MORPHOLOGICAL VARIATION IN SHALLOT VIRUS-X PRODUCED IN MONOINFECTED PLANTS

Virus preparations obtained from individual Allium ascalonicum plants infected solely with shallot virus X were found to contain virions of two morphological types. Type I was represented by flexuous particles of modal length 800 nm and diameter 12 nm, with characteristic cross-s triation. Type 2, thinner (6 nm), more flexible, and aggregation-prone particles were minor in most preparations but constituted the bulk of the viral population in about 5% of plants. These morphologically dis tinct particles were shown to be formed of homologous genomic RNAs and serologically close 37K coat proteins. Thus they could be regarded as variants of the ShVX virion.