Since 2007, the annual green tide disaster in the Yellow Sea has brought serious economic losses to China. There is no research on the genetic similarities of four constituent species of green tide algae at the genomic level. We previously determined the mitochondrial genomes of Ulva prolifera, Ulva linza and Ulva flexuosa. In the present work, the mitochondrial genome of another green tide (Ulva compressa) was sequenced and analyzed. With the length of 62,311 bp, it contained 29 encoding genes, 26 tRNAs and 10 open reading frames. By comparing these four mitochondrial genomes, we found that U. compressa was quite different from the other three types of Ulva species. However, there were similarities between U. prolifera and U. linza in the number, distribution and homology of open reading frames, evolutionary and codon variation of tRNA, evolutionary relationship and selection pressure of coding genes. Repetitive sequence analysis of simple sequence repeats, tandem repeat and forward repeats further supposed that they have evolved from the same origin. In addition, we directly analyzed gene homologies and translocation of four green tide algae by Mauve alignment. There were gene order rearrangements among them. With fast-evolving genomes, these four green algal mitochondria have both conservatism and variation, thus opening another window for the understanding of origin and evolution of Ulva.

中文翻译：

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绿潮藻有丝分裂基因组的比较研究

2007年以来，一年一度的黄海绿潮灾害给我国带来了严重的经济损失。没有在基因组水平上研究绿潮藻四种组成物种的遗传相似性。我们以前确定了石莼、石莼和石莼的线粒体基因组。在目前的工作中，对另一种绿潮（Ulva compressa）的线粒体基因组进行了测序和分析。全长62,311 bp，包含29个编码基因、26个tRNA和10个开放阅读框。通过比较这四种线粒体基因组，我们发现 U. compressa 与其他三种类型的石莼属有很大不同。然而，U. prolifera 和 U. linza 在开放阅读框的数量、分布和同源性、tRNA 的进化和密码子变异等方面存在相似之处，编码基因的进化关系和选择压力。简单序列重复、串联重复和正向重复的重复序列分析进一步假设它们是从同一起源进化而来的。此外，我们通过紫红色比对直接分析了四种绿潮藻的基因同源性和易位。它们之间存在基因顺序重排。凭借快速进化的基因组，这四种绿藻线粒体既有保守性又有变异性，从而为了解石莼的起源和进化打开了另一个窗口。我们通过紫红色比对直接分析了四种绿潮藻的基因同源性和易位。它们之间存在基因顺序重排。凭借快速进化的基因组，这四种绿藻线粒体既有保守性又有变异性，从而为了解石莼的起源和进化打开了另一个窗口。我们通过紫红色比对直接分析了四种绿潮藻的基因同源性和易位。它们之间存在基因顺序重排。凭借快速进化的基因组，这四种绿藻线粒体同时具有保守性和变异性，从而为了解石莼的起源和进化打开了另一个窗口。