Comparative analysis of the complete mitogenomes of var. and var. provide insights into evolution and phylogeny relationship.

INTRODUCTION

Among cultivated tea plants (), only four mitogenomes for var. (CSA) have been reported so far but none for var. (CSS). Here, two mitogenomes of CSS (CSSDHP and CSSRG) have been sequenced and assembled.

METHODS

Using a combination of Illumina and Nanopore data for the first time. Comparison between CSS and CSA mitogenomes revealed a huge heterogeneity.

RESULTS

The number of the repetitive sequences was proportional to the mitogenome size and the repetitive sequences dominated the intracellular gene transfer segments (accounting for 88.7%- 92.8% of the total length). Predictive RNA editing analysis revealed that there might be significant editing in NADH dehydrogenase subunit transcripts. Codon preference analysis showed a tendency to favor A/T bases and T was used more frequently at the third base of the codon. ENc plots analysis showed that the natural selection play an important role in shaping the codon usage bias, and Ka/Ks ratios analysis indicated and genes may have undergone positive selection. Further, phylogenetic analysis shows that six clustered together, with the CSA and CSS forming two distinct branches, suggesting two different evolutionary pathway.

DISCUSSION

Altogether, this investigation provided an insight into evolution and phylogeny relationship of mitogenome, thereby enhancing comprehension of the evolutionary patterns within species.