Phytopathology. 2014 Sep;104(9):1001-6. doi: 10.1094/PHYTO-12-13-0348-R.
Asparagus virus 2 (AV-2) is a member of the genus Ilarvirus and thought to induce the asparagus decline syndrome. AV-2 is known to be transmitted by seed, and the possibility of pollen transmission was proposed 25 years ago but not verified. In AV-2 sequence analyses, we have unexpectedly found mixed infection by two distinct AV-2 isolates in two asparagus plants. Because mixed infections by two related viruses are normally prevented by cross protection, we suspected that pollen transmission of AV-2 is involved in mixed infection. Immunohistochemical analyses and in situ hybridization using AV-2-infected tobacco plants revealed that AV-2 was localized in the meristem and associated with pollen grains. To experimentally produce a mixed infection via pollen transmission, two Nicotiana benthamiana plants that were infected with each of two AV-2 isolates were crossed. Derived cleaved-amplified polymorphic sequence analysis identified each AV-2 isolate in the progeny seedlings, suggesting that pollen transmission could indeed result in a mixed infection, at least in N. benthamiana.
芦笋病毒 2（AV-2）是 Ilarvirus 属的一员，被认为会引起芦笋衰退综合征。已知 AV-2 通过种子传播，25 年前就提出了花粉传播的可能性，但尚未得到证实。在对 AV-2 序列的分析中，我们意外地发现了两株芦笋植物中两种不同的 AV-2 分离株的混合感染。因为两种相关病毒的混合感染通常会被交叉保护所阻止，所以我们怀疑 AV-2 的花粉传播参与了混合感染。使用感染 AV-2 的烟草植物进行免疫组织化学分析和原位杂交表明，AV-2 定位于顶端分生组织并与花粉粒相关。为了通过花粉传播实验产生混合感染，将感染了两种 AV-2 分离株的两株 Nicotiana benthamiana 植物进行杂交。衍生的切割扩增多态性序列分析鉴定了子代幼苗中的每个 AV-2 分离株，表明花粉传播确实可以导致混合感染，至少在 N. benthamiana 中是这样。
