TRANSFER OF THE 3' NON-TRANSLATED REGION OF GRAPEVINE CHROME MOSAIC-VIRUS RNA-1 BY RECOMBINATION TO TOMATO BLACK RING VIRUS RNA-2 IN PSEUDORECOMBINANT ISOLATES

In grapevine chrome mosaic and tomato black ring viruses (GCMV and TBR V), as in many other nepoviruses, the 3' non-translated regions (3'NTR ) are identical between the two genomic RNAs. We have investigated the structure of the 3'NTR of two recombinant isolated which contain GCMV RNA-1 and TBRV RNA-2. In these isolates, the 3'NTR of RNA-1 was trans ferred to RNA-2, thus restoring the 3' identity. The transfer occurred within three passages, and probably contributes to the spread of rand omly appearing mutations from one genomic RNA to the other. The site o f recombination is near the 3' end of the open reading frame.