PAN-MITOGENOMICS

As a result of sequencing an increasing number of genomes of any nature (nuclear, chloroplast, and also mitochondrial), it became obvious that not a single reference genome of a particular species reflects all the genetic diversity inherent in this species. In this connection the sequencing of the genomes of several samples of the concrete species began to develop and the so-called pangenomes were composed, and thus genomics began to transform into pangenomics. Complete nuclear genomes of plants have already been sequenced in more than one and a half thousand species, complete plastomes have been sequenced in more than 13 thousand species, while complete mitogenomes have been sequenced in less than 300 plant species. The reason for this "lag" in sequencing plant mitogenomes is their large size (on average about 400 thousand bp) compared to plastomes (on average about 140 thousand bp), the difficulty of assembling nucleotide sequences due to the multitude of repetitive elements, as well as less clarity of their structural organization and active recombination processes. Despite mainly matrilineal inheritance, mitogenomes and plastomes are different genetic systems with their own rates of evolution, different mutational and recombination processes, and it may be useful to compare closely related species with the construction of phylogenetic trees based on the genomes of both organelles. Moreover, it is very important to know the intraspecific polymorphism of the nucleotide sequences of mitogenomes, which leads to the creation of pan-mitogenomes, which very few have been compiled for plants so far. Thus, it was created a pan-mitogenomes for rapeseed and Citrus super-pan-mitogenomes for a number of citrus species. In addition, two or more mitogenomes have been sequenced for 20 more species, which can be considered a pangenomic approach. In this, the plant mitogenome is lagging far behind, while plant nuclear pangenomes and panplastomes have been constructed for about one a half hundred and three dozen species respectively, and multiple plastomes have been sequenced in 130 more species.