Strain Specificity and Simultaneous Transmission of Closely Related Strains of a <I>Potyvirus</I> by <I>Myzus persicae</I>

Abstract

Potato virus Y (PVY), a Potyvirus, is transmitted by aphids in a nonpersistent manner. PVY severely affects potato production worldwide. Single and mixed infections of PVY strains, namely PVY(O), PVY(NTN), and PVY(N:O) are a common occurrence in potato systems. However, information available on the ability of aphids to simultaneously transmit multiple PVY strains, specificity associated with simultaneous transmission, and factors affecting specificity are limited. Aphid-mediated transmission experiments were conducted to test the ability of individual aphids to transmit multiple strains using a PVY indicator host. Preliminary results revealed that aphids can transmit at least two viral strains simultaneously. Subsequently, aphid-mediated transmission of three dual-strain combinations was tested using potato plants. Individual aphids transmitted two viral strains simultaneously for all three dual-strain combinations. In all aphid-mediated dual-strain infections involving PVY(NTN), the rate of PVY(NTN) infection was greater than the infection rates of the second strain and dual-strain combinations, indicating specificity associated with transmission of PVY strains. Results of aphid-mediated transmission experiments were compared with results obtained through mechanical transmission. In general, PVY infection rates from aphid-mediated transmission were lower than the rates obtained through mechanical transmission. Unlike aphid-mediated transmission, component strains in dual-strain inoculations were not eliminated during mechanical transmission. These results suggest that there may also be interference associated with aphid-mediated transmission of closely related PVY strains. Perhaps, the observed specificity and/or interference may explain the increase in the incidence of PVY(NTN) and other necrotic strains in recent years.

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

“…The highest rates of virus transmission by single aphids were recorded with PVY NTN isolates and the lowest ones with PVY O isolates. These results are in general agreement with those reported recently (Kaliciak & Syller, ; Srinivasan et al ., ) and confirm those reported by Srinivasan et al . () on the ability of single aphids of M. persicae to simultaneously transmit two PVY isolates.…”

Interactions Within Susceptible Hosts Drive Establishment of Genetically Distinct Variants of an Insect-Borne Pathogen

“…Different lowercase letters would indicate differences in overall transmission of GLRaV-3 (I, VI, or both) from source plants infected with different combinations of genetically distinct variants of single source plant with a mixed infection have either concluded that the outcome was due to virus interactions within the vector, or did not discern whether the outcome was determined within vector or susceptible host. Leaf-rub inoculations introduce a much larger quantity of virus than vector-mediated inoculations (Srinivasan et al 2012, Salvaudon et al 2013, Péréfarres et al 2014), and may consequently overpower possible effects of host defenses; therefore, comparing leaf-rub and vector inoculations might lead to erroneous conclusions about the effect of insect vectors on virus establishment in a new host plant (Moury et al 2007, Péréfarres et al 2014). In our study, the signature of superiority of one variant over another was actually stronger when competition within the vector was eliminated, by transferring vectors from each of two singly infected source plants to one uninfected test plant, suggesting that virus-virus interactions during establishment in a new host plant may be more important than interactions within the vector.…”

“…Vectors can affect the differential transmission of plant pathogens and consequent disease spread (Srinivasan et al 2012, Salvaudon et al 2013. In some cases, a pathogen already present at low prevalence can become widespread after a new more effective vector is introduced (Purcell and Feil 2001), or after adaptation by a pathogen to a vector that is already present (Tsetsarkin et al 2011).…”

“…One pathogen in a vector can affect the transmission of another pathogen; for example, potato aucuba mosaic virus can be transmitted by aphids only if they have fed on plants infected with potato virus Y (Kassanis and Govier 1971). Furthermore, vector transmission from a coinfected source can lead to differential transmission between two virus strains (Srinivasan et al 2012, Péréfarres et al 2014. For vector-borne plant viruses transmitted both in a circulative and noncirculative manner, insects transmit one to a few virus particles or genomes per inoculation event, even when several million virus genomes are present in the insect; thus, vectors can be strong bottlenecks (Moury et al 2007, Péréfarres et al 2014.…”

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. .…”