Nicotiana benthamiana is a model plant utilised internationally in plant virology because of its apparent hyper-susceptibility to virus infection. Previously, others showed that all laboratory accessions of N. benthamiana have a very narrow genetic basis, probably originating from a single source. It is unknown if responses to virus infection exhibited by the laboratory accession are typical of the species as a whole. To test this, 23 accessions of N. benthamiana were collected from wild populations and challenged with one to four viruses. Additionally, accessions of 21 other Nicotiana species and subspecies from Australia, one from Peru and one from Namibia were tested for susceptibility to the viruses, and for the presence of a mutated RNA-dependent RNA polymerase I allele (Nb-RDR1m) described previously from a laboratory accession of N. benthamiana. All Australian Nicotiana accessions tested were susceptible to virus infections, although there was symptom variability within and between species. The most striking difference was that plants of a laboratory accession of N. benthamiana (RA-4) exhibited hypersensitivity to Yellow tailflower mild mottle tobamovirus infection and died, whereas plants of wild N. benthamiana accessions responded with non-necrotic symptoms. Plants of certain N. occidentalis accessions also exhibited initial hypersensitivity to Yellow tailflower mild mottle virus resembling that of N. benthamiana RA-4 plants, but later recovered. The mutant Nb-RDR1m allele was identified from N. benthamiana RA-4 but not from any of 51 other Nicotiana accessions, including wild accessions of N. benthamiana, demonstrating that the accession of N. benthamiana used widely in laboratories is unusual.

Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/ppa.12416 This article is protected by copyright. All rights reserved. Accepted ArticleThis article is protected by copyright. All rights reserved. SW13 were obtained. YTMMV-Kalbarri shared 97% nucleotide pairwise identity with the sequence of the type isolate YTMMV-Cervantes. The sequence PZSV-SW13 shared greatest sequence identity with the partial sequence of an Australian isolate of PZSV also from a wild plant, and with a sunflower-derived isolate of PZSV from Argentina. An experimental host range study was done of YTMMV-Kalbarri using cultivated and wild solanaceous and nonsolanaceous plants. Most solanaceous plants became systemically infected, with symptoms of systemic infection ranging from asymptomatic to whole plant necrosis. Based on these studies, we suggest that YTMMV has the potential to become a pathogen of commercial species of Solanaceae. This study provides further evidence that PZSV is present in wild plants in Australia, in this case an indigenous host species, and possible routes by which it invaded Australia are discussed.

Tobamovirus is a group of viruses that have become serious pathogens of crop plants. As part of a study informing risk of wild plant virus spill over to crops, we investigated the capacity of a solanaceous-infecting tobamovirus from an isolated indigenous flora to adapt to new exotic hosts. Yellow tailflower mild mottle virus (YTMMV) (genus Tobamovirus, family Virgaviridae) was isolated from a wild plant of yellow tailflower (Anthocercis littoria, family Solanaceae) and initially passaged through a plant of Nicotiana benthamiana, then one of Nicotiana glutinosa where a single local lesion was used to inoculate a N. benthamiana plant. Sap from this plant was used as starting material for nine serial passages through three plant species. The virus titre was recorded periodically, and 85% of the virus genome was sequenced at each passage for each host. Six polymorphic sites were found in the YTMMV genome across all hosts and passages. At five of these, the alternate alleles became fixed in the viral genome until the end of the experiment. Of these five alleles, one was a non-synonymous mutation (U1499C) that occurred only when the virus replicated in tomato. The mutant isolate harbouring U1499C, designated YTMMV-δ, increased its titre over passages in tomato and outcompeted the wild-type isolate when both were co-inoculated to tomato. That YTMMV-δ had greater reproductive fitness in an exotic host than did the wild type isolate suggests YTMMV evolution is influenced by host changes.

Catharanthus mosaic virus: a potyvirus from a gymnosperm, Welwitschia mirabilis, Virus Research (2015), http://dx.doi.org/10. 1016/j.virusres.2015.03.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Page 1 of 19A c c e p t e d M a n u s c r i p t America (Mollov et al., 2014). Experimentally it also infects Nicotiana 36 benthamiana systemically (family Solanaceae), and Chenopodium amaranticolor 37 and C. quinoa locally (family Amaranthaceae) (Maciel et al., 2011). CatMV 38 infection in C. roseus typically induces moderately severe symptoms of leaf 39 mosaic patterns and deformation, leaf blade reduction and reduced seed fertility 40 (Maciel et al., 2011), and in Mandevilla mosaic symptoms and deformation in 41 leaves, premature leaf senescence and vine dieback (Mollov et al., 2014). 42Welwitschia mirabilis is a monotypic species in the monotypic order 43Welwitschiales (Division Gnetophyta) endemic to the Namib Desert of Namibia 44and Angola in south-west Africa. Welwitschia is known to be one of the longest-45 lived plants on Earth, living up to 3000 years old (Jacobson and Lester, 2003). 46There is fossil evidence that members of the family Welwitschiaceae existed in 47 South America in the Mesozoic era, and its current distribution probably reflects 48 its Gondwanan origins and climatic changes during the Tertiary and Quaternary 49 (Jacobson and Lester, 2003). There are only two true leaves on a Welwitschia 50 plant, and these split to form several leaf strips, which grow longitudinally along 51 the ground. Welwitschia's peculiar morphology and natural history makes it an 52 unusual and interesting ornamental plant. To date, there is no record of viruses 53 infecting Welwitschia. 54There are two CatMV sequences available in GenBank, which comprise the 55 partial replicase (NIb), the complete coat protein (CP) and the 3' untranslated 56 region (UTR) of the genome (Maciel et al., 2011; Mollov et al., 2014). Here, the 57 first complete genome sequence of an isolate of CatMV from Welwitschia in 58Australia was generated, demonstrating that CatMV has a broader host range and 59 wider geographical distribution than previously recognized. Total nucleic acids were extracted from infected N. benthamiana leaves and 70 enriched for dsRNA using a cellulose based method (Morris and Dodds, 1979). 71 cDNA was synthesized using GoScript™ reverse transcriptase (Promega) with a 72 random primer. An index sequence was added by randomly-primed PCR (Table 73 S1) using the following cycling conditions: 95 ºC for 3 min, 30 cycles of 95 ºC for 74 30 s, 60 ºC for 30 s, 72 ºC for 30 s and the final extension of 72 ºC fo...

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