【作者】 杜振国；

【导师】 吴祖建；

【作者基本信息】 福建农林大学 ， 微生物学， 2008， 硕士

【摘要】 miRNAs是一种基因组编码的非蛋白质编码小RNA。他们通过控制翻译或mRNA的稳定性或其他一些机制来调节遗传信息的流动。他们在植物的生长发育,信号传导以及胁迫反应中发挥着重要的作用。许多研究表明病毒的侵染经常会导致植物miRNA途径的不正常。虽然目前还不确定病毒对miRNA的这种影响是偶然的还是特异的,对miRNA途径的改变已经被公认为是植物病毒致病的一个关键因素。水稻矮缩病毒(RDV)是最重要的水稻病毒之一。在有些地区长造成严重减产。RDV侵染水稻的典型症状是被侵染植株严重的矮缩,分蘖增加,和叶片上不连续的白点。这些症状与一些miRNA途径的突变体非常地相似,暗示着miRNA可能在RDV致病过程中起了非常重要的作用。本实验研究了RDV侵染后水稻miRNA的转录谱。结果表明RDV对水稻miRNA几乎没有影响。只有miR397在RDV侵染后表现了轻微的上调。这表明miRNA途径的改变在RDV致病过程中可能没有发挥多大的作用。最近一些转录谱实验表明病毒侵染后许多的核糖体蛋白基因表达量升高了。考虑到有很多病毒编码定位于核仁的蛋白和核仁在核糖体生成中的作用,本实验对病毒侵染会影响到核仁生理这种可能性进行了研究。本实验选取了两个核仁基因并对他们进行了RT-PCR定量。这两个基因编码的分别是fibrillarin和Nop5。其中fibrillarin是核仁中大量存在的三种蛋白之一,Nop5是C/D盒小核仁核蛋白的一个组分。结果表明,所研究的两个基因在RDV侵染的水稻中都显著地上调了,本文中对此进行了讨论。更多还原

【Abstract】 MicroRNAs (miRNAs) are genomically encoded small non-coding RNAs that regulate flow of genetic information by controlling translation or stability of mRNAs or other ill defined mechanisms. They play important roles in plant development, signal transduction and stress responses. Many studies showed that virus infection leads to the microRNA pathway malfunction in the infected plants. Alteration of the microRNA pathway has been considered one of the most important mechanisms of viral patogenesis, although currently it is not known whether such alterations are coincidental or diliberate.RDV (Rice Dwarf Virus) is one of the most important rice infecting viruses, which causes great yield losses in some areas. Symptoms associated with RDV infection include severe dwarfism, increased tilling and white chlorotic specks on the infected leaves. These phynotypes strikingly resemble those resulted from microRNA pathway mutants. In this study, transcriptome of the microRNAs of RDV infectd rice plants were profiled, using mock inoculated rice plants as control. The results showed that RDV infection had marginal effects on rice micro RNA metabolism. Only one mieroRNA, miR397, showed morderate upregulation in RDV infected rice plants, implying that microRNAs might be not important in RDV pathogenesis.Recent transcriptome analysises of virus infected plants revealed that increased expression of a set of ribosomal genes might be a general response of plants to many viruses. Considering the fact that many viruses encode nucleolus-targeting products and the well established role of nucleolus in ribosomal biogenesis. Posibility of the alteration of nucleolar physiology in virus infected plants were investigated by detecting changes of two nucleolar genes using RT-PCR. These two genes were a gene encoding fibrillarin, one of the three most abundant proteins in the nucleolus and a gene encoding nucleolar Nop5, a component common to the box C/D small nucleolar ribonucleoproteins. The results showed that both of the two genes were significantly upregulated in RDV infected rice plants. This suggested that nucleolus might be a target of RDV infection. Implications of the nucleolus-targeting of RDV infection were disscussed.更多还原