Purification, characterization and serology of strawberry pseudo mild yellow edge virus.

Abstract

Strawberry pseudo mild yellow edge virus (SPMYEV) was detected from strawberry cv. Hoko-wase. SPMYEV was readily transmitted from infected plants by the aphids, Chaetosiphon fragaefolii and Aphis gossypii to Fragaria species, but not by inoculation of sap. Filamentous virus particles were consistently observed in dip preparations and ultrathin sections of SPMYEV infected leaves, but not in healthy control leaves. They were therefore thought to be the particles of SPMYEV. The virus was successfully purified from infected Alpine strawberry by differential centrifugation in sucrose cushion, followed by sucrose density gradient centrifugation and CsC1 equilibrium density gradient centrifugation. The purified preparations contained filamentous particles 625nm in length and 12nm in width, and showed a typical UV spectrum of a nucleoprotein with max. and min. absorption at 260nm and 246nm, respectively. The A260/A280 ratio was 1.19. The bouyant density of purified virus in CsCl was 1.32g/cm3. The virus had a single stranded RNA with the mol. wt. of 2.5×106 daltons and one coat protein with the mol. wt. of 33, 500 daltons. The virus was serologically related to carnation latent virus. From these results, it is concluded that SPMYEV is a new member of the carlavirus group.