Lake Baikal and its invertebrates became a subject of systematic evolutionary studies more than a century ago. Exceptional taxonomic diversity of the lake’s fauna, high variability of habitats and large volume of auxiliary knowledge on the ecosystem enables one to study fine details of speciation mechanisms hardly accessible in other model systems. Parallel to the development of technological and methodological potential of biology most of new approaches were employed in studies of Lake Baikal. This review deals mostly with the results obtained during last two decades by means of molecular phylogenetics. The main common features found to date include, first of all, a relatively young age of the most recent common ancestor of the majority of species flocks. Second, it was found that almost all speciation events studied took place in sympatry and according to quite complicated scenarios. The latter is due to the fact that in the course of geological evolution of Lake Baikal there were no or very few episodes of its fragmentation sufficiently long for allopatric mechanisms to leave detectable traces. Reproductive barriers may temporarily disappear causing frequent mitochondrial or nuclear introgressions. As a result, intermediary forms of organisms of unclear taxonomic identity are a common occurrence. Another interesting feature is a practically absolute absence of evidence for co-evolution even of ecologically tightly connected organisms.

Tuco-tucos, South American rodents of the genus Ctenomys represent an interesting model of speciation. Their strict territorial and solitary life under the earth, vast but highly fragmented habitats, low migration activity were the causes of their very fast radiation. About 60 species of this genus have been described. They are found in a variety of habitats, from the mountains of the Andes to the coastal dunes of the Atlantic, from humid steppes of Pampas to dry deserts of Chaco. Tuco-tucos have a very high level of chromosomal polymorphism and polytypism based on Robertsonian and whole-arm reciprocal translocations and inversions, and can therefore be used to test different versions of chromosomal speciation hypothesis. The classic version of this hypothesis emphasizes the sterility of the hybrids, due to incorrect or incomplete chromosome synapsis in heterozygotes for rearrangements, germ cells death, chromosome nondisjunction and the generation of unbalanced gametes. The modern version of chromosomal speciation hypothesis suggests that the reduction of gene flow across chromosomal hybrid zones is due to the suppression of recombination in hybrids around the break points of rearrangements distinguishing the parental species. Field studies have not revealed strong negative effects of chromosomal heterozygosity on the fitness of the carriers. These results cast doubt on the validity of the classic version of the hypothesis. Analysis of chromosome behavior in the meiotic prophase in the chromosomal heterozygotes revealed significant changes in the frequency and distribution of recombination: crossingover suppression around the breakpoint and chiasma distalization. These changes can modulate the flow of genes between chromosomal races and amplify the divergence which has arisen due to spatial isolation. These data confirm the recombinational model of chromosomal speciation.

Wide hybridization is an important factor of angiosperm speciation and provides an introgression of genes between species. In experimental conditions wide hybridization is used to increase the genetic diversity of cultivated plants. Since the emergence of reproductive barriers is of great importance for speciation, plant capacity for wide crosses is determined by a possibility of overcoming these barriers. The review discusses the main types of incompatibility in wide crossing plants, as well as factors and methodological approaches that contribute to overcoming them. The role of Kr genes, which determine incompatibility between wheat and rye, is one of the examples of prezygotic isolation mechanism. Postzygotic incompatibility may be associated with a highly pronounced genetic and epigenetic variability induced by wide crossings. Early stages of the postzygotic period are crucial for developing hybrid seeds due to embryo’s death, including those associated with uniparental chromosome elimination in hybrid cells and abnormal development of the endosperm. A depression and a lethality of F1 hybrids may be the result of interaction between complementary genes, which cause hybrid necrosis, hybrid chlorosis, and hybrid dwarfness. The causes of hybrid sterility are discussed. Nuclearcytoplasmic interactions are regarded as one of the mechanisms of incompatibility in wide crosses. Reciprocal hybrids and alloplasmic lines are the main models for studying cytoplasm effects and nuclearcytoplasmic interactions. Problems concerning work with their models are emphasized. There are some examples underlining the fact that alloplasmic lines are not a plain combination of nuclear genome and cytoplasm of different species. Development of alloplasmatic lines is connected with structural and functional variability of nuclear and organelle genomes.

Lifespan is a complex quantitative characteristic that makes a significant contribution to the Darwinian adaptiveness. The disclosure of the genetic structure of longevity is a fundamental problem of the evolution of ontogeny, evolutionary genetics and molecular gerontology. Under optimal conditions, the lifespan is determined by the aging rate. The aging process is made up of interrelated processes that take place at the organismal, tissue, cellular, molecular and genetic levels. These include deregulation processes of homeostasis maintenance, metabolic reactions and sending intra- and intercellular signals, accumulation of senescent cells, damaged organelles and macromolecules, epigenetic changes and genetic instability. The objective of this review is to summarize the available information about underlying genetic determinants of longevity and aging. Genes and signaling pathways that regulate stress response, metabolism, growth of cells and organism, maintaining of genome and proteome integrity, qualitative and quantitative mitochondria composition, inflammatory response, apoptosis and selection of viable cells, as well as circadian rhythms were considered. The redistribution of energy resources from one pathway to the other can induce or inhibit the ”longevity program”, providing increased vitality and aging slowdown. Based on the analysis of geroprotective potential of examined genes’ regulation, main targets have been identified to slowdown aging and achieve healthy longevity. These trends include heterochromatin recovery, retrotransposition suppression, aneuploidy elimination; restoring the acidity of lysosomes; telomere elongation; suppression of chronic inflammation; elimination of protein cross-links; elimination of senescent cells; recovery of NAD+ levels; inhibition of mTOR, S6K, TGF-β, AT1; controlled activation of the ”longevity program” genes FOXO, AMPK, PGC1α, NRF2.

Stem cells are undifferentiated cells of multicellular organisms that can divide, self-renew and differentiate. Despite the differences of properties, general principles of the existence of stem cells can be distinguished in all multicellular organisms. In plants, stem cells are found in meristems – the structures that ensure the continuous growth of plant and provide material for the formation of various specialized tissues. There are numerous types of meristems: shoot and root apical meristems, lateral meristems (procambium, cambium, pericycle), as well as the so-called irregular meristems, developing under certain conditions (callus, meristems of symbiotic nodules, spontaneous and pathogen-induced tumors, etc.). For each of meristems, specific mechanisms of regulation, which are based on the interaction of plant hormones and the major groups of transcription factors, were identified. The activity of meristems is based on two opposite processes: proliferation and self-renewal of stem cells in the central part of the meristem and differentiation of specialized cells in the periphery. WOX-CLAVATA systems are a regulatory component conservative for different meristems and providing consistency of the composition of the meristem, as well as the balance of stem cell proliferation and differentiation. In this review, we will consider the similarities and differences between the principles of organization of stem cell niches in plants and animals, as well as in a variety of meristems of higher plants; special attention will be paid to the role of WOX-CLAVATA systems in maintaining meristems and their interaction with other meristem regulators.

WUSCHEL RELATED HOMEOBOX 5 (WOX5) gene encodes the transcription factor, which is one of the key regulators, maintaining structure and functioning of the stem cell niche in plant root tips. Protein WOX5 is expressed in the quiescent center of the root apical meristem, preventing differentiation of columella initials and altogether with SCR, SHR, PLT1 and PLT2 participating in the control of differentiation of other root meristem initials. However, the details of WOX5 functioning are unclear. The WOX5 protein belongs to WUSCHEL related homeobox (WOX) family, the founder of which is the transcription factor WUSCHEL (WUS) providing maintenance of the stem cell niche in the shoot apical meristem. WOX5 and WUS diverged from a common ancestor at the base of angiosperms, which resulted in a specialization of shoot and root stem cell niches. However, the problem of WOX5 structural and functional divergence during angiosperm evolution was poorly addressed. In this review we present a systems biology analysis of the WOX5 gene to reveal specific features of its evolution and functioning. To this end, we performed a phylogenetic analysis on 62 publicly available WOX5 amino acid sequences, generalized published data about WOX5 expression domain in Arabidopsis and other species and its role in development, integrated the results of experiments on identification of primary and secondary targets for this transcription factor. Data on possible mechanisms of direct and indirect regulation of WOX5 expression were discussed. Particularly, we performed the analysis of WOX5 promoter regions from 30 species. Possible direct regulators of the WOX5 gene expression were proposed based on the presence of putative binding sites for the candidate transcription factors in conserved WOX5 promoter regions.

Transgenic plants are widely used for the investigation of functions of particular genes as well as for reconstruction of complex gene networks controlling plant morphology, biochemistry, and physiology during different development stages and in response to various external stimuli. Gene engineering instruments for the design of transgenic plants with either elevated or suppressed expression of target genes are discussed. Genetic constructs for protein synthesis or antisense RNA/self-complementary double-stranded RNA transcription are described. Transgenic plants with elevated or decreased levels of expression of S-like ribonucleases and decreased expression of the proline dehydrogenase gene are considered as examples. It was believed that S-like RNase functions concern mainly phosphate remobilization from senescent organs. However, expression patterns of some genes coding for S-like RNases were similar to some pathogen-responsive genes (both local and systemic induction after wounding or pathogen inoculation). In addition, some pathogenesis-related proteins (PR-4 family) possess RNase activity and can inhibit growth of pathogenic fungi. Investigation of transgenic plants revealed that high ribonuclease activity in apoplast correlated with increased resistance against tobacco mosaic virus. Thus, S-like RNases may have a new function as a part of the plant basal antiviral defense mechanism. Another set of transgenic plants bears an antisense suppressor of the proline dehydrogenase gene (PDH) constructed with an Arabidopsis target gene segment. Tobacco, maize and sunflower plants with this heterologous suppressor were characterized with a moderate decrease in PDH activity and a mild (1.5–3-fold) increase in the proline content under normal conditions. It was also found that these plants were more tolerant to various abiotic stresses (drought, NaCl, cold, toxic heavy metals), which may result from the protective proline effect early in exposure to stress, preventing the cellular gene expression machinery from damage by stress-generated free radicals.

The phenomenon of heterosis, known as superior performance of hybrid organism compared with either of their parents, has been exploited by agricultural practices in the production of various crops since the beginning of the last century; however, its genetic basis has remained obscure. With experimental data obtained from the study of maize hybrids, and mathematical calculations, some genetic models have been proposed to explain heterosis from various types of gene interaction, such as dominance, over-dominance and epistasis. However, any of the proposed concepts has weak points, which place limitations on the possibility of overall interpretation of heterotic response in F1. In this review we gather a brief account of findings from various studies for critical evaluation of the main theoretical concepts based on the information accumulated to date by genetics and molecular biology and focused on particular mechanisms acting for specific traits. We discussed some aspects concerning the role of mutation loads in the formation of heterotic phenotype. Also, we gathered a brief account of findings for interpretation of genetic effects due to linkage and non-allelic genes’ interactions that make nuances to analysis of dominance and over-dominance. We have provided information about combining ability, its practical application in the context of the concept of heterotic groups. Here we also discussed some aspects of “genotype–environment” interaction. Recent advancements in genetics and molecular biology indicate the importance of various types of gene action for heterosis and confirm the necessity of systemlevel approaches to understanding this unique phenomenon.

The CRISPR/Cas9 system was initially described as an element of archeal and bacterial immunity, but gained much attention recently for its outstanding ability to be programmed to target any genomic loci through a short 20-nucleotide sgRNA region. Here we review some modern applications of the CRISPR/Cas9 system. First, we describe the basic mechanism of the CRISPR/Cas9 DNA recognition and binding, focusing in particular on its off-target activity. The CRISPR/Cas9 off-target activity refers to a non-specific recognition of genomic sites that have partial homology with sgRNA, occasionally resulting in unwanted mutations throughout the genome. We also note some recent improvements for enhancing Cas9 specificity or adding new functions to the system. Since Cas9-related hype is mostly driven by its remarkable potential for gene therapy and genome engineering, the latest CRISPR/Cas9 applications in these areas are also covered in our review. For instance, the CRISPR/Cas9 was recently used to control HIV infection and to repair genetic abnormalities, such as Duchenne muscular dystrophy or retinitis pigmentosa, both in cell cultures and rodent models. A programmable nature of CRISPR/Cas9 facilitates the creation of transgenic organisms through sitespecific gene mutations, knock-ins or large chromosomal rearrangements (deletions, inversions and duplications). CRISPR/Cas9 proved to be especially useful in pronuclear microinjections of farm animals as well, having strong impact on biotechnology. In addition, we review Cas9-augmented genetic screens that allow an unbiased search for new genes and pathways involved in a plethora of biological aspects, owing to Cas9 efficiency and versatility. Finally, we argue that gene drivers based on CRISPR/ Cas9 represent a powerful tool to modify ecosystems in the nearest future.

The potential of molecular approaches in the management of the technological properties of wheat grain affecting the quality of the end product of bread industry is considered. Currently, along with the growth of grain production, the traditional range of staples is crowded out, the quality of most popular bread varieties deteriorates, and dozens of different substances of biological and chemical origin are used as bread improvers. Meanwhile, the genetic potential of wheat allows the development of varieties with technological parameters of grain suitable for production of high-quality bread. In Russia, multiple examples of the creation of varieties for the production of first and second-class grain are known, and modern molecular genetics offers techniques that can supplement classical breeding approaches and accelerate the development of new varieties adapted to the conditions and requirements of the baking industry, using the natural genetic potential of wheat. We summarize the diversity of requirements for grain and flour for different end-use products. Statistics on the volume and structure of grain quality in Russia in 2011–2014 is analyzed. An essential deformation of the quality structure of the produced wheat grain in favor of less valuable classes is observed. A brief retrospective analysis of research in wheat genetics, demonstrating the contribution of genetic factors to grain and flour technological properties, is performed. Various approaches to rapid breeding of varieties with desired properties are considered in relation with the development of plant molecular genetics. The paper provides examples illustrating the feasibility of using methods of DNA diagnostics in various stages of the process, during which the genetic potential of food crops expresses itself and affects the quality of the end product. The results of molecular studies on the localization and isolation of genes determining technological properties (protein and wet gluten contents, milling properties, rheological properties, flour color, and starch properties) are reviewed. The data on diagnostic DNA markers, which are suitable for efficient selection of genotypes instead of the time-consuming analysis of technological properties during breeding process, are summarized. Thus, the information about the genetic potential of bread wheat and modern technologies that provide grounds for moving from excessive use of chemicals to a more benign and organic effect on the quality of the products throughout the "grain – flour – bread" chain, is summarized. 

DNA technology has increasingly become more and more important over last years. They can be used to improve the breeding of agricultural plants. Grapevine is one of the oldest and most important cultured plants. This article presents a review of the world’s main achievements in grapevine genetics and markerassisted selection after the Vitis genome sequence. The process of creating new forms of grapes, as well as all crops, is based on the use of existing genetic diversity. For this reason, the problem of a detailed study of the gene pool of the genus Vitis, wild populations and varieties created by men during the long cultivation history of this crop becomes more and more important every year. The genome of Vitis vinifera L. is the fourth sequenced nuclear genome of higher plants. A number of genes and quantitative trait loci were identified and mapped by various research groups, and so were sets of DNA markers for the genes of economically valuable traits. The genes for resistance to the most harmful fungal pathogens Plasmopara vitikola, Erysiphe necator are the most studied. Advancements in genetic mapping and the use of DNA markers in traditional breeding made it possible to refine the genetic mechanism of seedlessness, an important trait in the breeding of table grapes. The study of the genetic control of the content of substances that determine the organoleptic properties of wines has also progressed. Marker-assisted selection (MAS) is used in practice increasingly. Markers associated with disease resistance genes currently used for elimination of susceptible seedlings at the initial stage of large-scale breeding programs carried out in Germany, Italy and the United States. Thus, advances in molecular biology of grapevines creates a conducive situation for active use of DNA-marker technology in this culture.

The study of genetic diversity of wheat (Triticum aestivum L.) plants-regenerants produced by anther culture method from hybrids involved in the Latvian wheat breeding programme was performed. Flow cytometry was used to test ploidy of 3×103 cells of each green plantregenerant, and universal retrotransposon based iPBS (inter primer binding sites) method were used to establish genetic diversity of plants-regenerants. Progenies of 13 genetically distant hybrids were involved in the study. Most of plants-regenerants have leaves with mixoploid cells. Seeds were formed only by plants-regenerants that had cells with (2n = 6x) ploidy. Majority of fertile plantsregenerants have more than 40 % of hexaploid (6x) cells. The percentage of 6x cells in plants-regenerants and diversity in cell ploidy demonstrated association with mother plant (hybrid) genotype. Percent of spontaneous diplodization was also genotype-dependent. In this experiment colchicine treatment had no significant influence on outcome of fertile plants- regenerants. New dominant allele in a hybrid plant was found in comparison with both parents what indicated possible retrotransposon moving. Genetic diversity of the plants-regenerants obtained in anther culture is a combination of parent’s allele segregation and somaclonal variation.

The present review offers an overview of genetic research on grain protein content (GPC) in various Triticum L. and Aegilops L. species. Regularities in geographic variability of GPC and the results of a longterm screening of accessions from the VIR collection for this trait are considered. On the basis of these assessments, a core-collection of genetic sources with high GPC has been formed. It includes the diploid Aegilops species as donors of B, G and D genomes for allopolyploid wheats, as well as accessions of di-, tetra- and hexaploid wheat species. The use of highprotein sources in wheat breeding in the United States and Canada in the 1970’s–1980’s resulted in the bread wheat GPC increase by 0.5–3.0 %; however, further purposeful attempts at increasing GPC by traditional breeding methods failed. A breakthrough in increasing the total GPC has been achieved as a result of molecular genetics methods and molecular markers development. For the first time, a functional locus, or the Gpc-B1 gene (chromosome 6BS) affecting the accumulation of protein, Zn and Fe in grain, was identified in T. dicoccoides, cloned and studied in detail. The application of molecular markers has revealed the active allele of this gene in some landraces and old cul-tivars of T. dicoccum, T. durum, T. spelta and T. aestivum. Moreover, Gpc-A1, Gpc-D1, and Gpc-2 wheat genes have been found in chromosomes 6A, 6D and homeologous group 2, respectively. All these genes have been identified as NAC transcription factors, which play an important role in the accelerated senescence of plants and remobilization of nutrients from leaves to grain. The genes related to Gpc-B1 from T. dicoccoides were found in the G genome of T. timopheevii and B (=S) genome of different species of Aegilops sect. sitopsis. Functional Gpc-B1 alleles have been introduced into commercial tetra- and hexaploid wheat cultivars, and it resulted in the creation of new highprotein and high-yield cultivars and series of nearly isogenic lines in different countries. They are promising sources for research and wheat breeding purposes.

The Michurinsk Department of the Vavilov Society of Geneticists and Breeding Scientists (VOGiS) was formed in 1966 after the constituent congress of VOGiS and nowadays includes 54 members. The scientists are engaged in 4 scientific institutions affiliated with FASO of Russia. The paper presents investigations of the individual genetics of leading fruit crops (pear, cherry, apple), identified genes, regularities of inheriting resistance to low temperatures, the most harmful diseases and several characters responsible for fruit quality. Some genes were identified for the first time. These are genes regulating Coccomyces hiemalis Higg. resistance (A), retarded growth habit in cherry (O2), astringency (Ta) and juiciness (Su) of fruit in pear. On the base of hybridological analysis and DNA marking, genotypes were identified. These genotypes carry target alleles of the following genes: columnar growth habit (Co) in apple, dwarf trait (PcDw) in pear, retardant growth (O2) in cherry. It was found that the markers C18470-25831, Mdo.chr 10.12, Co04R12 do not always show robust results for screening of young apple seedlings with columnar growth habit (Co) because they are identified as non-columnar forms. The primer pairs of 29f1 и jwi1r are the most robust ones for identification of columnar genotypes. These primers amplify specific PCR product of 586 bp (5’CR). On the basis of molecular-genetic analysis of apple initial forms and hybrid seedlings, there were identified targeted alleles of monogenic scab resistance genes including dominant homozygous genotype (Rvi6Rvi6) and also alleles of genes involved in the control of the biosynthesis of ethylene (Md-ACS1 and Md-ACO1) and expansin (Md-Exp7) controlling fruit long shelf life and pulp firmness.