Insights into the selective pressures restricting Pelargonium flower break virus genome variability: Evidence for host adaptation.
The molecular diversity of Pelargonium flower break virus (PFBV) was assessed using a collection of isolates from different geographical origins, hosts, and collecting times. The genomic region examined was 1,828 nucleotides (nt) long and comprised the coding sequences for the movement (p7 and p12) and the coat (CP) proteins, as well as flanking segments including the entire 3' untranslated region (3' UTR). Some constraints limiting viral heterogeneity could be inferred from sequence analyses, such as the conservation of the amino acid sequences of p7 and of the shell domain of the CP, the maintenance of a leucine zipper motif in p12, and the preservation of a particular folding in the 3' UTR. A remarkable covariation, involving five specific amino acid sites, was found in the CP of isolates largely propagated in the local lesion host Chenopodium quinoa and in the progeny of a PFBV variant subjected to serial passages in this host. Concomitant with this covariation, up to 30 nucleotide substitutions in a 1,428-nt region of the viral RNA could be attributable to C. quinoa-specific adaptation, representing one of the most outstanding cases of host-driven genome variation for a plant virus. Globally, the results indicate that the selective pressures exerted by the host play a critical role in shaping PFBV populations and that these populations are likely being selected for at both protein and RNA levels.
Rico
Patricia
P
Instituto de Biología Molecular y Celular de Plantas (CSIC-UPV), Campus Universidad Politécnica de Valencia, Avenida de los Naranjos s/n, 46022 Valencia, Spain.
Ivars
Pilar
P
Elena
Santiago F
SF
Hernández
Carmen
C
D020413:3' Untranslated Regions / Q000737:chemistry / Q000378:metabolism; D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001483:Base Sequence; D036022:Capsid Proteins / Q000145:classification / Q000235:genetics*; D019184:Carmovirus / Q000235:genetics*; D027465:Chenopodium quinoa / Q000502:physiology / Q000821:virology; D017124:Conserved Sequence; D014644:Genetic Variation; D016679:Genome, Viral; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012641:Selection, Genetic
D020413:3' Untranslated Regions; D036022:Capsid Proteins