|Doddapaneni,, Harsha - UC DAVIS|
|Venkatesan, Sengoda - WASHINGTON STATE UNIV|
Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 28, 2008
Publication Date: March 1, 2009
Citation: Lin, H., Doddapaneni,, H., Munyaneza, J.E., Civerolo, E.L., Venkatesan, S.G., Buchman, J.L., Stenger, D.C. 2009. Molecular characterization and Phylogenetic analysis of 16S rRNA from a new Candidatus Liberibacter strain associated with Zebra chip disease of Potato (Solanum tuberosum L.) and the potato psyllid. Journal of Plant Pathology. 91:215-219. Interpretive Summary: Zebra chip disease is a serious disease of unknown cause affecting potato. Chips processed from diseased tubers have dark colored stripes, rendering them unmarketable. In an effort to identify the causal agent of Zebra Chip disease, a PCR assay able to detect Candidatus Liberibacter DNA was developed. PCR results indicated that Ca. liberabacter DNA was present not only in diseased potato tubers, but also in the potato pysllid, the presumed insect vector of the Zebra Chip disease agent. DNA sequence comparisons indicated that the Zebra chip disease-associated Ca. Liberibacter was related to but distinct from three other Ca. Liberibacter species previously associated with Huanglongbing disease of citrus.
Technical Abstract: The full-length 16S rRNA gene region of a new Candidatus Liberibacter strain was PCR amplified from tubers of potato plants showing Zebra Chip (ZC) disease symptoms and also from the potato psyllid [Bactericera (= Paratrioza) cockerelli Sulc], the presumptive vector of the ZC disease causal agent. Primers were designed based on conserved regions of 16S rRNA gene from three known Ca. Liberibacter spp. (associated with citrus Huanglongbing disease) and used to amplify target DNA sequences from plant tissues infected with each known Ca. Liberibacter spp. and also from ZC diseased potatoes and potato psyllid samples. Sequences of the amplicons from ZC diseased potato and potato psyllids were 100 % identical but differed from Ca. L. asiaticus (Las) and Ca. L. africanus (Laf) by 4 % and from Ca. L. americanus (Lam) by 6.0 – 6.3 %. Sequence alignments revealed that a 20 bp deletion was unique to Lam. Neighbor-joining analysis placed the ZC disease-associated sequences in a monophyletic clade consisting of all known Ca. Liberibacter spp., positioned in the tree basal to a node shared exclusively by Las and Laf but proximal to a node shared by Lam and all other Ca. Liberibacter spp. Collectively, these results indicate that the potato ZC associated strain is related to but distinct from previously characterized Ca. Liberibacter spp. associated with Huanglongbing disease of citrus.