PDF(Pubmed)
Abstract：
BACKGROUND: Grapevine fanleaf virus (GFLV) is one of the most detrimental viral pathogens of grapevines worldwide but no information is available on its effect on the root system architecture (RSA) of plant hosts. We used two wildtype GFLV strains and their single amino acid mutants to assess RSA traits in infected Nicotiana benthamiana and evaluate transcriptomic changes in host root gene expression in replicated time course 3\'RNA-Seq experiments. Mutations targeted the multi-functional GFLV-encoded protein 1EPol*/Sd, a putative RNA-dependent RNA polymerase and determinant of foliar symptoms in N. benthamiana plants.
RESULTS: Plant infection with wildtype GFLV strain GHu and mutant GFLV strain F13 1EPol G802K, both carrying a lysine in position 802 of protein 1EPol*/Sd, resulted in a significantly lower number of root tips (-30%), and a significantly increased average root diameter (+ 20%) at 17 days post inoculation (dpi) in comparison with roots of mock inoculated plants. In contrast, the RSA of plants infected with wildtype GFLV strain F13 and mutant GFLV strain GHu 1EPol K802G, both carrying a glycine in position 802 of protein 1EPol*/Sd, resembled that of mock inoculated plants. Modifications of RSA traits were not associated with GFLV titer. Root tissue transcriptome analysis at 17 dpi indicated dysregulation of pattern recognition receptors, plant hormones, RNA silencing, and genes related to the production of reactive oxygen species (ROS). For wildtype GFLV strain GHu, RSA modifications were correlated with an abundant accumulation of ROS in the pericycle of primary roots at 7 dpi and the duration of vein clearing symptom expression in apical leaves. Dysegulation of a hypersensitive response was an overarching gene ontology found through enrichment analyses of 3\'RNA-Seq data.
CONCLUSIONS: Our findings revealed the causative role of lysine in position 802 of protein 1EPol*/Sd in a novel RSA phenotype during viral infection and documented GFLV-N. benthamiana interactions at the root level based on (i) antiviral response, (ii) receptor mediated production of ROS, and (iii) hormone regulation. A correlation between above and below ground symptoms was reported for the first time in plants infected with wildtype GFLV strain GHu. Further work is warranted to test whether the modified RSA of a plant host might impact GFLV acquisition and transmission by the ectoparasitic dagger nematode Xiphinema index.
RESULTS: Plant infection with wildtype GFLV strain GHu and mutant GFLV strain F13 1EPol G802K, both carrying a lysine in position 802 of protein 1EPol*/Sd, resulted in a significantly lower number of root tips (-30%), and a significantly increased average root diameter (+ 20%) at 17 days post inoculation (dpi) in comparison with roots of mock inoculated plants. In contrast, the RSA of plants infected with wildtype GFLV strain F13 and mutant GFLV strain GHu 1EPol K802G, both carrying a glycine in position 802 of protein 1EPol*/Sd, resembled that of mock inoculated plants. Modifications of RSA traits were not associated with GFLV titer. Root tissue transcriptome analysis at 17 dpi indicated dysregulation of pattern recognition receptors, plant hormones, RNA silencing, and genes related to the production of reactive oxygen species (ROS). For wildtype GFLV strain GHu, RSA modifications were correlated with an abundant accumulation of ROS in the pericycle of primary roots at 7 dpi and the duration of vein clearing symptom expression in apical leaves. Dysegulation of a hypersensitive response was an overarching gene ontology found through enrichment analyses of 3\'RNA-Seq data.
CONCLUSIONS: Our findings revealed the causative role of lysine in position 802 of protein 1EPol*/Sd in a novel RSA phenotype during viral infection and documented GFLV-N. benthamiana interactions at the root level based on (i) antiviral response, (ii) receptor mediated production of ROS, and (iii) hormone regulation. A correlation between above and below ground symptoms was reported for the first time in plants infected with wildtype GFLV strain GHu. Further work is warranted to test whether the modified RSA of a plant host might impact GFLV acquisition and transmission by the ectoparasitic dagger nematode Xiphinema index.
摘要：
背景：葡萄扇叶病毒（GFLV）是世界范围内葡萄最有害的病毒病原体之一，但没有关于其对植物宿主根系结构（RSA）的影响的信息。我们使用了两个野生型GFLV菌株及其单氨基酸突变体来评估感染的本氏烟草中的RSA性状，并在复制的时间过程3'RNA-Seq实验中评估宿主根基因表达的转录组变化。针对多功能GFLV编码蛋白1EPol*/Sd的突变，一种推定的RNA依赖性RNA聚合酶和N.benthamiana植物叶面症状的决定因素。
结果：植物感染野生型GFLV菌株Ghu和突变型GFLV菌株F131EPolG802K，都在蛋白质1EPol*/Sd的802位携带赖氨酸，导致根尖数量明显减少（-30%），与模拟接种的植物的根相比,在接种后17天(dpi),平均根直径显著增加(+20%)。相比之下,用野生型GFLV菌株F13和突变GFLV菌株Ghu1EcolK802G感染的植物的RSA，都在蛋白质1EPol*/Sd的802位携带甘氨酸，类似于模拟接种的植物。RSA性状的修饰与GFLV滴度无关。17dpi的根组织转录组分析表明模式识别受体失调，植物激素,RNA沉默，以及与活性氧（ROS）产生相关的基因。对于野生型GFLV菌株Ghu，RSA修饰与7dpi时初生根周周期中ROS的大量积累以及根尖叶中静脉清除症状表达的持续时间相关。通过对3个RNA-Seq数据的富集分析，发现了超敏反应的二分段是一个总体基因本体论。
结论：我们的发现揭示了在病毒感染期间一种新型RSA表型中，赖氨酸在蛋白1EPol*/Sd的位置802中的致病作用，并记录了GFLV-N。基于（i）抗病毒反应，在根水平上的benthamiana相互作用，（ii）受体介导的ROS产生，和（iii）激素调节。首次报道了感染野生型GFLV菌株Ghu的植物中地上和地下症状之间的相关性。需要进一步的工作来测试植物宿主的改良RSA是否可能通过外寄生匕首线虫Xiphinema指数影响GFLV的获取和传播。
结果：植物感染野生型GFLV菌株Ghu和突变型GFLV菌株F131EPolG802K，都在蛋白质1EPol*/Sd的802位携带赖氨酸，导致根尖数量明显减少（-30%），与模拟接种的植物的根相比,在接种后17天(dpi),平均根直径显著增加(+20%)。相比之下,用野生型GFLV菌株F13和突变GFLV菌株Ghu1EcolK802G感染的植物的RSA，都在蛋白质1EPol*/Sd的802位携带甘氨酸，类似于模拟接种的植物。RSA性状的修饰与GFLV滴度无关。17dpi的根组织转录组分析表明模式识别受体失调，植物激素,RNA沉默，以及与活性氧（ROS）产生相关的基因。对于野生型GFLV菌株Ghu，RSA修饰与7dpi时初生根周周期中ROS的大量积累以及根尖叶中静脉清除症状表达的持续时间相关。通过对3个RNA-Seq数据的富集分析，发现了超敏反应的二分段是一个总体基因本体论。
结论：我们的发现揭示了在病毒感染期间一种新型RSA表型中，赖氨酸在蛋白1EPol*/Sd的位置802中的致病作用，并记录了GFLV-N。基于（i）抗病毒反应，在根水平上的benthamiana相互作用，（ii）受体介导的ROS产生，和（iii）激素调节。首次报道了感染野生型GFLV菌株Ghu的植物中地上和地下症状之间的相关性。需要进一步的工作来测试植物宿主的改良RSA是否可能通过外寄生匕首线虫Xiphinema指数影响GFLV的获取和传播。
