Yellow tailflower mild mottle virus and Pelargonium zonate spot virus co‐infect a wild plant of red‐striped tailflower in Australia

Isolates of an Australian indigenous virus, Yellow tailﬂower mild mottle virus (YTMMV-Kalbarri), and an exotic virus,Pelargonium zonate spot virus (PZSV-SW13), are described from Anthocercis ilicifolia subsp. ilicifolia (red-striped tail-ﬂower, family Solanaceae), a species endemic to Western Australia. This is the ﬁrst report of either virus fromthis plant species. The complete genome sequences of YTMMV-Kalbarri and of PZSV-SW13 were obtained. YTMMV-Kalbarri shared 97% nucleotide pairwise identity with the sequence of the type isolate YTMMV-Cervantes. Thesequence PZSV-SW13 shared greatest sequence identity with the partial sequence of an Australian isolate of PZSV, alsofrom a wild plant, and with a sunﬂower-derived isolate of PZSV from Argentina. An experimental host range studywas done of YTMMV-Kalbarri using cultivated and wild solanaceous and non-solanaceous plants. Most solanaceousplants became systemically infected, with symptoms of systemic infection ranging from symptomless to whole plantnecrosis. Based on these studies, it is suggested that YTMMV has the potential to become a pathogen of commercialspecies of Solanaceae. This study provides further evidence that PZSV is present in wild plants in Australia, in this casean indigenous host species, and possible routes by which it invaded Australia are discussed.Keywords: anulavirus, indigenous plant virus, plant virus ecology, tobamovirus, virus invasion, virus emergenceAnthocercis (family Solanaceae, subfamily Nicotianoi-deae) is a genus of 15 plant species endemic to southernAustralia (Haegi, 1986). Previously, a tobamovirus(genus Tobamovirus, family Virgaviridae) was isolatedfrom A. littoria (yellow tailﬂower), a spindly shrub, 3 min height, that grows along the coastline in calcareoussand, limestone ridges and sand dunes of southwesternAustralia, but the virus was not detected from A. viscosa(sticky tailﬂower) plants growing in Albany, 400 km tothe south. The new tobamovirus was named Yellow tail-ﬂower mild mottle virus (YTMMV; Wylie et al., 2014). Pelargonium zonate spot virus (PZSV; genus Anulavi-rus, family Bromoviridae) was ﬁrst isolated from Pelar-gonium zonale (Geraniaceae) in Italy (Quacquarelli G Luis-Arteaga & Cambra,2000; Gebre-Selassie et al., 2002; Finetti-Sialer & Galli-telli, 2003; Liu & Sears, 2007; Escriu et al., 2009; Gulat-i-Sakhuja et al., 2009; Lapidot et al., 2010; Blouin et al.,2013; Giolitti et al., 2014). Its geographical rangeincludes much of Europe and the Americas. In Australia,PZSV was recently described for the ﬁrst time in Cakilemaritima (Brassicaceae), a self-introduced exotic weedspecies (Luo et al., 2010). This study describes the complete genome sequences ofnew isolates of YTMMV and PZSV that co-infected a wildplant of Anthocercis ilicifolia subsp. ilicifolia (red-stripedtailﬂower), a new host species for both viruses. Althoughdetails of the host range of PZSV have been published, thepotential host range of YTMMV is not known. The natu-ral hosts of YTMMV live at the interface between wildand managed systems, and consequently the opportunityexists for the virus to expand its host range into cultivatedplant species. Thus, an experimental host range study wasundertaken of the new YTMMV isolate and the type YT-MMV isolate, and the potential of YTMMV to emerge asa pathogen of commercial importance is discussed. Fur-ther, it is speculated as to how PZSV may have enteredAustralia, given that it has not yet been detected there incommercial plantings.