The mitochondrial genome of the bloom-forming green alga Ulva prolifera

From 2007 to 2015, massive green tides formed by Ulva prolifera O. F. Muller have broken out for nine consecutive years in the Yellow Sea of China. Here, we determined the complete mitochondrial genome sequence of U. prolifera. The circular U. prolifera mitogenome is 63 845 bp in size, with the overall A + T content of 66.04% which is similar to the other three ulvophyceans (60.66%-67.83%). The mitogenome encodes 74 genes and the coding sequences account for 77.3% of the genome. Nine introns are identified in five genes and each of these introns contains an ORF. Two long tandem repeats identified have a period of 11 bp with a copy number of 62.5 and 19.5, respectively. The genome organization of U. prolifera is similar to that in Ulva sp., and its reduced spacer region makes it more compact than the latter. The present data will provide important information on phylogenetics and molecular evolution of Ulva species.