Horizontal gene transfer

Horizontal gene transfer (HGT) is the movement of genetic material between unicellular and/or multicellular organisms other than via vertical transmission (the transmission of DNA from parent to offspring.) HGT is synonymous with lateral gene transfer (LGT) and the terms are interchangeable. HGT has been shown to be an important factor in the evolution of many organisms.

Horizontal gene transfer is the primary reason for the spread of antibiotic resistance in bacteria and plays an important role in the evolution of bacteria that can degrade novel compounds such as human-created pesticides and in the evolution, maintenance, and transmission of virulence. This horizontal gene transfer often involves temperate bacteriophages and plasmids. Genes that are responsible for antibiotic resistance in one species of bacteria can be transferred to another species of bacteria through various mechanisms such as F-pilus), subsequently arming the antibiotic resistant genes' recipient against antibiotics, which is becoming a medical challenge to deal with.

Most thinking in genetics has focused upon vertical transfer, but there is a growing awareness that horizontal gene transfer is a highly significant phenomenon and among single-celled organisms, perhaps the dominant form of genetic transfer.

Artificial horizontal gene transfer is a form of genetic engineering.

Horizontal genetic transfer was first described in Seattle in 1951 in a publication which demonstrated that the transfer of a viral gene into Corynebacterium diphtheriae created a virulent from a non-virulent strain, also simultaneously solving the riddle of diphtheria (that patients could be infected with the bacteria but not have any symptoms, and then suddenly convert later or never), and giving the first example for the relevance of the lysogenic cycle. Inter-bacterial gene transfer was first described in Japan in a 1959 publication that demonstrated the transfer of antibiotic resistance between different species of bacteria. In the mid-1980s, Syvanen predicted that lateral gene transfer existed, had biological significance, and was involved in shaping evolutionary history from the beginning of life on Earth.

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