B. B. Brodie

The origin and distribution of the golden nematode and its potential in the U.S.A.

Potato cyst-nematodes,Globodera pallida andG. rostochiensis (golden nematode), and their preferred host, the potato, originated in the Andes of South America. Both were introduced into Europe from the Andean region, the potato about 1570 and the nematode nearly 300 years later. Potato cyst-nematodes are believed to have been introduced into Europe in the 1850’s along with potato collections from the Andes for use in breeding for late blight resistance, but the nematodes went unnoticed until 1881. Since that time the nematodes have spread to virtually everywhere that potatoes are grown, as one or both species have now been reported from 47 countries. It is believed that the golden nematode was introduced into the U.S.A. from Europe on military equipment brought back after the First World War to Long Island, NY, but the nematode was not recognized until some 20 years later. Yield losses in countries with general infestations of potato cyst-nematodes are probably 9% or more; the potential for losses is greatest in countries where average yields are greatest, such as the U.S.A. Good resistance to the pathotype of the nematode that occurs in the U.S.A. is commercially available. If all potatoes grown in the U.S.A. contained this resistance, further spread would be restricted and the golden nematode could perhaps be eliminated from the U.S.A.; but the present supply and diversity of resistant varieties are insufficient for the total potato acreage. Restricting spread of the golden nematode in the U.S.A. minimizes costs borne by growers and government agencies in dealing with the pest. At present, the most promising approach to restricting spread is through management systems developed for keeping nematode densities below the critical level above which spread will occur. If the golden nematode is to be contained, management systems must eventually be applied to all potato acreages. Increased research effort is needed to develop resistant varieties, resistance to a broad range of pathotypes, nematode management systems, and biological controlResumenEl nemátodo de quiste de la papa,Globodera pallida yG. rostochiensis (nemátodo dorado), y su hospedero preferido, la papa, se originaron en los Andes de América del Sur. Ambos fueron introducidos a Europa casi 300 años después. Se cree que los nemátodos de quiste de papa fueron introducidos en la década de 1850 conjuntamente con colecciones de papa provenientes de los Andes con fines de ser utilizadas en mejoramiento a resistencia contra el tizón tardío, pero los nemátodos pasaron desapercibidos hasta 1881. Desde esa fecha los nemátodos se han dispersado casi por todas las regiones donde se siembra papa, y 47 países han reportado una o ambas especies. Se piensa que el nemátodo dorado fué introducido a los Estados Unidos desde Europa en equipo militar traido a Long Island, N.Y. después de la primera guerra mundial, pero ésto no fué reconocido hasta 20 años después. Mermas en rendimiento en países donde la infestatión es generalizada es probablemente 9% o más; el potencial de péridas es mayor en países donde los rendimientos promedios están entre los más altos, tal como los Estados Unidos. Existe un nivel muy alto de resistencia al patotipo que se encuentra en los Estados Unidos en variedades comerciales. Si todas las papas sembradas en los Estados Unidos tuvieran esta resistencia, se restringiría su dispersión y el nemátodo dorado podría ser eliminado de este país pero la oferta y diversidad actual de variedades resistentes no abastece el hectareaje requerido de papa. Restringiendo la dispersión del nemátodo dorado se minimizaría el costo sufrido por los agricultures y de las agencias gubernamentales que están a cargo de esta plaga. En el présente, el enfoque más prometedor para restringir la dispersión es por medio de un manejo desarrollado para mantener las densidades de nemátodos por debajo de un nivel crítico, por encima del cual sí ocurre la dispersión. Si se va a contener el nemátodo de quiste, el sistema de manejo tendría que ser utilizado en todo el hectareaje de papa. Se necesita incrementar la investigatión para desarrollar variedades resistentes a un rango amplio de patotipos, sistema de manejo y control biológico

Selecting for resistance to diseases in early generations

Screening in the seedling and first clonal generations is a potentially cost-effective and efficient way to incorporate resistance to important diseases and reduce large breeding populations to manageable size. In practice, however, early screening is often limited by the need to maintain clean seedstocks of promising clones, unreliability of single-plant evaluations, associations of disease resistance with undesirable horticultural characteristics, or the higher priority placed on traits other than disease resistance. Possible methods to overcome these limitations are discussed. Examples of early generation screening for resistance to several diseases are given.ResumenTamizar en el estado de plántula y durante la primera generación clonal es un método eficiente y potencialmente económico para incorporar resistencia a importantes enfermedades y reducir poblaciones muy grandes a tamaños manejables. En práctica, sin embargo, el tamizado temprano es a menudo limitado por la necesidad de mantener limpios stocks de semilla de clones promisorios, por la poca confiabilidad de evaluar una planta, por las asociaciones de resistencia y características agronómicas no deseables, o por la mayor prioridad de colocar primero otras características que la resistencia a enfermedades. Posibles métodos para solucionar estas limitaciones se discuten Ejemplos de tamizados en generaciones tempranas para resistencia a varias enfermedades son dados.

Eva:A midseason golden nematode- and virus-resistant variety for use as tablestock or chipstock

Eva is a new potato variety being released by the New York and Pennsylvania Experiment Stations. Eva is notable for its bright clear skin and attractive round to oval shape. It produces a chip color comparable to Monona from 9 C storage and has specific gravity 014 less than that of Atlantic. It has exceptionally long tuber dormancy and has extreme resistance to PVX, PVY, and race RO1 of the golden nematode. Scab resistance is like that of Monona. It is expected that Eva will find primary acceptance as a tablestock variety.ResumenEva es una nueva variedad de papa recientemente liberadad por la Estación Experimental de Pennsylvania y Nueva York. Eva se caracteriza por su piel clara y brillante y una atractiva forma semi ovalada. Produce hojuelas de un color similar a las de Monona, se almacena desde 9°C y su gravedad específica es 014 menos que Atlantic. Los tubérculos poseen una dormancia excepcionalmente larga y tiene resistencia extrema a PVX, PVY y la raza RO1 del nematodo dorado. La textura de su cáscara es similar a la Monona. Se espera que Eva sea aceptada como una variedad favorita para la mesa.

The incorporation of resistance toGlobodera Pallida intoSolanum Tuberosum germplasm adapted to North America 1

Potato seeds of 24 families consisting primarily ofSolanum tuberosum ssp.andigena with someS. vernei germplasm that were segregating for resistance to potato cyst nematodes (Globodera pallida races P4A and P5A andG. rostochiensis race R1A) were obtained from the International Potato Center. These seeds produced 468 clones with sufficient tubers for evaluation for resistance toG. pallida races P4A and P5A in pot tests at the International Potato Center. Twenty-six of these clones, selected for a high degree of resistance toG. pallida races P4A and P5A, were crossed with neotuberosum ×Solanum tuberosurn hybrids that had been selected for resistance toG. rostochiensis race R1A (golden nematode) and the viruses PVX and PVY. The resultant progenies possessed a high degree of resistance to all three races of the potato cyst nematode. From these progenies, 23 clones were selected for resistance to the three races (G. pallida P4A and P5A,G. rostochiensis R1A) of potato cyst nematodes. The better adapted clones with resistance to the 3 races of potato cyst nematodes will be used in the next cycle of back-crossing.CompendioSe obtuvo del Centro Internacional de la Papa semillas de papa de 24 familias consistentes principalmente deSolanum tuberosum ssp.andigena con Algún germoplasma deS. vernei que segregaban para resistencia al nematodo del quiste de la papa (Globodera pallida, razas P4Ay P5AyG. rostochiensis, raza R1A). Estas semillas produjeron 468 clones con suficientes tubérculos para la evaluación de resistencia aG. pallida, razas P4Ay P5A en pruebas en macetas en el Centro Internacional de la Papa. Veintiseis de estos clones, seleccionados por un alto grado de resistencia aG. pallida, razas P4Ay P5A fueron cruzados con neotuberosum x híbridosSolarium tuberosum que habían sido seleccionados para resistencia aG. rostochiensis, raza R1A (nematodo dorado) y a los virus PVX y PVY. Las progenies resultantes tuvieron un alto grado de resistencia a las trez razas del nematodo del quiste de la papa. De estas progenies, veintitrés clones fueron seleccionados para resistencia a las tres razas (G. pallida P4Ay P5A,G. rostochiensis R1A) del nematodo del quiste de la papa. Los clones mejor adaptados, con resistencia a las tres razas de nematodos del quiste de la papa, serán utilizados en el próximo ciclo de retrocruzamiento.

Pike: A full season scab and golden nematode resistant chipstock variety

Pike is a chipstock variety released jointly by the Cornell and Pennsylvania Experiment Stations in March 1996. Pike has a specific gravity comparable to Atlantic and the ability to produce light-colored chips after 7 C storage. Most of the chip color data were taken in December, January, and February. It has scab resistance comparable to that of Superior and is golden nematode resistant. It is a full season variety, somewhat earlier than Snowden. In 23 trials in New York, internal necrosis and hollow heart of Pike was 5% compared to 18% for Atlantic. When grown at high temperatures, Pike is susceptible to a unique expression o f heat necrosis that is net-like in appearance which is different from the internal brown spot of Atlantic. The yield has been about 95% of the yield of Atlantic.

Elba: A late maturing, blight resistant potato variety

Elba is a high yielding cultivar which combines resistance to the golden nematode, foliar infection byPhytophthora infestans andAlternaria solani, andVerticillium wilt. Elba is a late maturing tablestock cultivar especially well adapted to organic soils. In small plots and on farmers’ fields it has demonstrated its worth in reducing the need for foliar fungicides to prevent blight.ResumenElba, es una variedad de alto rendimiento que combina la resistencia al nematodo dorado de la papa, a las infecciones foliares porPhytophthora infestans yAlternaria solani, y a la marchitez porVerticillium. Elba es una variedad importante de maduración tardía especialmente adaptada a suelos orgánicos. En parcelas pequenas, y en campos de los agricultores, ha demostrado su valor en la reduccion de la necesidad de aplicar fungicidas foliares para prevenir el tizön.

The loss of expression of theH 1 gene inBt transgenic potatoes

During evaluation of potato clones and cultivars from the Cornell seed production program to confirm their resistance toGlobodera rostochiensis (Wollenweber) Behrens (golden nematode) pathotype Ro1, several cysts developed on the transgenic cultivar Atlantic NewLeaf. This transformed cultivar resulted from the insertion of aBt endotoxin gene into the golden-nematode-resistant cultivar Atlantic. In subsequent bioassay tests, golden nematode cysts developed freely on the transgenic cultivar that originated from Atlantic NewLeaf clone 6, but not on Atlantic NewLeaf clones 31 and 36. Clones 31 and 36 were from differentBt transformation events of the cultivar Atlantic that were never commercialized. RFLP analysis of Atlantic used in the transformations and the Atlantic NewLeaf clones 6, 31, and 36 showed that they possessed the marker for theH1 gene that confers resistance to golden nematode pathotype Rol. These data indicate that theBt transformation process adversely affected the expression of theH1 gene in the transgenic cultivar Atlantic NewLeaf. This finding highlights the importance of pre-release evaluation of transgenic plants for any previously known major traits such as pest and disease resistance before they are commercialized.ResumenDurante la evaluación de clones y cultivares de papa realizados en el programa de producción de semilla de Cornell, para confirmar su resistencia aGlobodera rostochiensis (Wollenweber) Behrens (nematodo dorado) patotipo Ro1, desarrollaron varios quistes en plantas del cultivar transgénico Atlantic New Leaf. Este cultivar transformado es el resultado de la inserción de un gen de endotoxinaBt al cultivar resistente Atlantic. En bioensayos subsiguientes, los quistes del nematodo dorado desarrollaron libremente en el cultivar que se originó del clon 6 de Atlantic New Leaf, pero no en los clones 31 y 36 de este mismo cultivar. Los clones 31 y 36 provienen de diferentes eventos de transformaciónBt del cultivar Atlantic que nunca fueron comercializados. Los análisis de RFLP de Atlantic utilizado en las transformaciones y los clones 6, 31 y 36 de Atlantic New Leaf demostraron poseer el marcador para el genH1 que confiere resistencia al patotipo Rol del nematodo dorado. Estos datos indican que el proceso de transformaciónBt afecta adversamente la expresión del genH1 en el cultivar transgénico Atlantic New Leaf. Este hallazgo destaca la importancia que tiene la evaluación de plantas transgénicas antes de su liberación, con el objeto de determinar cualquier característica importante previamente conocida como es el caso de la resistencia a plagas y enfermedades, antes de que sean comercializadas.

Rosa: A new golden nematode resistant variety for chipping and tablestock

Rosa is a golden nematode resistant variety with chipping potential comparable to Norchip and with good cooking quality. It is resistant to early blight and leaf roll, and moderately resistant to late blight. Rosa is a hybrid between North AmericanSolarium tuberosum ssp. and South AmericanS. tuberosum ssp.Andigena clones.ResumenRosa es una variedad resistente al nematodo dorado y con un potencial para “chipping” comparable al de Norchip y además con una buena calidad de cocción. Es resistente al tizón temprano y virus enrollamiento de las hojas y moderadamente resistente al tizón tardío. Rosa es un híbrido entreSolanum tuberosum ssp.tuberosum norteamericano yS. tuberosum ssp.andigena sudamericano.

Andover: An early to midseason golden nematode resistant variety for use as chipstock or tablestock

Andover may be used as an early to midseason tablestock and chipstock variety. It has a very rapid emergence and early tuber set. The vine maturity is similar to Superior in the absence of severe stress. In New York trials harvested 90 days after planting, the yields of Andover and Superior are nearly equal, 274 cwt/A. At 120 days, over eight seasons at two Ithaca locations, Andover yielded 87% Atlantic. Andover appears to be susceptible to drought and heat stress which can cause early senescence and reduce late season yields. It has few external and internal defectS. Specific gravity is high for an early variety, being .009 less than Atlantic. Andover has excellent chip color from the field from a range of environments and from 7 C storage. It has good boiling and baking properties. The mealiness of the baked potatoes is especially good. Tuber dormancy is two weeks longer than Atlantic. The reaction to common scab is like that of Monona, which is considered to be resistant. It is also resistant to powdery scab and the golden nematode.

Allegany: a late season golden nematode resistant variety.

Allegany is a golden nematode resistant variety with potential for both tablestock and chipping. It is late in vine maturity and when allowed to grow full season, has very high yield potential. In the Northeast, the specific gravity and chip color of tubers soon after harvest and after 10°C storage are comparable to Norchip. The tubers have exceptionally long dormancy Allegany is resistant to early blight, Verticillium wilt, and scab as well as the golden nematode.