Potato virus Y Transmission Efficiency from Potato Infected with Single or Multiple Virus Strains

Abstract

There has been a recent shift in the prevalence of Potato virus Y (PVY) strains affecting potato with the ordinary strain PVY declining and the recombinant strains PVY and PVY emerging in the United States. Multiple PVY strains are commonly found in potato fields and even in individual plants. Factors contributing to the emergence of the recombinant strains are not well defined but differential aphid transmission of strains from single and mixed infections may play a role. We found that the transmission efficiencies by Myzus persicae, the green peach aphid, of PVY, PVY, and PVY varied depending on the potato cultivar serving as the virus source. Overall transmission efficiency was highest from sources infected with three virus strains, whereas transmission from sources infected with one or two virus strains was not significantly different. Two strains were concomitantly transmitted by individual aphids from many of the mixed-source combinations, especially if PVY was present. Triple-strain infections were not transmitted by any single aphid. PVY was transmitted most efficiently from mixed-strain infection sources. The data do not support the hypothesis that differential transmission of PVY strains by M. persicae is a major contributing factor in the emergence of recombinant PVY strains in the U.S. potato crop.

Transmission modes affect the population structure of potato virus Y in potato

“…Transmission efficiency for PVY N and PVY N-Wi was shown not to differ in a previous study [ 34 ], which is consistent with the N e values estimated for this two strains in our study. Even though some studies demonstrated different efficiency of transmission for different PVY strains [ 35 ], conclusions between different studies are not consistent [ 36 ] and can be influenced by, e . g ., potato cultivar, viral titer in the source leaf [ 37 , 38 ], virus strain, virus isolate, aphid species and clonal populations [ 25 ].…”

Virus and helper component interactions favour the transmission of recombinant potato virus Y strains

“…‘Red Maria’ potato seedlings grown from true seed were used as recipient plants in all transmission assays. This method was adopted from previous studies [5, 10] and is an efficient and easy way to generate large numbers of similar sized seedlings that do not differ in susceptibility.…”

“…The green peach aphids ( Myzus persicae ) used in this study were previously described [10, 25] and maintained on ‘Purple Top White Globe’ turnip ( Brassica rapa subsp rapa ) plants.…”

“…While it is known that differential aphid transmission is a contributing factor behind this strain shift and some transmission studies have reported higher transmission efficiencies for recombinant PVY strains over PVY O from single- and mixed-strain infections [3, 4], several others reported either similar or lower transmission efficiency for recombinant strains [5–8]. It is evident from all of the PVY transmission studies that transmission efficiency is influenced by many factors including virus strain and isolate, aphid species and biotype, source and recipient plant species and cultivar, as well as experimental conditions [3, 5, 9, 10, 4, 8, 11, 12]. Generalisations regarding the transmission outcomes are not possible or appropriate.…”

Different potato virus Y strains frequently co-localize in single epidermal leaf cells and in the aphid stylet

“…Green peach aphids (Myzus persicae) were reared on 'Purple Top White Globe' turnip (Brassica rapa subsp rapa) as previously described [62,63]. Apterous third and fourth instar aphids were collected and starved for 1-2 h before being placed on the abaxial surface of a young, fully expanded, detached tobacco or potato leaf systemically infected with different individual PVY strains or mixtures of strains and allowed a 2-3 min acquisition access period (AAP).…”