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The mitochondrial genome of moss Mielichhoferia elongata has been sequenced and assembled with Spades genome assembler. It consists of 100,342 base pairs and has practically the same gene set and its order as in other known bryophyte chondriomes. The genome contains 66 genes including three rRNAs, 24 tRNAs, and 40 conserved mitochondrial proteins genes. Unlike the majority of previously sequenced bryophyte mitogenomes, it lacks the functional nad7 gene. The phylogenetic reconstruction and scrutiny analysis of the primary structure of nad7 gene carried out in this study suggest its independent pseudogenization in different bryophyte lineages. Evaluation of the microsatellite (simple sequence repeat) content of the Mielichhoferia elongata mitochondrial genome indicates that it could be used as a tool in further studies as a phylogenetic marker. The strongly supported phylogenetic tree presented here, derived from 31 protein coding sequences of 40 bryophyte species is consistent with other reconstructions based on a number of different data sets.
This version takes into account all the remarks and corrections made by reviewers. The INTRODUCTION was improved, the main ideas, motivations, and context are more clearly communicated. The information regarding the life style/cycle of mosses, the general features and the current research progress in the mitochondrial genome of mosses were provided. The phrases about heavy metals tolerance mechanisms as a goal of a study were excluded. We excluded also phrases in INTRODUCTION and DISCUSSION about possible involvement of mitochondrial genome features in heavy metal tolerance. The information about nad7 gene function was added. The data about sample preparation and DNA isolation were provided. A number of CDS was corrected and a new list of them is inserted. All figures were redrawn and a new reference and an acknowledgment were added in this connection. One more grant was added in the Declaration. The manuscript was reviewed by Academic English Language Editing services and some typos were corrected.
The phylogenetic tree based on nuclear rDNA region (5.8S rDNA - ITS 2 - 5‘-end of 26S rDNA). The alignment consists of 440 positions. The tree reconstruction was conducted in TREECON software (Van de Peer & De Wachter, 1994) using the Neighbor-Joining method (Saitou & Nei 1987) with 500 bootstrap replications. Bootstrap support values >50% are shown next to the branches. The evolutionary distances were computed using the Kimura method (1980) with gaps taken into account as it implemented in the TREECON package.