Genome sequence of a polerovirus isolated from wild oat in Australia.

We present the genome sequence of a polerovirus (family Solemoviridae) isolated from wild oat (Avena fatua) in Australia. The genome sequence consists of 5,631 nucleotides and shares 87% nucleotide identity with its closest relative, cereal yellow dwarf virus RPV isolate 010 (GenBank accession number EF521830).

Turnip yellows virus variants differ in host range, transmissibility, and virulence.

Turnip yellows virus (TuYV; family Solemoviridae, genus Polerovirus, species Turnip yellows virus) is a genetically diverse virus that infects a broad range of plant species across the world. Due to its global economic significance, most attention has been given to the impact of TuYV on canola (syn. oilseed rape; Brassica napus). In Australia, a major canola-exporting country, TuYV isolates are highly diverse, with the most variation concentrated in open reading frame 5 (ORF 5), which encodes the readthrough domain (P5) component of the readthrough protein (P3P5), which plays an important role in host adaptation and aphid transmission. When analysing ORF 5, Australian TuYV isolates form three phylogenetic groups with just 45 to 49% amino acid sequence identity: variants P5-I, P5-II, and P5-III. Despite the possible implications for TuYV epidemiology and management, research examining phenotypic differences between TuYV variants is scarce. This study was designed to test the hypothesis that three TuYV isolates, representing each of the Australian P5 variants, differ phenotypically. In particular, the host range, vector species, transmissibility, and virulence of isolates 5414 (P5-I5414), 5509 (P5-II5509), and 5594 (P5-III5594) were examined in a series of glasshouse experiments. Only P5-I5414 readily infected faba bean (Vicia faba), only P5-II5509 infected chickpea (Cicer arietinum), and only P5-I5414 and P5-III5594 infected lettuce (Lactuca sativa). Myzus persicae transmitted each isolate, but Brevicoryne brassicae and Lipaphis pseudobrassicae did not. When using individual M. persicae to inoculate canola seedlings, P5-I5414 had significantly higher transmission rates (82%) than P5-II5509 (62%) and P5-III5594 (59%). As indicated by enzyme-linked immunosorbent assay absorbance values, P5-I5414 reached higher virus titers in canola than P5-II5509, which, in turn, reached higher titers than P5-III5594. P5-I5414 was also more virulent in canola than P5-II5509 and P5-III5594, inducing more severe foliar symptoms, stunting, and, in one of two experiments, seed yield loss. Results from this study compared to those of previous studies suggest that analysis of ORF 5 alone is insufficient to assign isolates to coherent strain categories, and further sequencing and phenotyping of field isolates is required.

Genome Sequence and Phylogeny of a Bean Yellow Mosaic Virus Isolate Obtained from a 14-Year-Old Australian Lentil Sample.

Using RNA strand-specific sequencing followed by de novo assembly, a Bean yellow mosaic virus (BYMV) genome was obtained from a lentil sample (Aus14BY) collected in Victoria, Australia, in 2005. When compared with 51 BYMV genomes, it closely resembled the Western Australian isolate PN83A (Lupinus angustifolius), with 98.4% nucleotide identity.

Coding-Complete Sequences of Barley Virus G Isolates from Australia, Obtained from a 34-Year-Old and a 1-Year-Old Sample.

Coding-complete sequences of two barley virus G isolates from Australia were obtained from a 34-year-old oat sample (isolate Aus8) and a 1-year-old barley sample (isolate Aus17N). The Aus8 and Aus17N isolates share 96.3% nucleotide identity with each other and 95.7 to 95.8% nucleotide identity with the South Korean isolate Uiseong.

Metagenomic Analysis Reveals a Nearly Complete Genome Sequence of Alfalfa Mosaic Virus from a Field Pea in Australia.

Here, we report the first nearly complete genome sequence of Alfalfa mosaic virus (AMV) obtained from a symptomatic field pea sample (Aus295) in Australia. Its genome RNA1 and RNA2 segments resembled those of the Argentinian isolate Manfredi, with 99.4% and 96.7% nucleotide (nt) identity, respectively; its RNA3 segment resembled that of Chinese isolate AMV-Gyn, with 99.6% nt identity.