title: Colonization and Intrusive Invasion of Potato Psyllid by 'Candidatus Liberibacter solanacearum'.
abstract: Previous studies have shown that the fastidious bacterial plant pathogen 'Candidatus Liberibacter solanacearum' (CLso) is transmitted circulatively and propagatively by the potato psyllid (PoP) Bactericera cockerelli. In this study, the temporal and spatial interrelationships between CLso PoP were investigated by scanning electron microscopy of the digestive system of PoP immature and adult instars and salivary glands of adults post CLso ingestion. CLso biofilms were not detectable on the outer midgut surface of the first and second instars; however, for third to fifth instars and teneral and mature adults, biofilms were observed in increasing numbers in each successive developmental stage. In adult PoP midguts, CLso cells were observed between the basal lamina and basal epithelial cell membranes; in basal laminar perforations, on the outer basal laminar surface, and in the ventricular lumen, epithelial cytosol, and filter chamber periventricular space. CLso were also abundantly visible in the salivary gland pericellular spaces and in the epidermal cell cytosol of the head. Collectively, these results point to an intrusive, systemic invasion of PoP by CLso that employs an endo/exocytosis-like mechanism, in the context of a propagative, circulative mode of transmission.
authors.affiliation: First, second, and fifth authors: School of Plant Sciences, 303 Forbes Bld., University of Arizona, Tucson 85721; and third and fourth authors: Southwest Florida Research & Education Center, University of Florida IFAS, 2685 State Road 29 North, Immokalee 34142.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Cicero
authors.affiliation: First, second, and fifth authors: School of Plant Sciences, 303 Forbes Bld., University of Arizona, Tucson 85721; and third and fourth authors: Southwest Florida Research & Education Center, University of Florida IFAS, 2685 State Road 29 North, Immokalee 34142.
authors.forename: Tonja W
authors.initials: TW
authors.lastname: Fisher
authors.affiliation: First, second, and fifth authors: School of Plant Sciences, 303 Forbes Bld., University of Arizona, Tucson 85721; and third and fourth authors: Southwest Florida Research & Education Center, University of Florida IFAS, 2685 State Road 29 North, Immokalee 34142.
authors.forename: Jawwad A
authors.initials: JA
authors.lastname: Qureshi
authors.affiliation: First, second, and fifth authors: School of Plant Sciences, 303 Forbes Bld., University of Arizona, Tucson 85721; and third and fourth authors: Southwest Florida Research & Education Center, University of Florida IFAS, 2685 State Road 29 North, Immokalee 34142.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Stansly
authors.affiliation: First, second, and fifth authors: School of Plant Sciences, 303 Forbes Bld., University of Arizona, Tucson 85721; and third and fourth authors: Southwest Florida Research & Education Center, University of Florida IFAS, 2685 State Road 29 North, Immokalee 34142.
authors.forename: Judith K
authors.identifier: http://orcid.org/0000-0003-4669-8443
authors.initials: JK
authors.lastname: Brown
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D005260:Female; D041981:Gastrointestinal Tract / Q000382:microbiology / Q000648:ultrastructure; D006430:Hemiptera / Q000382:microbiology* / Q000648:ultrastructure; D007303:Insect Vectors / Q000382:microbiology* / Q000648:ultrastructure; D010935:Plant Diseases / Q000382:microbiology*; D012230:Rhizobiaceae / Q000502:physiology* / Q000648:ultrastructure; D012469:Salivary Glands / Q000382:microbiology; D011198:Solanum tuberosum / Q000382:microbiology*