Biochemistry and molecular biology of a model viroid.

一株模型类病毒的生物化学和分子生物学研究 类病毒感染世界各地的高等植物，引起疾病，不仅影响到粮食，还影响到观赏植物和工业植物，给农业造成重大损失。类病毒是小的(250-400个核苷酸)，单链的环状RNA，通过DNA独立的滚环机制进行复制。尽管它们不编码任何已知的蛋白质，也不受蛋白质衣壳的保护，但类病毒可以避开植物的细胞防御机制，充当寄生虫，使它们成为迄今发现的最小的自我复制的遗传元件。从本质上讲，这些物种构成了详细分析RNA结构/功能的理想生物系统。我们的模式种是桃潜伏花叶类病毒(PLMVd)。 我们的长期目标是了解类病毒是如何在受感染的树木中引起致病的。为此，我们将回答来自不同学科的三个问题，说明该研究计划的综合方法： 1.通过深度测序，我们将研究PLMVd内的种群动态，并提出一个实用的准种(遗传)的定义； 2.我们将进一步分析类病毒小干扰RNA，并鉴定受感染树中表达发生变化的桃树内源miRNA，以了解这种机制与发病机制的关系(分子生物学)； 3.考虑到结构的阐明对了解类病毒的生活史至关重要，我们将确定每个类病毒物种的至少一个变种的结构和相关的环状卫星RNA(结构生物化学)。 简而言之，我们将使用类病毒来推进生命科学的边界。

Biochemistry and Molecular Biology of a Model Viroid Viroids infect higher plants worldwide causing diseases which result in significant losses for agriculture affecting not only food, but ornamental and industrial plants. Viroids are small (250-400 nt), single-stranded, circular RNAs that replicate through a DNA-independent rolling circle mechanism. Although they do not code for any known protein and are not protected by a protein capsid, viroids can obviate a plant's cellular defense mechanism and act as parasites, making them the smallest self-replicating genetic elements identified to date. In essence, these species constitute an ideal biological system for detailed RNA structure/function analyses. Our model species is the Peach latent mosaic viroid (PLMVd). Our long term goal is to learn how viroids elicit pathogenesis in infected trees. To do so, we will address three questions, from distinct disciplines, illustrating the integrative approach of this research program: 1. By deep-sequencing, we will investigate the dynamics of population within PLMVd, and put forth a practical definition of quasispecies (Genetic); 2. We will further our analysis of viroid small interfering RNAs and identify peach endogenous miRNA with altered expression in infected trees in order to understand how this mechanism relates to pathogenesis (Molecular Biology); and; 3. Considering that structure elucidation is paramount to understanding viroid life cycle, we will determine the structure of at least one variant of every viroid species and related circular satellite RNAs (Structural Biochemistry). In brief, we will use viroids to advance boundaries of life sciences.