Jumping genes and the rise of flowering plants

Scientists from Murdoch University have developed a theory of evolution that explains what Charles Darwin described as an “abominable mystery” - the rapid rise of flowering plants. Their work has been published in the journal Genome Biology & Evolution.

Associate Professor Wayne Greene said there are at least 350,000 species of flowering plants, while their non-flowering relatives are evolving slowly and number barely 1000 species.

“Modern explanations for the success of flowering plants include their ability to undergo duplications of their entire genome as well as interspecies hybridisation and modifications for pollination by birds and insects and seed dispersal,” Associate Professor Greene said.

“While these theories are valid, they don’t fully explain the amazing diversification of flowering plants.”

Associate Professor Greene and his colleagues, Dr Keith Oliver and Professor Jen McComb, explain that transposable elements (TEs), more commonly known as ‘jumping genes’, help provide the explanation for the prolific evolution of flowering plants.

Jumping genes are mobile segments of DNA that can actively insert themselves, or a copy of themselves, into new positions within the genome. They can arise spontaneously or can be introduced into a genome by transferring across from other species. They are also a dominant feature of most flowering plant genomes.

The last two decades have shown that jumping genes have been responsible for numerous traits in a wide variety of organisms, “such as purple cauliflower, blood oranges, white grapes, the modern shape of corn plants, spring wheat, roma tomatoes, sticky rice and wrinkled peas”, Associate Professor Greene said.

TE-Thrust (the activity of TEs) explains why some biological lineages have a great number of species and others have few; different rates of evolution; and the existence of seemingly unchanged species known as living fossils.

“TE-Thrust supports a punctuated equilibrium model of evolution, periods of rapid evolution interspersed by slower periods consistent with the fossil record,” Associate Professor Greene said.

“The high percentage of mobile DNA sequences in flowering plant genomes means that they will strongly exhibit the extra evolutionary boost that TE-Thrust can provide.”

The researchers concluded, “Together with traditional explanations, the enhanced genomic plasticity facilitated by TE-Thrust suggests a more complete and satisfactory explanation for Darwin’s ‘abominable mystery’.”