Potato Virus YO Research Articles

The Effects of High Temperature on Infection by Potato virus Y, Potato virus A, and Potato leafroll virus.

We examined the effects of temperature on acquisition of Potato virus Y-O (PVY-O), Potato virus A (PVA), and Potato leafroll virus (PLRV) by Myzus persicae by performing transmission tests with aphids that acquired each virus at different temperatures. Infection by PVY-O/PVA and PLRV increased with increasing plant temperature in Nicotiana benthamiana and Physalis floridana, respectively, after being transmitted by aphids that acquired them within a temperature range of 10–20°C. However, infection rates subsequently decreased. Direct qRT-PCR of RNA extracted from a single aphid showed that PLRV infection increased in the 10–20°C range, but this trend also declined shortly thereafter. We examined the effect of temperature on establishment of virus infection. The greatest number of plants became infected when N. benthamiana was held at 20°C after inoculation with PVY-O or PVA. The largest number of P. floridana plants became infected with PLRV when the plants were maintained at 25°C. PLRV levels were highest in P. floridana kept at 20–25°C. These results indicate that the optimum temperatures for proliferation of PVY-O/PVA and PLRV differed. Western blot analysis showed that accumulations of PVY-O and PVA coat proteins (CPs) were lower at 10°C or 15°C than at 20°C during early infection. However, accumulation increased over time. At 25°C or 30°C, the CPs of both viruses accumulated during early infection but disappeared as time passed. Our results suggest that symptom attenuation and reduction of PVY-O and PVA CP accumulation at higher temperatures appear to be attributable to increased RNA silencing.

Detection of stylet-borne and circulative potato viruses in aphids by duplex reverse transcription polymerase chain reaction.

A reverse transcription polymerase chain reaction (RT-PCR) assay was designed to amplify stylet-borne potato virus Yo (PVYo) in aphids using primers located in the viral capsid gene. A 480 bp long product was detected in aphids exposed to PVYo-infected potato plants. Approximately 40% of Myzus persicae and 15% of Aphis nasturtii exposed briefly to PVYo-infected plants acquired the virus. This rate of acquisition by both species of aphids was typical of our earlier observation of the virus transmission tests. No significant difference in virus detection was observed whether the aphids were tested immediately after exposure to virus sources or stored for up to 45 days in ethanol at room temperature. The addition of a second pair to primers located in the capsid gene of circulative potato leafroll virus (PLRV) allowed simultaneous amplification of two viruses (duplex RT-PCR) in single aphids. Acquisition of PVYo by the aphids already viruliferous with PLRV was significantly reduced, compared to aphids not carrying PLRV. Duplex RT-PCR for PVYo and PLRV could be applied to analyze aphids collected from the field to ascertain the relative presence of both viruses in a single test.

Extreme Resistance is Epistatic to Hypersensitive Resistance to Potato Virus YO in aSolanum tubersum subsp. Andigena-Derived Potato Genotype

Resistance to potato virus Y (PPY o ) was examined in diploid potato progeny from a cross of two diploid, interspecific hybrids, 2X(V-2)7 (extremely resistant ot PVY o ) and 84.191.30 (susceptible to PVY o ). The pedigree of 2X(V-2)7 includes Solanum tuberosum subsp. andigena (extremely resistant to PVY o ) and S. t. tuberosum (susceptible to PVY o ). Following inoculation, 34 F 1 progeny (Ry/ry Ny/ny or Ry/ny ny/ny) and 2X(V-2)7 (Ry/ry Ny/ny) remained symptomless and no virus was detected by ELISA, which is characteristic of extreme resistance controled by the Ry adg gene

The development of mature plant resistance in four potato cultivars against aphid-inoculated potato virus YO and YN in four potato cultivars

Field-grown potato plants of cvs King Edward, Record, Maris Piper and Desiree were inoculated on seven different dates during the growing season of 1987 and 1988 with either potato virus YO (PVYO) or PVYN, using three viruliferous peach-potato aphids (Myzus persicae) per plant. In each cultivar, the proportion of progeny tubers infected with PVYO or PVYN was high in plants inoculated during the four weeks following emergence, the proportion declining to zero or close to zero in the subsequent 4–6 wks.

Aphid migration and the importance of some aphid species as vectors of potato virus Yo (PVYo) in Sweden

The relationship between the occurrence of alate aphids and the proportion of progeny tubers infected by potato virus Yo (PVYo) was studied in 7 regions of Sweden from 1976 until 1984. The importance of mature-plant resistance and the proportion of PVYo diseased potato source plants were also considered.

Mature-plant resistance of potato plants against potato virus YO (PVYO)

Mature-plant resistance of potato plants against potato virus YO (PVYO) was studied in field experiments in 1976–1979 in southern Sweden. At intervals of 7 days, from mid June until mid August, PVYO was mechanically inoculated to one well-developed upper leaf per stem of each plant. Each week, a new group of plants were inoculated. In 1976–1977, the natural spread of PVYO by aphids was studied in relation to three different stages of potato plant development. The results of mechanical inoculation demonstrated that mature-plant resistance increases during July in southern Sweden but there were great differences between developmental stages. Early planting with sprouted seed resulted in plants with a considerable mature-plant resistance in mid July when late developed potato plants still were very susceptible.

The relative efficiency of some aphid species as vectors of potato virus Yo (PVYo)

The relative efficiency of 7 aphid species as vectors of potato virus Yo (PVYo) was investigated. Winged aphids of one species were released in a net cage containing PVYo-infected potato plants as a virus source and healthy young potato plants as test plants. After 35 hours the glasshouse chamber was fumigated and the young plants tested for PVYo by ELISA at 10-days intervals.Myzus persicae andAcyrthosiphon pisum were the most effective vectors, infecting 26 and 25% of the test plants, respectively.Aphis fabae, Aphis nasturtii andRhopalosiphum padi infected only 1–7% test plants.Sitobion avenae andBrevicoryne brassicae did not transmit PVYo. Relative ‘efficiency factors’ are suggested from these and other results.

The infection pressure of potato virus Yo and the occurrence of winged aphids in potato fields in Sweden

Water-filled yellow trays sited in a potato field were used to catch different species of winged aphids. The catches, enumerated weekly, were compared with the spread of potato virus Yo (PVYo), detected by bait plants of tobacco and potato, during the growing season for four years.