Effect of plant genotype, virus isolate and temperature on the expression of the potato tuber necrotic ringspot disease (PTNRD)

Abstract

The present study shows that a large range of potato cultivars (29/33 tested), widely grown in the world, are susceptible to potato tuber necrotic ringspot disease caused by potato virus Y. The three factors studied in this work, which proved to influence the level of tuber necrosis reaction, were, first, the plant genotype, since varietal behaviour exhibited large differences; second, the virus genotype, since variations of virulence occurred between the four isolates tested; and third, the environmental conditions, as shown by the different rates of tuber necrosis obtained under contrasting conditions of temperature as much during the growing period as during storage. Three of the cultivars tested, Spunta, Maris Piper and Thalassa, failed to produce necrotic tubers, although infected with a virulent tuber-necrosing isolate. This result, following observations on the inheritance of the tuber necrosis trait, suggests that at least a major dominant gene controls this reaction in non-sensitive cultivars. On the other hand, the extreme resistance genes (Ry) provide a good resistance to virus infection, thus, preventing tuber necrosis under field conditions.

Selection of DNA markers for detection of extreme resistance to potato virus Y in tetraploid potato (Solanum tuberosum L.) F₁ progenies

“…Depending on the genotype, PVY may reduce the yield from 10 to 80% (De Bokx & Huttinga 1981). The strain PVY NTN affects the tuber quality negatively by forming necrotic ring (Leromancer & Nedellec 1997). In order to prevent the spread of PVY from one vegetative generation to the next one, many countries have implemented seed certification schemes that guarantee virus-free seed potatoes (Hinrich et al 1998).…”

Diferenciação de estirpes de Potato virus Y (PVY) por RT-PCR

“…A solução foi misturada a 100 mg de extrato foliar e o RNA total foi precipitado após a adição de clorofórmio para a separação das fases. 3) método de hidrocloreto de guanidina (LOGEMANN et al, 1987) com a adição de quatro gotas de extrato de folha em 200 µl de tampão hidrocloreto de guanidina a 8,0 M. O RNA total foi extraído com fenol/clorofórmio, precipitado com etanol, seguido de lavagens com acetato de sódio a 3 M, pH 5,2, e etanol 70%. Após a secagem do precipitado nos três métodos, o RNA total foi ressuspendido com 50 µl de água e alíquotas de 10 µl foram armazenadas a -20 o C.…”

A hypersensitive response-like mechanism is involved in resistance of potato plants bearing the Ry(sto) gene to the potyviruses potato virus Y and tobacco etch virus.

“…isolates (Fernandez-Northcote, 1983) including the tuber necrosis causing isolate PVY NTN (Chrzanowska, 1995 ;Dolnicar, 1995 ;Le Romancer & Nedellec, 1997). To date, no breakdown of resistance has been observed.…”