AVANCES EN LA INVESTIGACIÓN COLABORATIVA Y CONTROL INTEGRADO DE LA "HOJA DE HOZ" EN LOS CULTIVOS DE OLIVO DE TACNA Y ARICA

Las zonas agroecológicas áridas y salinas del norte de Chile y sur del Perú presentan un enorme potencial agrícola para el cultivo y explotación agro-industrial de variedades mejoradas y comerciales de olivo (Oteo europeas). Más de 5000 hectáreas de olivo de las variedades Azapeña y Sevillana son cultivadas en las zonas desérticas de Tacna y Arica. Estas variedades han mostrado en forma sostenible una remarcable adaptación y tolerancia a los estreses abióticos más comunes de estos suelos desérticos, tales como salinidad, toxicidad de boro y riego restringido. Sin embargo, algunos estreses bióticos como las plagas insectiles Orthesia y Margaronia siguen siendo un problema muy serio en el cultivo del olivo. Durante los dos últimos años se ha venido realizando uno investigación colaborativa entre el Centro Internacional de la Papa, la Universidad Nacional de Tacna y la Universidad de Tarapacá a nivel de campo y laboratorio sobre la frecuencia e intensidad de la enfermedad del follaje conocida como "HOJA DE HOZ DEL OLIVO". Los resultados de esta investigación muestran una disminución gradual y significativa del rendimiento comercial del olivo por efecto de esa enfermedad. Los análisis preliminares de ADN de los extractos de las hojas enfermas con síntomas de Hoja de Hoz muestran que el microorganismo patógeno causante de esa enfermedad sería un VIROIDE transmitido mayormente de planta a planta mediante injertos y podas. Dentro del sistema del control integrado de esa enfermedad se plantea la utilización masal y comercial de plántulas in vitro y yemas de injertos libres de patógenos generados en un programa de biotecnología para zonas áridas

Towards the implementation of a DNA barcode library for the identification of Peruvian species of Anastrepha (Diptera: Tephritidae).

The genus Anastrepha is a diverse lineage of fruit-damaging tephritid flies widespread across the Neotropical Region. Accurate taxonomic identification of these flies is therefore of paramount importance in agricultural contexts. DNA barcoding libraries are molecular-based tools based on a short sequence of the mitochondrial COI gene enabling rapid taxonomic identification of biological species. In this study, we evaluate the utility of this method for species identification of Peruvian species of Anastrepha and assemble a preliminary barcode profile for the group. We obtained 73 individual sequences representing the 15 most common species, 13 of which were either assigned to previously recognized or newly established BINs. Intraspecific genetic divergence between sampled species averaged 1.01% (range 0-3.3%), whereas maximum interspecific values averaged 8.67 (range 8.26-17.12%). DNA barcoding was found to be an effective method to discriminate between many Peruvian species of Anastrepha that were tested, except for most species of the fraterculus species group, which were all assigned to the same BIN as they shared similar and, in some cases, identical barcodes. We complemented this newly produced dataset with 86 published sequences to build a DNA barcoding library of 159 sequences representing 56 Peruvian species of Anastrepha (approx. 58% of species reported from that country). We conclude that DNA barcoding is an effective method to distinguish among Peruvian species of Anastrepha outside the fraterculus group, and that complementary methods (e.g., morphometrics, additional genetic markers) would be desirable to assist sensu stricto species identification for phytosanitary surveillance and management practices of this important group of pestiferous flies

Unificación y Fortalecimiento del Sistema de Protección Fitosanitaria en la Comunidad Andina (CAN) Caso-Modelo: Virus en Musáceas ( Plátano y Banano ) de importancia económica en la CAN.

Este proyecto establece las bases para unificación y fortalecimiento del sistema de protección fitosanitaria en la Comunidad Andina (CAN) implementando un caso modelo de trabajo en el aspecto de detección y control de virus de importancia económica en la cadena productiva de Musáceas (Banano y Plátano). Este proyecto hace parte del proyecto marco financiado por la Comunidad Económica Europea. "Facilidad de Asistencia Técnica al Comercio" que tiene como objetivo fortalecer el proceso e integración, contribuir al desarrollo de las negociaciones entre UE y los países de la CAN e intensificar el intercambio comercial intra-regional entre la Unión Europea y la Comunidad Andina, para lo cual apoya a las instituciones públicas y privadas involucradas con la integración regional andina y el comercio intra-regional con el bloque europeo, en la solución a sus problemas técnicos, legales y comerciales

Diagnostic and diversity of a novel secovirid affecting cassava in the Americas

We have developed a protocol for the detection, and characterization of pathogens in cassava (Manihot esculenta Crantz, Fam. Euphorbiaceae) widely cultivated in the tropics of Africa, Asia and Latin America. These processes guarantee the extraction of nucleic acids of high quality and yield to ensure their use in the detection of DNA and RNA viruses and the sequencing of viral genomes. An average of 2.11 μg of nucleic acids per mg of dry tissue can be obtained using silica gel as a desiccant avoiding the use of liquid nitrogen and phenol. Diverse families of viruses infect cassava, causing significant economic losses and affecting food security. In the Americas, Cassava torrado-like virus (CsTLV) belongs to the Family Secoviridae, Genus Torradovirus have been found in mixed virus infections in Colombia and Brazil, associated with severe disease symptoms in leaves and roots of cassava. In single infections CsTLV can induce leaf chlorotic spots symptoms. Using Oxford Nanopore Technology we complete the genome sequence of a field isolate of CsTLV, showing the characteristic genome arrangement of members of the genus Torradovirus. interestingly CsTLV encodes an atypical Maf / HAM1 domain that functions in eukaryotes to protect cells against mutagenesis only present in heterologous viruses of the Potyviridae family. Using this protocol, we analyzed field surveys in Colombia and a cassava country-wide collection from Peru, detecting the diverse isolates of CsTLV and the occurrence of the virus in the Americas

Marker-free PLRV resistant potato mediated by Cre-loxP excision and RNAi

An inverted repeat construct corresponding to a segment of the potato leaf roll virus coat protein gene was created under control of a constitutive promoter and transferred into a transformation vector with a heat inducible Cre-loxP system to excise the nptII antibiotic resistance marker gene. Fifty-eight transgenic events were evaluated for resistance to PLRV by greenhouse inoculations, which lead to the identification of 7 highly resistant events, of which 4 were extremely resistant. This resistance was also highly effective against accumulation in subsequent tuber generations from inoculated plants, which has not been reported before. Northern blot analysis showed correlation of PLRV specific siRNA accumulation with the level of PLRV resistance. Heat mediated excision of the nptII antibiotic resistance gene in PLRV resistant events was highly efficient in one event with full excision in 71 % of treated explants. On the other hand 8 out of 10 analyzed events showed truncated T-DNA insertions lacking one of the two loxP sites as determined by PCR and confirmed by sequencing flanking regions in 2 events, suggesting cryptic LB sites in the non-coding region between the nptII gene and the flanking loxP site. Accordingly, it is proposed to modify the Cre-loxP vector by reducing the 1 kb size of the region between nptII, loxP, and the LB

Molecular and genetic characterization of the Ry locus on chromosome XI from Andigena potatoes conferring extreme resistance to potato virus Y

We have elucidated the Andigena origin of the potato Ry gene on chromosome XI of CIP breeding lines and developed two marker assays to facilitate its introgression in potato by marker-assisted selection. Potato virus Y (PVY) is causing yield and quality losses forcing farmers to renew periodically their seeds from clean stocks. Two loci for extreme resistance to PVY, one on chromosome XI and the other on XII, have been identified and used in breeding. The latter corresponds to a well-known source of resistance (Solanum stoloniferum), whereas the one on chromosome XI was reported from S. stoloniferum and S. tuberosum group Andigena as well. To elucidate its taxonomic origin in our breeding lines, we analyzed the nucleotide sequences of tightly linked markers (M45, M6) and screened 251 landraces of S. tuberosum group Andigena for the presence of this gene. Our results indicate that the PVY resistance allele on chromosome XI in our breeding lines originated from S. tuberosum group Andigena. We have developed two marker assays to accelerate the introgression of Ry gene into breeding lines by marker-assisted selection (MAS). First, we have multiplexed RYSC3, M6 and M45 DNA markers flanking the Ry gene and validated it on potato varieties with known presence/absence of the Ry gene and a progeny of 6,521 individuals. Secondly, we developed an allele-dosage assay particularly useful to identify multiplex Ry progenitors. The assay based on high-resolution melting analysis at the M6 marker confirmed Ry plex level as nulliplex, simplex and duplex progenitors and few triplex progenies. These marker assays have been validated and can be used to facilitate MAS in potato breeding