Biochemistry and molecular biology of a model viroid

类病毒是小的单链环状RNA，通过DNA独立的滚环机制进行复制。当它们感染高等植物时，它们会引起疾病，导致农业的重大损失。这些RNA物种同时具有遗传型和表型(例如催化RNA)特性。因此，它们被描述为细胞前RNA世界的模型“遗迹”。从本质上讲，类病毒构成了一个最小的生物系统，非常适合于详细的RNA结构/功能分析。自上一次资助以来，我们在桃潜伏花叶类病毒(PLMVd)作为模式RNA物种的表征方面取得了重大进展，在寻找新的变体、研究其结构、阐明其复制机制以及显示它如何启动转录后基因沉默方面取得了进展。我们目前的目标仍然是完全理解PLMVd的生命周期。根据这一目标，我们的具体目标是：

Viroids are small, single-stranded, circular RNAs that replicate through a DNA-independent rolling circle mechanism. When they infect higher plants, they cause diseases that result in significant losses in the agricultural industry. These RNA species possess both genotypic and phenotypic (e.g. catalytic RNA) properties. They have consequently been described as model "relics" of a pre-cellular RNA world. In essence, viroids constitute a minimal biological system ideal for detailed RNA structure/function analyses. Since our last funding, we have made significant progress in the characterization of the peach latent mosaic viroid (PLMVd) as a model RNA species, with advances in finding new variants, studying its structure, elucidating its replication mechanism, and showing how it switches "on" posttranscriptional gene silencing. Our current goal remains to fully comprehend the PLMVd life cycle. Inherent to this goal, our specific objectives are: