Abstract: Nicotiana tabacum is a plant containing cellular T-DNA (T-DNA obtained by plants from Agrobacterium during evolution as a result of horizontal gene transfer) in the genome. Within the species N. tabacum, many varieties are distinguished, and phylogenetic relationships among them have not been established yet. Despite the diversity of phenotypes, N. tabacum varieties are known to have a low level of genetic diversity, so clarification of intraspecific phylogeny is complicated. This article proposes a new marker for studying the phylogeny of the Nicotiana tabacum species on the basis of the results of a comparative analysis of the cT-DNA TA and TB fragments and the PMT2 gene in 11 varieties of Nicotiana tabacum. It has been shown that, for sequences of agrobacterial origin in the genomes of plants, the same evolutionary mechanisms are typical, as for plant sequences. Thus, the cT-DNA (namely, TA) sequences can be used as a phylogenetic marker for the species N. tabacum, since the varieties can be separated into two groups based on the structure of the TA central region.
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