Charles R. Brown

Pigmented Potato Consumption Alters Oxidative Stress and Inflammatory Damage in Men

Pigmented potatoes contain high concentrations of antioxidants, including phenolic acids, anthocyanins, and carotenoids. These bioactive compounds have been implicated in the inhibition or prevention of cellular oxidative damage and chronic disease susceptibility. We assessed the effects of pigmented potato consumption on oxidative stress and inflammation biomarkers in adult males. Free-living healthy men (18-40 y; n = 12/group) consumed 150 g of cooked white- (WP), yellow- (YP), or purple-flesh potatoes (PP) once per day for 6 wk in a randomized study. Blood was collected at baseline and wk 6 to analyze total antioxidant capacity (TAC), DNA damage as assessed by plasma 8-hydroxydeoxyguanosine (8-OHdG), protein oxidation, lipid peroxidation, C-reactive protein (CRP), inflammatory cytokines, lymphoproliferation, NK cytotoxicity, and phenotypes. Potatoes were analyzed for TAC, phenolic acids, anthocyanins, and carotenoids. Compared with the WP group, the YP group had higher concentrations of phenolic acids (P < 0.002) and carotenoids (P < 0.001), whereas the PP group had higher concentrations of phenolic acids (P < 0.002) and anthocyanins (P < 0.001). Men who consumed YP and PP tended to have lower (P < 0.08) plasma IL-6 compared with those consuming WP. The PP group tended to have a lower plasma CRP concentration than the WP group (P = 0.07). The 8-OHdG concentration was lower in men who consumed either YP or PP compared with WP. Pigmented potato consumption reduced inflammation and DNA damage in healthy adult males. This offers consumers an improved nutritional choice in potato consumption.

The Occurrence of PVYO, PVYN, and PVYN:O Strains of Potato virus Y in Certified Potato Seed Lot Trials in Washington and Oregon

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.

Regulatory control of high levels of carotenoid accumulation in potato tubers

Potato (Solanum tuberosum L.) tubers contain a wide range of carotenoid contents. To decipher the key factors controlling carotenoid levels in tubers, four potato lines (Atlantic, Désirée, 91E22 and POR03) were examined by a combination of biochemical, molecular and genomics approaches. These lines contained incremental levels of carotenoids, which were found to be associated with enhanced capacity of carotenoid biosynthesis as evident from norflurazon treatment. Microarray analysis of high and low carotenoid lines (POR03 versus Atlantic) revealed 381 genes that showed significantly differential expression. The carotenoid metabolic pathway genes β-carotene hydroxylase 2 (BCH2) and β-carotene hydroxylase 1 (BCH1), along with zeaxanthin epoxidase (ZEP), and carotenoid cleavage dioxygenase 1A (CCD1A) were among the most highly differentially expressed genes. The transcript levels of BCH2 and BCH1 were lowest in Atlantic and highest in POR03, whereas those of ZEP and CCD1A were high in low carotenoid lines and low in high carotenoid lines. The high expression of BCH2 in POR03 line was associated with enhanced response to sugars. Our results indicate that high levels of carotenoid accumulation in potato tubers were due to an increased metabolic flux into carotenoid biosynthetic pathway, as well as the differential expression of carotenoid metabolic genes.

Validation and Implementation of Marker-Assisted Selection (MAS) for PVY Resistance (Ry adg gene) in a Tetraploid Potato Breeding Program

The gene Ryadg from S. tuberosum ssp. andigena provides extreme resistance to PVY. This gene has been genetically mapped to chromosome XI and linked PCR-based DNA markers have been identified. Advanced tetraploid russeted potato clones developed by the U.S. Pacific Northwest Potato Breeding (‘Tri-State’) Program with Ryadg PVY resistance were used in this study. The objective of this work was to assess the usefulness of molecular markers linked to Ryadg as a tool for selecting PVY resistance in a tetraploid potato breeding program. To achieve this, a full-sib tetraploid population segregating for Ryadg was screened with molecular markers linked to Ryadg, artificially inoculated with PVYO and evaluated in the greenhouse. A large percentage (96.4%) of the segregating lines showed coincidence between molecular markers and ELISA results at 40xa0days 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 Ryadg as a simplex in the PVY resistant parent OR00030-1. Additional full-sib populations segregating for the Ryadg 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.ResumenEl gen Ryadg 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 Ryadg al PVY fueron utilizados en este estudio. El objetivo de este trabajo fue evaluar la utilidad de los marcadores moleculares ligados a Ryadg, 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 Ryadg fue tamizada mediante marcadores moleculares ligados al Ryadg, inoculada artificialmente con PVYo y 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 Ryadg como un simplex en el progenitor PVY resistente OR00030-1. Poblaciones adicionales de hermanos completos segregantes para el gen Ryadg y provenientes de OR00030-1 y de un clon relacionado, AOR00628-3, fueron evaluadas bajo condiciones de campo. MAS (selección asistida por marcadores) puede ser utilizada como una herramienta rápida y eficiente para seleccionar resistencia al PVY, reduciendo el número de líneas susceptibles al PVY retenidas para evaluaciones de campo futuras y así incrementar las probabilidades de generar variedades de papa resistentes al PVY.

Variability of Phytonutrient Content of Potato in Relation to Growing Location and Cooking Method

Potato has a defined complement of metabolites that contribute to the human diet. Among these are the carotenoids and anthocyanins. Carotenoids are found in all potatoes in the flesh. White-fleshed varieties have 50 to 100xa0μg per 100xa0g fresh weight (FW), while moderately yellow-fleshed varieties will generally possess from 100 to 350xa0μg per 100xa0g FW. The more intensely yellow-fleshed genotypes, which may look orange, at the higher extremes are at levels above 1,000xa0μg per 100xa0g FW. The highest level published is 2,600xa0μg per 100xa0g FW in diploid germplasm derived from South American Papa Amarilla cultivars. Potato generally has predominantly lutein, a xanthophyll which is also found in the human retina, and must be obtained in the diet. The genotypes with extremely high levels of total carotenoids have zeaxanthin, an isomer of lutein, which is also present in the human retina. Anthocyanins are present in red- or purple-skinned and fleshed varieties. Total anthocyanins range from 1.5xa0mg to 48xa0mg per 100xa0g FW in a solidly pigmented purple-skinned, purple-fleshed breeding line. The degree of pigmentation in the flesh appears to be under polygenic control. Anthocyanins are potent antioxidants and anti-inflammatory substances. The level of total anthocyanins is correlated with antioxidant level (ru2009=u20090.94, Pu2009<u20090.001). Several methods of cooking interacted with genotypes in the antioxidant level remaining after cooking compared to raw potatoes. No method of cooking completely eliminated antioxidant activity, while boiling appeared to increase it compared to raw potato in the case of the most highly pigmented clone.

First Report of the Necrotic Strain of Potato virus Y (PVYN) on Potatoes in the Northwestern United States

More than 50 isolates of Potato virus Y (PVY) with characteristics of strains that cause tobacco veinal necrosis (PVYN) were obtained from potatoes (Solanum tuberosum L.) grown in the northwestern United States. These isolates are being characterized at the biological and molecular levels. Isolate RR1 was obtained from leaves of potato cv. Ranger Russet showing distinct mottling and leaf deformity, which is in contrast to the leaf-drop and necrosis usually observed with ordinary strains of PVY (PVYO) in this variety. Isolate AL1 was obtained from tubers of potato cv. Alturas showing distinct internal light brown rings and blotches. When RR1 and AL1 were transmitted to tobacco (Nicotiana tabacum L. cvs. Samsun NN and 423), they caused systemic veinal necrosis, including stem and petiole lesions typical of PVYN strains (2). Symptoms induced by RR1 and AL1 on tobacco appeared 9 to 11 days after inoculation, whereas some other isolates caused delayed veinal necrosis. All isolates that produced veinal necrosis on tobacco were detectable with PVY polyclonal antisera. Potato virus X was not detected by enzyme-linked immunosorbent assay in tobacco plants showing veinal necrosis. Some isolates, including AL1, failed to react in serological tests using PVYN-specific monoclonal antibodies obtained from three commercial sources. Other isolates, including RR1, were detectable with these monoclonal antibodies. Reverse transcription-polymerase chain reaction (RT-PCR) products obtained with primers specific for the coat protein (CP) open reading frame (ORF) were cloned and sequenced. AL1 possesses a CP more closely related to PVYO type isolates, which would account for its failure to react with PVYN monoclonal antibodies. In this regard, AL1 is similar to the PVYN-Wilga isolate (1). Other isolates that are detectable with the PVYN monoclonal antibodies possess a CP more consistent with N strains of the virus. Results of RT-PCR tests using primers derived from the P1 ORF sequence (3), and the restriction enzyme analysis and sequencing of the RT-PCR products, all suggest that AL1 and RR1 are related to European-type members of PVY tuber necrotic (NTN) or N strains. However, other isolates under investigation appear to be more closely related to previously reported North American NTN types (3). The symptomatology of these viruses on tobacco and potato, and the serological and molecular data clearly show that at least two distinct variants of PVYN have been found for the first time in a major potato production area of the United States, and pose a potential threat to the potato industry. References: (1) B. Blanco-Urgoiti et al. Eur. J. Plant Pathol. 104:811, 1998. (2) J. A. de Bokx and H. Huttinga. Potato virus Y. Descriptions of Plant Viruses. No. 242, CMI/AAB, Surrey, England, 1981. (3) R. P. Singh et al. Can J. Plant Pathol. 20:227, 1998.

Resistance to potato leafroll virus derived from Solanum chacoense: characterization and inheritance

SummaryResistance to potato leafroll virus (PLRV) was detected in an accession of Solanum chacoense. Inoculations with viruliferous aphids and subsequent graft challenges using Datura tatula and potato as PLRV sources determined that resistance appears to be of an extreme type. Virus was not detectable using enzyme-linked immunosorbent assay (ELISA) in S. chacoense, and in resistant F1 and BC1 progenies after attempts to transmit the virus through grafting. The segregation ratios of BC1 progenies for positive and negative ELISA tests are consistent with simple dominant inheritance.

Serological and molecular detection of tobacco veinal necrosis isolates ofPotato virus Y (PVYN) from potatoes grown in the Western United States

Isolates ofPotato virus Y potyvirus that induced systemic veinal necrosis in tobacco (PVYN) were transmitted from potatoes grown in Washington, Oregon, California, and Idaho. The detection of these viruses by serological and molecular methods was evaluated. In addition to PVYN-like isolates, putative recombinant isolates (PVYN:O) were detected. ELISA tests using monoclonal antibodies specific for ordinary (PVYO) or necrosis-inducing (PVYN) serotypes of the virus indicated that both O and N serotypes were represented among the PVYN isolates. All of the necrosis-inducing PVYN and PVYN:O isolates were rapidly detected and differentiated from the ordinary strain using a novel coupled, one-tube, duplex reverse transcription-polymerase chain reaction (cRT-PCR) assay.ResumenAislamientos del potivirus Y de la papa, inductores de necrosis sistémica de las nervaduras en tabaco (PVYN), fueron transmitidos a partir de papa proveniente de Oregon, California e Idaho. Se evaluó la detección de estos virus por métodos serológicos y moleculares. Adicionalmente a los aislamientos similares a PVYN, se detectaron aislamientos supuestamente recombinantes (PVYN:O). Las pruebas de ELISA, utiliando anticuerpos monoclonales específicos para PVYO común o de serotipos inductores de necrosis (PVYN), indican que ambos serotipos O y N han estado presentes en los aislamientos de PVYN. Todos los aislamientos de de PVYN y PVYN:O han sido fácilmente detectados y diferenciados del variante común, utilizando una nueva prueba con iniciadores específicos, de un solo paso y de transmisión reversa, previamente a la prueba de reacción en cadena de la polimerasa (cRT-PCR).

Stability and Broad-Sense Heritability of Mineral Content in Potato: Iron

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 62xa0ug 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.ResumenLa 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 (Tri-State, 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), respectivamente. En general, la amplitud de la media en el contenido de hierro con base clonal fue de 17 a 62xa0ug 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.

Resistance to Columbia root-knot nematode inSolanum ssp. and in hybrids ofS. hougasii with tetraploid cultivated potato

Several tuber-bearingSolanum species were screened for resistance to races 1 and 2 of Columbia root-knot nematode,Meloidogyne chitwoodi. Reproductive factor (Rf = Pf/Pi) was assessed and used to infer host resistance. Several clonal selections in one Plant Introduction accession ofSolanum hougasii showed high levels of resistance to both races. Crosses ofS. hougasii with tetraploid breeding clones yielded 14 vigorous F1 hybrids. Three of these interspecific hybrids expressed non-host (Rf<0.1) responses to race 1 and poor host (0.11.0) to race 2. Three hybrids were good hosts to both races, and one was a poor host to race 1 and non-host to race 2. The occurrence of resistance to both races in the F1 hybrids indicates success in the first step of introducing resistance to races 1 and 2 ofM. chitwoodi to the cultivated potato gene pool.CompendioSe evaluaron y seleccionaron varias especies deSolanum tuberizantes para resistencia a las razas 1 y 2 del nematodo del nódulo de la raíz de Columbia,Meloidogyne chitwoodi. Se determinó el factor de reproducción (Rf = Pf/Pi) para inferir la resistencia del hospedante. Varias selecciones clonales en una entrada de la Introductión de Plantas desolanum bougassi mostraron altos niveles de resistencia a ambas razas. Cruzamientos con clones tetraploides de mejoramiento rindieron 14 vigorosos híbridos F1. Tres de estos híbridos interespecíficos no expresaron respuesta del hospedante (Rf<0,1) a la raza 1 y respondieron pobremente (0,11,0). Tres híbridos fueron buenos hospedantes para ambas razas y uno fue un pobre hospedante para la raza 1 y no fue hospedante de la raza 2. La presencia de resistencia a ambas razas en los híbridos F1 indica el éxito del primer paso de la introducción de la resistencia a las razas 1 y 2 deM. chitwoodi al pul de genes de la papa cultivada.