Characterization and Field Studies of a Cucumber Mosaic Virus Isolate from Spinach in the Winter Garden Area of Texas. A. D. Wilson, Former Graduate Student, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843. R. S. Halliwell, Professor, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843. Plant Dis. 69:751-754. Accepted for publication 13 March 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-751.

An isolate of cucumber mosaic virus (CMV) was identified from spinach in the Winter Garden area of Texas. The isolate was very closely related serologically to strain S of CMV and is designated the Texas spinach isolate of CMV-S. The virus infected 39 species of crop plants and wild hosts in 12 of 13 families tested. The green peach aphid efficiently transmitted the virus experimentally. The isolate had a sedimentation coefficient of 91.8 ± 0.1 S as determined by analytical ultracentrifugal analysis. Virions with a mean diameter of 28.9 ± 0.3 nm were found in purified preparations with electron microscropy. A single protein subunit with a mean molecular weight of 25,300 ± 255 daltons was found by sodium dodecyl sulfate polacrylamide gel electrophoresis (SDS-PAGE). Four separate RNA species were resolved by agarose-gel electrophoresis under denaturing conditions. The mean molecular weight distribution of the viral genome was 1.22, 1.09, 0.77, and 0.36 × 10⁶ daltons. CARNA 5 was not jointly encapsidated with the viral genome. In the field studies, planting date and plant age at inoculation had no significant effect on crop yield, although CMV infection was highly significant. The isolate significantly affected yields of three spinach cultivars, with reductions ranging from 23.8 to 47.4%.

Keyword(s): spinach blight, Spinacia oleracea.