Ullucus virus C, a newly recognised comovirus infecting Ullucus tuberosus (Basellaceae)

Abstract

SUMMARY Ullucus virus C (UVC) is a comovirus prevalent in Ullucus tuberosus grown at high altitudes in the Bolivian and Peruvian Andes. It was transmitted mechanically to U. tuberosus (Basellaceae) and to five of 26 species from three of eight other families, infecting U. tuberosus symptomlessly but inducing conspicuous systemic infection in Chenopodium amaranticolor and C. quinoa. Sap from infected C. quinoa was usually infective after 10 min at 70 but not 75 °C, after dilution to 10‐7 but not 10‐8, and after 8 but not 16 wk at 20 °C. UVC was not transmitted by either of two aphid species (Aphis gossypii and Myzus persicae) or through seed of C. quinoa, but it was transmitted by leaf contact between infected and healthy plants. UVC has isometric particles which, in neutral phosphotungstate, are c. 28 nm in diameter. The particles sediment as three components (T, M and B) with sedimentation coefficients (s˚20, w) of 51 S (T), 95 S (M) and 116 S (B). M component particles have a buoyant density (g cm‐3) in caesium chloride of 1.404, and B component particles separated into minor and major sub‐components with densities of 1.409 and 1.463, respectively. T, M and B particles were serologically indistinguishable, and each contained similar relative amounts of two polypeptides of mol. wts 20 700 and 45 100. T particles contained only protein, but M particles also contained c. 30% ss‐RNA of mol. wt 1–45 ×106 and B particles c. 38% ss‐RNA of mol. wt 2·2 × 106. The virus is serologically distantly related to cowpea mosaic virus but, as it showed no relationship to any of 11 other similar viruses, it is probably a distinct member of the comovirus group.

Using high‐throughput sequencing in support of a plant health outbreak reveals novel viruses in Ullucus tuberosus (Basellaceae)

“…There is similarity at the genus level of the viruses detected from the UK and those previously reported in Ullucus . It is possible that the isolates identified during this investigation provide novel sequence data for viruses previously characterized by serology and test plant symptomology (Brunt et al ., ,b; Offei et al ., ; Lizarraga et al ., ,b). Some of the novel viruses share serological similarities with those previously reported from U. tuberosus .…”

“…Given a lack of familiarity with the host, it is possible some of these symptoms may be the natural phenotype of the plant or due to varietal differences, or may have been the consequence of multiple viruses as complex infections. Some viruses have been previously reported to symptomlessly infect U. tuberosus (Brunt et al ., ,b) and complex infections are commonly reported (Brunt et al ., ; Lizarraga et al ., ). With multiple infections being present in many samples, further work is needed to clarify the cause of symptoms in affected ulluco plants in this study.…”

“…From the early 1980s, ulluco tubers collected from a number of locations in the Andes were shown to contain a range of previously undescribed viruses and virus strains. These included a distinct strain of Papaya mosaic virus (PapMV/U, genus Potexvirus ), Ullucus virus C (UVC, genus Comovirus ), Ullucus mild mottle virus (UMMV, genus Tobamovirus ) and the potyvirus Ullucus mosaic virus (UMV) (Brunt et al ., ,b; Offei et al ., ). These viruses were commonly found to be present in mixed infections of three or four viruses (Brunt et al ., ).…”

Turnip ringspot virus recognised on Chinese cabbage in Russia

“…The genus Comovirus comprises fifteen definitive virus species with the last one added more-than 20 years ago (Brunt et al 1982). Comoviruses are characterised by a bipartite + ssRNA genome encapsidated separately in isometric virions constructed from two polypeptide species.…”

Viruses detected in Ullucus tuberosus (Basellaceae) from Peru and Bolivia

“…We describe here the detection of viruses in U. tuberosus, their separation from naturally-occurring complexes and the identification of three, respectively, as a strain of papaya mosaic virus (PMV/U), a tobamovirus (TMV/U) and a potyvirus tentatively designated ullucus mosaic virus (UMV). Some hosts and properties of the fourth virus, a previously undescribed comovirus which we call ullucus virus C (UVC), are described in an accompanying paper (Brunt. Barton, Phillips & Jones, 1982).…”