From ScienceDaily:
Transposons are DNA elements that can multiply and change their location within an organism’s genome. Discovered in the 1940s, for years they were thought to be unimportant and were called “junk DNA.” Also referred to as transposable elements and jumping genes, they are snippets of “selfish DNA” that spread in their host genomes serving no other biological purpose but their own existence.
but
Working on the model plant Arabidopsis, they found that the COPIA-R7 transposon, which has jumped into the plant disease resistance gene RPP7, enhances the immunity of its host against a pathogenic microorganism that is representative of a large group of fungus-like parasites that cause various detrimental plant diseases.
“We provide a new example for an ‘adaptive transposon insertion’ event — transposon insertions that can have beneficial effects for their respective host organisms — and uncover the mechanistic basis of its beneficial effects for plants,” said Thomas Eulgem, an associate professor of plant cell biology and the senior author of the research paper. “While it has been known for a while that transposon insertions can have positive effects for their respective host organisms and accelerate evolution of their hosts, cases of such adaptive transposon insertions have been rarely documented and are, so far, poorly understood.”
Jumping genes are not so much “poorly understood” as”Darwinianly understood.” But we mustn’t repeat ourselves.