‘Candidatus Liberibacter solanacearum’ distribution and diversity in Scotland and the characterisation of novel haplotypes from Craspedolepta spp. (Psylloidea: Aphalaridae)

Abstract

The phloem limited bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) is associated with disease in Solanaceous and Apiaceous crops. This bacterium has previously been found in the UK in Trioza anthrisci, but its impact on UK crops is unknown. Psyllid and Lso diversity and distribution among fields across the major carrot growing areas of Scotland were assessed using real-time PCR and DNA barcoding techniques. Four Lso haplotypes were found: C, U, and two novel haplotypes. Lso haplotype C was also found in a small percentage of asymptomatic carrot plants (9.34%, n = 139) from a field in Milnathort where known vectors of this haplotype were not found. This is the first report of Lso in cultivated carrot growing in the UK and raises concern for the carrot and potato growing industry regarding the potential spread of new and existing Lso haplotypes into crops. Trioza anthrisci was found present only in sites in Elgin, Moray with 100% of individuals harbouring Lso haplotype C. Lso haplotype U was found at all sites infecting Trioza urticae and at some sites infecting Urtica dioica with 77.55% and 24.37% average infection, respectively. The two novel haplotypes were found in Craspedolepta nebulosa and Craspedolepta subpunctata and named Cras1 and Cras2. This is the first report of Lso in psyllids from the Aphalaridae. These new haplotypes were most closely related to Lso haplotype H recently found in carrot and parsnip. Lso was also detected in several weed plants surrounding carrot and parsnip fields. These included two Apiaceous species Aegropodium podagraria (hap undetermined) and Anthriscus sylvestris (hap C); one Gallium sp. (Rubiaceae) (hap undetermined); and Chenopodium album (Amaranthaceae) (hap undetermined).

Uncovering Symbionts Across the Psyllid Tree of Life and the Discovery of a New Liberibacter Species, “Candidatus” Liberibacter capsica

“…The species Ca. L. psyllaurous is known to establish facultative infections in psyllids within the Bactericera and Trioza genera and has recently been detected in two Craspedolepta species (family Aphalaridae) collected in the United Kingdom (Sumner-Kalkun et al, 2020). Ca.…”

Identification of three new ‘Candidatus Liberibacter solanacearum’ haplotypes in four psyllid species (Hemiptera: Psylloidea)

“…Phylogenetic comparison of the nucleic acid sequences from each of these genes identified these new sequences as most closely related to the newly described Ca. L. solanacearum haplotype H, identified in Finland from plant species in the Polygonaceae, and haplotypes Cras1a/1b and Cras2, discovered in Scotland infecting Craspedolepta (Aphalaridae) psyllids 19,20 . 'Ca.…”

Assessment of Psyllid Handling and DNA Extraction Methods in the Detection of ‘Candidatus Liberibacter Solanacearum’ by qPCR

“…Two haplotypes designated as H were described, one in carrots and in two species of Poligonaceae: Persicaria lapathifolia L. and Fallopia convolvulus L. in Finland [12], and another in Convolvulaceae species in USA [28]. Finally, haplotypes Cra1 and Cra2 have been found in psyllids from the Aphalaridae family: Craspedolepta nebulosa (Zetterstedt, 1828) and C. subpunctata (Foerster, 1848) in United Kingdom [29].…”