No abstract

No abstract

No abstract

S U M M A R Y Raspberry bushy dwarf virus (RBDV) was found in all plants of LloydGeorge raspberry with bushy dwarf disease and occurred occasionally in plants of some other cultivars. It was transmitted by inoculation of sap to fifty-five other species in twelve families of flowering plants and infected most of them symptomlessly. It caused systemic symptoms in some species of Amaranthaceae, Chenopodiaceae and Cucurbitaceae, and necrotic local lesions in some Leguminosae. It did not induce bushy dwarf disease when returned to Lloyd George raspberry.Chenopodium quinoa was used for propagating the virus and Vigna cylindrica for local lesion assay. In C. quinoa sap, RBDV lost infectivity when diluted I O -~, heated for 10 min at 65 "C or stored for 4 days at 22 "C. Preparations made by twice precipitating the virus at pH 4.8 and resuspending it at pH 7-0, followed by ultracentrifugation and exclusion chromatography in columns of 2 % agarose beads, contained isometric particles about 33 nm in diameter, which sedimented as two components, with sedimentation coefficients of I I I and I 16 S. Only a few particles, all of them disrupted, were seen in preparations mounted in phosphotungstate, but the particles were well preserved in uranyl formate provided that they were first dispersed in a salt such as MgC1, instead of distilled water. Many particles were oval in outline as though distorted during drying.No serological relationship was detected between RBDV and twenty-four other isometric viruses nor between RBDV and the filamentous virus apple chlorotic leafspot, to which it was previously thought to be related. An isolate of loganberry degeneration virus was serologically indistinguishable from RBDV.

The amino acid sequence of the 287-residue coat protein of peanut stripe virus (PStV) was determined from the sequences of overlapping peptide fragments. Results indicated that the amino terminus was blocked by an acetyl group, as has previously been found for the coat protein of Johnsongrass mosaic potyvirus. Comparison of the PStV sequence with coat proteins of 20 distinct potyviruses gave sequence identities of 47-57%, except for zucchini yellow mosaic virus (ZYMV), passionfruit woodiness virus (PWV), and the related strains watermelon mosaic virus 2 (WMV 2) and soybean mosaic virus-N, which showed sequence identities of 70-76%. Several amino acid residues which were common to the core sequences of these coat proteins were at positions previously found to be invariant among potyvirus coat proteins. The degree of these similarities suggests that although PStV, WMV 2, ZYMV, and PWV are distinct potyviruses, they share a common ancestor in their evolutionary development.