Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/10/2013
Publication Date: 7/10/2013
Citation: Munyaneza, J.E., Sengoda, V.G., Aguilar, E., Bextine, B.R., Mc Cue, K.F. 2013. First report of "Candidatus Liberibacter solanacearum" infecting eggplant in Honduras. Plant Disease. 97:1654 http://dx.doi.org/10.1094/PDIS-06-13-0641-PDN. Interpretive Summary: Liberibacter is an economically important bacterium that severely damages several crops including potato, tomato, pepper, and other related crops. This plant pathogen is transmitted to these crops by the potato psyllid, a serious insect pest in the United States. Researchers at USDA-ARS Wapato, WA and Albany, CA, University of Texas, and Zamorano University in Honduras discovered for the first time that this bacterium was infecting eggplant crops in Honduras, posing a serious threat to the vegetable industry in the country. Eggplants constitute an important commodity in Central America; therefore, developing effective management strategies for both the bacterium and its insect vector is important to world food security.
Technical Abstract: In May of 2012, eggplant (Solanum melongena) plants in an experimental research plot located at Zamorano in the Department of Francisco Morazán, Honduras, were observed with symptoms that included leaf chlorosis and cupping, overall stunting, and production of small and malformed fruits. The research plot was planted next to a commercial tomato field heavily infested with the psyllid Bactericera cockerelli, a vector “Candidatus Liberibacter solanacearum”. This bacterium severely affects potato and other solanaceous species and is the putative causal agent of zebra chip disease. The plot was planted with the eggplant variety “China” and about 25% of the plants were symptomatic. A total of 10 eggplant samples, including five symptomatic and five asymptomatic plants, were collected from the plot. Total DNA was extracted from the leaf tissue of each of the collected plants with the cetyltrimethylammonium bromide (CTAB) buffer extraction method. The DNA samples were then tested by PCR using specific primer sets OA2/OI2c and OMB 1482f/2086r, to amplify a portion of 16S rDNA and the outer membrane protein (OMB) genes, respectively, of “Ca. L. solanacearum”. OMB gene and 16S rDNA fragments of 605 and 1168 bp, respectively, were amplified from the DNA of two of the five (40%) symptomatic plants with each primer set, indicating the presence of “Ca. L. solanacearum”. No “Ca. L. solanacearum” was detected in the five asymptomatic plants with either primer sets. Further cloning and sequencing the amplified products confirmed presence in the eggplants. To our knowledge, this is the first report of “Ca. L. solanacearum” associated with eggplant in Honduras. Eggplant is an economically important commodity in Central America and serious damage to this crop due to this plant pathogen could expand throughout the region, especially if its insect vector B. cockerelli is not properly managed.