ABSTRACT
Triple gene block 1 (TGB1) and coat protein (CP) sequences of 30 hosta virus X (HVX) isolates from Tennessee (TN), USA, were determined and compared with available sequences in GenBank. The CPs of all known HVX isolates, including those from TN, shared 98.3-100% and 98.2-100% nucleotide and amino acid sequence identity, respectively, whereas TGB1 shared 97.4-100% nucleotide and 97-100% amino acid sequence identity. TGB1 of TN isolates were all longer by one codon from that of a Korean isolate, which is the only sequence publicly available. Phylogenetic analysis of nucleotide and amino acid sequences of TGB1 and CP of all known HVX isolates, separately or combined, revealed a close relationship, suggesting that all of them are derived from a common ancestor. Phylogenetic analysis with the type member of each genus of the family Flexiviridae confirmed that HVX is a member of a distinct species of the genus Potexvirus.
Subject(s)
Genetic Variation , Hosta/virology , Phylogeny , Plant Diseases/virology , Potexvirus , Capsid Proteins/genetics , Molecular Sequence Data , Potexvirus/classification , Potexvirus/genetics , Potexvirus/isolation & purification , Sequence Analysis, DNA , Species Specificity , Tennessee , Viral Proteins/geneticsABSTRACT
Sclerotinia homoeocarpa is the causal agent of dollar spot disease that reduces the uniformity and aesthetic value of golf putting greens. Fungicide-resistant isolates of S. homoeocarpa were collected from putting greens at 10 locations across Tennessee and northern Mississippi. Genetic diversity among the 60 isolates was investigated using vegetative compatibility, conserved gene sequences, and amplified fragment length polymorphism (AFLP). Six tester strains were paired with Tennessee and northern Mississippi isolates on potato dextrose agar. Some of the 60 isolates were delineated into vegetative compatibility groups, but fungicide resistance could not be associated with a particular vegetative compatibility group. Genetic similarities of isolates at the vegetative compatibility level could be attributed to founder effects. Sequencing the regions of CAD, EF1-α, ß-tubulin, and internal transcribed spacers revealed 100% homology among isolates. Capillary gel electrophoresis and analysis of AFLP fragments indicated 86 to 100% similarity between the isolates. Vegetative compatibility and molecular data indicate that the populations of the pathogen are clonal. Isolates did not cluster according to fungicide resistance during unweighted pair group with arithmetic means analysis, but did appear to cluster according to vegetative compatibility group and location. Although associations could not be made between molecular markers and fungicide resistance, links between vegetative compatibility and AFLP markers may provide a foundation from which other studies could be performed.
