Sources and Effectiveness of Potato PVY Resistance in IHAR’s Breeding Research

Abstract

Resistance to Potato virus Y (PVY) is one of the most important traits in seed and ware potato production. Currently the tobacco-necrosis inducing PVY N strain including PVY N-Wi and PVY NTN dominates in the PVY population in Poland. The PVY O strain which dominated in early 1980s is rarely detected. Since early 1950s, breeding for PVY resistance in IHAR was a part of the program developing parental lines, which resulted in selecting lines extremely resistant to PVY. The selection of these lines was improved by the application of developed molecular markers. Moreover, the group of genes conferring comprehensive hypersensitive resistance (HR) to all strains of PVY was identified and mapped. The cultivars obtained from parental lines have enhanced level of resistance to PVY. For registered cultivars, the level of resistance to PVY is monitored in field exposure tests, while the reaction to four different isolates of PVY is examined by artificial inoculations. The 36 cultivars with field resistance scores 7.5 and 9 expressed resistance to all tested isolates and 23 of them originated from IHAR parental lines. Several moderately resistant culti-vars varied in sensitivity to the PVY isolates and in majority they were more sensitive to isolates Wi (collect-ed in 1984) and 12/94 (collected in 1994), than to older isolates LW and Ny collected in 1970-ties. Resumen La resistencia al virus Y de la papa (PVY) es uno de los caracteres más importantes en la producción de papa para semilla y consumo. Actualmente, la variante que induce necro-sis en tabaco PVY N incluyendo PVY N-Wi y PVY NTN domina en la población de PVY en Polonia. Se detecta raramente la variante PVY O que dominó a principio de los 1980s. Desde el inicio de los 1950s el mejoramiento para resistencia a PVY en IHAR era parte del programa para el desarrollo de líneas parentales, lo que resultó en la selección de líneas extremada-mente resistentes al PVY. Se mejoró la selección de estas líneas mediante la aplicación de marcadores moleculares desarrolla-dos. Más aún, se identificó y mapeó el grupo de genes que confieren reacciones de hipersensibilidad (HR) que incluyen a todas las variantes de PVY. Las variedades que se obtuvieron de las líneas parentales han incrementado su nivel de resistencia al PVY. Para variedades registradas, se monitorea el nivel de resistencia al PVY en pruebas de exposición en el campo, mientras que se examina la reacción a cuatro variantes difer-entes de PVY mediante inoculaciones artificiales. Las 36 var-iedades con resistencia de campo alcanzan calificaciones de 7.5. Nueve expresaron resistencia a todos los aislamientos probados, y 23 de ellas se originaron de líneas parentales de IHAR. Diversas variedades moderadamente resistentes fluc-tuaron en sensibilidad a los aislamientos de PVY y en su mayoría fueron más sensibles a los aislamientos Wi (colectados en 1984) y 12/94 (colectados en 1994), que a aislamientos más viejos LW y Ny colectados en los 1970s.

The Rate of Virus Spread in New Potato Cultivars in the North of Poland

“…General assessment of field resistance against PVY, performed by COBORU in Poland does not differentiate the resistance to particular strains of PVY. During the last decade, the genetic structure of the Polish PVY population has changed, and it was found that different PVY strains may dominate in successive years (Zimnoch-Guzowska et al 2013). Thus, it may happen that cultivars resistant to most strains will be more susceptible to another particular strain or isolate.…”

“…Genomes of these strains additionally tend to re-combine easily which leads to the formation of recombinants of different biological and immunological features, e.g., PVY NTN-NW (Chikh Ali et al 2010). At present in Poland, there are mainly isolates of PVY N-Wi and PVY NTN (Zimnoch-Guzowska et al 2013). In 2008, about 65% of the entire PVY population was constituted by the PVY NTN strain and 30% by PVY N-Wi .…”

“…In general, one can say that nearly 90% of the overall PVY population is represented by the PVY N strain which dominates also in other European countries (Dědič et al 2008; Van der Vlugt et al 2008;Lindner 2008;Rolot and Steyer 2008). Once frequent, PVY O has been very rare in Poland over the past few years (Kaczmarek et al 1998;Chrzanowska 2009;Zimnoch-Guzowska et al 2013). However, in some countries, like for instance the USA or Canada, it is of more significance than in Europe (Bai et al 2010;Gray et al 2013).…”

Hypersensitive response to Potato virus Y in potato cultivar Sárpo Mira is conferred by the Ny-Smira gene located on the long arm of chromosome IX

“…The Ry sto gene provides high levels of resistance to PVY in a number of potato cultivars released from various breeding programs worldwide which have proved to be durable for over 30 years (Flis et al 2005; Song et al 2005; Dalla Rizza et al 2006; Valkonen et al 2008; Ottoman et al 2009; Zimnoch-Guzowska et al 2013). However, a monogenic resistance is, more than other resistance types, threatened by the possible evolution of new, mutated pathogen strains that overcome the single resistance.…”

Interspecific potato hybrids as donors of durable resistance to pathogens

“…Длительную устойчивость к YBK имеют сорта карто-феля с генами Rysto и Ryadg (Solomon-Blackburn, Barker, 2001;Zimnoch-Guzowska et al, 2013). Использование не-скольких разных источников -образцов S. stoloniferum -стало причиной различий по признаку фертильности между клонами и сортами российской, польской и не-мецкой селекции, одни из которых унаследовали мужскую стерильность и γ-тип цитоплазмы (Lindner et al, 2011), а другие являются фертильными (Flis et al, 2005).…”