Zingeria (Poaceae) is a small genus that includes Z. biebersteiniana, a diploid species with the lowest chromosome number known in plants (2n = 4) as well as hexaploid Z. kochii and tetraploid Z. pisidica, and/or Z. trichopoda species. The relationship between these species and the other low-chromosomes species Colpodium versicolor are unclear. To explore the intragenomic polymorphism and genome composition of these species we examined the sequences of the internal transcribed spacer 1 of the 35S rRNA gene via NGS approach. Our study revealed six groups of ribotypes in Zingeria species. Their distribution confirmed the allopolyploid nature of Z. kochii, whose probable ancestors were Colpodium versicolor and Z. pisidica. Z. pisidica has 98% of rDNA characteristic only for this species, and about 0.3% of rDNA related to that of Z. biebersteiniana. We assume that hexaploid Z. kochii is either an old allopolyploid or a homodiploid that has lost most of the rRNA genes obtained from Z. biebersteiniana. In Z. trichopoda about 81% of rDNA is related to rDNA of Z. biebersteiniana and 19% of rDNA is derived from Poa diaphora sensu lato. The composition of the ribotypes of the two plants determined by a taxonomy specialist as Z. pisidica and Z. trichopoda is very different. Two singleton species are proposed on this base with ribotypes as discriminative characters. So, in all four studied Zingeria species, even if the morphological difference among the studied species was modest, the genomic constitution was significantly different, which suggests that these are allopolyploids that obtained genomes from different ancestors.

Arbuscular mycorrhiza (AM) is a widespread symbiosis formed by most land plants with fungi from Glomeromycotina subdivision. The main problem in study of AM fungi is the complication in identification, associated with high intra- and interspecific genetic polymorphism, as well as obligate status of AM fungi in relation to host plant. The methodology for AM fungi identification is constantly undergoing major changes. In the review the selection of optimal methods of molecular genetic identification for AM fungi is carried out. The sample preparation, selection of species-specific marker DNA fragments and primers design, amplification including nested PCR are considered. The prospects for cloning and next generation sequencing for AM fungi identification are analyzed and substantiated.

The study represents the results of research of intragenic polymorphism in transcribed spacer ITS1 of the 35S rRNA genes in representatives of subgenus Xanthosparganium genus Sparganium which were obtained by means of locus-specific next generation sequencing on the platform Illumina MiSeq. It was shown that ribotype variations in studied samples generally correspond to the division of this genus into three sections Erecta (subgenus Sparganium), Natantia and Minima (subgenus Xanthosparganium). High level of intragenic polymorphism was revealed in S. hyperboreum, with ribotypes distributed among several groups. Genome of this species includes ribotypes which are typical for other species in subgenus Xanthosparganium. For two investigated S. glomeratum samples, there were no ribotypes similar to such ribotypes in other species of Natantia section. S. glomeratum has got ribotypes identical with S. hyperboreum of Minima section. This feature may be the evidence of ancient intersectional hybridization of these two species. Characteristics of rDNA in S. glomeratum are in favor of putting this species into Minima section. It was suggested that speciation processes within the genus could be based not only on hybridization but also went on in allopatric way. The fist statement is supported by the presence of similar and identical ribotypes in S. emersum, S. longifolium, S. gramineum and S. hyperboreum, the second as it was mentioned by other researchers, is due to close relationship between North American and Eurasian taxa.

The review is aimed to analyze molecular mechanisms of carbohydrate transport during the formation of arbuscular mycorrhiza (AM), a widespread symbiosis of plants with Glomeromycotina subdivision fungi. Due to AM-symbiosis, plants receive microelements, mainly phosphorus, and fungi are supplied by products of carbon assimilation. The study of sugar transport mechanisms in plants as well as between plants and symbiont is methodologically difficult because of the obligatory status of AM fungi. The mechanisms of carbohydrate transport in leaf and root cells are concerned, particular interest is paid to transporters, specific to AM structures. Several resumptive schemes are designed. SWEET family of transporters (Sugars Will Eventually be Exported Transporters), including AM-specific uniporters are reviewed. We summarize results on expression of genes encoding transporter in cells of plants without AM, in AM-plant cells with arbuscules and AM-plant cells without arbuscules. The data on genes of MST proteins family (Monosaccharide Transporters) participating in direct transport of sugars from the soil to the foliar mycelium of AM fungi are considered.

The authors wish to make the following corrections to their paper

The nuclear ITS1–5.8S rDNA–ITS2 region is among the most widely used markers for phylogenetic studies in plants. We sequenced the ITS1–5.8S rDNA–ITS2 region in several species of Selenicereus, two species of Deamia and Epiphyllum chrysocardium. The newly generated sequences were found to be more closely related to ITS and 5.8S rDNA sequences from representatives of other cactus tribes than to the Selenicereus ITS sequences previously deposited in GenBank by research group O. Plume. Importantly, all these sequences retained three conserved motifs of the 5.8S rRNA gene that are commonly used to distinguish functional copies from pseudogenes. Then we analyzed available genome assemblies representing 12 species of Cactaceae. In contrast to the ribotypes identified in this study, the previously reported 5.8S rDNA variants in the assembled genomes of Selenicereus and Carnegiea were represented by a single copy flanked by highly degraded 18S and 28S rDNA sequences. Phylogenetic analyses based on the newly generated ITS sequences and Genbank data supported the monophyly of the subtribes Hylocereinae, Rhipsalideae, and Trichocereinae, as well as the tribes Rhipsalideae, Notocacteae, and Cylindropuntieae. These results demonstrate that the functional ITS1-5.8S rDNA–ITS2 region represents an informative marker for phylogenetic studies within the Cactaceae.