Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA.
Proc Biol Sci. 2013 Feb 13;280(1756):20122959. doi: 10.1098/rspb.2012.2959. Print 2013 Apr 7.
Recent studies have documented effects of plant viruses on host plants that appear to enhance transmission by insect vectors. But, almost no empirical work has explored the implications of such apparent manipulation for interactions among co-infecting pathogens. We examined single and mixed infections of two potyviruses, watermelon mosaic virus (WMV) and zucchini yellow mosaic virus (ZYMV), that frequently co-occur in cucurbitaceae populations and share the same aphid vectors. We found that ZYMV isolates replicated at similar rates in single and mixed infections, whereas WMV strains accumulated to significantly lower levels in the presence of ZYMV. Furthermore, ZYMV induced changes in leaf colour and volatile emissions that enhanced aphid (Aphis gossypii) recruitment to infected plants. By contrast, WMV did not elicit strong effects on plant-aphid interactions. Nevertheless, WMV was still readily transmitted from mixed infections, despite fairing poorly in in-plant competition. These findings suggest that pathogen effects on host-vector interactions may well influence competition among co-infecting pathogens. For example, if non-manipulative pathogens benefit from the increased vector traffic elicited by manipulative competitors, their costs of competition may be mitigated to some extent. Conversely, the benefits of manipulation may be limited by free-rider effects in systems where there is strong competition among pathogens for host resources and/or access to vectors.
最近的研究记录了植物病毒对宿主植物的影响，这些影响似乎增强了昆虫媒介的传播。但是，几乎没有实证工作探索这种明显的操纵对共同感染病原体之间相互作用的影响。我们研究了两种马铃薯 Y 病毒（WMV）和南瓜黄花叶病毒（ZYMV）的单感染和混合感染，这两种病毒经常在葫芦科种群中共存，并且共享相同的蚜虫媒介。我们发现，ZYMV 分离株在单感染和混合感染中的复制率相似，而 WMV 株系在存在 ZYMV 时积累到明显较低的水平。此外，ZYMV 诱导叶片颜色和挥发性排放的变化，从而增强了蚜虫（棉蚜）对感染植物的招募。相比之下，WMV 对植物-蚜虫相互作用没有产生强烈的影响。然而，尽管在植物内竞争中表现不佳，WMV 仍能从混合感染中轻易传播。这些发现表明，病原体对宿主-媒介相互作用的影响可能会影响共同感染病原体之间的竞争。例如，如果非操纵性病原体从操纵性竞争者引起的增加的媒介流量中受益，那么它们竞争的成本可能在一定程度上得到减轻。相反，在病原体之间存在强烈竞争以获取宿主资源和/或接触媒介的系统中，操纵的好处可能会受到搭便车效应的限制。
