Differential replication in zucchini squash of a cucumber mosaic virus satellite RNA maps to RNA 1 of the helper virus.

Cucumber mosaic virus (CMV) supports the replication and encapsidation of its satellite RNA, both in solanaceous and cucurbit host plants; however, different strains of CMV support the replication of satellite RNAs with different efficiency. In addition, replication of satellite RNA is very efficient in solanaceous host plants and generally poor in cucurbit host plants. The WL1-satellite (WL1-sat) RNA is an exception, and replicates to high levels in both solanaceous and curcubit host plants with most CMV strains as the helper virus. Two strains of CMV were used in this study: Fny-CMV, which replicates the WL1-sat RNA efficiently in all hosts tested; and Sny-CMV, which does not replicate the WL1-sat RNA to detectable levels in zucchini squash (Cucurbita pepo), but does replicate WL1-sat RNA efficiently in other hosts. Using pseudorecombinants constructed between Fny-CMV and Sny-CMV we have mapped to RNA 1 the ability to support the efficient replication of WL1-sat RNA in zucchini squash.