Mol Plant Microbe Interact. 2013 Oct;26(10):1165-75. doi: 10.1094/MPMI-05-13-0137-R.
Some viruses only infect plants at cool temperatures but the molecular mechanism underlying this low-temperature dependence remains unclear. Chinese wheat mosaic virus (CWMV, genus Furovirus) was able to infect wheat and Nicotiana benthamiana plants at 16 but not at 24°C. When CWMV-infected plants were transferred to 24°C for 2 weeks, the newly emerged leaves and roots became virus free. Co-infection with Potato virus Y rescued CWMV accumulation in N. benthamiana plants after a temperature shift to 24°C. In transgenic N. benthamiana plants silenced for the N. benthamiana RNA-dependent RNA polymerase 6 (NbRDR6), CWMV was able to accumulate in roots but not in leaves after a temperature shift to 24°C. Deep sequencing of small RNAs showed that, at 16°C, abundant CWMV small interfering (si)RNAs accumulated in infected N. benthamiana plants. Silencing of NbRDR6 increased the abundance of CWMV siRNAs and the generation of siRNAs from hotspots in the CWMV genome. In contrast, when shifted to 24°C for 1 week, CWMV siRNAs were markedly fewer in roots of NbRDR6-silenced than in roots of wild-type plants but were similar in the leaves of those plants. Our results demonstrate the root-specific role of NbRDR6 in the inhibition of CWMV accumulation and biogenesis of CWMV siRNAs at higher temperatures.
有些病毒只在低温下感染植物，但这种低温依赖性的分子机制尚不清楚。中国小麦花叶病毒（CWMV，属斐诺病毒）能够在 16°C 而不是 24°C 感染小麦和黄花烟植株。当 CWMV 感染的植物被转移到 24°C 2 周后，新长出的叶片和根部就不再有病毒。在温度转移到 24°C 后，与马铃薯 Y 病毒共感染可挽救 CWMV 在黄花烟植株中的积累。在沉默了黄花烟 RNA 依赖性 RNA 聚合酶 6（NbRDR6）的转基因黄花烟植株中，CWMV 在温度转移到 24°C 后能够在根部积累，但不能在叶片中积累。对小 RNA 的深度测序表明，在 16°C 时，大量 CWMV 小干扰（si）RNA 在感染的黄花烟植株中积累。沉默 NbRDR6 增加了 CWMV siRNA 的丰度，并增加了 CWMV 基因组热点处 siRNA 的生成。相比之下，当在 24°C 下转移 1 周时，沉默 NbRDR6 的植物根部的 CWMV siRNA 明显少于野生型植物的根部，但在这些植物的叶片中则相似。我们的结果表明，NbRDR6 在高温下抑制 CWMV 积累和 CWMV siRNA 的生物发生方面具有根特异性。
