred to one plant of sweet pepper cv. Magda for a 24-h inoculation access period. The sweet pepper plant exhibited the original symptoms on the leaves 67 days after inoculation under greenhouse conditions. Infection by ToCV was confirmed by RT-PCR. The susceptibility of sweet pepper plants to ToCV was previously reported in Spain (2), whereas in the United States, this species was experimentally found as nonhost for this virus (4). Further studies are needed to better understand the variable susceptibility of sweet pepper to ToCV. References: (1) C. I. Dovas et al. Plant Dis. 86:1345, 2002. (2) G. Lozano et al. Plant Dis. 88:224, 2004. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993. (4) W. M. Wintermantel et al. Plant Dis. 90:814, 2006.

First Report of Tomato chlorosis virus Infecting Tomato Crops in Brazil

During 2006 and 2007 in the region of Sumaré, state of São Paulo, Brazil, surveys were done on tomato (Solanum lycopersicum L.) virus diseases in three open field-grown crops. The data revealed low incidence (0.25 to 3.42%) of randomly distributed plants exhibiting interveinal chlorosis and some necrosis on the basal leaves. Symptoms were only observed on old fruit-bearing plants. Preliminary analysis of thin sections of symptomatic leaves from one plant by transmission electron microscopy revealed the presence of aggregates of thin, flexible, and elongated particles in some phloem vessels, suggesting infection with a member of the genus Crinivirus, family Closteroviridae. Total RNA was extracted separately from leaves of 10 symptomatic plants and used for one-step reverse transcription (RT)-PCR using the HS-11/HS-12 primer pair, which amplifies a fragment of 587 bp from the highly conserved region of the heat shock protein (HSP-70) homolog gene reported for Tomato infectious chlorosis virus (TICV) and Tomato chlorosis virus (ToCV) (1). The RT-PCR product was subsequently tested by nested-PCR for single detection of TICV and ToCV using primer pairs TIC-3/TIC-4 and ToC-5/ToC-6, respectively (1). Only one fragment of approximately 463 bp was amplified from 7 of the 10 plants with the primer pair specific for ToCV. No amplification was obtained with the primers specific for TICV. Two amplicons of 463 bp were purified and directly sequenced in both directions. Sequence comparisons of the 463-bp consensus sequence (GenBank Accession No. EU868927) revealed 99% identity with the reported sequence of ToCV from the United States (GenBank Accession No. AY903448) (3). Virus-free adults of Bemisia tabaci biotype B confined on symptomatic tomato leaves for a 24-h acquisition access period were able to transmit the virus to healthy tomato plants, which reproduced the original symptoms on the bottom leaves 65 days after inoculation under greenhouse conditions. Infection from transmission was confirmed by RT-PCR using the HS-11/HS-12 primer pair. In addition to B. tabaci biotype B, the greenhouse whitefly, Trialeurodes vaporariorum, has also been reported as a vector of ToCV, although it is less efficient than the B. tabaci biotype B in transmission of this virus (4). T. vaporariorum, which was previously considered limited to greenhouses, was recently reported in tomato and green bean (Phaseolus vulgaris L.) crops under field conditions in São Paulo State (2). Therefore, it might also contribute to the spread of ToCV in tomato crops in São Paulo. To our knowledge, this is the first report of ToCV in Brazil and South America. References: (1) C. I. Dovas et al. Plant Dis.86:1345, 2002. (2) A. L. Lourenção et al. Neotrop. Entomol. 37:89, 2008. (3) W. M. Wintermantel et al. Arch. Virol. 15:2287, 2005. (4) W. M. Wintermantel and G. C. Wisler. Plant Dis. 90:814, 2006.

Resistance to Passion fruit woodiness virus in Transgenic Passionflower Expressing the Virus Coat Protein Gene

We report the use of the coat protein (CP) gene from Passion fruit woodiness virus (PWV) to produce resistant transgenic plants of yellow passion fruit. A full-length CP gene from a severe PWV isolate from the state of São Paulo, Brazil (PWV-SP) was cloned into pCAMBIA 2300 binary vector, which was further introduced into Agrobacterium tumefaciens strain EHA 105. Leaf disks were used as explants for transformation assays, e.g., 2,700 and 2,730 disks excised from plants from the Brazilian cultivars IAC-275 and IAC-277, respectively. In vitro selection was performed in kanamycin. After transferring to the elongation medium, 119 and 109 plantlets of IAC-275 and IAC-277, respectively, were recovered. Integration of the PWV CP gene was confirmed in seven of eight plants evaluated by Southern blot analysis, showing different numbers of insertional events for the CP gene. Three transgenic plants (T3, T4, and T7) expressed the expected transcript, but the 32 kDa PWV CP was detected by Western blot in only two plants (T3 and T4). The results of three successive mechanical inoculations against the transgenic plants using three PWV isolates showed that the primary transformant T2 of IAC-277 was immune to all isolates.

Passion fruit green spot virus vectored by Brevipalpus phoenicis (Acari: Tenuipalpidae) on passion fruit in Brazil

Passion fruit green spot disease was first identified in 1997 after a severe outbreak at Vera Cruz County, state of São Paulo, Brazil. Mature yellow fruits of Passiflora edulis Simms f. flavicarpa Degener showed characteristic green spots, 2-5 mm in diameter and patches of green tissues were present on senescent leaves. The devastating effect to passion flower is caused by necrotic lesions that encircle the stems and kill the plant. In severe cases, entire orchards of a few hectares in size have been completely destroyed. The disease was always preceded by heavy infestations of Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae). Transmission electron microscopy of affected tissues (fruits, leaves, and stems) consistently revealed the presence of short, bacilliform particles (50-70 nm x 100-120 nm) in the cisternae of the endoplasmic reticulum, as well as the presence of a dense viroplasm in the cytoplasm. This cytopathic effect has been found in several other Brevipalpus-transmitted or associated viruses and is classified as a cytoplasmic type of disease. Experimental reproduction of the leaf and stem symptoms was achieved by transferring B. phoenicis collected from affected field passion flower plants onto healthy plants. The evidence supports a viral etiology for the disease and the agent was named passion fruit green spot virus. Its relationship with other B. phoenicis related viruses continues to be studied. The disease was also found in the Brazilian states of Bahia, Sergipe, Rondonia, Minas Gerais, Rio de Janeiro, and in the Federal District. Use of one or more of the following acaricides (hexythiazox, fenbutatin-oxide, propargite, quinomethionate, or dicofol) has significantly reduced the incidence of the disease.

Cyclanthera pedata var. edulis: New Host of Papaya ringspot virus-type W in Brazil

Stuffing cucumber (Cyclanthera pedata var. edulis Schrad.) is native to the Americas, where it often occurs as an escape. The species is monoecious, with small flowers and large and deeply palmately lobed leaves. Fruits are puffy, partially hollow, and measure 5 × 15 cm long. The plant has soft spines, a tapered neck, and black seeds. The species has long been cultivated in Asia, where fruits are eaten raw as a substitute for cucumber or cooked (1). One plant showing intense mosaic, without leaf malformation, was found near a squash crop (Cucurbita moschata) in Anhembi County, State of São Paulo. Electron microscopic examination of a negatively stained sap preparation from leaves of this plant showed that it contained numerous flexuous rod-shaped particles, approximately 700 × 760 nm long, similar to those of potyviruses. Extracts from symptomatic leaves were rub-inoculated to zucchini squash (Cucurbita pepo), Carica papaya, Chenopodium amaranticolor, C. quinoa, Gomphrena globosa, and Phaseolus vulgaris cv. Black Turtle 2. Only zucchini squash was infected and developed severe mosaic with intense leaf malformation. Extracts from field infected stuffing cucumber and experimentally inoculated zucchini squash were tested by plate-trapped antigen enzyme linked immunosorbent assay (PTA-ELISA) with antisera against the following potyviruses: Papaya ringspot virus-type W (PRSV-W), Zucchini yellow mosaic virus (ZYMV), and Watermelon mosaic virus-2 (WMV-2). Samples were also tested with antisera against a tospovirus (Zucchini lethal chlorosis virus) and a cucumovirus (Cucumber mosaic virus). Both samples were positive in PTA-ELISA only with PRSV-W antiserum. This is the first report of C. pedata var. edulis as a natural host for PRSV-W in Brazil. References: (1) R. W. Robinson and D. S. Decker-Walters. 1997. Cucurbits. CAB International, UK.

Occurrence, Distribution, and Relative Incidence of Five Viruses Infecting Cucurbits in the State of São Paulo, Brazil

Cucurbits species grown in 38 of 40 agricultural regions in the state of São Paulo, Brazil, were surveyed for the relative incidence of Cucumber mosaic virus (CMV), Papaya ringspot virus-type W (PRSV-W), Watermelon mosaic virus-2 (WMV-2), Zucchini lethal chlorosis virus(ZLCV), and Zucchini yellow mosaic virus (ZYMV) during May 1997 and June 1999. Samples from 621 plants, representing eight cultivated species, six wild species, and one commercial hybrid (Cucurbita moschata × C. maxima), were analyzed by plate trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA). PRSV-W and ZYMV were the most frequently found viruses, accounting for 49.1 and 24.8%, respectively, of 605 samples tested. ZLCV, CMV, and WMV-2 were detected in 7.8, 6.0, and 4.5% of 612, 497, and 423 samples tested, respectively. Double infection was found in 97 samples, and triple infection was found in 10 samples. Quadruple infection was detected in one C. pepo sample. Plants that were symptomatic but negative by PTA-ELISA might be due to abiotic agents, infection by virus for which antiserum was not available, such as Squash mosaic virus, or infection with an as yet uncharacterized virus.

Cayaponia tibiricae: New Host of Zucchini Yellow Mosaic Virus in Brazil

Cayaponia tibiricae Cogn. (CT) is a wild Cucurbitaceae species found in secondary forests in the State of São Paulo, Brazil. The species has indefinite growth and bears oblong dark green fruits, 15 to 20 mm long (1,2). CT plants showing yellow mosaic symptoms were found in Atibaia County. Extracts from symptomatic plants were rub inoculated to zucchini squash (Cucurbita pepo L.) and Chenopodium amaranticolor Coste & Reyn. Zucchini squash plants developed severe yellow mosaic with intense leaf malformation, while C. amaranticolor showed necrotic local lesions. Extracts from naturally infected CT, zucchini squash, and C. amaranticolor were tested by plate trapped antigen-enzyme-linked immunosorbent assay (PTA-ELISA) with antisera against papaya ringspot virus type W (PRSV-W), zucchini yellow mosaic virus (ZYMV), zucchini lethal chlorosis virus (ZLCV), watermelon mosaic virus 2 (WMV-2), and cucumber mosaic virus (CMV). All samples were positive in PTA-ELISA only with ZYMV antiserum. Also, in Western blot (immunoblot) assay, ZYMV antiserum labeled a protein of approximately 36 kDa. Electron microscopic examination of ultrathin sections from infected CT tissue revealed the presence of pinwheel inclusions typical of potyvirus (type 1) infection in the cytoplasm of the cell. CT seedlings were susceptible to mechanical inoculation with the ZYMV isolated from this species. This is the first report of CT as a natural host for ZYMV in Brazil. References: (1) A. Cogniaux. Flora Brasiliensis 6:1, 1878. (2) M. Pio Corrêa. 1926. Diccionário das plantas úteis do Brasil e das exóticas cultivadas. Vol 1. Ministério da Agricultura, Rio de Janeiro, Brazil.

Control of Papaya Ringspot Virus-Type W in Zucchini Squash by Cross-Protection in Brazil

Two mild strains of papaya ringspot virus-type W (PRSV-W) were tested under greenhouse and field conditions to study the potential of cross-protection for control of zucchini squash mosaic. Protected plants of zucchini squash cultivars Caserta and Clarinda were challenged with three severe strains from different geographic regions of the country in tests carried out in the greenhouse. Challenge inoculations were done mechanically 10 and 20 days after the protective inoculation. The mild strains did not have a visible negative effect on the development of the plants and offered effective protection against the severe strains. Field tests of protected Caserta plants were carried out in Piracicaba County, São Paulo. Comparative evaluation based on the symptoms and development of protected and unprotected plants of zucchini squash showed that both mild strains effectively protected the plants against the effects of the severe strain present in the field. Yield of marketable fruits harvested from protected plants was only 10% less than that of the healthy plants in one field trial. Compared with the yield from plants infected with the severe strains, protected plants showed an increase of 511 and 633% in the number and weight of marketable fruits, respectively, in a test in 1994. In a second experiment in 1995, an increase of 327% in the number and 344% in the weight of marketable fruits was recorded. These studies demonstrate the effectiveness of cross-protection for the control of the mosaic disease caused by PRSV-W in zucchini squash and offer growers a method for large-scale application of this technology.