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Title: SYSTEMIC MOVEMENT OF POTATO SPINDLE TUBER VIROID PROVIDES INSIGHTS INTO RNA TRAFFICKING

Author
item ZHU, YALI - OK ST UNIV STILLWATER OK
item GREEN, LARRY - OK ST UNIV STILLWATER OK
item YOUNG-MIN, WOO - OK ST UNIV STILLWATER OK
item Owens, Robert
item DING, BIAO - OK ST UNIV STILLWATER OK

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Viroids are the smallest known agents of infectious disease -- small, highly structured, RNA molecules lacking the protein coat characteristic of conventional viruses. A wide variety of crop species are susceptible to viroid infection, and several of the resulting diseases are of considerable economic importance. A lack of conventional genetic resistance has frustrated breeders' efforts to produce plants that are resistant/immune to viroid diseases, and we are trying to identify novel strategies to create such resistance de novo. This study describes certain events that occur as viroids move throughout an infected plant. These events represent potential targets that, if interrupted, could render plants resistant to viroid infection. Our results will be of greatest interest to other researchers interested in how viruses and other RNAs move in plants. Additional research is necessary before we can begin efforts to develop disease-resistant plants.

Technical Abstract: Viroids are small, non-translatable pathogenic RNAs that replicate autonomously and traffic systemically in their host plants. We have used in situ hybridization to analyze the trafficking pattern of potato spindle tuber viroid (PSTVd) in tomato and Nicotiana benthamiana. When PSTVd was inoculated onto the stem of a plant, it replicated and trafficked to sink, but not source, leaves. PSTVd was absent from shoot apical meristems. In the flowers of infected plants, PSTVd was present in the sepals, but was absent in the petals, stamens, and ovary. The replicative form of PSTVd was detected in the phloem. Our data demonstrate the (i) PSTVd traffics long distance in the phloem and this trafficking is likely sustained by replication of the viroid in the phloem, and (ii) PSTVd trafficking is governed by plant developmental and cellular factors. We suggest that PSTVd employs cellular mechanisms for RNA trafficking and that viroids may be used to uncover such mechanisms.