The origin and fate of fungal mitochondrial horizontal gene transferred sequences in orchids (Orchidaceae)

Abstract

The transfer of DNA among distantly related organisms is relatively common in bacteria but less prevalent in eukaryotes. Among fungi and plants, few of these events have been reported. Two segments of fungal mitochondrial DNA have been recently discovered in the mitogenome of orchids. Here, we build on that work to understand the timing of those transfer events, which orchids retain the fungal DNA and the fate of the foreign DNA during orchid evolution. We update the content of the large DNA fragment and establish that it was transferred to the most recent common ancestor of a highly diverse clade of epidendroid orchids that lived ~28–43 Mya. Also, we present hypotheses of the origin of the small transferred fragment. Our findings deepen the knowledge of these interesting DNA transfers among organelles and we formulate a probable mechanism for these horizontal gene transfer events.