Virus en cultivos de cebolla asociados a arvenses de Morelos y Michoacán.

Abstract

Las arvenses son uno de los principales problemas en la agricultura especialmente en cultivos hortícolas como la cebolla (Allium cepa L.). Muchas arvenses son hospedantes alternos de virus de importancia agrícola. Los objetivos de la presente investigación fue detectar hospederos alternos de Onion yellow dwarf virus-OYDV, Leek yellow stripe virus-LYSV, Tomato spotted wilt virus-TSWV, Groundnut bud necrosis virus-GBNV y/o Iris yellow spot virus-IYSV en zonas productoras de cebolla en el estado de Morelos y Michoacán, e identificar los hospedantes alternos del putativo vector de IYSV. Se realizaron muestreos de plantas de cebolla y arvenses en 10 localidades en ambos estados, en presencia y ausencia del cultivo de la cebolla. Las plantas de cebolla se analizaron por RT-PCR y las arvenses por DAS-ELISA. Con los trips detectados en las arvenses se establecieron colonias en condiciones de laboratorio para su identificación por PCR COI. Se analizaron e identificaron un total de 190 muestras (29 especies de Morelos y 18 de Michoacán) de arvenses para los virus OYDV, LYSV, TSWV y GBNV. Tithonia diversifolia y Amaranthus hybridus colectadas de Michoacán fueron positivos para OYDV. Salvia gracilis y Chenopodium murale de Michoacán y A. hybridus, A. spinosus y Portulaca oleraceae colectadas de Morelos fueron positivos para LYSV. Solo A. hybridus, C. murale y A. spinosus mostraron síntomas, el resto de las plantas positivas para los virus, fueron asintomáticas. Ninguna planta resulto positiva para TSWV y GBNV. Para el caso de IYSV, se analizaron e identificaron 295 arvenses agrupadas en 56 especies. Ninguna arvense resultó positiva para el virus, pero se detectaron en 75 arvenses (17 especies de arvenses) poblaciones de trips, de las cuales se analizaron 33 colonias (22 de Morelos y 11 de Michoacán) con una homología en sus secuencias superior a 97% para Thrips tabaci. En Ricinus communis and Acalypha ostryifolia se encontraron con mayor número de T. tabaci. Se confirmó la presencia de IYSV por RT-PCR en las 10 parcelas de cebolla muestreadas. Este es el primer reporte de IYSV en el cultivo de la cebolla en el estado de Michoacán. _______________ VIRUSES IN ONION CROPS ASSOCIATED TO ARVENSES OF MORELOS AND MICHOACÁN. ABSTRACT: Weeds are one of the main problems for agriculture especially on horticultural crops such as onion (Allium cepa L.). Several species of weeds are alternate hosts of viruses of agricultural importance. The main goal of this research was to detect alternate hosts of Onion yellow dwarf virus-OYDV, Leek yellow stripe virus-LYSV, Tomato spotted wilt virus-TSWV, Groundnut bud necrosis virus-GBNV and / or Iris yellow spot virus-IYSV in producing regions of onion in the state of Morelos and Michoacan, as well as to identify alternate hosts of the putative vector of IYSV. Onion and weeds were sampled in 10 locations in both states, in the presence and absence of the crop. Onion plants were analyzed by RT-PCR and weeds by DAS-ELISA. Thrips found on weeds were collected and colonies were established under laboratory conditions for identification by COI PCR. A total of 190 samples (29 species from Morelos and 18 from Michoacan) were identified and tested for OYDV, LYSV, TSWV and GBNV viruses. Tithonia diversifolia and Amaranthus hybridus from Michoacan were positive for OYDV. Salvia gracilis and Chenopodium murale from Michoacan and A. hybridus, A. spinosus and Portulaca oleraceae from Morelos were positive for LYSV. Only A. hybridus, C. murale and A. spinosus showed symptoms, the rest of plants positive for viruses, were asymptomatic. No weed was positive for TSWV and GBNV. In the case of IYSV, 295 weeds were identified in 56 species and tested for this virus. No weeds were positive for IYSV, but thrips were detected in 75 weeds (17 species of weeds), and 33 colonies were obtained (22 from Morelos and 11 from Michoacan) and their sequences were analyzed resulting in a homology greater than 97% for Thrips tabaci. Ricinus communis and Acalypha ostryifolia were found with high number of T. Tabaci. The presence of IYSV on onion was confirmed by RT-PCR on all the sampled plot in both states. To the best of our knowledge this is the first report of IYSV affecting onion in Michoacan state.