Viroid models to study evolution of RNA trafficking motifs for host adaptation

感染性rna，包括类病毒和病毒，必须在细胞之间进行运输，以建立全身性感染。该项目解决了非编码RNA结构基序在宿主适应贩运中的作用。它验证了以下假设：(i)感染性RNA可以快速进化出新的三维（3D）基序用于运输，作为宿主适应的一种手段，以及（ii）不同的感染性RNA可以进化出不同的运输基序以适应同一宿主。这一假设是根据以下观察得出的。首先，当马铃薯纺锤体块茎类病毒（PSTVd）的一个称为环19的特定基序被删除以消除实验寄主植物烟叶（Nicotiana benthamiana）中的贩运（但不复制）时，进化出一个新的环19*来恢复贩运。其次，一些类病毒，如Hop stunt virus (HSVd)，在序列上与PSTVd有显著差异，但也能全身感染benthamiana。为了验证这一假设，将进行以下实验：1)阐明环19的三维结构，确定环19*是否具有相似的结构；2)确定环19和环19*发挥作用的细胞边界；3)对hsv转运基序进行全基因组突变鉴定，并将其与已经鉴定的PSTVd基序进行异同比较。该项目将为感染性rna进化的分子机制以及控制不同rna系统运输的统一和独特原理提供新的知识。新的研究工具和实验系统的开发也可能有助于改变RNA结构-功能关系的一般原理的研究。该项目将培养本科生/研究生发展前沿的跨学科方法来研究基础生物学问题，并帮助加强对小学/初中/高中学生的科学教育，包括传统上代表性不足的群体。

Infectious RNAs including viroids and viruses must traffic between cells in order to establish systemic infection. This project addresses the role of noncoding RNA structural motifs for trafficking in host adaptation. It tests the hypothesis that (i) an infectious RNA can rapidly evolve new three-dimensional (3D) motifs for trafficking as a means of host adaptation, and (ii) different infectious RNAs can evolve distinct trafficking motifs for adaptation to the same host. This hypothesis was developed from the following observations. First, when a particular motif, called loop 19, of Potato spindle tuber viroid (PSTVd) was obliterated to abolish trafficking (but not replication) in the experimental host plant Nicotiana benthamiana, a new loop (loop 19*) evolved to restore trafficking. Second, some viroids, such as Hop stunt viroid (HSVd), differ significantly in sequences from PSTVd but also can infect N. benthamiana systemically. To test this hypothesis, the following experiments will be performed: 1) to elucidate the 3D structure of loop 19 and determine whether loop 19* is similarly structured, 2) to determine the cellular boundary at which loop 19 and loop 19* function, and 3) to perform a genome-wide mutational identification of HSVd trafficking motifs and compare them with the PSTVd motifs that have already been identified for similarities and differences.This project will contribute new knowledge about the molecular mechanisms underlying the evolution of infectious RNAs and broadly the unifying and unique principles controlling the systemic trafficking of different RNAs. New research tools and experimental systems developed may also help transform research on the general principles of RNA structure-function relationships. This project will train undergraduate/graduate students in developing cutting-edge cross-disciplinary approaches to study fundamental biological problems, and help enhance science education for elementary/middle/high school students, including traditionally underrepresented groups.