Chloroplast Genomes of the Green-Tide Forming Alga Ulva compressa: Comparative Chloroplast Genomics in the Genus Ulva (Ulvophyceae, Chlorophyta)

To understand the evolution of Ulva chloroplast genomes at intraspecific and interspecific levels, in this study, three complete compressa Linnaeus were sequenced compared with available cpDNA data. Our comparative analyses unveiled many noticeable findings. First, genome size variations cpDNAs levels mainly caused by differences gain or loss group I/II introns, integration foreign DNA fragments, content non-coding intergenic spacer regions. Second, U. shared same 100 conserved genes as other cpDNA, whereas flexuosa appears to be only species minD gene retained its cpDNA. Third, five types I most which carry a LAGLIDADG GIY-YIG homing endonuclease, II usually encoding reverse transcriptase/maturase, detected 26 insertion sites 14 host 23 genomes, intron insertion-sites have been found for first time Chlorophyta. Fourth, one degenerate previously ignored has infA all species, but not closest neighbor, Pseudoneochloris marina , chlorophycean taxa, indicating that it should result an independent invasion event occurred common ancestor species. Finally, seven represented novel order was different from cpDNAs. The structure is conserved, remarkably plastic, due multiple rearrangement events.