Molecular studies on a complex of potyviruses infecting solanaceous crops, and some specific virus-host interactions

摘要: This thesis constitutes a comprehensive analysis of the molecular and biological characteristics three potyviruses (genus Potyvirus, family Potyviridae) naturally occurring in cultivated wild species Solanaceae: Peru tomato virus (PTV), Potato V (PVV) Wild potato mosaic (WPMV). In addition, studies presented this focus on genetic variability isolates PTV PVV role A (PVA) 6K2 protein as host-specific determinant movement symptom induction. Determination complete genomic sequences PVV, WPMV demonstrated that these viruses are typical members genus Potyvirus. Furthermore, comparison polyprotein amino acid serological supported their current taxonomic position independent The nucleotide P1 protein, coat non-translated regions European South American were determined compared. Results showed limited among isolates, contrast to higher found PVV. Phylogenetic defined two distinct clusters, grouping together but placing different group; did not induce hypersensitive response an Nv gene-carrying cultivar isolates. Thus, belong strain groups. great was detected Analysis phylogenetic relationships PTV, other Potyvirus commonly infecting solanaceous crop plants most closely related which with Y, Pepper mottle virus, severe yellow constitute group distinguishable from potyviruses. seem share common ancestor. PVA modified by deleting various portions or introducing six histidine residues (6xHis) into positions protein. These modifications disturbed functions required for viral infection Nicotiana tabacum. inoculation insertion constructs N. benthamiana result systemic exception one plant. plant lacked symptoms had titers similar infected type virus: single point mutation (Gly2 ® Cys2) 6xHis-containing restored functions. However, partial deletion 6xHis-tag gain original size restore induction enable Taken together, results indicate is long-distance exemplify mutations arise during propagation represent mechanisms can evolve adapt hosts.