title: Differential tropism in roots and shoots infected by Citrus tristeza virus.
abstract: Virus tropism is a result of interactions between virus, host and vector species, and determines the fate of an infection. In this study, we examined the infection process of Citrus tristeza virus (CTV) in susceptible and resistant species, and found that the tropism of CTV is not simply phloem limited, but tissue specific. In resistant species, virus infection was not prevented, but mostly restricted to the roots. This phenomenon was also observed after partial replacement of genes of one CTV strain from another, despite both parental strains being capable of systemic infection. Finally, the roots remained susceptible in the absence of viral gene products needed for systemic infection of shoots. Our results suggest that all phloem cells within a plant are not equally susceptible and that changes in host or virus may produce a novel tropism: restriction by the host to a location where further virus spread is prevented.
authors.affiliation: Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA. Electronic address: sjharper@ufl.edu.
authors.forename: S J
authors.initials: SJ
authors.lastname: Harper
authors.affiliation: Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Cowell
authors.affiliation: Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Robertson
authors.affiliation: Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA.
authors.forename: W O
authors.initials: WO
authors.lastname: Dawson
mesh_terms: D002957:Citrus / Q000821:virology*; D017790:Closterovirus / Q000502:physiology*; D052585:Phloem / Q000821:virology; D010935:Plant Diseases / Q000821:virology*; D018517:Plant Roots / Q000821:virology*; D018520:Plant Shoots / Q000821:virology*; D056189:Viral Tropism
keywords: Citrus tristeza virus; Movement; Resistance; Tropism