Genetic diversity and management of Potato Virus Y in Canada

Potato virus Y (PVY) is one of the most economically important pathogens in potato. It is an evolving problem throughout the world. PVY made the headlines in Canada in 1990s when PVYN was discovered in Eastern Canada, which resulted in the loss of the export market. Since then significant progress has been made in PVY research in the country. A Canada-wide survey conducted in 2004-2006 revealed that PVYO was the predominant strain although other strains, including the recombinant strains PVYN:O, PVYN-Wi and PVYNTN, were present. Similar results were observed in a survey conducted in New Brunswick (NB) in 2009. However, the populations of PVY strains have shifted dramatically toward recombinant strains since then. A continuous survey of PVY strains in NB from 2009 to 2016 indicated that PVYO dropped from 82% of infections in 2010 to 14% in 2016, replaced mostly by PVYNTN (64%) and PVYN:O (22%). It is largely consistent with the global trend in PVY population structure. Studies on various aspects, such as barcoding PVY-vectoring aphid species, the effectiveness of mineral oil application with insecticides, and the monitoring current season spread during the growing season, have led to the establishment of improved integrated management practices for managing PVY. These practices have been recommended to and adopted by growers, leading to the significant reduction of PVY incidences in seed potatoes in Canada. The responses of various potato germplasm to major PVY strains have been resulted in the identification of potato clones with different resistances including the hypersensitive resistance and the extreme resistance (ER). High resolution DNA melting markers have been developed for high throughput screening for ER.