|OWENS, ROBERT - Retired ARS Employee|
|DEAHL, KENNETH - Retired ARS Employee|
Submitted to: Journal of Virological Methods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2013
Publication Date: 12/31/2013
Citation: Kovalskaya, N.Y., Owens, R.A., Baker, C.J., Deahl, K., Hammond, R. 2013. Application of a modified EDTA-mediated exudation technique and guttation fluid analysis for potato spindle tuber viroid RNA detection in tomato plants (Solanum lycopersicum). Journal of Virological Methods. 198:75-81.
Interpretive Summary: Yield losses caused by viroids (small noncoding infectious RNAs) can reach 17-64% depending on the viroid strain and plant crop species. To develop effective measures to combat viroid infection, it is important to understand how the viroids spread throughout the plant and to identify signal molecules responsible for plant immunity. We modified and applied methods for detection of viroid RNA exclusively in phloem and xylem cells that transport nutrients and water in plants. We report the presence of viroid RNA in phloem and its absence in xylem tissues. The results of our research will be of interest to scientists who are developing new approaches for detection of wide range of plant pathogens and signal molecules involved in plant resistance.
Technical Abstract: Potato spindle tuber viroid (PSTVd) is a small plant pathogenic circular RNA that does not encode proteins, replicates autonomously, and traffics systemically in infected plants. Long-distance transport occurs by way of the phloem; however one report in the literature describes the presence of viroid RNA in the xylem ring. In this study, we applied a modified method based on an EDTA-mediated phloem exudation technique for detection of PSTVd in the phloem of infected tomato plants. RT-PCR, nucleic acid sequencing, and Southern blot analyses of RT-PCR products verified the presence of viroid RNA in phloem exudates. In addition, we analyzed guttation fluid collected from the leaves of PSTVd-infected tomato plants and demonstrated the absence of viroid RNA in the xylem sap. To our knowledge, this is the first report of PSTVd RNA detection in phloem exudates obtained by the EDTA-mediated exudation technique.