Electron Microscopy of an Isometric Caulimo‐Like Virus from Sweet Potato (Ipomoea batatas)

Abstract

A newly recognised virus with isometric particles 50 nm in diameter was detected in Ipomoea batatas (sweet potato) by graft-transmission to /. setosa. Virus particles and intracellular inclusions, although not seen in infected /. batatus, were found in the cytoplasm of most cell types of /. setosa. The caulimo-Iike particles were most abundant with vesicles immediately adjacent to inclusions. The ovoid or spherical inclusions, which differ markedly from those of caulimoviruses, have a large central lacuna and usually several smaller peripheral lacunae. Infected vascular parenchyma cells sometimes protrude into, and occasionally completely occlude, adjacent xylem vessels, observations possibly explaining the sudden wilting and premature senescence of infected leaves.

Distinct cavemoviruses interact synergistically with sweet potato chlorotic stunt virus (genus Crinivirus) in cultivated sweet potato

“…To study a possible interaction between cavemoviruses and SPCSV, we carried out co-infection studies in sweet potato cultivar ‘Huachano’ and SPCSV isolate m2-47 which has been previously shown to synergistically interact with heterologous RNA viruses in sweet potato (Untiveros et al , 2007). As originally observed for SPCV (Atkey & Brunt, 1987), no symptoms could be observed, and serological detection was impossible in sweet potato plants infected with either cavemovirus under our conditions (). In double infection with SPCSV, however, detection of SPCV or SPVCV in sweet potato was possible and correlated with the appearance of vein-clearing symptoms.…”

“…To date only a single caulimovirid, sweet potato caulimo-like virus (SPCV) has been reported (Atkey & Brunt, 1987; De Souza & Cuellar, 2010), but despite its widespread occurrence (Atkey & Brunt, 1987; Wambugu, 1991; Aritua et al , 2007), SPCV is not officially recognized by the International Committee on Taxonomy of Viruses (Fauquet et al , 2005). In addition to the complete sequence of SPCV, we report here the isolation and complete genome characterization of a second caulimovirid showing similar but not identical characteristics to SPCV.…”

Incidence of five viruses infecting sweetpotatoes in Uganda; the first evidence of Sweet potato caulimo‐like virus in Africa

“…SPCFV, a recently identified virus (Fuentes & Salazar, 1992), was also reported previously in Uganda and elsewhere in East Africa, as well as having a worldwide distribution (Salazar & Fuentes, 2000). By contrast, after its first isolation from Puerto Rico in 1987 (Atkey & Brunt, 1987), SPCaLV has only been detected in Papua New Guinea, New Zealand, the Solomon Islands and Madeira (Salazar & Fuentes, 2000). Its identification in this study is therefore only the second report of its occurrence outside Australasia and the first of its occurrence on the African mainland.…”

Apparent absence of viruses in most symptomless field‐grown sweet potato in Uganda

“…These standard luts contained both positive and negative controls pre-spotted onto membranes, and whether the final colour development of test spots was clearly stronger than control spots was judged by eye. Additional samples were spotted on nitro-cellulose membranes and sent to CIP (Lima) to be analysed for sweet potato caulimo-like virus (SPCa-LV: a possible member of the genus Caulitnovirus) (Atkey & Brunt, 1987). SPSVV was not tested for by ELISA because at the time when these tests were being done it was not reported that this virus occurred in E Africa; however, the E African serotype causes clear symptoms in all sweet potato cultivars tested so far and also produces symptoms in Zpomoea setosa seedlings (R W Gibson, unpublished).…”