Distribution, Polymorphism, Evolution And Characteristic Of Transposition Of Mariner-like Elements In Bambusoideae Subfamily

Mariner transposon which was an autonomous DNA transposon was first discovered from mutation of eye color in Drosophila mauritiana. The DNA transposons with motifs similar to the mariner were named as mariner-like elements (MLE) and were found widespread in animal. MLE transposons were widespread and abundant in plant.Two full-length mariner-like elements (Phmar1 and Phmar2) were isolated first by genome walking based on modified magnetic enrichment from Phyllostachys edulis. They had 4760bp and 5967bp respectively. They contained the typical MLE TIRs (Terminal inverted repeats) and MLE TSDs (Target Site Duplications). TIRs of Phmar1 and Phmar2 were 28bp and 27bp respectively. Both TSDs of them were all TA. Phmar1 and Phmar2 contained complete and intact ORF of mariner-like transposase. Phmar1 contained 3 introns and 4 exons which encoded 499 amino acids. Phmar2 contained 2 introns and 3 exons which encoded 449 amino acids. The DD39D motifs and the helix-turn-helix (HTH) motifs in the N-terminal ends of phmar1 and phmar2 were found.A pair of primers outside ORF of Phmar1 isolated above was designed to detect mutation and evolution of the transposase in a large spectrum of bamboo species genomes. 79 full-length mariner-like transposases were isolated from 69 representative bamboo species from 38 genera within six subtribes mainly found in China, indicating that mariner-like transposases were widespread and abundant in Bambusoideae subfamily. All of the transposases were with high identities and similar GC content and grouped into the subclade A2, showing that they were derived from the same ancestor. There were also no frame-shift, indels and nonsense mutations identified in 79 full-length mariner-like transposases, showing that they were relatively young.The transposase sequence Sa-1 which was same to the consensus sequence of 79 transposases was tested in yeast. The result showed that Sa-1 still had the activity of transposition.Here we presented the first comprehensive characterization and analysis of the distribution and evolution of full-length mariner-like transposases in Bambusoideae subfamily and firstly demonstrated that transposition activity of bamboo mariner-like element in the yeast. This study will provide a foundation for future making a new genetic tool based on mariner-like elements available for plant gene tagging.