Detection and Identification of a ' Candidatus Liberibacter solanacearum' Species from Ash Tree Infesting Psyllids

• Published in: Phytopathology Vol. 112; no. 1; pp. 76 - 80
• Main Authors: Wamonje, Francis O, Zhou, Ningxing, Bamrah, Ramandeep, Wist, Tyler, Prager, Sean M
• Format: Journal Article
• Language: English
• Published: United States 01.01.2022
• Subjects: Animals; Fraxinus; Hemiptera; Liberibacter; Plant Diseases; Rhizobiaceae - genetics; forest pathology; host–parasite interactions; pathogen detection; cottony ash psyllid; Candidatus Liberibacter; bioinformatics; ash dieback disease; microbe–genome sequencing
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO-02-21-0060-SC

' Liberibacter' species are associated with severe, economically important diseases. Nearly all known species are putatively insect transmitted, specifically by psyllids. Detection of ' Liberibacter' in plants is complicated by their uneven distribution in host plants and largely fastidius nature. The death of black ( ) and mancana ( ) ash trees in Saskatchewan, Canada has been associated with infestation by the cottony ash psyllid ( ). A combination of conventional PCR amplification and Sanger sequencing of the 16S recombinant DNA was used to detect and identify ' Liberibacter' in psyllids collected from ash trees in Saskatchewan. BLAST analysis of two 16S sequences that were 1,058 and 1,085 bp long (NTHA 5, GenBank accession number MK942379 and NTHA 6, GenBank accession number MK937570, respectively) revealed they were 99 to 100% similar to a ' Liberibacter solanacearum' sequence (GenBank accession number KX197200) isolated from the Nearctic psyllid ( ) of U.S. provenance. Sequencing the psyllid genes and confirmed that the psyllids from which the bacterial DNA was isolated were , based on comparisons with sequences in GenBank and BOLD and a reference sample from the United Kingdom. These results provide the first evidence that ' Liberibacter solanacearum' species are associated with psyllids collected from ash trees and specifically . The recent episodes of dieback of ash in Saskatchewan associated with psyllid feeding are consistent with disease symptoms caused by ' Liberibacter' pathogens, and this possibility warrants further study.