The effects of co‐infection by different Potato virus Y (PVY) isolates on virus concentration in solanaceous hosts and efficiency of transmission

Abstract

The influence of co‐infection on concentration and accumulation of genetically different isolates of Potato virus Y (PVY) in potato and tobacco plants and the efficiency of transmission by Myzus persicae of PVY isolates from doubly versus singly infected plants were evaluated. The vector ability to simultaneously transmit two virus isolates was examined. Eight PVY isolates represented three strain groups: PVYO (pathotype and serotype O), PVYNW (pathotype N and serotype O), and PVYNTN (pathotype and serotype N). Different diagnostic methods, including DAS‐ELISA, multiplex RT‐PCR, aphid transmission tests and bioassays, were applied to detect the presence of PVY isolates in source and assay plants. Significant reductions in concentrations of certain PVY isolates during co‐infection with other isolates were found both in potato and tobacco plants. The observed effects were both isolate‐ and host‐dependent in form. The highest rates of virus transmission by single aphids were recorded with PVYNTN isolates, and the lowest ones with PVYO isolates. Individual aphids of M. persicae were able to simultaneously transmit two PVY isolates. The frequency of transmission was generally low, but it reached as high as 20% for one of the isolate combinations. The findings presented in the work provide proof for antagonistic within‐plant interactions between isolates of PVY, with some implications of these interactions for virus transmission by aphid vectors. Consequently, this research contributes to a better understanding of the epidemiology of the disease caused by PVY.

Preferential acquisition and inoculation of PVYNTN over PVYO in potato by the green peach aphid Myzus persicae (Sulzer)

“…Therefore, an aphid need not acquire both strains from one source plant in order to transmit multiple viruses. In fact, acquisition and subsequent transmission of both virus strains from a mixedinfected plant is not generally efficient (Srinivasan et al, 2012;Syller & Grupa, 2014) and mixed-infected plants are not abundant in the field (Gray et al, 2010). Our results suggest that mixed-infected plants would more likely be generated in the field via inoculation by multiple aphids that have fed on plants infected with different strains than by single aphids probing multiple plants singly (Fig.…”

“…Multiple studies report that PVY NTN is more efficiently transmitted by aphid vectors than other strains (Cervantes & Alvarez, 2011;Srinivasan et al, 2012), although contrasting findings have also been published (Davis et al, 2005;Verbeek et al, 2010). In mixed strain infections, PVY NTN seems to outcompete other PVY strains in potato, which may contribute to enhanced transmission efficiency (Cervantes & Alvarez, 2011;Syller & Grupa, 2014). During surveys of US seed potatoes (Gray et al, 2010), PVY NTN was often found in the same field and occasionally in the same plant with PVY O .…”

“…Perhaps PVY NTN has a stronger silencing suppressor (Kasschau & Carrington, 1998) (Srinivasan et al, 2012;Syller & Grupa, 2014) despite the use of different clones of M. persicae, different isolates of the virus strains and different host plant species (both as source and recipient). Also, PVY NTN titre in mixed-infected recipient plants is usually higher than PVY O titre (Srinivasan et al, 2012;Syller & Grupa, 2014 and this study). Our results here suggest PVY NTN will also have a competitive advantage over PVY O as a result of sequential acquisition or inoculation.…”

Cross‐protection between a Naturally Occurring Mild Isolate of Potato virus M (PVM) and a More Virulent Isolate in Datura metel Plants

“…For total RNA isolation and cDNA synthesis, the procedure described by Syller and Grupa () was employed. The RT‐PCR was performed as described by Xu et al.…”

Biological and molecular events associated with simultaneous transmission of plant viruses by invertebrate and fungal vectors

“…(), Srinivasan et al . () and Syller and Grupa (), can be explained as proposed above, and illustrated in Fig. .…”