Direct tuber testing for Potato Y potyvirus by real‐time RT‐PCR and ELISA: reliable options for post‐harvest testing?*

Abstract

The method currently used for testing potato tubers for viruses following harvest involves a growing-on test. This takes up to 6 weeks to complete, and there is therefore a demand for more rapid test results. The sensitivity and reliability of direct tuber testing by DAS-ELISA and real-time RT-PCR (TaqMan) were compared with the growing-on test. In addition, the reliability of all three methods for the detection of Potato Y potyvirus (PVY) in tubers was compared over post-harvest intervals of 6, 10, 14 and 18 weeks. The test material came from plots of tubers (cv. 'Maris Piper') containing a primary infection of strains PVY N and PVY O , following aphid transmission from marked infector plants grown during the 2003 season. Sample material was homogenized and divided, to provide comparative test material for detection of PVY by ELISA and real-time RT-PCR. Tuber eye-plugs were then taken and subjected to the growing-on test. The remainder of the tuber was also grown on and tested, to ensure infection was not missed as a consequence of an uneven distribution of virus throughout the tuber material. The results obtained using the two methods for direct testing of the tubers, and those results obtained from the traditional growing-on test, are compared. The advantages and disadvantages of each method are discussed.

Comparison of three methods for the detection of Potato virus Y in seed potato certification

“…RT-qPCR was done 33 weeks after harvest using dormant potato tubers. Fox et al (2005) demonstrated that the reliability of ELISA from tuber samples drastically decreases when tubers start sprouting. Therefore, we assume that using non-dormant tuber samples RT-qPCR is more reliable than ELISA.…”

“…Furthermore, direct tuber testing is faster and less space-consuming than growing-on tests and therefore represents a cheaper method for detecting PVY, especially since no greenhouse is needed. However, the use of single tubers can lead to a lower reliability of the test, since not all tubers of an infected plant carry the virus (Fox et al 2005). This phenomenon is clearly shown by our results (Table 2).…”

Mosaic Virus Symptoms in Potato Crops and the Occurrence of Growth Cracking in Tubers

“…Ten pairs of replicates were sampled from three different areas (blocks) in each crop in order to take account of variability within the crop. A sample of four leaflets was collected from the middle of stems of each plant and tested by DAS-ELISA for PVA, PVV, PVX, Potato virus S, Potato virus M, PVY O , PVY N , Potato leaf roll virus, Tomato black ring virus, and Potato mop top virus (Fox et al 2005). The tubers produced by each plant were harvested carefully by fork to ensure that, as far as possible, harvested tubers were from the test plant and placed separately in new paper bags.…”

Detección del virus del amarillamiento de las nervaduras de la hoja de la papa en diferentes órganos de Solanum tuberosum grupo Phureja cv Criolla Colombia utilizando RT-PCR convencional y en tiempo real

“…Hay poca información de la distribución de virus en plantas de papa infectadas, varios autores han demostrado que algunos virus se distribuyen en la planta de manera heterogénea (Leisner et al, 1992;Singh y Singh, 1996y 1998Gosálves et al, 2003;Fox et al, 2005;Sánchez-Navarro et al, 2007;Kogovšek et al, 2011); Kogovšek et al (2011) hacen uso de la técnica de qRT-PCR para analizar el título viral del Potato virus Y (PVY, Potyviridae) en diferentes órganos de plantas de Solanum tuberosum infectadas con el virus, reportando que el PVY presenta mayores títulos virales en tallos y foliolos sintomáticos, en foliolos no sintomáticos y tubérculos hay menores títulos virales, lo que demuestra que su distribución es heterogénea. Para PYVV se ha sugerido una distribución heterogénea del virus dentro del tubérculo (López et al, 2006).…”