title: PPV long-distance movement is occasionally permitted in resistant apricot hosts.
abstract: The interactions between Plum pox virus (PPV), a member of the Potyvirus genus, and Prunus host plants are, up to now, poorly understood. In the current paper, fluorescence stereomicroscopy, in situ hybridisation and immunogold detection were performed in order to evaluate the virus transport and cellular distribution. The behavior of PPV in several susceptible (cv. "Moniqui" and "Screara") and resistant apricot genotypes (cv. "Harlayne", "Henderson", "Harcot", "Goldrich", "Stella" and "Stark Early Orange") were compared. Viral RNA was detected by in situ hybridisation in stem tissues close to the inoculation point, irrespective of the resistance status of the variety. Systemic infection was evidenced by virus immunodetection and by fluorescence detection of a GFP-tagged PPV in distant leaf sections. The signal obtained by in situ hybridisation colocalised with the fluorescence produced by GFP-tagged PPV in the same plant material but did not colocalise with the signal obtained by immunostaining. Intensity of the PPV infection in susceptible apricot cultivars varied depending on genotypes. The behavior of PPV in systemic leaves was clearly distinct between susceptible and resistant cultivars. While PPV was spreading widely around the major and minor veins in susceptible leaves, in the resistant apricot genotypes it was restricted to isolated spots consisting of few cells embedded in the mesophyll tissue. In summary, differences in the ability of PPV to systemically infect susceptible and resistant apricot cultivars were evident but nevertheless, long-distance transport of PPV occured in resistant apricot scions.
authors.affiliation: Unité Mixte de Recherches INRA-Université Bordeaux 2 Génomique et Développement du Pouvoir Pathogène, IBVM, BP 81, F-33883 Villenave d'Ornon, France.
authors.forename: Ligia
authors.initials: L
authors.lastname: Ion-Nagy
authors.forename: Micheline
authors.initials: M
authors.lastname: Lansac
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Eyquard
authors.forename: Beatriz
authors.initials: B
authors.lastname: Salvador
authors.forename: Juan-Antonio
authors.initials: JA
authors.lastname: Garcia
authors.forename: Olivier
authors.initials: O
authors.lastname: Le Gall
authors.forename: Michel
authors.initials: M
authors.lastname: Hernould
authors.forename: Valérie
authors.initials: V
authors.lastname: Schurdi-Levraud
authors.forename: Véronique
authors.initials: V
authors.lastname: Decroocq
mesh_terms: D004198:Disease Susceptibility; D008124:Locomotion; D010935:Plant Diseases / Q000821:virology; D018515:Plant Leaves / Q000821:virology; D017801:Plum Pox Virus / Q000502:physiology*; D027861:Prunus / Q000235:genetics / Q000821:virology*; D013045:Species Specificity