Incidencia de potyvirus y caracterización molecular de PVY en regiones productoras de papa (Solanum tuberosum L) de Colombia / Incidence of potyvirus and molecular characterization of PVY in potato (Solanum tuberosum L) growing regions of Colombia

Los problemas virales reducen los rendimientos y la calidad del tubérculo semilla en cultivos de papa de todo el mundo. Esta investigación se planteó con el fin de evaluar los niveles de incidencia de potyvirus en diez de las principales regiones cultivadoras de papa de los departamentos de Antioquia, Boyacá, Cundinamarca y Nariño (Colombia), y las características genotípicas del virus Y de la papa (Potato virus Y, PVY), seleccionado por ser el potyvirus más limitante de este cultivo. Para la evaluación de la incidencia se utilizaron pruebas de Elisa con anticuerpos que reconocen epítopes comunes a los potyvirus, mientras que las pruebas moleculares incluyeron el análisis filogenético de secuencias parciales del gen de la cápside viral de 33 aislamientos, así como la secuenciación de una porción de los extremos 5´ y 3´del genoma de dos cepas colombianas de este virus. Los resultados confirmaron la presencia de potyvirus en los cultivos de los cuatro departamentos evaluados, con una incidencia promedio del 72%, siendo este nivel superior al 56% en todas las zonas evaluadas. Los análisis moleculares del PVY, permitieron asociar las cepas colombianas estudiadas con las razas PVYN y la variante PVYNTN, esta última responsable de la enfermedad conocida en el mundo como PTNRD (Potato tuber necrotic ringspot disease).

Potato viruses are responsible for significant reductions in seed quality and crop yields around the world. In this study, we evaluate the levels of incidence of potyvirus in ten potato growing regions of Colombia from the provinces of Antioquia, Boyacá, Cundinamarca and Nariño. As PVY is the most limiting potyvirus in potato farming, a molecular characterization of Colombian PVY strains was also performed. Incidence was evaluated by ELISA using general potyvirus antibodies. Phylogenetic analysis were made on the partial sequence of the capsid gene from 33 isolates. A portion of the 5´ and 3' genome ends was obtained from two Colombian strains. Results confirmed the presence of potyvirus in the four provinces with an average incidence of 72%. The lowest incidence value was 56%. Molecular analysis clustered all Colombian isolates with strains PVYN and PVYNTN, the latter responsible for the disease known as PTNRD (Potato tuber necrotic ringspot disease).

A mosaic of beach bean (Canavalia rosea) caused by an isolate of Cowpea aphid-borne mosaic virus (CABMV) in Brazil.

Beach bean (Canavalia rosea) plants showing mosaic symptoms were found at Massaguaçú beach, Caraguatatuba, Brazil. A potyvirus was found to be responsible for the symptoms, based on transmission assays and electron microscopy. A positive reaction in ELISA was obtained against cowpea aphid-borne mosaic (CABMV) antisera. Viral identity was confirmed by RT-PCR using specific primers to amplify part of the NIb and the entire CP coding region of the genome and the 3'NTR. Comparison of the amplified sequences with that of CABMV showed a nucleotide sequence identity of 97% for the CP coding region. Thus, the potyvirus from beach bean should be considered a CABMV isolate, referred to as CABMV-Cr.

Localization of sweet potato chlorotic stunt virus (SPCSV) in synergic infection with potyviruses in sweet potato.

Among diseases reported worldwidely for sweet potato (Ipomoea batatas (L) Lam) crop, one of the most frequent is the Sweet potato virus disease (SPVD), caused by sweet potato chlorotic stunt virus (SPCSV) and sweet potato feathery mottle virus (SPFMV) co-infection. In Argentina, there exists the sweet potato chlorotic dwarf (SPCD), a sweet potato disease caused by triple co-infection with SPCSV, SPFMV and sweet potato mild speckling virus (SPMSV). Both diseases cause a synergism between the potyviruses (SPFMV and SPMSV) and the crinivirus (SPCSV). Up to date, studies carried out on the interaction among these three viruses have not described their localization in the infected tissues. In single infections, virions of the crinivirus genus are limited to the phloem while potyviral virions are found in most tissues of the infected plant. The purpose of this work was to localize the heat shock protein 70 homolog (HSP70h), a movement protein for genus crinivirus, of an Argentinean SPCSV isolate in its single infection and in its double and triple co-infection with SPFMV and SPMSV. The localization was made by in situ hybridization (ISH) for electron microscopy (EM) on ultrathin sections of sweet potato cv. Morada INTA infected tissues. The results demonstrated that viral RNA coding HSP70h is restricted to phloem cells during crinivirus single infection, while it was detected outside the phloem in infections combined with the potyviruses involved in chlorotic dwarf disease.

Natural infection of Alternanthera tenella (Amaranthaceae) by a new potyvirus.

A virus was isolated from joyweed (Alternanthera tenella Colla-Amaranthaceae), a common weed in tropical and sub-tropical regions. Examination by electron microscopy showed long flexuous particles with an average length of 756 nm in crude sap. Serological results showed positive reaction with antisera to PVY-O. A fragment of 1772 nucleotides was sequenced. The CP sequence shares 76% of identity with the CP of Potato virus Y strain NTN. These results confirm that the virus is a new potyvirus infecting A. tenella, and the name Alternanthera mild mosaic virus (AltMMV) is proposed.

Localization of sweet potato chlorotic stunt virus (SPCSV) in synergic infection with potyviruses in sweet potato

Among diseases reported worldwidely for sweet potato (Ipomoea batatas (L) Lam) crop, one of the most frequent is the Sweet potato virus disease (SPVD), caused by sweet potato chlorotic stunt virus (SPCSV) and sweet potato feathery mottle virus (SPFMV) co-infection. In Argentina, there exists the sweet potato chlorotic dwarf (SPCD), a sweet potato disease caused by triple co-infection with SPCSV, SPFMV and sweet potato mild speckling virus (SPMSV). Both diseases cause a synergism between the potyviruses (SPFMV and SPMSV) and the crinivirus (SPCSV). Up to date, studies carried out on the interaction among these three viruses have not described their localization in the infected tissues. In single infections, virions of the crinivirus genus are limited to the phloem while potyviral virions are found in most tissues of the infected plant. The purpose of this work was to localize the heat shock protein 70 homolog (HSP70h), a movement protein for genus crinivirus, of an Argentinean SPCSV isolate in its single infection and in its double and triple co-infection with SPFMV and SPMSV. The localization was made by in situ hybridization (ISH) for electron microscopy (EM) on ultrathin sections of sweet potato cv. Morada INTA infected tissues. The results demonstrated that viral RNA coding HSP70h is restricted to phloem cells during crinivirus single infection, while it was detected outside the phloem in infections combined with the potyviruses involved in chlorotic dwarf disease.(AU)

Localization of sweet potato chlorotic stunt virus (SPCSV) in synergic infection with potyviruses in sweet potato

Among diseases reported worldwidely for sweet potato (Ipomoea batatas (L) Lam) crop, one of the most frequent is the Sweet potato virus disease (SPVD), caused by sweet potato chlorotic stunt virus (SPCSV) and sweet potato feathery mottle virus (SPFMV) co-infection. In Argentina, there exists the sweet potato chlorotic dwarf (SPCD), a sweet potato disease caused by triple co-infection with SPCSV, SPFMV and sweet potato mild speckling virus (SPMSV). Both diseases cause a synergism between the potyviruses (SPFMV and SPMSV) and the crinivirus (SPCSV). Up to date, studies carried out on the interaction among these three viruses have not described their localization in the infected tissues. In single infections, virions of the crinivirus genus are limited to the phloem while potyviral virions are found in most tissues of the infected plant. The purpose of this work was to localize the heat shock protein 70 homolog (HSP70h), a movement protein for genus crinivirus, of an Argentinean SPCSV isolate in its single infection and in its double and triple co-infection with SPFMV and SPMSV. The localization was made by in situ hybridization (ISH) for electron microscopy (EM) on ultrathin sections of sweet potato cv. Morada INTA infected tissues. The results demonstrated that viral RNA coding HSP70h is restricted to phloem cells during crinivirus single infection, while it was detected outside the phloem in infections combined with the potyviruses involved in chlorotic dwarf disease.

Occurrence of Colombian datura virus in Brugmansia hybrids, Physalis peruviana L. and Solanum muricatum Ait. in Hungary.

Colombian datura virus (CDV) has been found to infect angel trumpets (Brugmansia spp.) frequently and cape gooseberry (Physalis peruviana) and pepino (Solanum muricatum) sporadically in Hungary. A CDV BRG/H isolate was characterized. It had flexuous thread-like virions of about 750 x 12 nm in size. Host range and symptomathological studies revealed its great similarity to authentic CDV isolates. Nicotiana tabacum cultivars and lines resistant to Potato virus Y (PVYN) either genically or transgenically proved highly susceptible to the BRG/H isolate. Tomato (L. esculentum cvs.) was systemically susceptible to this isolate, but some lines of Lycopersicon hirsutum and L. peruvianum turned out to be resistant. Browallia demissa, Ipomoea purpurea, N. megalosiphon and S. scabrum were demonstrated as new experimental hosts of CDV. The BRG/ H isolate proved to be transmissible by the aphid Myzus persicae Sulz. in a non-persistent manner. Potyvirus-specific coat protein (CP) gene sequences of about 1700 bp from angel trumpet, cape gooseberry and pepino plants were amplified by RT-PCR. The cloned BRG/H CP gene showed a 99.12-99.31% identity with other CDV isolates. CDV has been found for the first time to infect naturally cape gooseberry and pepino. Since the botanical genus name of original hosts of CDV has changed from Datura to Brugmansia, we propose to change the virus name from CDV to Angel trumpet mosaic virus (ATMV).

Sweet potato feathery mottle potyvirus (C1 isolate) virion and RNA purification.

A procedure for the purification of a Peruvian isolate (C1) of sweet potato feathery mottle potyvirus (SPFMV) and infective RNA has been developed. The use of Hepes [N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid] buffer containing urea and sodium EDTA as a base for tissue extraction and virus suspension enabled good yields of virus (35-50 mg/100 g) to be obtained from Nicotiana benthamiana L. Domin. A short RNA isolation procedure yielded infectious RNA, from which ds cDNA of nearly genome size could be obtained. Sweet potato feathery mottle potyvirus, Purification, RNA isolation, cDNA synthesis.