Kundu Jiban Kumar, Briard Pascal, Hily Jean Michel, Ravelonandro Michel, Scorza Ralph
UMR, GDPP, Virologie, INRA-Bordeaux, BP-81, Villenave d'Ornon 33883, France.
Virus Genes. 2008 Feb;36(1):215-20. doi: 10.1007/s11262-007-0176-y. Epub 2007 Dec 11.
The reaction of a genetically engineered plum clone (C5) resistant to plum pox virus (PPV) by graft inoculation with the virus was evaluated. The resistance in this clone has been demonstrated to be mediated through post-transcriptional gene silencing (PTGS). A single C5 plant out of 30 plants inoculated with PPV M strain by double chip-budding showed mild diffuse mosaic 'Sharka' symptom at the bottom section of the scion. The upper leaves of this PPV-infected C5 plant remained symptomless and the virus was not detected in them by either DAS-ELISA or RT-PCR. An RNA silencing associated small interfering RNA duplex, siRNA (21-26 nt), was detected in non-inoculated C5 plants and in the portions of inoculated C5 plant in which PPV could not be detected. In the PPV-infected portion of the C5 plant and in C6 PPV susceptible plants only the approximately 21-22 nt siRNAs was detected. Cytosine-methylation was confirmed in C5 plants both uninfected and showing PPV symptoms. The 25-26 nt siRNA normally present in C5 was absent in PPV-infected C5 tissues confirming the critical role of this siRNA in the resistance of clone C5 to PPV infection. We also show that this PPV infection was limited and transient. It was only detected in one plant at one of four post-dormancy sampling dates and did not appear to affect the overall PPV resistance of the C5 clone.
通过嫁接接种李子痘病毒（PPV），对一种经基因工程改造的抗李子痘病毒的李子克隆体（C5）的反应进行了评估。已证明该克隆体中的抗性是通过转录后基因沉默（PTGS）介导的。在通过双芯片芽接接种PPV M株系的30株植物中，有一株C5植物在接穗底部出现了轻度的弥漫性花叶“沙卡”症状。这株感染PPV的C5植物的上部叶片无症状，通过双抗夹心酶联免疫吸附测定（DAS-ELISA）或逆转录聚合酶链反应（RT-PCR）均未在其中检测到病毒。在未接种的C5植物以及接种的C5植物中未检测到PPV的部分中，检测到了一种与RNA沉默相关的小干扰RNA双链体，即siRNA（21 - 26核苷酸）。在C5植物感染PPV的部分以及C6易感PPV的植物中，仅检测到了约21 - 22核苷酸的siRNA。在未感染和表现出PPV症状的C5植物中均证实了胞嘧啶甲基化。在感染PPV的C5组织中，通常存在于C5中的25 - 26核苷酸的siRNA缺失，这证实了这种siRNA在克隆体C5对PPV感染的抗性中起关键作用。我们还表明，这种PPV感染是有限的且短暂的。仅在四个休眠后采样日期之一的一株植物中检测到，并且似乎未影响C5克隆体的整体PPV抗性。
