Purification and properties of closterovirus‐like particles associated with a whitefly‐transmitted disease of sweet potato

Abstract

SummaryA virus causing sunken veins on ‘Georgia Jet’ sweet potato, and yellow brittle leaves and stunting on Ipomoea setosa, was purified and a specific antiserum was prepared. Flexuous particles with a normal length of 850 nm and a diameter of 12 nm with an open helical structure typical of closteroviruses were observed. The virus particle protein has an apparent mol. wt of c. 34 kD. Double‐stranded RNA isolated from SPSVV‐infected I. setosa and subjected to electrophoresis in agarose consisted of one major band with an estimated Mr of 10.5 kbp and two minor bands with Mr of 9.0 and 5.0 kbp. Fibril‐containing vesicles in phloem cells were observed in ultrathin sections of infected leaf tissues. The virus was transmitted by the whitefly Bemisia tabaci in a semi‐persistent manner and by grafting, but not mechanically. The virus could be transmitted to various Ipomoea species, to Nicotiana clevelandii, N. benthamiana and Amaranthus palmeri. The virus did not react with an antiserum to lettuce infectious yellows virus. Based on particle morphology, serology and symptom expression, the virus appears unique and different from all other reported whitefly‐transmitted closteroviruses. We propose it be named “sweet potato sunken vein virus” (SPSVV).

Analysis of gene content in sweet potato chlorotic stunt virus RNA1 reveals the presence of the p22 RNA silencing suppressor in only a few isolates: implications for viral evolution and synergism

“…SPCSV-m2-47 was isolated from an infected sweetpotato plant grown in the Cañete valley, Peru (Gutiérrez et al, 2003). SPCSV-Is, previously described as SPSVV in Israel (Cohen et al, 1992;Milgram et al, 1996), was kindly provided by Professor Gad Loebestein (The Volcani Center, Bet Dagan, Israel). The isolate of SPFMV (SPFMV-Nam1) used in this study was originally obtained from an infected sweetpotato plant in Uganda and belongs to the EA strain of SPFMV Kreuze et al, 2000).…”

“…However, SPCSV isolates from Nigeria, Israel and the USA have been found to be related to each other (Hoyer et al, 1996b;Pio-Ribeiro et al, 1996;Vetten et al, 1996) and assigned to the strain WA, named according to the original description of SPCSV as a 'chlorotic stunt'-causing agent in sweetpotatoes in Nigeria, West Africa (Schaefers & Terry, 1976). Closterovirus-like particles were later detected in sweetpotatoes showing chlorotic stunt symptoms in Nigeria (Winter et al, 1992), Israel (Cohen et al, 1992) and Kenya (Hoyer et al, 1996a, b). The virus in these plants was named sweet potato sunken vein virus.…”

Production of antiserum and immunodetection of Cucurbit chlorotic yellows virus, a novel whitefly-transmitted crinivirus

“…It has been reported that localization of criniviruses in planta is generally confined to sieve cells (Cohen et al 1992;Hourani and Abou-Jawdah 2003;Medina et al 2003;Winter et al 1992;Wisler et al 1998b;Yamashita et al 1979). To determine whether this is true for CCYV, we performed tissue print analysis, in which a cross-sectioned petiole was blotted on a nylon membrane followed by Each point is the average of the readings from two wells immunostaining, as described by Hourani and AbouJawdah (2003).…”

Complete Genome Sequence and Analyses of the Subgenomic RNAs of Sweet Potato Chlorotic Stunt Virus Reveal Several New Features for the Genus Crinivirus

“…SPCSV virions were purified from infected plants of I. setosa (10), and RNA was extracted from the virions (36). RNA concentration was determined by absorbance at 260 nm with a UV spectrophotometer.…”

“…For instance, SPCSV is phloem limited in sweet potato plants (35) and is transmitted by whiteflies (10,56). In the flexuous filamentous virions, the viral genome of Closteroviridae is encapsidated by two types of coat protein (CP) arranged in a polar configuration (3,21,58).…”