[The effect of the 5'-leader of potato X-virus on expression of the gene for the potato Y virus membrane protein in transgenic Solanum tuberosum]

Abstract

The 5'-leader of potato virus X (PVX) genomic RNA was successfully used to generate potato plants expressing the coat protein of the potato virus YN (Russian isolate) (PVY CP). Two expression cassettes were constructed that carried the PVY CP coding sequence along with the PVY 3'untranslated region under the control of the CaMV 35S promoter and poly(A) signal. The cassettes contained different sequences between the 35S promoter and the CP artificial AUG initiating codon of the coat protein: either a polylinker or a shortened variant of the PVX leader. Transgenic Belorusskii-3 potato plants generated by agrobacterial transformation were shown to express the PVY CP gene to different extents depending on the cassette integrated into the plant genome. The cassette containing the PVX leader provided detectable amounts of the coat protein in all tested plants, whereas plants carrying the cassette with the polylinker leader produced no coat protein above the Western detection threshold. Northern analysis revealed that the presence of the PVX leader in front of the PVY CP gene initiating codon resulted in a 10-fold increase in the PVY CP mRNA steady-state levels, thus suggesting an influence of the PVX leader on mRNA stability.