Potato virus Y Strain Spectrum in New Zealand – Absence of Recombinant N:O Strains

Abstract

Potato virus Y (PVY) is a serious plant pathogen, causing severe yield losses worldwide on members of the Solanaceae, including potato, pepper, tomato and tobacco. During the last two decades new virus strains have been detected, including those representing recombinants between N-and O-strains, now designated PVY NTN and PVY N -Wilga, respectively. The question of whether recombination is easily induced in nature by mixed infections of potato might be answered by an investigation of strains appearing under isolated conditions such as those in New Zealand. More than 30 PVY isolates collected during the last 20 years were characterized biologically, serologically and using molecular biological approaches. The New Zealand population of PVY isolates was mainly composed of PVY N and PVY O . To date no recombinant strains have been found among the isolates tested. Similarly, experiments performed with these isolates on potatoes under greenhouse conditions with mixed infection PVY N ⁄PVY O did not result in signs of recombination. This raises the question as to the driving force for the appearance of recombinant strains. It also demonstrates the efficacy of plant quarantine measures in New Zealand over the past 20 years.

Genetic Diversity of the Ordinary Strain of Potato virus Y (PVY) and Origin of Recombinant PVY Strains

“…However, in the United States and Canada, PVY O remains the predominant strain infecting potato, and PVY N is rare, although recombinant strains are increasing in incidence and distribution (1,10,14,24). In New Zealand, contrary to the situation in Europe and even in North America, recombinant PVY strains have not been identified and only the PVY O and PVY N strains were found in potato (8). The relative success of nonrecombinant PVY strains in North America and, especially, in New Zealand, can be partly explained by their closed potato seed production systems and the lack of substantial importation of seed potato and new recombinant PVY strains with it (8,10).…”

“…In New Zealand, contrary to the situation in Europe and even in North America, recombinant PVY strains have not been identified and only the PVY O and PVY N strains were found in potato (8). The relative success of nonrecombinant PVY strains in North America and, especially, in New Zealand, can be partly explained by their closed potato seed production systems and the lack of substantial importation of seed potato and new recombinant PVY strains with it (8,10). Nevertheless, other factors may also be involved (i.e., evolution of those nonrecombinant strains through mutations that may make them more competitive).…”

Molecular and Biological Characterization of Potato virus Y Isolates from Vietnam

“…) in 50‐ μ l reaction volume containing 3 μ l of the cDNA reaction mix, 200 n m of each primer (Fomitcheva et al. ), 0.5 m m dNTP's, 10 m m Tris‐HCl, 50 m m KCl, 2.5 m m MgCl 2 , pH 8.3 @ 25°C. PCR conditions were 2 min at 96°C followed by 32 cycles of 20 s/96°C, 20 s/58°C and 3 min/72°C.…”

“…RNA was eluted from the columns with 50 ll of the water provided. For cloning purposes, cDNA was synthesized using the different primers listed in Fomitcheva et al (2009) and MMLV reverse transcriptase (Thermo Fisher Scientific Inc., Waltham, MA, USA) in 25 ll of reaction volume with 3 ll of RNA elute, again following the manufacturer's instructions.…”

“…Molecular investigations revealed the recombinant nature of PVY NTN (Singh et al 2008). Later, it was shown that isolates of PVY N can also cause tuber necrosis (Fomitcheva et al 2009). Isolates causing veinal necrosis in tobacco were further divided on the basis of their serological reactions (Chrzanowska 1994).…”