Genetically engineered tomato plants. The petri dish contains cultures of Flavr Savr tomato plants; the first genetically engineered whole food. Each plantlet has been cultured from a single cell, grown on agarose medium. Flavr Savr tomatoes have a gene that allows the fruit to ripen on the vine without softening; so they are tastier, do not need ripening with ethylene gas, and are not damaged during shipping. Tomato softening occurs due to the enzyme polygalacturonase. Flavr Savr tomatoes contain an anti-sense gene that blocks the enzyme. Research conducted at Calgene in California, USA. .