Effect of Co-Infection with Systemic Viruses on the Localization of Tobacco Mosaic Virus in Cucumber Cotyledons.

Abstract

When cucumber cotyledons that had been inoculated with tobacco mosaic virus (TMV) were challenge-inoculated with cucumber green mottle mosaic virus (CGMMV), the multiplication of TMV and the size and number of starch-lesions in the cotyledons remained the same as in single inoculation with TMV. Inoculation with CGMMV before TMV-infection, however, decreased the amount of TMV and the number of starch-lesions. The same results were obtained when cucumber mosaic virus (CMV) was inoculated before or after TMV. When cucumber cotyledons were inoculated with zucchini yellow mosaic virus (ZYMV) 4 days before TMV inoculation or jointly inoculated with ZYMV and TMV, TMV concentration increased roughly 7 and 4 times, respectively. In this case, TMV was widely distributed in horizontal and vertical directions in the cotyledon tissues, but eventually localized. In cucumber cotyledons co-infected with ZYMV and CGMMV, CGMMV concentration was not affected by ZYMV infection. Factors involved in the localization of TMV are discussed based on these observations.