A new tospovirus was identified in iris cultivations in the Netherlands. Both serological comparisons and sequence determination of the S RNA demonstrate that this virus represents a new and distinct species, belonging to a separate serogroup, and for which the name iris yellow spot virus (IYSV) is proposed. The disease symptoms on iris are characterized by yellow spots on the leaves. Its experimental host range is very narrow and, in addition to iris, only includes Nicotiana benthamiana and Datura stramonium. The nucleoprotein of IYSV shows only 30 to 44% sequence identity with those of other tospoviruses identified so far; the highest homology being found with the tospovirus species of serogroup IV.

Twenty-two biotypes of Conyza canadensis (Canadian fleabane, horseweed) from a conventional orchard in Crete displayed varying degrees of reduced glyphosate susceptibility in standard whole plant assays. A refined shikimate leaf disc assay was developed to precisely determine the resistance levels, permitting early detection of resistance evolution and integrated management of the weed. The 5-enolpyruvoylshikimate-3-phosphate synthase (EPSPS) homologue genes (1 and 2) were sequenced for three different biotypes (one of reduced susceptibility from Crete, one resistant from mainland Greece and one resistant from the USA), and no amino acid substitution of Pro106 was found. Real-time qRT-PCR was used to study the expression profiles for EPSPS and the M10 and M11 ABC transporter genes, following glyphosate application. The expression levels of the EPSPS genes were not significantly altered following glyphosate application in any biotype, but both M10 and M11 were found to be highly upregulated in glyphosate-treated reduced susceptibility or resistant biotypes and not in a susceptible biotype. These results are in accordance with data recently reported by other researchers, supporting a role of the M10 and M11 ABC transporter genes in glyphosate resistance in Conyza canadensis, because of reduced translocation.

Various plant factors are co-opted by virus elements (RNA, proteins) and have been shown to act in pathways affecting virus accumulation and plant defence. Here, an interaction between Pepino mosaic virus (PepMV) triple gene block protein 1 (TGBp1; p26) and tomato catalase 1 (CAT1), a crucial enzyme in the decomposition of toxic hydrogen peroxide (H₂O₂), was identified using the yeast two-hybrid assay, and confirmed via an in vitro pull-down assay and bimolecular fluorescent complementation (BiFC) in planta. Each protein was independently localized within loci in the cytoplasm and nuclei, sites at which their interaction had been visualized by BiFC. Following PepMV inoculation, CAT mRNA and protein levels in leaves were unaltered at 0, 3 and 6 days (locally) and 8 days (systemically) post-inoculation; however, leaf extracts from the last two time points contained increased CAT activity and lower H₂O₂ evels. Overexpression of PepMV p26 in vitro and in planta conferred the same effect, suggesting an additional involvement of TGBp1 in potexvirus pathogenesis. The accumulation of PepMV genomic and subgenomic RNAs and the expression of viral coat protein in noninoculated (systemic) leaves were reduced significantly in CAT-silenced plants. It is postulated that, during PepMV infection, a p26-CAT1 interaction increases H₂O₂ cavenging, thus acting as a negative regulator of plant defence mechanisms to promote PepMV infections.

Double-stranded RNA preparations produced from potato plants graft-inoculated with a Peruvian isolate of Potato yellow vein virus (PYVV; genus Crinivirus, family Closteroviridae) contain five RNA species denoted RNA 1, RNA 2, RNA 3, x and y of approximately 8, 5·3, 3·8, 2·0 and 1·8 kbp, respectively. The complete nucleotide sequences of PYVV RNAs 1, 2 and 3 and Northern hybridization analysis showed that PYVV RNA 1 contained the replication module and an additional open reading frame (p7), while two distinct species, RNAs 2 and 3, contain the Closteroviridae hallmark gene array. Pairwise comparisons and phylogeny of genome-encoded proteins showed that PYVV shares significant homology with other criniviruses but is most closely related to the Trialeurodes vaporariorum-vectored Cucumber yellows virus. Secondary structure prediction of the 3′-untranslated regions of all three PYVV RNAs revealed four conserved stem–loop structures and a 3′-terminal pseudoknot structure, also predicted for all fully characterized members of the genus Crinivirus and some members of the genera Closterovirus and Ampelovirus.

A protocol is described that permits rapid, inexpensive and reliable synthesis and amplification of 5′‐ and 3′‐terminal cDNAs using viral double‐stranded (ds) RNA templates. The method of RNA ligase‐mediated amplification of cDNA ends for amplification of single‐stranded RNAs (Liu and Gorovsky, 1993) was adapted for dsRNAs to generate the amplicons. These amplicons can be easily cloned and sequenced to complete the sequencing of 5′‐ and 3′‐termini of any particular virus genome. The method is of great utility and can be used on viral genomic dsRNA or viral dsRNA replicative forms when the virion RNA is unavailable.