Diversity and evolution of Pong-like elements in Bambusoideae subfamily

The PIF/IS5 is a recently discovered superfamily of DNA transposons which include Pong-like elements and PIF-like elements and has been successively detected in the genomes of many flowering plants, fungi and diverse animals. Here we present the first comprehensive characterization and analysis of Pong-like elements in Bambusoideae subfamily. Eighty-two Pong-like elements were cloned and sequenced from 44 representative species of Bambusoideae. Phylogenetic analysis of 82 distinct Pong-like elements sequences showed that Pong-like elements were widespread, diverse and abundant in Bambusoideae. A molecular phylogeny of Bambusoideae was established by using the internal transcribed spacer sequence of nuclear ribosomal DNA (ITS) information. The comparison between ITS and Pong-like elements based trees reveals obviously incongruent. The results suggest that 1) there are multiple Pong-like element families in Bambusoideae; 2) a single Pong-like element family could be present in multiple bamboo species; 3) Pong-like elements from the same family from different bamboo species could be more similar than elements from different families in the same bamboo species or closely related species.