The gene Ry adg from S. tuberosum ssp. andigena provides extreme resistance to PVY. This gene has been genetically mapped to chromosome XI and linked PCRbased DNA markers have been identified. Advanced tetraploid russeted potato clones developed by the U.S. Pacific Northwest Potato Breeding ('Tri-State') Program with Ry adg PVY resistance were used in this study. The objective of this work was to assess the usefulness of molecular markers linked to Ry adg as a tool for selecting PVY resistance in a tetraploid potato breeding program. To achieve this, a full-sib tetraploid population segregating for Ry adg was screened with molecular markers linked to Ry adg , artificially inoculated with PVY O and evaluated in the greenhouse. A large percentage (96.4%) of the segregating lines showed coincidence between molecular markers and ELISA results at 40 days after inoculation. This justifies the use of molecular markers as an alternative to artificial inoculation followed by ELISA. Segregation (resistant vs. susceptible) based on ELISA and molecular marker results in the full-sib population indicated the presence of Ry adg as a simplex in the PVY resistant parent OR00030-1. Additional full-sib populations segregating for the Ry adg gene coming from OR00030-1 and from a related clone, AOR00628-3, were evaluated under field conditions. MAS can be used as a fast and efficient tool to select for PVY resistance, reducing the number of PVY susceptible lines retained for succeeding field evaluations, and thereby increasing the odds of generating PVY resistant potato varieties.Resumen El gen Ry adg de S. tuberosum ssp. andígena ofrece resistencia extrema contra el virus Y de la papa (PVY). Este gen ha sido genéticamente mapeado en el cromosoma XI y se han identificado marcadores ligados de ADN basado en PCR (reacción en cadena de la polimerasa). Clones avanzados tetraploides de papa rugosas, desarrollados por el Programa de Mejoramiento del Pacífico Noroeste de los Estados Unidos (`Tri-State´) con resistencia Ry adg al PVY fueron utilizados en este estudio. El objetivo de este trabajo fue evaluar la utilidad de los marcadores moleculares ligados a Ry adg , como una herramienta para seleccionar resistencia al PVY en un programa de mejoramiento de papa tetraploide. Para lograr esto, una población tetraploide de hermanos completos, segregantes para Ry adg fue tamizada mediante marcadores moleculares ligados al Ry adg , inoculada artificialmente con PVY o y Am. evaluada en invernadero. Un alto porcentaje (96.4%) de las líneas segregantes mostró coincidencia entre los marcadores moleculares y los resultados de ELISA 40 días después de la inoculación. Esto justifica el uso de marcadores moleculares como una alternativa a la inoculación artificial seguida por ELISA. La segregación (resistente vs. susceptible) basada en ELISA y los resultados de los marcadores moleculares en la población de hermanos completos, indicó la presencia de Ry adg como un simplex en el progenitor PVY resistente OR00030-1. Poblaciones adicionales de hermanos comp...

Iron deficiency in humans occurs in all regions of the world. Potatoes are a modest source of iron. The purpose of this study was to determine if genetic variation for potato tuber iron content exists. Iron content in unpeeled potato was measured in 33 clones, including varieties and advanced breeding selections, in three trials (Tri-State, Western Regional Russet, Western Specialty/Red) which in total were grown in twelve environments. In two trials significant genotype × environment interaction occurred. Thirteen clones contributed significantly to this genotype × environment interaction, making them unstable across environments, including the variety Russet Burbank. Broad-sense heritabilities and their 95% confidence intervals (in parentheses) in the Tri-State, Western Regional Russet and Western Specialty/Red Trials were 0.00 (0.00, 0.38), 0.64 (0.17, 0.87), and 0.73 (0.25, 0.90), respectively. Overall the range of mean iron content on a clonal basis was 17 to 62 ug per gram dry weight. The upper limit is three times higher than generally reported values of potato. The five highest values were found in the Western Specialty/Red trial and were red-skinned, white-fleshed clones. These results suggest that genetic variation for tuber iron content exists and that breeding for enhanced iron content would be feasible.Resumen La deficiencia de hierro en humanos se presenta en todas las regiones del mundo. Las papas son una fuente modesta de hierro. El propósito de este estudio fue determinar si existe variación genética del contenido de hierro en el tubérculo de papa. Se midió el contenido de hierro en papa sin pelar de 33 clones, incluyendo variedades y selecciones avanzadas, en tres ensayos (TriState, Russet Regional del Oeste, Especialidades Rojas del Oeste) que en total se cultivaron en doce ambientes. En dos ensayos se presentó una interacción significativa clon × ambiente. Trece clones contribuyeron significativamente a esta interacción clon × ambiente, haciéndolas inestables en los ambientes, incluyendo la variedad Russet Burbank. Las heredabilidades en un amplio sentido y su intervalo de confianza de 95% (en paréntesis) en Tri-State, Russet Regional del Oeste y Especialidades Rojas del Oeste fueron 0.00 (0.00, 0.38), 0.64 (0.17, 0.87), y 0.73 (0.25, 0.90), C. R. Brown (*) respectivamente. En general, la amplitud de la media en el contenido de hierro con base clonal fue de 17 a 62 ug por gramo de peso seco. El límite superior es tres veces más alto que lo que generalmente se reporta en valores de papa. Los cinco valores más altos se encontraron en el ensayo de Especialidades Rojas del Oeste, en clones de piel roja y pulpa blanca. Estos resultados sugieren que existe la variación genética para el contenido de hierro en el tubérculo y que pudiera ser posible el mejoramiento para aumentar el contenido de hierro.

Totals of 960 and 286 certified potato seed lots from locations across North America were planted in trials in Washington and Oregon, respectively, in 2001 to 2003 and tested for strains of Potato virus Y (PVY). The incidence of PVYO-infected lots averaged 16.4 and 25.9% in the Washington and Oregon trials, respectively. There was a general trend of increasing incidence of the PVYO, PVYN:O, and PVYN strains during this period, as evidenced by more infected cultivars, sites of seed origin, and number of seed growers providing infected seed lots. In particular, there was a dramatic increase in seed lots with the PVYN:O strain from 2002 to 2003. PVYN:O, in contrast to PVYO, which only causes yield reduction, also causes internal and external damage to tubers, making them unmarketable. In 2003, PVYN:O occurred in seed lots originating in eight states and three Canadian provinces. The increased incidence of PVYN:O was likely due to the difficulty in differentiating this strain from PVYO. The prevalence of PVY in potato seed lots documented herein poses a threat to potato production in the United States and suggests that current measures to reduce the incidence of this virus are inadequate.

The evaluation of potato germplasm for resistance to potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a valuable component of integrated pest management; however, few attempts have been made to identify natural genetic tuber resistance to tuberworm on potato germplasm. The objective of this study was to screen potato germplasm with potential tuberworm resistance for tuber resistance under field and laboratory conditions. Experiments were conducted over a 2-yr period at the Hermiston Agricultural Research and Extension Center, Hermiston, OR. Of 125 germplasm that were tested in 2006, q13 were selected for further screening in 2007. These germplasm were: A0008-1TE, A97066LB, NY123, PA00N10-5, PA99N2, PA99N82, Paciencia, Q174-2, Russet Burbank, Rubi, Ranger Russet, Spunta G2, and T88-4. Tuber resistance of potato germplasm was determined based on the number of mines per tuber and the number of live larvae. Tubers of transgenic clone Spunta G2 were resistant to tuberworm damage. All other germplasm tested in this study, including Russet Burbank and Ranger Russet, were susceptible to tuberworm in the field and laboratory experiments. Incorporation of host plant resistance to tuber penetration by larvae together with appropriate cultural practices including limiting exposure time of tubers in the field may provide the best management option in the future.

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