Intraspecific Hybrids Research Articles

Evolutionary Modes of wtf Meiotic Driver Genes in Schizosaccharomyces pombe.

Killer meiotic drivers are a class of selfish genetic elements that bias inheritance in their favor by destroying meiotic progeny that do not carry them. How killer meiotic drivers evolve is not well understood. In the fission yeast, Schizosaccharomyces pombe, the largest gene family, known as the wtf genes, is a killer meiotic driver family that causes intraspecific hybrid sterility. Here, we investigate how wtf genes evolve using long-read-based genome assemblies of 31 distinct S. pombe natural isolates, which encompass the known genetic diversity of S. pombe. Our analysis, involving nearly 1,000 wtf genes in these isolates, yields a comprehensive portrayal of the intraspecific diversity of wtf genes. Leveraging single-nucleotide polymorphisms in adjacent unique sequences, we pinpoint wtf gene-containing loci that have recently undergone gene conversion events and infer their ancestral state. These events include the revival of wtf pseudogenes, lending support to the notion that gene conversion plays a role in preserving this gene family from extinction. Moreover, our investigation reveals that solo long terminal repeats of retrotransposons, frequently found near wtf genes, can act as recombination arms, influencing the upstream regulatory sequences of wtf genes. Additionally, our exploration of the outer boundaries of wtf genes uncovers a previously unrecognized type of directly oriented repeats flanking wtf genes. These repeats may have facilitated the early expansion of the wtf gene family in S. pombe. Our findings enhance the understanding of the mechanisms influencing the evolution of this killer meiotic driver gene family.

Hybridization and growth characteristics of interspecific crosses between Crassostrea hongkongensis and Crassostrea iredalei

Interspecific hybridization of oysters is a highly efficient breeding strategy that can produce commercially viable phenotypes. Crassostrea hongkongensis, the primary cultivar in southern China, faces increasing summer mortality risks and slow growth rates, which elevate commercial risks for farmers. C. iredalei, a commercially cultivated species in Southeast Asia, has been expanding its ecological niche northward in recent years, providing opportunities for interspecific hybridization with C. hongkongensis. This study conducted a 2 × 2 factorial cross between C. hongkongensis and C. iredalei (II: C. iredalei ♀ × C. iredalei ♂, HH: C. hongkongensis ♀ × C. hongkongensis ♂; IH: C. iredalei ♀ × C. hongkongensis ♂, HI: C. hongkongensis ♀ × C. iredalei ♂) and set up 6 salinity treatments (14, 17, 20, 23, 26 and 29 ppt) to explore the optimal salinity for embryo hatching. The results showed that the hybridization was successful, despite bidirectional fertilization and pronounced asymmetry in fertilization success. The optimal hatching salinity for C. iredalei and C. hongkongensis was 23 ppt and 17–20 ppt, respectively, while the optimal salinity for reciprocal hybrids was 20 ppt. Notably, the hatching rate of IH was lower than that of the control group at the optimal salinity. During the pelagic larval stage, hybrid larvae exhibited significant hybrid inferiority, with slower growth rates and higher mortality rates compared to intraspecific hybridization. It is worth noting that IH failed to overcome genetic incompatibility, resulting in complete mortality during the pelagic larval stage and failure to enter the growth stage. At the 360th day of the growth period, HI hybrids grown in Sanbaimen Sea exhibited significant hybrid vigor in shell height (15.65 %), and in Daya Bay Marine Biology Research Station, Chinese Academy of Sciences (MBRS), they showed significant single-parent hybrid advantages in shell height (28.44 %) and cumulative survival rate (58.11 %) compared to C. hongkongensis. In terms of gonadal development, HI hybrids were able to produce functional and viable gametes, although with some delay compared to their parents. The hybrid offspring inherited the phenotypic traits of their parents, with a grayish-yellow flesh color intermediate between the two oyster species. HI is a valuable genetic resource for oyster breeding, and its growth potential should be further explored to meet commercialization demands.

Characterization of genetic diversity in Eragrostis tef (zucc.) Trotter through microsatellite and morphological markers

Eragrostis tef (Zucc.) Trotter is Ethiopia's most significantly important grain crop; however, its productivity is quite low (1.7 tons per hectare) due to a variety of issues, including the poor yield potential of varieties produced thus far. To achieve future production improvements in tef, comprehensive study of the crop's genetic variability and variety, utilizing both genetic and morphological markers, necessary. The study was designed to assess the genetic diversity of 64 tef genotypes utilizing 10 Simple Sequence Repeats (SSRs) markers. This investigation took place at the Agricultural Biotechnology Research Center in Holeta, Ethiopia. Field phenotypic diversity evaluation was conducted at two distinct locations: Debre Zeit and Worabe, applied a simple lattice design during 2020/21 season. Molecular analysis of variance demonstrated a substantial proportion of variation among individuals (46 %), followed closely variation among individuals (43 %), with the least variation observed within population (11 %). Concurrently, analysis of morphological data, encompassing twenty phenotypic characteristics, revealed significant variation (P ≤ 0.01) among almost all the tested genotypes for recorded parameters, as indicated by combined analysis of variance across sites. These findings underscore the high diversity among the studied genotypes, suggesting a considerable potential for crop improvement through direct selection and intra-specific hybridization strategies. From the perspectives of both conservation and utilization of tef genetic materials, there is a pressing need for more extensive and systematic molecular level research. Promoting field trials and genotype-by-environment interaction research is crucial. These efforts will enhance our understanding of tef genetic and contribute to its effective conservation and utilization.

Evaluation of genetic diversity using simple sequence repeat markers and analysis of cross compatibility in hydrangeas

AbstractHydrangeas with large inflorescences are widely used as cut flowers and in floral arrangements. However, the genetic diversity of commercially grown hydrangeas has been limited owing to the breeding focus on popular species. Therefore, this study was conducted to suggest interspecific breeding strategies for expanding the genetic diversity in Hydrangea L. by evaluating genetic diversity in the seven main species collected in Korea and analyzing cross compatibility via intra- and interspecific hybridization. Interspecific diversity evaluation using simple sequence repeat markers resulted in the segregation of 35 varieties accounting for seven species into five groups as follows: (1) Hydrangea paniculate group, (2) Hydrangea arborescnes group, (3) Hydrangea anomala and Hydrangea aspera group, (4) Hydrangea quercifolia group, and (5) Hydrangea macrophylla and Hydrangea serrata group. Cross compatibility was confirmed via intra- and interspecific crossing, and hybrids were obtained in 18 crossing combinations. Intraspecific hybrids tend to be easy to obtain, but interspecific hybrids are difficult to obtain due to a variety of factors. While most of the interspecific hybrids were obtained using ovule culture, the crossing between H. macrophylla and H. serrata created hybrids from seed sowing, indicating that H. serrata is a subspecies of H. macrophylla. Bilateral and unilateral incompatibilities were observed across the obtained hybrids. Particularly, weak bilateral compatibility was observed between H. serrata and H.paniculata. Accordingly, it was proposed that hybrids between H. macrophylla and H. serrata can be successfully used as parental materials in crossing with H. paniculata to improve cold tolerance. In addition, cross compatibility was improved in interspecific crossing using H. macrophylla and H. arborescens as maternal plants. It is anticipated that these finding will help improve the genetic diversity in commercial hydrangeas.

Lineage diversification and rampant hybridization among subspecies explain taxonomic confusion in the endemic Hawaiian fern Polypodium pellucidum.

Polypodium pellucidum, a fern endemic to the Hawaiian Islands, encompasses five ecologically and morphologically variable subspecies, suggesting a complex history involving both rapid divergence and rampant hybridization. We employed a large target-capture data set to investigate the evolution of genetic, morphological, and ecological variation in P. pellucidum. With a broad sampling across five Hawaiian Islands, we deciphered the evolutionary history of P. pellucidum, identified nonhybrid lineages and intraspecific hybrids, and inferred the relative influence of geography and ecology on their distributions. Polypodium pellucidum is monophyletic, dispersing to the Hawaiian archipelago 11.53-7.77 Ma and diversifying into extant clades between 5.66 and 4.73 Ma. We identified four nonhybrid clades with unique morphologies, ecological niches, and distributions. Additionally, we elucidated several intraspecific hybrid combinations and evidence for undiscovered or extinct "ghost" lineages contributing to extant hybrid populations. We provide a foundation for revising the taxonomy of P. pellucidum to account for cryptic lineages and intraspecific hybrids. Geologic succession of the Hawaiian Islands through cycles of volcanism, vegetative succession, and erosion has determined the available habitats and distribution of ecologically specific, divergent clades within P. pellucidum. Intraspecific hybrids have likely arisen due to ecological and or geological transitions, often persisting after the local extinction of their progenitors. This research contributes to our understanding of the evolution of Hawai'i's diverse fern flora and illuminated cryptic taxa to allow better-informed conservation efforts.

Manifestation of the Effect of Growth Heterosis in Intraspecific Hybrids of Soft Wheat

The presented article presents the results of the study of height inheritance in hybrid combinations of the first generation (F1) of bread wheat. The research was conducted in the 2019-2020 growing season at the Apsheron District Experimental Farm under irrigation conditions. In 32 combinations of hybrids of the first generation (F1), obtained as a result of reciprocal crossing of 9 local varieties («Mirbashir-128», «Azeri», «Gobustan», «Fatima», «Gyrmyzy gul-1», «Murov-2», «Askeran», «Matin» and «Onur»). Studied the height of plants in comparison with parental forms and determined the degree of true heterosis and dominance. In the studied hybrid combinations, a variety from high dominance to depression was found in the transmission of heredity. When analyzing hybrids of bread wheat of the first generation (F1) according to the inheritance of plant height, high dominance was determined in 19 combinations (59.4%), depression — in 8 combinations (25.0%), intermediate heredity - in 5 combinations (15.6% ). Positive heterosis was revealed in 19 combinations (59.4%), negative heterosis - in 13 combinations (40.6%). As a result of the research, it is possible to initially conclude that it is possible to obtain low-growing hybrids by involving in the hybridization a variety of the same height.

Intraspecific diploidization of a halophyte root fungus drives heterosis

How organisms respond to environmental stress is a key topic in evolutionary biology. This study focused on the genomic evolution of Laburnicola rhizohalophila, a dark-septate endophytic fungus from roots of a halophyte. Chromosome-level assemblies were generated from five representative isolates from structured subpopulations. The data revealed significant genomic plasticity resulting from chromosomal polymorphisms created by fusion and fission events, known as dysploidy. Analyses of genomic features, phylogenomics, and macrosynteny have provided clear evidence for the origin of intraspecific diploid-like hybrids. Notably, one diploid phenotype stood out as an outlier and exhibited a conditional fitness advantage when exposed to a range of abiotic stresses compared with its parents. By comparing the gene expression patterns in each hybrid parent triad under the four growth conditions, the mechanisms underlying growth vigor were corroborated through an analysis of transgressively upregulated genes enriched in membrane glycerolipid biosynthesis and transmembrane transporter activity. In vitro assays suggested increased membrane integrity and lipid accumulation, as well as decreased malondialdehyde production under optimal salt conditions (0.3 M NaCl) in the hybrid. These attributes have been implicated in salinity tolerance. This study supports the notion that hybridization-induced genome doubling leads to the emergence of phenotypic innovations in an extremophilic endophyte.

Biparental graph strategy to represent and analyze hybrid plant genomes.

Hybrid plants are found extensively in the wild, and they often demonstrate superior performance of complex traits over their parents and other selfing plants. This phenomenon, known as heterosis, has been extensively applied in plant breeding for decades. However, the process of decoding hybrid plant genomes has seriously lagged due to the challenges associated with genome assembly and the lack of appropriate methodologies for their subsequent representation and analysis. Here, we present the assembly and analysis of 2 hybrids, an intraspecific hybrid between 2 maize (Zea mays ssp. mays) inbred lines and an interspecific hybrid between maize and its wild relative teosinte (Z. mays ssp. parviglumis), utilizing a combination of PacBio High Fidelity sequencing and chromatin conformation capture sequencing data. The haplotypic assemblies are well phased at chromosomal scale, successfully resolving the complex loci with extensive parental structural variations (SVs). By integrating into a biparental genome graph, the haplotypic assemblies can facilitate downstream short-read-based SV calling and allele-specific gene expression analysis, demonstrating outstanding advantages over a single linear genome. Our work offers a comprehensive workflow that aims to facilitate the decoding of numerous hybrid plant genomes, particularly those with unknown or inaccessible parentage, thereby enhancing our understanding of genome evolution and heterosis.

Unlocking the secrets of intraspecific hybrids (Vitis vinifera L.) cold hardiness: A comprehensive study of genetic factors and trait correlations

Challenges arise in global viticulture due to low temperatures. To ensure the sustainable and high-quality development of the wine industry, it is essential to breed wine grape varieties that are not only of high quality but also possess cold hardiness. Intraspecific recurrent selection in Vitis vinifera can enhance cold hardiness while maintaining fruit quality. In this study, we used ‘Ecolly ’as an intermediary grape variety for crossing with ‘Cabernet Sauvignon’, ‘Marselan’, and ‘Dunkelfelder’, including three reciprocal crosses and a total of 1,657 intraspecific hybrids. We characterized the cold hardiness of these intraspecific hybrids and analyzed the genetic aspects of cold hardiness, ultimately identifying excellent strains with cold hardiness. Parameters like mean high-temperature exotherm (mHTE), mean low-temperature exotherm (mLTE), bound/free water ratio, water loss ratio in vitro, frost damage grades, and overall performance displayed partially normal distributions. In intraspecific hybrids, there was a maternal advantage in traits related to bound/free water ratio and water loss ratio. Some hybrid populations exhibited values for mHTE, mLTE, and water loss ratio that were lower than the low parent's values, while bound/free water ratio showed values higher than the high parent's values. Among the 1,657 intraspecific hybrids, 52 strains could bud under stress at −18 °C, and seven of these strains excelled in three important cold hardiness measures. Our study revealed that cold hardiness in V. vinifera is influenced by multiple genes and is a quantitative trait. Intraspecific hybridization can produce a small number of superior strains with enhanced cold hardiness.

Introgression affects Salmo trutta juvenile life-history traits generations after stocking with non-native strains.

Introgression of non-native conspecifics changes the genetic composition of wild populations, potentially leading to loss of local adaptations and fitness declines. However, long-term data from wild populations are still relatively few. Here, we studied the effects of introgression in a Danish brown trout (Salmo trutta, L.) population, subjected to intensive stocking with domesticated hatchery fish of non-native origin. We used wild-caught genetically wild and admixed trout as well as fish from the partly domesticated hatchery strain used for stocking the river up until ~15 years prior to this study, to produce 22 families varying in hatchery/wild admixture. Following a replicated common-garden experiment conducted in fish tanks from first feeding through 23 weeks at 7, 12, and 16°C, we observed a significant positive relationship between family admixture and fish size upon termination, an effect observed through all levels of admixture. Furthermore, the admixture effect was most distinct at the higher rearing temperatures. Although the hatchery strain used for stocking had been in culture for ~7 generations, it had not been deliberately selected for increased growth. These data thus demonstrate: (i) that growth had increased in the hatchery strain even in the absence of deliberate directional selection for this trait, (ii) that the increasing effect of admixture by temperature could represent inadvertent selection for performance in the hatchery strain at higher temperatures, and most significantly, (iii) that despite undergoing up to five generations of natural selection in the admixed wild population, the genetically increased growth potential was still detectable and thus persistent. Our findings suggest that altered growth patterns and potentially their cascading effects are of importance to the severity of hatchery/wild introgression, especially under changing-climate scenarios and are of general significance to conservation practitioners seeking to evaluate long-term effects of intra-specific hybridization including under recovery.

Characterization of a new strain (SR-11) with thin blades and fast growth in Pyropia haitanensis (Bangiales, Rhodophyta)

A new strain (SR-11) was selected from an intraspecific hybridization of a new cultivar (SF-2, ♀) and an improved strain (HR-6, ♂) of Pyropia haitanensis, and the characteristics of blades thickness, growth rate, phycobiliprotein content, and differentiation rate of conchocelis of SR-11 were analyzed through laboratory culture. After being cultured for 45 days, the mean thickness of SR-11 was 22.9 μm, which was 37.1% and 18.5% thinner than that of SF-2 and HR-6, respectively; the phycobiliprotein of SR-11 was 94.6 mg/g, increased by 4.1% and decreased by 8.4% compared with that of SF-2 and HR-6, respectively. After being cultured for 55 days, the mean length of the SR-11 was 293.7 cm, which was 3.1 and 7.2 times longer than that of SF-2 and HR-6, respectively. After the conchocelis inoculated shell were raised the temperature and shrunk of light time, the time for the emergence of a lot of conchosporangial branches in SR-11 was shorter than that of SF-2. The total number of conchospores released from per shell in SR-11 was 144.5 × 104, which was 78.1% and 11.9% higher than that of SF-2 and HR-6, respectively. In summary, the SR-11 has thinner blades, and its fresh blades may be further processed into higher value-added products. Besides, it has the advantages of fast growth, high quality and large number of conchospores released, which is expected to be applied in production cultivation.

Utilisation of GMS lines for production ofheterotic bacterial wilt resistant hybrids in <i>Tagetes</i> spp.

The study was conducted using six testers, of which two (KAU M-1 and KAU M-2) were completely bacterial wilt resistant, and four genetic male sterile lines (GMS), in a line x tester model and further the F1 hybrids were evaluated in a bacterial wilt sick plot for various vegetative, floral and yield parameters along with their response to wilt incidence. Field evaluation for bacterial wilt resistance revealed that out of 24 hybrids, 13 hybrids involving KAU M-1 and KAU M-2 as testers exhibited bacterial wilt resistance. Analysis on heterosis for various characters viz., vegetative, floral, yield and total carotenoids content showed significant heterosis for many of the hybrids over mid parent, better parent and the check variety. The highest standard heterosis for yield was observed for the interspecific hybrid KU Ms-6 xx KAU M-47 (190.84%) followed by an intraspecific hybrid KAU Ms-42 x KAU M-2 (70.93%). Based on the wilt resistance and heterotic performance, these two hybrids can be suggested for commercial cultivation in wilt affected areas.

Obtainment of intraspecific hybrids in strictly cleistogamous Vicia ervilia (L.) Willd.

Bitter vetch (Vicia ervilia (L.) Willd.), one of the Near Eastern founder crops, is an annual cleistogamous legume domesticated during the Neolithic period. Originally used for human consumption, over time it was replaced by other pulses and downgraded to a fodder crop. When coupled with a small degree of cross hybridization, cleistogamy confers evolutive plasticity to the plant species. The aim of the present work consisted in setting up optimal conditions to overcome the existing cross hybridization barriers in V. ervilia. Genotypes of Turkish origin, characterized by an erect growth habit were crossed with Italian counterparts characterized by high seed production. A detailed cyto-histological analysis of flower development was undertaken to determine the optimal stage for emasculation and manual cross. Ninety-eight crosses were carried out and the hybrid nature of the putative F1 progenies was assessed by SSR (simple sequence repeat) DNA markers. Fifty-five seeds were obtained of which only five gave rise to hybrid plants. Among these, only three turned out to be fertile and two of which generated a consistent number of F2 seeds whose plants were assessed in greenhouse for seed production and plant growth habit. Most of the evaluated traits showed mean values of the F2 plants intermediate between the two initial parents, confirming that intraspecific hybridization is not only possible but also useful to exploit the diversity confined in different bitter vetch populations.

Microscopic observation and transcriptome analysis provide insights into mechanisms of hybrid incompatibility in Rhododendron

Hybridization across species has been widely utilized to improve agriculturally important traits in Rhododendron. These interspecific hybridizations are often inhibited by reproductive barriers at the prezygotic and postzygotic stages. Thus, in order to character the barriers and reveal the underlying regulation mechanism of interspecific hybrid incompatibility in Rhododendron, we compared the pollen germination and pollen tube growth, fruit growth, seed number and germination rate between intraspecific (Rhododendron ‘XXL’ × R. ‘XXL’) and interspecific (R. ‘XXL’ × R. delavayi) hybridizations. After pollination, the pollen germination rate and pollen tube growth rate of interspecific hybridization (Inter) were always higher than that of intraspecific hybridization (Intra) during the whole observation period. Conversely, the fruits and ovules of Intra grew faster than that of Inter after 20 DAP. The ratio of shrunken embryos of Inter was 73.27 ± 10.19 %, which was significantly higher than that of Intra with 28.41 ± 8.33 % at 40 DAP. Moreover, the fruit setting rate, the average number of seeds per fruit and seed germination rate of Intra were significantly higher than that of Inter at 150 DAP. These results indicated that the barriers of interspecific incompatibility between R. ‘XXL’ × R. delavayi could be mainly ascribed to post-fertilization isolation. Consequently, RNA-Seq analysis on ovaries at three developmental stages from two hybridizations indicated that plant hormone signal transduction, flavonoid biosynthesis, MAPK signaling pathway and plant-pathogen interaction pathways might play important roles in regulation of hybrid incompatibility between R. ‘XXL’ × R. delavayi. The results can provide a basis for the study of the hybrid incompatibility mechanism of Rhododendron, and provide useful information for the breeding and conservation of genetic resources of Rhododendron.

Transcriptome variations in hybrids of wild emmer wheat (Triticum turgidum ssp. dicoccoides)

BackgroundWild emmer wheat is a great candidate to revitalize domesticated wheat genetic diversity. Recent years have seen intensive investigation into the evolution and domestication of wild emmer wheat, including whole-genome DNA and transcriptome sequencing. However, the impact of intraspecific hybridization on the transcriptome of wild emmer wheat has been poorly studied. In this study, we assessed changes in methylation patterns and transcriptomic variations in two accessions of wild emmer wheat collected from two marginal populations, Mt. Hermon and Mt. Amasa, and in their stable F4 hybrid.ResultsMethylation-Sensitive Amplified Polymorphism (MSAP) detected significant cytosine demethylation in F4 hybrids vs. parental lines, suggesting potential transcriptome variation. After a detailed analysis, we examined nine RNA-Seq samples, which included three biological replicates from the F4 hybrid and its parental lines. RNA-Seq databases contained approximately 200 million reads, with each library consisting of 15 to 25 million reads. There are a total of 62,490 well-annotated genes in these databases, with 6,602 genes showing differential expression between F4 hybrid and parental lines Mt. Hermon and Mt. Amasa. The differentially expressed genes were classified into four main categories based on their expression patterns. Gene ontology (GO) analysis revealed that differentially expressed genes are associated with DNA/RNA metabolism, photosynthesis, stress response, phosphorylation and developmental processes.ConclusionThis study highlights the significant transcriptomic changes resulting from intraspecific hybridization within natural plant populations, which might aid the nascent hybrid in adapting to various environmental conditions.

A natural intra‐specific hybridization between populations of B. mucronatus with European and East Asian genotypes, in pine forests

AbstractBursaphelenchus mucronatus Mamiya & Enda, 1979 is a wood nematode widely distributed over Palearctic coniferous forests. It has two subspecies, that is, B. mucronatus mucronatus and B. mucronatus kolymensis, which present molecularly different East Asian and European genotypes, respectively. The European subspecies is found mainly in Europe and Siberia, while the East Asian subspecies occupies mostly Eastern regions of Asia. However, local isolates of both subspecies have been occasionally reported from various localities in Europe and Asia. Our field isolation and molecular (DNA ITS‐RFLP) identification of 21 recently collected populations of B. mucronatus revealed only 4 isolates representing clearly East Asian or European genotypes, while the remaining 17 isolates showed intermediate genotypes with electrophoretic band characters of both the above types. Further individual crossbreeding, in vitro, of nematodes representing European, East Asian, and intermediate genotypes provided experimental evidence for the process of intraspecific hybridization between both subspecies, spontaneously taking place in the forest. Such a widening of the B. mucronatus genetic variation may have its effect on a range of reported in the literature direct interactions between this native, nonpathogenic nematode species and the genetically similar, causative agent of the pine wilt disease B. xylophilus which can colonize the same host trees, use the same insect vectors, compete, and crossbreed inter‐specifically.

Перспективы селекции вики озимой мохнатой (Vicia villosa Roth.) в Нечерноземной зоне России

In the Non-Chernozem zone, winter vetch is the only legume component of winter grain crops for forage purposes. In spring, summer and autumn, it can be used for feeding animals, harvesting hay, silage, and haylage. However, due to the relatively low winter hardiness, it has not yet been widely used in the feed production of the Non-Chernozem zone. The average winter hardiness of most vetch varieties in the Moscow region is 57–65%. In Federal Williams Research Center of Forage Production and Agroecology has developed a strategy for creating winter vetch varieties with high winter hardiness, resistance to abiotic stresses, high yields in green mass and seeds. The work was based on the thesis that the external environment can be used as an effective selective background, allowing genotypes with low adaptive potential to stress factors to be excluded from the population during the replanting process. As a source material, it is recommended to use old-town, naturally formed populations belonging to the Central Russian ecological and geographical group by the method of intraspecific hybridization in combination with targeted artificial and natural selection in phytocenosis and provocative backgrounds, varieties of winter vetch Lugovskaya 2 and Lugovskaya 3 were created. Winter hardiness of these varieties reaches 90–92%, dry matter yield 52–79 centner/ha, seeds 9.1–10.5 centner/ha. The values of the Serpukhovskaya standard variety were 64%, 37 and 4.1 centner/ha, respectively. High winter hardiness and increased competitiveness in the phytocenosis of new varieties is provided mainly by the formation of shoots from underground and lower aboveground nodes.

Feasibility exploration and comparative analysis of interspecific hybridization between Crassostrea hongkongensis and Crassostrea dianbaiensis

Interspecific hybridization plays a significant role in the genetic improvement of oysters in aquaculture, with the main objective being to obtain progeny that inherit the desirable traits of both parents and establish a stable inheritance pattern. Crassostrea hongkongensis is well-known for its large size and excellent meat quality. However, it exhibits poor resistance to external environmental changes and a high mortality rate. To address these shortcomings, this study conducted a 2 × 2 interspecific hybridization between Crassostrea dianbaiensis and C. hongkongensis. D larvae from C. hongkongensis ♀ × C. dianbaiensis ♂ (HD) and C. dianbaiensis ♀ × C. hongkongensis ♂ (DH) crosses were successfully hatched. However, the hatching index of both groups was lower than that of C. hongkongensis ♀ × C. hongkongensis ♂ (HH) and C. dianbaiensis ♀ × C. dianbaiensis ♂ (DD) groups. The average shell height of DH on the 15th day was only 111.50 ± 6.31 μm, and all individuals were dead by the 18th day. Despite experiments being repeated many times, no attached DH larvae were obtained. Compared with intraspecific hybridization, HD grew slower in the larval stage and had a lower survival rate, but the shell height of HD was slightly higher than that of HH on the 450th day (P > 0.05). The cumulative survival rate of HD throughout the growth period was higher than that of HH and DD, demonstrating a clear hybrid advantage in terms of relative yield and survival rate, especially higher than that of C. hongkongensis. Moreover, the gonads of HD can develop normally and produce gametes, and the color of the inner shell and body is between that of C. hongkongensis and C. dianbaiensis. These results indicate that HD effectively improved the survival rate of C. hongkongensis, demonstrating its great application potential and promising prospects in aquaculture.

Achievements in world and domestic breeding of peonies (<i>Paeonia</i> L.)

The genus Paeonia L. includes both popular ornamental and medicinal plants with a rich history of cultivation and breeding. Breeding is an important process of increasing the diversity of the assortment and creating new cultivars of peonies with various economically important characteristics, such as the shape and color of flowers, different flowering periods and resistance to diseases and abiotic stressors. The main methods used in the breeding of peonies are traditional methods, including intraspecific, interspecific and intersectional hybridization, however, such factors as a long reproduction cycle and the complexity of the breeding process limit the possibilities for good progress in this work. The application of methods of biotechnology and molecular genetics make the breeding process more efficient. The use of germplasm resources and hybridization will accelerate the process of creating new cultivars not only with various decorative features, but also those with high adaptability to biotic and abiotic factors and resistance to phytopathogens and diseases. This review highlights the history of domestic and foreign breeding, modern trends and methodology of peony breeding. Information is provided on the achievements and limitations that exist in the field of molecular biological study of peonies.

Multiple Transitions between Y Chromosome and Autosome in Tago's Brown Frog Species Complex.

Sex chromosome turnover is the transition between sex chromosomes and autosomes. Although many cases have been reported in poikilothermic vertebrates, their evolutionary causes and genetic mechanisms remain unclear. In this study, we report multiple transitions between the Y chromosome and autosome in the Japanese Tago's brown frog complex. Using chromosome banding and molecular analyses (sex-linked and autosomal single nucleotide polymorphisms, SNPs, from the nuclear genome), we investigated the frogs of geographic populations ranging from northern to southern Japan of two species, Rana tagoi and Rana sakuraii (2n = 26). Particularly, the Chiba populations of East Japan and Akita populations of North Japan in R. tagoi have been, for the first time, investigated here. As a result, we identified three different sex chromosomes, namely chromosomes 3, 7, and 13, in the populations of the two species. Furthermore, we found that the transition between the Y chromosome (chromosome 7) and autosome was repeated through hybridization between two or three different populations belonging to the two species, followed by restricted chromosome introgression. These dynamic sex chromosome turnovers represent the first such findings in vertebrates and imply that speciation associated with inter- or intraspecific hybridization plays an important role in sex chromosome turnover in frogs.