Species of the genus Salicornia (Amaranthaceae s.l.) are widespread throughout the globe and are resistant to salinity. They can be used as food and for biofuel production. The formation of pure lines as a result of self-pollination along with the possibility of sporadic cross-pollination, polyploidy, a high degree of physiological plasticity and a small number of diagnostic characters greatly complicate the taxonomy of the genus. Salicornia is an evolutionarily young group, where the number of informative substitutions in traditionally analyzed regions of nuclear and plastid DNA turned out to be insufficient to establish relationships between species, and the very concept of a species in this genus remains a subject of debate. To clarify the relationships of the Eastern European species, we used high-throughput sequencing to determine the sequences and perform a phylogenetic analysis of the plastomes of 11 samples representing all the main morphotypes of the Eastern European glassworts, and analyzed the variability of the nuclear rDNA external transcribed spacer (nrETS). The sizes of the assembled plastomes varied from 153,290 bp to 153,504 bp and had a typical architecture with a large single-copy region (84,625-84,797 bp in length), a small single-copy region (18,818-18,870 bp in length), and two inverted repeats (24,898-24,908 bp in length). Comparison of phylogenetic trees reconstructed from all currently available plastome data and nrETS alignments of the same glasswort accessions revealed a discrepancy in the arrangement of tetraploid S. procumbens subsp. pojarkovae and S. brachiata accessions, which show affinities to different lineages depending on the use of plastid or nuclear (nrETS) data. Our results highlight the role of reticulate evolution in the genus Salicornia.
Samigullin et al. (Wed,) studied this question.