Mitochondrial Genome Of Selaginella Sinensis(Desv.) Spring(Lycophyte)

Mitochondrial are semi-autonomous organelles in eukaryotic cell and their own genetic material anfgenetic system.In 1967,American botansis proposed the“endosymbiont hypothesis” in “on the Origin of Mitosing Cells”,beleveing that mitochondria originated from bacterica instead of archaea.Mitochondria are playing a central role in metabolism and energy transfer of plants and animals.At odds with their animal and fungi counterparts,mitochondrial genomes of plants exhibit extremely high variation and complexity.The mitochondrial genomes of plants very greatly in size,and the Silence conica,which is the largest known,is 11 Mb.The smallest plant mitochondrial genome is the mistletoe plant Uiscum scurruloideum,which is only 66 kb in size.Most plant are between 200-800 kb.The structure of the mitochondrial genome of plants is very complex,which is usually composed of a main genome and many subgenomes of different size derived from recombination mediated by repeats,and there is substoichiometric migration between different conformations.In the mitochondrial genome of higher plant,there are usually 41 protein-coding genes,but there are different level of deletion and pseudogenylation in different groups.RNA editing is a plant-transcriptional regulation of plant mitochondrial genome RNA,the plant organell type of RNA editing exchanges the pyrimidine nucleotides cytidine and uridine at specific transcript sites and thus alters the encoded information at the RNA level.Lycophytes are the sister clade to all other vascular plants(tracheophytes).Extant lycophytes comprise three well-defined orders,the Isoetales(quillworts),the Selaginellales(spike mosses),and the Lycopodiales(club mosses),And the study on the mitochondrial genome of S.moellendorfii?H.squarrosa?I.isoetes shows that the mitochondrial genome of those three plants have their own characteristics and are very different from each other.In this study,to explore the energetic genomic features and molecular evolutionary prtterns of mitochondrial genome of Selaginella sinensis,we reported a highly variable mitochondrial genome in the oldest vascular plant lineage Selaginella,Selaginella sinensis.We used the data from both the Next Generation Sequencing(Illumina Hiseq)and Single Molecule Real-time Sequencing(Pac Bio Sequel),and combined transcriptome data(mRNA and total RNA)to conduct the assembly and annotation of the mitochondrial genome.Consequently,the overall mitochondrial genomic features of S.sinensis in this study have been revealed by comparative genomic analysis,including genome size,genomic architecture,gene content,genomic composition,RNA editing,and evolutionary rates.The results showed that: numerous recombination events mediated mainly via long sequence repeats result in a complex mitochondrial DNA structure.The S.sinensis mitochondrial DNA complexity is essentially explained by thirteen large sequence repeats,labeled R1 through R13.Finally,we assembled the S.sinensis mitochondrial genome which has 8 parts,including 6 ring and 2 liner structures.The size is 185 kb,GC content is68.70%,and it has 17 genes.The RNA editing with a total of 1904 sites,1784 were C to U and 120 were U to C.The synonymous(d S)and nonsynonymous(d N)of the genes were significantly different from H.squarrosa and I.isoetes.To sum up,the structure of the mitochondrial genome of S.sinensis was complex,the gene content was significantly decreased compared of angiosperms,but consistent with S.moellendorfii.A yet higher GC content than previously observed in S.moellendorfii is impressive as such,and RNA editing site-richest.This particular mitochondrial genome is characteristic of the Selaginella.