Our manuscript on one of the oldest known horizontal transfers of transposable elements has been accepted for publication on Genome Biology and Evolution! By the way, this is also one of the very few cases of DNA transfer from animals to plants and the only known transfer of transposable elements between animals and plants.
Before the sequencing of conifer genomes, Penelope-like elements (PLEs) were supposedly occurring only in animals. In this article we describe a new group on PLEs, which we named Dryads, found in loblolly pine and other conifers. Fluorescent in situ hybridization on pine chromosomes, PCR assays and a whole lot of bioinformatics work we have done in the past two years show that Dryads are common in conifers but not other gymnosperms. All the phylogenies we made also point to PLEs from arthropods as Dryads’ sister group. This means that Dryads derive from a PLE lineage that was horizontally transferred from a yet unknown arthropod to the common ancestor of conifers ~340 million years ago! This is quite remarkable given that most documented horizontal transfers of transposable elements occurred much more recently. Who knows what other surprising evolutionary stories are awaiting to be discovered in the enormous genomes of conifer trees.
Congratulations to co-authors Xuan Lin (PhD student in my lab) and Dr. Nurul Faridi (USDA Forest Service cytogeneticist extraordinaire).