Serological, molecular and immunofluorescent evidence for interference competition between isolates of Potato virus Y

Abstract

Under natural field conditions, the abundance of plant viruses sharing the same host frequently results in mixed infections. Viruses co‐occurring inside host tissues often interact with one another synergistically or antagonistically. This paper addresses within‐host interactions among genetically different isolates of Potato virus Y (PVY), a serious pathogen that attacks solanaceous crops, particularly potato and tobacco. Manifold aspects of the relationships between six PVY isolates representing PVYO, PVYN‐Wi/PVYN:O and PVYNTN strains have been characterized. Plants of tobacco cv. Samsun and of two potato cultivars were inoculated both simultaneously and sequentially with different inoculation sequences and different time intervals between inoculations. Symptoms exhibited by doubly inoculated plants varied, primarily depending on the isolates involved as well as on the order of inoculation. Significant reductions of the titres of PVYN:O and PVYN‐Wi isolates in plants inoculated sequentially or simultaneously with PVYNTN isolates were recorded. These reductions were most probably due to inhibition of replication and accumulation of one isolate by another. In some combinations, a pre‐existing infection with PVYNTN prevented infection with the secondary virus. By contrast, challenge inoculation by PVYN:O, PVYN‐Wi or PVYO had no marked effects on the titre of the pre‐inoculated PVYNTN isolate. Microscopic visualization revealed a tendency of strains towards separation from each other in host tissues. These results provide strong experimental evidence for the existence of antagonistic interactions among PVY isolates. Moreover, these results demonstrate the occurrence of complete or at least partial cross‐protection among PVY isolates, with NTN isolates being evidently more fit than their counterparts.

Molecular Characterization of Potato Virus Y (PVY) Using High-Throughput Sequencing: Constraints on Full Genome Reconstructions Imposed by Mixed Infection Involving Recombinant PVY Strains

“…Several reports of PVY interactions in mixed infections have been previously published, showing an antagonistic nature, depending on the viral strains [13,47], and even partial cross-protection [48]. It was shown that PVY-NTN superinfection decreased the titers of PVY-N:O and PVY-N-Wi, while existing PVY-NTN infection prevented infection by secondary virus in some cases, while its titer was unaffected by PVY-N:O, PVY-N-Wi, or PVY-O [48]. Such information could be useful to discriminate between potential strain mixtures as in the case reported here, although it would be impossible to determine the time of infection by individual strains.…”

Spatiotemporal Changes in Xylan-1/Xyloglucan and Xyloglucan Xyloglucosyl Transferase (XTH-Xet5) as a Step-In of Ultrastructural Cell Wall Remodelling in Potato–Potato Virus Y (PVYNTN) Hypersensitive and Susceptible Reaction

“…To double-check the potato cultivars, all analysed potato plants were tested for the presence of PVY using ELISA [ 52 ]. ELISA testing was performed according to [ 53 ], and the results are presented in Table S1 . Absorbance was measured at 405 nm.…”

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

“…In a recent study, Grupa et al . [78] reported that two different strains of PVY rarely occupied the same cells of infected potato at 21 to 35 days p.i. In another previous study Dietrich and Maiss [40] found that co-infections of differently labelled strains of three potyviruses remained spatially separated with the exception of a few cells at the infection interface, whereas co-infections of any of the potyviruses with potato virus X led to a preponderance of co-infected cells.…”