EFFECT OF POTATO-VIRUS-X 5'-LEADER ON EXPRESSION OF THE POTATO-VIRUS-Y COAT PROTEIN GENE IN TRANSGENIC SOLANUM-TUBEROSUM PLANTS

Two expression cassettes were constructed carrying the coding region of potato virus Y coat protein (PVY CP) with the artificial initiation codon controlled by the CaMV 35S promoter and poly(A) signal. The 5'-leader of PVY CP mRNA was represented by a 37-nucleotide polylinker in the first cassette, and by an 80-nucleotide leader containing a shortened variant of potato virus X 5'-leader in the second. The cassettes were transferred to the genome of Belorusskii-3 potato plants by agrobacterial transformation. The analysis of PVY CP gene expression was performed for several independent lines of transgenic plants. In the presence of the PVX leader in front of the ATG initiation codon of the PVY CP gene, the coat protein was accumulated in all the plants tested, whereas among the plants carrying the cassette with the polylinker leader the coat protein was not detected. In the presence of the PVX leader the PVY CP mRNA steady-state content was 10 times higher than with polylinker leader. The effect of the PVX leader on PVY CP mRNA stability and translatability is discussed.