中国树花线粒体基因组特征及系统发育分析

Characterization and phylogenetic analysis of Ramalina sinensis mitogenome

中国树花是广布于北半球的一种地衣,具有抗病毒、抗菌、抗氧化、抗肿瘤、抗炎和治疗糖尿病等生物活性。本研究首次对中国树花Ramalina sinensis的线粒体基因组进行测序、组装和注释,结果表明其线粒体基因组是一个长度为38265 bp的环状分子,共编码42个基因(15个蛋白质编码基因(PCGs)、2个rRNA基因和25个tRNA基因),碱基组成具有明显AT偏好性,其中24个tRNA被成功预测为典型三叶草结构。密码子偏好性分析显示该线粒体基因组对A/U结尾的密码子具有明显偏好性。树花科地衣共线性分析没有发现大面积的基因重排现象。与间枝树花R.intermedia的线粒体基因组比较分析显示这2个物种有着较为亲密的适应性进化关系。15个PCGs的Ka/Ks值各不相同,说明这些基因正在接受不同的选择压力。系统发育分析表明中国树花与间枝树花的亲缘关系很紧密。本研究为树花属的资源保护、系统进化以及遗传多样性研究提供基础数据。

Ramalina sinensis is a widespread lichen in the Northern Hemisphere,and its metabolites have various biological activities such as antiviral,antimicrobial,antioxidant,antitumor,anti-inflammatory,and antidiabetic activities.Complete mitogenome of R.sinensiswe was sequenced,assembled,and annotated for the first time.The mitochondrial genome is of closed-loop structure with total length of 38265 bp,encoding 42 genes including 15 protein-coding genes,2 rRNA genes and 25 tRNA genes.R.sinensis mitochondrial genome had a significant AT preference.Twenty-four tRNAs were successfully predicted as typical cloverleaf structures.Relative synonymous codon usage analysis revealed a significant preference for A/U ending codons.Ramalinaceae collinearity analysis revealed no large gene rearrangements.Comparative analysis of the mitochondrial genomes showed a more intimate evolutionary relationship between R.sinensis and R.intermedia.Fifteen protein-coding genes had different Ka/Ks values,showing there were under different selection pressures.The phylogenetic analysis showed R.sinensis and R.intermedia has close relationship.This study provides basic data for future studies of phylogenetic evolution and genetic diversity of Ramalina.