Submitted to: International Organization of Citrus Virologists Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/22/2005
Publication Date: 1/10/2007
Citation: Palmieri, M., Donis, I., Salazar, A.L., Cruz, N., Paniagua, A., Brlansky, R.H., Guerra-Moreno, A., Keremane, M.L., Ballance, P.M., Lee, R.F. 2007. Citrus Viruses in Guatemala: Application of Laboratory-Based Assays. International Organization of Citrus Virologists Proceedings, 16th Conference, Pgs. 386-391. Interpretive Summary: There was a need to identify what citrus graft transmissible pathogens were present in Guatemala, but this was difficult because of the lack of indicator plants and facilities for biological indexing. A procedure was developed whereby total nucleic acid extracts were done from field plants surveyed in Guatemala. These extracts were later tested for several graft transmissible pathogens, both viruses and prokaryotes, using laboratory assays. The procedure reported should be useful to testing of multiple pathogens in germplasm collections from the same extraction. The results of the survey from Guatemala are reported.
Technical Abstract: In preparation for a citrus certification in Guatemala, there was an urgent need to determine which graft transmissible citrus pathogens were present. Because of the lack of biological indicator plants, Citrus tristeza virus (CTV) and Xylella fastidiosa, causal agent for citrus variegated chlorosis, were tested for by ELISA, and we developed a protocol for the extraction of the total nucleic acids from the samples to enable later RT-PCR testing for CTV, Citrus psorosis virus, Citrus exocortis viroid (CEV), cachexia, Group III viroids and PCR testing for X. fastidiosa. CTV was found in all citrus areas sampled, but was less prevalent in the central citrus area. The RT-PCR testing proved to be more sensitive than the ELISA testing for CTV. X. fastidiosa was detected in one sample by ELISA testing, but this was not confirmed by PCR testing. Viroids (CEV, cachexia, and Group III viroids) were commonly found in samples collected from the three main citrus areas. Psorosis virus was not detected by RT-PCR, and these results were confirmed later by biological indexing.