The resistance mechanism of plants against virus infection

Okuno的研究小组发现，要抑制红三叶坏死花叶病毒(RCNMV)，需要多种病毒成分，包括病毒RNA和可能的RNA复制酶蛋白。负链RNA合成所需的RNA元件与RNAi抑制之间的密切关系表明病毒RNA复制机制和RNAi机制之间有很强的联系。拟南芥DCL1突变体不支持RCNMV侵染，表明DCL1是RCNMV侵染所必需的寄主成分。RCNMV优先干扰发夹dsRNA诱导的RNAi中长的小干扰RNA(24-26个核苷酸)的积累。我们提出了一个模型，在这个模型中，为了复制，RCNMV剥夺了RNAi机制中一个可能是骰子样蛋白的因子，并抑制了DICER介导的dsRNA切割。他们还发现，作为RNA介导CP表达反式激活剂的茎环结构对于RCNMV本身的RNA2复制是至关重要的。Watanabe的研究小组发现，DCL1至少催化miRNA生物发生中的第一步和第二步切割，DCL1的双链RNA结合域参与切割位点的定位。我们的结果直接证明DCL1参与了Pri-和Pre-miRNA的加工。DCL1的(DsRNA)结合域参与切割位点的定位。他们还在胞间连丝中发现了几种与烟草花叶病毒运动蛋白相关的蛋白质。

Okuno's group found that to suppress Red clover necrotic mosaic virus (RCNMV) needs multiple viral components, including viral RNAs and putative RNA replicase proteins. A close relationship between the RNA elements required for negative-strand RNA synthesis and RNAi suppression suggests a strong link between the viral RNA replication machinery and the RNAi machinery. DCL1 mutants of Arabidopsis thaliana did not support RCNMV infection, suggesting DCL1 is a host component required for RCNMV infection. RCNMV preferentially interferes with the accumulation of long small-interfering RNAs (24-26 nt) in RNAi induced by a hairpin dsRNA. We propose a model in which, to replicate, RCNMV deprives the RNAi machinery of a factor that is probably a dicer-like protein, and suppresses Dicer-mediated dsRNA cleavage. They also found that the stem-loop structure that functions as a trans-activator for the RNA-mediated CP expression is critically required for RNA2 replication of RCNMV itself.Watanabe's group found that DCL1 catalyzes at least the first and second cleavage steps in miRNA biogenesis and that double-stranded RNA-binding domains of DCL1 are involved in positioning of the cleavage sites. Our result is direct evidence that DCL1 is involved in processing of pri-and pre-miRNA. (dsRNA )-binding domains of DCL1 are involved in positioning of the cleavage sites. They also identified several proteins associated with Tobacco mosaic virus movement protein in plasmodesmata.