EFFECT OF DELETIONS IN THE CAULIFLOWER MOSAIC-VIRUS POLYADENYLATION SEQUENCE ON THE CHOICE OF THE POLYADENYLATION SITES IN TOBACCO PROTOPLASTS

Deletions were made in the cauliflower mosaic virus polyadenylation sequence which was cloned downstream of the beta-glucuronidase gene (gus). The populations of mRNAs generated in tobacco mesophyll protoplasts by transient expression with the various constructs were analysed using a polymerase chain reaction procedure. When no deletion was present in the sequence, the mRNA appeared to be polyadenylated at two major polyadenylation sites. A deletion upstream from the AATAAA sequence made the population of polyadenylated mRNAs very heterogenous at their 3' ends. A deletion downstream of the AATAAA sequence had no effect on the choice of the site. Alternative polyadenylation sites were used when the native polyadenylation site was deleted. These results are discussed in relation to data obtained with other polyadenylation sequences from both plants and animals.