Did cancer come from plants?

A‘jumping gene’ known to cause cancer and neurological disorders may have been transferred to humans from plants, scientists say. Scientists from University of Adelaide in Australia have shown that widespread transfer of genes between species has radically changed the genomes of today’s mammals, and been an important driver of evolution.

In the world’s largest study of so-called “jumping genes”, researchers have traced two particular jumping genes across 759 species of plants, animals and fungi. These jumping genes are actually small pieces of DNA that can copy themselves throughout a genome and are known as transposable elements.

They have found that crossspecies transfers, even between plants and animals, have occurred frequently throughout evolution. Both of the transposable elements they traced L1 and BovB entered mammals as foreign DNA. This is the first time anyone has shown that the L1 element, important in humans, has jumped between species.

“Jumping genes, properly called retrotransposons, copy and paste themselves around genomes, and in genomes of other species” said David Adelson, from the University of Adelaide.

“This process is called horizontal transfer, differing from the normal parent-offspring transfer, and it’s had an enormous impact on mammalian evolution,” said Adelson. For example, 25 per cent of the genome of cows and sheep is derived from jumping genes.

L1 elements in humans have been associated with cancer and neurological disorders. Understanding the inheritance of this element is important for understanding the evolution of diseases, researchers said.