Gene subtraction is a technique used to inactivate existing genes in plants using antisense RNA. Antisense RNA is produced by cloning a gene in the reverse orientation, which produces RNA complementary to the target gene's mRNA. This antisense RNA binds to the target mRNA and prevents its translation, effectively blocking the expression of the target gene. Some applications of antisense technology include producing slow ripening tomatoes by inactivating the polygalacturonase gene involved in fruit softening, and delaying ethylene production in tomatoes by targeting the ACC synthase gene involved in ethylene synthesis. Gene subtraction allows for directed modification of plant traits and characteristics.