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ABSTRACT Yellow passion fruit crop is affected by multiple phytosanitary problems. Among the main ones are viruses of the genera Potyvirus (soybean mosaic virus, SMV), Cucumovirus (cucumber mosaic virus, CMV), Tymovirus (tymovirus passiflorae, PYMV) and Begomovirus (passionfruit leaf distortion virus, PLDV). Information about the prevalence and interaction between these viruses is scarce. The objective of this study was to verify the prevalence and identify the types of mixed viral infections of potyvirus, cucumovirus, tymovirus, and begomovirus in passion fruit crops in Valle del Cauca, Colombia. Passion fruit leaf samples with symptoms were collected and their nucleic acids were purified. Virus identification was performed by PCR using universal primers by viral genus, and specific primers for the SMV, CMV, PFYMV and PLDV viruses. The incidence of each virus by municipality was analyzed and the severity of the symptoms was compared with the diagnosis made. In total, 66 samples were collected in the municipalities of Toro, Dagua, Roldanillo, Bolívar, La Unión and El Cerrito. It was established that the most prevalent viruses are PLDV followed by SMV and CMV. The presence of PYMV was not detected in the samples analyzed. The presence of double and triple infections among potyvirus, cucumovirus and begomovirus were identified for the first time, finding greater severity of symptoms with a greater number of viruses identified per sample. This research provides key results for the design of control strategies for viral diseases in passion fruit.
RESUMEN El cultivo de maracuyá amarillo es afectado por múltiples problemas fitosanitarios. Entre los principales, están los virus de los géneros Potyvirus (soybean mosaic virus, SMV), Cucumovirus (cucumber mosaic virus, CMV), Tymovirus (passion fruit yellow mosaic virus, PFYMV) y Begomovirus (passionfruit leaf distortion virus, PLDV). Información acerca de la prevalencia e interacción entre estos virus es escasa. El objetivo del presente estudio fue verificar la prevalencia e identificar los tipos de infecciones virales mixtas de potyvirus, cucumovirus, tymovirus y begomovirus en cultivos de maracuyá en Valle del Cauca, Colombia. Muestras foliares de maracuyá con síntomas virales fueron recolectadas y se purificaron sus ácidos nucleicos. La identificación de los virus se realizó por PCR empleando cebadores universales por género viral, y cebadores específicos para los virus SMV, CMV, PFYMV y PLDV. Se analizó la incidencia de cada virus por municipio y se comparó la severidad de los síntomas con el diagnóstico realizado. En total se colectaron 66 muestras en los municipios de Toro, Dagua, Roldanillo, Bolívar, La Unión y El Cerrito. Se estableció que los virus con mayor prevalencia fueron PLDV, seguido por SMV y CMV. No se detectó la presencia de PFYMV en las muestras analizadas. Se identificó por primera vez la presencia de infecciones dobles y triples entre potyvirus, cucumovirus y begomovirus, encontrándose mayor severidad de síntomas a mayor número de virus identificado por muestra. La presente investigación provee resultados clave para el diseño de estrategias de control de enfermedades virales en maracuyá.
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KEY MESSAGE: A molecular analysis using informative SNP markers in 1570 clones of cassava from Vietnam reveals varietal composition from farmers' field and genebank collections Cassava is the most important smallholder cash crops in Southeast Asia and is especially used in industrial products. Yet, systematic genetic studies on molecular markers from Vietnamese germplasm have not been considered for breeding and conservation programs. We conducted a molecular analysis of 1570 clones of cassava germplasm from farms across six agro-ecological zones using informative SNP markers. We unraveled the genetic diversity and population structure and provided insights into the value of breeding and conservation programs. Duplicated genotypes comprised 98% of the total sample of the Central Highlands region. Ninety-six SNPs were amplified Central Highlands and South East provinces had the highest allelic richness, covering up to 83% of alleles. The average observed heterozygosity (Ho = 0.43) was slightly higher than expected (He = 0.40) across SNP markers, suggesting an excess of heterozygotes plants. Diversity indexes indicated that cassava populations from North West and Eastern Vietnam are genetically diverse (mean He = 0.40). Genetic parentage tests identified 85 unique genetic groups within the varieties KM94, KM419, BRA1305, KM101, KM140, PER262, KM60, KM57 and two unidentified varieties, which accounted for 82% of the frequency distribution. KM94 is the most dominant variety in Vietnamese farms surveyed (38%), reflecting its superior quality and productivity. Discriminant analysis of principal components (DAPC) revealed four main subgroups, which were partially corroborated by neighbor joining (NJ) analyses. After removing duplicates, 31 unique genotypes were distributed across five of the agro-ecological zones. These were well distributed in the subgroups revealed via DAPC and NJ analyses. The genetic groups identified herein could be used to select unique accessions that should ideally conform with ex situ germplasm collections and identify areas where on-farm conservation programs should be targeted. Newly identified genotypes may also contribute as genetic breeding resources that could be used to adapt cassava to future changes and farmers' needs.
Assuntos
Impressões Digitais de DNA , Manihot , Melhoramento Vegetal , Manihot/genética , VietnãRESUMO
Colombia es el país con mayor diversidad de Passifloraceae con 170 especies reportadas, tanto en formas silvestres como cultivadas. Sin embargo, existen zonas en el país donde esta riqueza ha sido poco explorada, como el departamento del Huila en el suroriente de la zona andina. Por esta razón, se revisaron las listas de inventarios con el objetivo de actualizar y establecer la distribución espacial de las especies en esta región con base en registros de herbario, literatura y datos de campo, para proponer estrategias de conservación. Un total de 26 especies pertenecientes al género Passiflora L. son registradas en el Huila entre los 1500 y 2500 msnm. Ocho de las especies son cultivadas y las otras 18 silvestres, se localizan principalmente en bordes de caminos y bosques secundarios. El bajo número de registros y de especies presentes en este departamento es el reflejo de la carencia de iniciativas de investigación sobre la biodiversidad florística. Lo anterior sugiere que esta región puede ser el escenario de muchas especies desconocidas en zonas poco o no exploradas. Por esta razón, la conservación in situ y de sus hábitats es una tarea urgente, al igual que la caracterización y evaluación de los recursos genéticos, lo que permitirá conocer los atributos de las especies silvestres y cultivadas para un mejor uso de la biodiversidad.
Colombia is the country with the greatest Passifloraceae diversity with 170 reported species of both wild and cultivated forms. However, there are areas in the country where this wealth has slightly been explored such as the department of Huila in the South East of the Andes. For this reason, inventory lists were reviewed in order to update and establish the spatial distribution of the species in this region based on herbarium records, literature and field data, and propose conservation strategies. A total of 26 species belonging to the genus Passiflora L. are recorded in Huila between 1500 and 2500 masl. Eight species are cultivated and the others 18 that are wild are found mainly along roadsides and in secondary forests. The low number of species records in this department reflects the lack of research initiatives on floristic biodiversity. This suggests that this region may harbor many unknown species in little or unexplored areas. For this reason, conservation of these species and their habitat is an urgent task, as well as the characterization and evaluation of these genetic resources.