Department of Plant Pathology, University of California, Davis, California, USA.
Department of Crop and Forest Sciences, University of Lleida, Lleida, Spain.
mBio. 2018 Nov 20;9(6):e02230-18. doi: 10.1128/mBio.02230-18.
Plant-infecting viruses utilize various strategies involving multiple viral and host factors to achieve successful systemic infections of their compatible hosts. (LIYV), genus , family , has long, filamentous flexuous virions and causes phloem-limited infections in its plant hosts. The LIYV-encoded P26 is a distinct non-virion protein that shows no similarities to proteins in current databases: it induces plasmalemma deposits over plasmadesmata (PD) pit fields and is speculated to have roles in LIYV virion transport within infected plants. In this study, P26 was demonstrated to be a PD-localized protein, and its biological significance was tested by mutagenesis analysis. An LIYV P26 knockout mutant (P26X) showed viral RNA replication and virion formation in inoculated leaves of plants, but failed to give systemic infection. Confirmation by using a modified green fluorescent protein (GFP)-tagged LIYV P26X showed GFP accumulation only in infiltrated leaf tissues, while wild-type LIYV GFP readily spread systemically in the phloem. Attempts to rescue P26X by complementation in were negative. However a translocated LIYV P26 gene in the LIYV genome rescued systemic infection, but P26 orthologs from other criniviruses did not. Mutagenesis assays showed that deletions in P26, as well as 2 of 11 specific alanine-scanning mutants, abolished the ability to systemically infect Plant viruses encode specific proteins that facilitate their ability to establish multicellular/systemic infections in their host plants. Relatively little is known of the transport mechanisms for plant viruses whose infections are phloem limited, including those of the family These viruses have complex, long filamentous virions that spread through the phloem. (LIYV) encodes a non-virion protein, P26, which forms plasmalemma deposits over plasmodesmata pit fields, and LIYV virions are consistently found attached to those deposits. Here we demonstrate that P26 is a unique movement protein required for LIYV systemic infection in plants. LIYV P26 shows no sequence similarities to other proteins, but other criniviruses encode P26 orthologs. However, these failed to complement movement of LIYV P26 mutants.
植物侵染病毒利用多种策略，涉及多种病毒和宿主因素，以实现对其相容宿主的成功系统性感染。(LIYV)，属，科，具有长而丝状的柔韧病毒粒子，并在其植物宿主中引起韧皮部限制感染。LIYV 编码的 P26 是一种独特的非病毒蛋白，与当前数据库中的蛋白质没有相似之处：它诱导质膜沉积物在质膜胞间连丝（PD）pit 场地上，推测在 LIYV 病毒粒子在感染植物内的运输中具有作用。在这项研究中，P26 被证明是一种 PD 定位蛋白，并通过突变分析测试了其生物学意义。LIYV P26 敲除突变体（P26X）在接种的 植物叶片中显示病毒 RNA 复制和病毒粒子形成，但未能引起系统性感染。使用改良的绿色荧光蛋白（GFP）标记的 LIYV P26X 的确认表明 GFP 仅在渗透叶片组织中积累，而野生型 LIYV GFP 很容易在韧皮部系统中传播。在 中通过互补来挽救 P26X 的尝试是阴性的。然而，LIYV 基因组中移位的 LIYV P26 基因挽救了系统性感染，但来自其他克鲁文病毒的 P26 同源物没有。突变分析表明，P26 的缺失以及 11 个特定丙氨酸扫描突变体中的 2 个，消除了系统感染 的能力 植物病毒编码特定的蛋白质，这些蛋白质有助于它们在宿主植物中建立多细胞/系统性感染的能力。对于感染局限于韧皮部的植物病毒的运输机制，包括家族的那些病毒，相对知之甚少。这些病毒具有复杂的、长丝状的病毒粒子，通过韧皮部传播。LIYV 编码一种非病毒蛋白 P26，它在质膜胞间连丝 pit 场地上形成质膜沉积物，LIYV 病毒粒子始终附着在这些沉积物上。在这里，我们证明 P26 是 LIYV 在植物中系统性感染所必需的独特运动蛋白。LIYV P26 与其他蛋白质没有序列相似性，但其他克鲁文病毒编码 P26 同源物。然而，这些未能补充 LIYV P26 突变体的运动。
