Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 8/3/2019
Publication Date: 10/21/2019
Citation: Swisher Grimm, K.D., Garczynski, S.F., Horton, D.R., Charlton, B.A. 2019. Identification of new ‘Candidatus Liberibacter solanacearum’ haplotypes in Solanum tuberosum and psyllid family Aphalaridae in Klamath Basin, Oregon. Phytopathology. 109:S.119-120.
Interpretive Summary: Zebra chip is an economically important disease of potato in the United States, associated with the 'Candidatus Liberibacter solanacearum' (Lso) bacterium that is vectored by the potato psyllid. Recently, researchers at the USDA Agricultural Research Service in Prosser and Wapato, Washington, identified a new genetic variant, or haplotype, of Lso in potato in the Klamath Basin of Oregon. To identify the insect vector of this new Lso haplotype, USDA researchers collaborated with Oregon State University to analyze psyllids collected in or near potato fields in this region of Oregon. Analyses identified another new haplotype of Lso in psyllids of the Aphalaridae family. These findings are the first report of this pathogen in potato and psyllids in this region of the United States, and indicate the need for further research to discover the potential impact of these Lso haplotypes on this important vegetable crop.
Technical Abstract: In the United States, two haplotypes of ‘Candidatus Liberibacter solanacearum,’ A and B, have been shown to cause zebra chip disease symptoms in potato, Solanum tuberosum. In 2017, a single potato tuber from the Klamath Basin of Oregon showed classic zebra chip symptoms of darkened, striped vascular tissue and tested positive for ‘Ca. L. solanacearum’ by conventional polymerase chain reaction. Analysis of the 16S ribosomal RNA gene, 50S ribosomal proteins L10/L12 genes, and the outer membrane protein gene identified a new haplotype of ‘Ca. L. solanacearum,’ designated as haplotype F. Since potato psyllid is the known vector of ‘Ca. L. solanacearum’ haplotypes A and B, psyllids were collected from sticky cards placed in or near potato fields in the Klamath Basin to identify the insect vector of ‘Ca. L. solanacearum’ haplotype F. No potato psyllids were seen, but psyllids of the Aphalaridae family (which likely do not develop on potato) were numerous, and a subset tested positive for ‘Ca. L. solanacearum.’ Further analysis of the 16S ribosomal RNA gene, 50S ribosomal proteins L10/L12 genes, and the outer membrane protein gene identified another new haplotype of ‘Ca. L. solanacearum’ in the Aphalaridae psyllids, designated as haplotype G. These findings are the first reported identification of ‘Ca. L. solanacearum’ in the Klamath Basin of Oregon. Further research to explore the impact of these haplotypes on potato in this region of the Pacific Northwest is needed.