PROPERTIES OF A STRAIN OF CUCUMBER-MOSAIC VIRUS ISOLATED FROM PRUNUS HOSTS

Abstract

Some of the stone-fruit viruses that are transmissible only to cucumber and other cucurbits have occasionally been accompanied by a second virus that can be isolated by transfer to tobacco. This virus, herein called CMVP, appears to be latent in Prunus hosts, but induces symptoms in bean, cowpea, cucumber, Datura stramonium, Nicotiana glutinosa, petunia, tobacco, spinach, sugar beet, Swiss chard, and zinnia. CMVP has a small thermal coefficient, a thermal inactivation point between 65° and 70 °C, and a dilution end point between 10−3 and 10−4. It remains infective in expressed sap up to 96 hours at room temperature and for more than 6 days under refrigeration. It can be transmitted between cucumber and tobacco by Aphis gossypii and Myzus persicae, in which it is nonpersistent. Spherical "virus particles" associated with CMVP are about 35 mμ in diameter. Tobacco plants infected with this virus are partially protected against cucumber mosaic virus but not against tobacco ring spot virus.In symptom expression and in some of its properties, CMVP resembles both alfalfa mosaic virus and cucumber mosaic virus. Its particle size and immunological reaction suggest that it is an atypical strain of the latter. It is considered not to be implicated in the etiology of cherry yellows and related stone-fruit viroses.