Discussion paper: The naming of Potato virus Y strains infecting potato

Abstract

Potato virus Y (PVY) strain groups are based on host response and resistance gene interactions. The strain groups PVY(O), PVY(C) and PVY(N) are well established for the isolates infecting potato in the field. A switch in the emphasis from host response to nucleotide sequence differences in the virus genomes, detection of isolates recombining sequences of different strains, and the need to recognize isolates that cause necrotic symptoms in potato tubers have led to the assignment of new acronyms, especially to isolates of the PVY(N) strain group. This discussion paper proposes that any newly found isolates should be described within the context of the original strain groups based on the original methods of distinguishing strains (i.e., tobacco and potato assays involving use of 'differential' potato cultivars). Additionally, sequence characterization of the complete genomes of isolates is highly recommended. However, it is acceptable to amend the names of PVY isolates with additional, specific codes to show that the isolate differs at the molecular, serological or phenotypic level from the typical strains within a strain group. The new isolates should preferably not be named using geographical, cultivar, or place-association designations. Since many new variants of PVY are being discovered, any new static classification system will be meaningless for the time being. A more systematic investigation and characterization of PVY from potato at the biological and molecular levels should eventually result in a biologically meaningful genetic strain concept.

Potato Cultivar and Seed Type Affect the Development of Systemic Potato virus Y (PVYN-Wi) Infection

“…PVY N does not induce an HR response in potatoes (i.e., Ny tbr or Nc tbr are not induced), whereas PVY N induces vein necrosis in tobacco (Cockerham 1970;Jones 1990;Karasev and Gray 2013;Rowley et al 2015;Singh et al 2008, and reviewed in Funke et al 2017). Similar to PVY N , PVY N-Wi does not induce an HR response in potato and causes vein necrosis in tobacco (Cockerham 1970;Jones 1990;Karasev and Gray 2013;Rowley et al 2015;Singh et al 2008; and reviewed in Funke et al 2017). PVY N-Wi infection of potato plants may be asymptomatic or result in transient mild mosaic patterning on foliage (Karasev and Gray 2013).…”

Complete nucleotide sequence of a potato isolate of strain group C of Potato virus Y from 1938

“…A survey in France in 1985 showed an infection rate of less than 5% with PVY C , while for PVY O and PVY N , infection levels of 80 and 12%, respectively, were reported [13]. In the Netherlands, field surveys conducted from 1994 to 2007 showed similar results [28].PVY also causes diseases and production loss in pepper (Capsicum annuum L.) [22], tomato (Solanum lycopersicum L.) and tobacco crops [25]. For some isolates from pepper, a high level of sequence identity to PVY C from potato was found [11,15,22].…”

“…PVY is one of the most common viruses of potato (Solanum tuberosum L.) and causes significant economic losses worldwide, especially in the production of seed potatoes. [12,16,24,25].PVY O and PVY C can be distinguished in potato cultivars bearing the resistance genes Ny tbr and Nc [7,25]. PVY C isolates are defined by the typical hypersensitive response they induce in potato cultivars carrying the Nc gene.…”

“…PVY is one of the most common viruses of potato (Solanum tuberosum L.) and causes significant economic losses worldwide, especially in the production of seed potatoes. [12,16,24,25].…”

“…PVY also causes diseases and production loss in pepper (Capsicum annuum L.) [22], tomato (Solanum lycopersicum L.) and tobacco crops [25]. For some isolates from pepper, a high level of sequence identity to PVY C from potato was found [11,15,22].…”