The review focuses on the genetic consequences of interspecific hybridization and discusses its role in speciation and increasing the genetic diversity of plants, including the diversity of...

Перспективы использования Illumina MiSeq для идентификации грибов арбускулярной микоризы

Aegilops comosa Smith in Sibthorp et Smith, 1806 is diploid grass with MM genome constitution occurring mainly in Greece. Two morphologically distinct subspecies – Ae. c. comosa Chennaveeraiah, 1960 and Ae. c. heldreichii (Holzmann ex Boissier) Eig, 1929 are discriminated within Ae. comosa, however, genetic and karyotypic bases of their divergence are not fully understood. We used Fluorescence in situ hybridization (FISH) with repetitive DNA probes and electrophoretic analysis of gliadins to characterize the genome and karyotype of Ae. comosa to assess the level of their genetic diversity and uncover mechanisms leading to radiation of subspecies. We show that two subspecies differ in size and morphology of chromosomes 3M and 6M, which can be due to reciprocal translocation. Subspecies also differ in the amount and distribution of microsatellite and satellite DNA sequences, the number and position of minor NORs, especially on 3M and 6M, and gliadin spectra mainly in the a-zone. Frequent occurrence of hybrids can be caused by open pollination, which, along with genetic heterogeneity of accessions and, probably, the lack of geographic or genetic barrier between the subspecies, may contribute to extremely broad intraspecific variation of GAA_n and gliadin patterns in Ae. comosa, which are usually not observed in endemic plant species.

Genetic colonization by agrobacteria is possible due to agrobacterial transformation, which implies interspecies transfer of genetic material (T-DNA). A transgenic tissue is formed on the whole non-transgenic plant during that process. However, it turned out that in nature there are plants containing T-DNA fragments in their genomes and they can inherit these T-DNAs sexually. Such T-DNA was called cellular, and such plants were called natural transgenic. Examples of such organisms are plants of the genus Vaccinium. In the genomes of two species of this genus we found cT-DNA, represented by a rolB/C-like gene [1]. Previously, analyzing the natural transgenes in another genus (Camellia L.) [2], we showed the importance of reconstructing the allelic states of transgenes for phylogenetic studies. In this study, we performed analysis of the spreading of the rolB/C-like gene for its use as a molecular marker within Vaccinium. We used molecular-genetic and bioinformatics methods for sequencing, assembly, and analysis of the rolB/C-like gene. We discovered 26 new Vaccinium species and Agapetes serpens (Wight) Sleumer as containing the rolB/C-like gene. Most of studied samples are characterized by the presence of full-size genes. This made it possible to develop approaches for alleles phasing of the rolB/C-like gene and reconstruct a Vaccinium phylogenetic relationship. We subjected the studied species to phylogenetic analysis based on sequences of the rolB/C-like gene. The resulting phylogenetic tree of the genus Vaccinium divided the species into sections in accordance with the classical genus system based on morphological characters. At the same time, our tree did not confirm the taxa determined on the basis of ITS.

The picture of intragenomic polymorphism of ITS1 region of rDNA repeats revealed by targeted high-throughput sequencing is a modern and simple method useful for phylogenetic purposes, and it can shed light on recent hybridizations. However, up to the present time it was not applied in Taraxacum, a taxonomically intricate genus with largely reticulate evolutionary pattern. We tested this approach on an exploratory set composed of 20 samples (8 species from 4 sections, including 5 species from the largest section Taraxacum), which were situated in different evolutionary and geographic distances from each other. Our results have shown that intragenomic polymorphism of ITS1 region of rDNA in Taraxacum may be successfully used for phylogenetic reconstructions. Species belonging to different sections were strikingly different by intragenomic polymorphism of rDNA, and substantial variability was also observed between some (but not all) specimens of section Taraxacum, giving preliminary evidence that this group may be not monomorphic. In the same time, 8 of 13 studied specimens from the section Taraxacum had ITS1 region substantially homogenized (dominant variant was at least 7 times more frequent than any other), which is considered connected with the age of the last hybridization event in corresponding lineages. Possibly, microspecies with substantially homogenized rDNA represent more strongly stabilized taxonomic units.