|Nelson, Warrick -|
|Sengoda, Venkatesan -|
|Alfaro-Fernandez, Ana -|
|Font, Maria -|
Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 17, 2012
Publication Date: March 3, 2013
Citation: Nelson, W.R., Sengoda, V.G., Alfaro-Fernandez, A.O., Font, M.I., Crosslin, J., Munyaneza, J.E. 2013. A new haplotype of 'Candidatus Liberibacter solanacearum' identified in the Mediterranean region. European Journal of Plant Pathology. 135:633-639. DOI:10.1007/s10658-012-0121-3. Interpretive Summary: Zebra chip, a new and economically important disease of potato in the United States, Mexico, Central America, and New Zealand, is caused by a previously undescribed species of the bacterium liberibacter vectored by the potato psyllid. Researchers at the USDA-ARS Yakima Agricultural Research Laboratory, in collaboration with scientists at USDA-ARS Prosser, Plant and Food Research Institute in New Zealand, and Polytechnic University of Valencia in Spain, identified a new genetic variant of this bacterium species in carrots in the Mediterranean region. Information from this research will help affected potato and carrot producers reduce damage caused by this important pathogen by effectively managing the appropriate bacterium variant and respective insect vectors.
Technical Abstract: “Candidatus Liberibacter solanacearum”, a phloem-limited and Gram-negative bacterium that is spread from infected to healthy plants by psyllid insect vectors, is an economically important pathogen of solanaceous and carrot crops in the Americas, New Zealand and Europe. Three haplotypes of “Ca. L. solanacearum” have previously been described, two (LsoA and LsoB) in relation to solanaceous crops in the Americas and New Zealand and the third (LsoC) to carrots in Finland. Herein, we describe a fourth haplotype of this ‘Candidatus Liberibacter’ species (LsoD), also associated with carrots, but from Spain and Canary Islands and vectored by the psyllid Bactericera trigonica. In addition, LsoC was confirmed in carrot and psyllid samples recently collected from Sweden and Norway. Phylogenetic analysis of the 16s rRNA gene suggests that two of the haplotypes, one in the Americas and the other in northern Europe are closer to each other in spite of a large geographic separation and host differences. Furthermore, during this study, potatoes with symptoms of zebra chip disease recently observed in potato crops in Idaho, Oregon and Washington states were analyzed for haplotype and were found to be positive for LsoA. This Liberibacter haplotype was found in psyllids associated with the diseased potato crops as well. This finding contrasts with an earlier report of LsoB from psyllids in Washington which came from a laboratory colony originally collected in Texas.