Paul Ameloot

Expression in plants of the cloned satellite tobacco necrosis virus genome and of derived insertion mutants

Mechanical inoculation of cowpea leaves with cloned full-size copies of satellite tobacco necrosis virus in the presence of tobacco necrosis (helper) virus resulted in the appearance of infectious virus particles. This could be clearly demonstrated by the detection of structural changes in the progeny viral RNA after inoculation with helper virus and hybrid plasmids containing an STNV-DNA copy with small (14-mer) oligodeoxynucleotides inserted at different sites in either the coding or the non-coding region. Furthermore, although orientation and position of the viral cDNA in the different plasmids did not seem to be of major importance for the ensuing infection process, the presence of adjacent complementary homopolymeric regions (dG/dC) at both ends of the STNV nucleotide sequence was necessary. Progeny STNV was obtained which carried oligonucleotide insertions at various positions of the genome.