Modern genetic engineering began in 1972 when United States Biochemists Herbert Boyer and Stanley Cohen used enzymes to cut a bacteria plasmid and insert another strand of DNA in the gap. Both bits of DNA were from the same type of bacteria, but this milestone, the invention of recombinant DNA technology, offered a window into the previously impossible—the mixing of traits between totally dissimilar organisms.
Allan Maxam and Walter Gilbert developed a DNA sequencing method based on chemical modification of DNA and subsequent cleavage at specific bases.
Although Maxam and Gilbert published their chemical sequencing method two years after the ground-breaking paper of Sanger and Coulson on plus-minus sequencing, Maxam–Gilbert sequencing rapidly became more popular, since purified DNA could be used directly, while the initial Sanger method required that each read start be cloned for production of single-stranded DNA. However, with the improvement of the chain-termination method (see below), Maxam-Gilbert sequencing has fallen out of favour due to its technical complexity prohibiting its use in standard molecular biology kits, extensive use of hazardous chemicals, and difficulties with scale-up.
DNA Plant Technology receives approval from the US Department of Agriculture to field test its Fish tomato but the plant is never successfully commercialized. The creation of a genetically modified plant, with a fish transgene designed for human consumption galvanizes citizen skepticism towards the emerging technology.
The first modern recombinant crop approved for sale in the U.S., in 1994, was the FlavrSavr tomato, which had a longer shelf life. However, higher costs and same bland flavor as conventional tomatoes led to it losing money and disappearing from the shelves.