Wong Chi Hzeng, Hu Chung-Chi, Tsai Ching-Hsiu, Lin Na-Sheng, Hsu Yau-Heiu, Lin Ming-Kuem, Huang Ying-Wen
Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan.
Advanced Plant and Food Crop Biotechnology Center, National Chung Hsing University, Taichung, Taiwan.
Mol Plant Pathol. 2025 Jun;26(6):e70099. doi: 10.1111/mpp.70099.
Plant viruses, as obligate parasites, depend on host cellular machinery for various processes essential to their life cycle, making the investigation of these interactions fundamentally important. Bamboo mosaic virus (BaMV), a positive-strand (+) RNA virus, serves as a model to explore host-virus interactions during replication. In this study, Nicotiana benthamiana 1-hydroxy-2-methyl-butenyl 4-diphosphate reductase (NbHDR), a key enzyme in the methylerythritol 4-phosphate (MEP) pathway, was identified as an interactor with BaMV replicase through immunoprecipitation, pull-down and yeast two-hybrid assays. Knockdown of NbHDR significantly reduced the accumulation of BaMV RNA and coat protein but did not affect infection with the close relative potato virus X, indicating its specific involvement in BaMV replication. Overexpression of NbHDR in N. benthamiana or the addition of NbHDR in in vitro RdRp reactions demonstrated that NbHDR enhances BaMV replication by promoting (+) RNA synthesis. To further explore whether the role of NbHDR in BaMV replication is linked to gibberellic acid (GA) synthesis through the MEP pathway, individual knockdowns of NbHDR and ent-kaurene synthase (KS), a key enzyme in GA biosynthesis, were performed. Silencing KS sireduced BaMV accumulation, which was rescued by exogenous GA, but GA supplementation was insufficient to restore BaMV levels after NbHDR silencing. These findings suggest that NbHDR associates with the BaMV replication complex to enhance viral replication efficiency through a mechanism independent of GA synthesis from the MEP pathway, providing new insights into host-virus interactions.
植物病毒作为专性寄生物，其生命周期中的各种基本过程依赖于宿主细胞机制，因此对这些相互作用的研究具有至关重要的意义。竹花叶病毒（BaMV）是一种正链（+）RNA病毒，是探索复制过程中宿主-病毒相互作用的模型。在本研究中，通过免疫沉淀、下拉和酵母双杂交试验，鉴定出甲基赤藓糖醇4-磷酸（MEP）途径中的关键酶——本氏烟草1-羟基-2-甲基丁烯基4-二磷酸还原酶（NbHDR）是与BaMV复制酶相互作用的蛋白。敲低NbHDR显著降低了BaMV RNA和外壳蛋白的积累，但不影响其近缘病毒马铃薯X病毒的感染，表明它特异性参与BaMV复制。在本氏烟草中过表达NbHDR或在体外RdRp反应中添加NbHDR表明，NbHDR通过促进（+）RNA合成来增强BaMV复制。为了进一步探究NbHDR在BaMV复制中的作用是否通过MEP途径与赤霉素（GA）合成相关，分别敲低了NbHDR和GA生物合成中的关键酶贝壳杉烯合酶（KS）。沉默KS基因降低了BaMV的积累，外源GA可使其恢复，但GA补充不足以在NbHDR沉默后恢复BaMV水平。这些发现表明，NbHDR与BaMV复制复合体相关联，通过一种独立于MEP途径GA合成的机制提高病毒复制效率，为宿主-病毒相互作用提供了新的见解。
