<p style="text-align: justify;">FLAVR SAVR&trade; tomatoes were developed using recombinant DNA techniques to express the trait of delayed softening of tomato fruit. The novel variety was developed by insertion of an additional copy of the polygalacturonase (PG) encoding gene in the &ldquo;antisense&rdquo; orientation, resulting in reduced translation of the endogenous PG messenger RNA (mRNA). The antisense PG gene is essentially a reverse copy of part of the native tomato PG gene that suppresses the expression of endogenous PG enzyme prior to the onset of fruit ripening. The mechanism of decreased PG activity in FLAVR SAVR&trade; tomato is likely linked to the hybridization of antisense and sense mRNA transcripts, resulting in a decreased amount of free positive sense mRNA available for protein translation. Reduced PG expression decreases the breakdown of pectin and leads to fruit with slowed cell wall breakdown, better viscosity characteristics and delayed softening. FLAVR SAVR&trade; tomatoes have improved harvest and processing properties that allow the transgenic tomatoes to remain longer on the vine to develop their natural flavour, maintain firmness for shipping and produce a thicker consistency in processing.</p>

<p style="text-align: justify;">An antibiotic resistance marker gene (<i>neo</i>) encoding the enzyme neomycin phosphotransferase II (NPTII), which inactivates aminoglycoside antibiotics such as kanamycin and neomycin, was also introduced into the genome of this transgenic tomato. This gene was derived from a bacterial transposon (Tn5 transposable element from <i>Escherichia coli</i>) and was included as a selectable marker to identify transformed plants during tissue culture regeneration and multiplication. The expression of the <i>neo</i> gene in these plants has no agronomic significance and the safety of the NPTII enzyme as a food additive was evaluated by the United States Food and Drug Administration in 1994 (US FDA, 1994).</p>
