title: Localization and Distribution of 'Candidatus Liberibacter asiaticus' in Citrus and Periwinkle by Direct Tissue Blot Immuno Assay with an Anti-OmpA Polyclonal Antibody.
abstract: 'Candidatus Liberibacter asiaticus' (CaLas), a non-cultured member of the α-proteobacteria, is the causal agent of citrus Huanglongbing (HLB). Due to the difficulties of in vitro culture, antibodies against CaLas have not been widely used in studies of this pathogen. We have used an anti-OmpA polyclonal antibody based direct tissue blot immunoassay to localize CaLas in different citrus tissues and in periwinkle leaves. In citrus petioles, CaLas was unevenly distributed in the phloem sieve tubes, and tended to colonize in phloem sieve tubes on the underside of petioles in preference to the upper side of petioles. Both the leaf abscission zone and the junction of the petiole and leaf midrib had fewer CaLas bacteria compared to the main portions of the petiole and the midribs. Colonies of CaLas in phloem sieve tubes were more frequently found in stems with symptomatic leaves than in stems with asymptomatic leaves with an uneven distribution pattern. In serial sections taken from the receptacle to the peduncle, more CaLas were observed in the peduncle sections adjacent to the stem. In seed, CaLas was located in the seed coat. Many fewer CaLas were found in the roots, as compared to the seeds and petioles when samples were collected from trees with obvious foliar symptoms. The direct tissue blot immuno assay was adapted to whole periwinkle leaves infected by CaLas. The pathogen was distributed throughout the lateral veins and the results were correlated with results of qPCR. Our data provide direct spatial and anatomical information for CaLas in planta. This simple and scalable method may facilitate the future research on the interaction of CaLas and host plant.
authors.affiliation: USDA ARS Molecular Plant Pathology Laboratory, Beltsville, Maryland, United States of America; College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, P. R. China.
authors.forename: Fang
authors.initials: F
authors.lastname: Ding
authors.affiliation: USDA ARS Horticultural Research Laboratory, Fort Pierce, Florida, United States of America.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Duan
authors.affiliation: USDA ARS Molecular Plant Pathology Laboratory, Beltsville, Maryland, United States of America.
authors.forename: Cristina
authors.initials: C
authors.lastname: Paul
authors.affiliation: University of Florida, citrus Research and Education Center, Lake Alfred, Florida, United States of America.
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Brlansky
authors.affiliation: USDA ARS Molecular Plant Pathology Laboratory, Beltsville, Maryland, United States of America.
authors.forename: John S
authors.initials: JS
authors.lastname: Hartung
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D032084:Citrus sinensis / Q000382:microbiology*; D016998:Helicobacter / Q000302:isolation & purification*; D015151:Immunoblotting; D052585:Phloem / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D012639:Seeds / Q000382:microbiology; D031053:Vinca / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; C078167:OMPA outer membrane proteins