Survey and Characterization of Viruses in Sweetpotato from Zimbabwe

ABSTRACT Thirty-one clones of sweetpotatoes collected from some parts of Zimbabwe were used as inoculum sources to mechanically inoculate 13 experimental hosts: Chenopodium amaranticolor, C. quinoa, Cucumis sativus, Datura stramoniumitalic, Gomphrena globosa, Ipomoea purpurea, I. quamoclit, I. rubrocorulea, Nicotiana benthamiana, N. clevelandii, N. glutinosa, N. rustica, and N. tabacum. Systemic vein clearing was observed in N. benthamiana inoculated with buffered sap from nine clones. Purification of the vein clearing inducing agent from one of the sweetpotato clones gave yields ranging from 2 to 17 mg/kg and the A260nm/A280nm was around 1.2. Electron microscopy revealed flexuous filamentous particles with a modal length of 830 nm. Protein analysis of purified virus preparations by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a major protein band of 40 kDa, and this was assumed to be the viral coat protein. Minor protein bands of 27, 37, and 46 kDa were also observed. The viral prot...