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Relevance. The action of viral phytopathogens changes the quality of the male gametophyte, which ultimately leads to a decrease in plant productivity. So, information on the features of the variability of morphofunctional characteristics of the microgametophyte becomes topical. Taking into account the expression of a part of the plant genome in pollen, the male gametophyte can be used as a reliable system for assessing the response of genotypes to the action of viral pathogens. Presuming that the problems of variability of characteristics of the male gametophyte in conditions of viral pathogenesis have not been enough studied, as well as the main factors determining the variability have not been identified, the aim of the research was to study the effect of viral phytopathogens on the male gametophyte characters in tomato.Material and methods. Hybrids F1 and varieties of tomato were used in the experiments. Plants were grown in a greenhouse. They were inoculated with tobacco mosaic virus (TMV) or tomato aspermia virus (TAV) in the 4-5 leaf phase. To determine the quality of pollen, flowers of control and infected plants were collected; pollen was isolated and sown on a nutrient medium. The preparations were analyzed under microscope. The viability of the pollen and the length of the pollen tubes were assessed, and the ratio of these indicators was calculated.Results. Infection of plants with viruses changes some functional characteristics of the male gametophyte. The responses manifested as stimulation, inhibition, or neutral effect. The main sources of variability in characters of pollen were the genotype and viral agents. In viral pathogenesis, unequal indicators of pollen grains were found in terms of the rate of germination and growth of pollen tubes (PT). Analysis of the heritability coefficients of the ratio of pollen viability and PT length (experiment / control) revealed positive dominance and overdominance in 70% of cases. Genotypes have been identified that combine a high level of viability when infected with different viruses. The prospect of their use in further research is proposed.

Triploid crucian carp (TCC) is obtained by hybridization of female diploid red crucian carp (Carassius auratus red var., RCC) and male allotetraploid hybrids. In this study, high-throughput sequencing was used to conduct the transcriptome analysis of the female hypothalamus of diploid RCC, diploid common carp (Cyprinus carpio L., CC) and TCC. The key functional expression genes of the hypothalamus were obtained through functional gene annotation and differential gene expression screening. A total of 71.56 G data and 47,572 genes were obtained through sequencing and genome mapping, respectively. The Fuzzy Analysis Clustering assigned the differentially expressed genes (DEGs) into eight groups, two of which, overdominance expression (6005, 12.62%) and underdominance expression (3849, 8.09%) in TCC were further studied. KEGG enrichment analysis showed that the DEGs in overdominance were mainly enriched in four pathways. The expression of several fertility-related genes was lower levels in TCC, whereas the expression of several growth-related genes and immune-related genes was higher levels in TCC. Besides, 15 DEGs were verified by quantitative real-time PCR (qPCR). The present study can provide a reference for breeding sterility, fast-growth, and disease-resistant varieties by distant hybridization.

Darwin spent years investigating the effects of self-fertilization, concluding that "nature abhors perpetual self-fertilization." Given that selection purges inbred populations of strongly deleterious mutations and drift fixes mild mutations, why does inbreeding depression (ID) persist in highly inbred taxa and why do no purely selfing taxa exist? Background selection, associations and interference among loci, and drift within small inbred populations all limit selection while often increasing fixation. These mechanisms help to explain why more inbred populations in most species consistently show more fixed load. This drift load is manifest in the considerable heterosis regularly observed in between-population crosses. Such heterosis results in subsequent high ID, suggesting a mechanism by which small populations could retain variation and inbreeding load. Multiple deleterious recessive mutations linked in repulsion generate pseudo-overdominance. Many tightly linked load loci could generate a balanced segregating load high enough to sustain ID over many generations. Such pseudo-overdominance blocks (or "PODs") are more likely to occur in regions of low recombination. They should also result in clear genetic signatures including genomic hotspots of heterozygosity; distinct haplotypes supporting alleles at intermediate frequency; and high linkage disequilibrium in and around POD regions. Simulation and empirical studies tend to support these predictions. Additional simulations and comparative genomic analyses should explore POD dynamics in greater detail to resolve whether PODs exist in sufficient strength and number to account for why ID and load persist within inbred lineages.

The current paper has presented the analysis results of the value of heterosis and the degree of phenotypic dominance of hybrids F1 obtained by saturating crossings of two-row and multi-row spring barley forms. The purpose of the study was to determine the value of heterosis and the degree of phenotypic dominance of the main quantitative traits of the multi-row hybrids of spring barley. The study was carried out in the laboratory for grain crops and groats breeding of the FSBSI FRC of Agrobiotechnologies of the Far East named after A. K. Chayka. There were studied 68 varieties of multi-row spring barley forms selected from the world collection of IPI of various ecological and geographical origin. The two-row varieties ‘Primorsky 98’, ‘Primorsky 44’, ‘Primorsky 89’, ‘Tikhookeansky’ and ‘Vostochny’ developed by FSBSI FRC of Agrobiotechnologies of the Far East named after A. K. Chayka were taken as maternal forms. Four multi-row barley varieties ‘Kazminsky’ (Khabarovsk Territory), ‘Peguis’ (Canada), ‘Kolchan’ (Altai Territory), ‘07N1’ (China) with valuable economic traits were taken as a paternal form. There was conducted a five-fold backcrossing of hybrids with paternal forms and there were selected the populations of multi-row genotypes. The most of the hybrids F1 manifested their heterosis simultaneously according to four traits, productive tillering, number of grains per main head, grain weight per main head, and grain weight per a plant. Only two hybrids ‘Primorsky 98 x Kolchan’ and ‘Primorsky 89 x Peguis’ showed a depression. There was identified heterosis by the traits ‘number of grains per main head’, ‘grain weight per main head’ in all hybrids. When analyzing the inheritance of the trait ‘grain weight per a plant’, there was established overdominance of this trait at the highest values of the hybrids ‘Tikhookeansky x Peguis’ (9.7) and ‘Primorsky 44 x 07N1’ (5.2), the heterosis degree was 50.4% and 82.2%, respectively. There has been established that three hybrids ‘Primorsky 98 x 07N1’, ‘Primorsky 44 x 07N1’, ‘Tikhookeansky x Peguis’ can belong to the most promising ones.

Pea is one of the important sources of protein, vitamin and minerals for human diet. The aim of the work was to study the inheritance of protein and mineral matter contents. The five pea cultivars (Jofs, Ultrillo, Rondo, Betagreen and Bolero) along with dialles crosses were used in a Jinks-Hayman type analysis. The population possessed high enough genetic variation for the quality characteristics. The environmental (VE) and additive genetic variations (VD) were insignificant for the traits. The dominant genetic variance was greater than that of additive genetic variance for all the traits studied, hence the D-H1 values were negative. Results indicate the presence of higher number of dominant genes compared to recessive ones governing the traits. The Wr, and Vr graphics of protein and phosphorus contents indicated partial dominance while for the remaining traits over dominance were evident. The relatively low narrow sense heritability values hinted that genetic gain would be slow via phenotypic selection., Bezelye insan beslenmesinde protein, vitamin ve mineral madde kaynaklarından birisidir. Bu çalışma, beş bezelye çeşidi (Jofs, Ultrillo, Rondo, Betagreen ve Bolero) ile bunların tam diallel melezlerinin oluşturduğu popülasyonda Jinks – Hayman tipi analiz kullanarak protein oranı ve bazı mineral maddeler bakımından genetik yapısını incelemek amacı ile yürütülmüştür. Bu araştırmada ele alınan kalite kriterleri bakımından incelenen populasyonda genetik olarak yeterli seviyede varyasyonun olduğu belirlenmiştir. Araştırma sonuçlarına göre popülasyonlarda ele alınan kalite kriterlerinde çevre varyansı (E) ve eklemeli gen varyansı (D) istatistiki olarak önemsiz olduğu belirlenmiştir. Tüm özelliklerin dominant gen varyanslarının eklemeli gen varyanslarından daha yüksek olduğu, buna paralel olarak da D-H1 değerleri ise negatif olarak tespit edilmiştir. İncelenen kalite özelliklerini yöneten genlerin populasyonda dominant genlerin resesif genlerden daha fazla olduğunu belirlenmiştir. Wr, Vr grafikleri sonucu protein oranı ve fosfor miktarı için kısmi dominantlık diğer özelliklerde ise aşırı dominantlık durumu saptanmıştır. Dar anlamda kalıtım derecelerinin tüm özelliklerde düşük olması bu özellikler bakımından yapılacak seleksiyonda başarı şansının düşük olduğunu göstermektedir.

Six wheat varieties were single crossed at 2017/18. Six parents and its 15 F1 single-crosses were cultivated under N-normal and N-stress at 2018/19, to study heterosis and the genetic parameters for yield and its components under normal and N-stress. Mean squares of wheat-gentypes, parent, F1-crosses and parent versus cross were highly significant or significant for most of traits under both conditions. The highest desirable heterosis and heterobeltiosis were detected by crosses No. 7 and No.8 for earliness; No.14, No.8 and No.3 for 100-Grain weight; crosses No.8 and No.13 for number of spikelets/spike; crosses No.9, No.7 and No.13 for number of grains per spike; cross No.4 for number of spikes/plant; crosses No.3, No.12 and No.10 for grain yield per plant, therefore, it might be decided that these crosses may be beneficial for enhancing wheat grain-yield programs under low or high N conditions. The median grade of dominance was greater than one for all characters under both conditions, suggesting the importance of over dominance gene effects in the genetics of these traits. Heritability in broad sense (hb.s.) had high values for all traits under both conditions. Lower heritability estimates in narrow sense (h2n.s.) were detected for all the studied traits under both conditions, except each of spikes number /plant, weight of 100-grain and protein % at both conditions which had moderate values of narrow sense heritability, reflecting the part of environmental factors and dominance genes in heirloom scheme of these characters.

Self-pollination for five selected cucumber indeterminate inbred lines was carried out for two generations, during summer and autumn season of 2016, to confirm their purity as parents in a hybrid breeding program. Complete diallel cross among the five inbred lines were conducted during summer season of 2017 to produce all possible hybrids combinations. The twenty-five genotypes (Five parents, their 10 F1 hybrids and 10 F1 reciprocals) were grown and evaluated under greenhouse conditions in three sowing dates (mid of each months February, March and May respectively) for two successive years (2018 and 2019) in a randomized complete block design with three replicates. Mean performance, heterosis % and Potence ratio were estimated, for characteristics of vegetative, flowering and fruit quality, yield and its components. The results clarified that there were significant and high significant differences between genotypes of the study in all studied traits. The best parents for vegetative growth, yield components and fruit quality traits were P4 followed by P5 and P2. Therefore, the three parental inbred liens P4, P5andP2 can be selected as tester parents, and for the sharing in hybrid combinations to predict the best hybrids. The best hybrid combinations for most traits were found to be F1hybrids of P2XP4 and P1XP5, and their reciprocals which recorded the highest productivity for total yield, number of fruits/plant and high average fruit weight and other fruit quality traits. Therefore, F1hybrids P2XP4 and P1XP5 and their reciprocals could be generally, considered the most important ones and promising new produced cucumber hybrids of this study. The results proved the existence of marked potence ratios and heterosis, either over the mid-parental value or that of the better parent for all studied traits. Heterosis values for vegetative measurements, early yield, total yield, number of fruits, average fruit weight and fruit length traits were positive and significant in the most crosses, while potence ratio estimates were positive and greater than one. Therefore, the inheritance of these traits involved complete to over dominance for high over low values. However, heterosis values for flowering and fruiting measurements were negative and significant in most crosses, also potence ratio estimates were negative and greater than one. Therefore, the inheritance of these traits seemed to have dominance to overdominance nature for early over late flowering and fruiting.

The emergence and persistence of polymorphism within populations generally requires specific regimes of natural or sexual selection. Here, we develop a unified theoretical framework to explore how polymorphism at targeted loci can be generated and maintained by either disassortative mating choice or balancing selection due to, for example, heterozygote advantage. To this aim, we model the dynamics of alleles at a single locus A in a population of haploid individuals, where reproductive success depends on the combination of alleles carried by the parents at locus A. Our theoretical study of the model confirms that the conditions for the persistence of a given level of allelic polymorphism depend on the relative reproductive advantages among pairs of individuals. Interestingly, equilibria with unbalanced allelic frequencies were shown to emerge from successive introduction of mutants. We then investigate the role of the function linking allelic divergence to reproductive advantage on the evolutionary fate of alleles within the population. Our results highlight the significance of the shape of this function for both the number of alleles maintained and their level of genetic divergence. Large number of alleles are maintained with substantial replacement of alleles, when disassortative advantage slowly increases with allelic differentiation . In contrast, few highly differentiated alleles are predicted to be maintained when genetic differentiation has a strong effect on disassortative advantage. These opposite effects predicted by our model explain how disassortative mate choice may lead to various levels of allelic differentiation and polymorphism, and shed light on the effect of mate preferences on the persistence of balanced and unbalanced polymorphism in natural population.

Gene action and their relative contribution in expression of characters is of great importance. Twenty one F1 hybrids were obtained by partial diallel crosses between seven parents to determine the nature of gene action and their relative contribution in expression of characters. Significant values of dominance components Ĥ1 and Ĥ2 for all the traits (except fruit weight for Ĥ2), along with significant values of additive components for number of fruits per plant, T.S.S. and ascorbic acid indicated the importance of both additive and dominance gene action in expression of these characters. However, additive ( ) component was lower in magnitude than dominance components of genetic variation for all the characters which revealed preponderance of dominance component of variance in the expression of fruit yield and its attributes. The average degree of dominance (Ĥ1 / )1/2 involve in the gene action was found as over dominance for all the traits. This suggested that heterosis breeding might be advantageous for improvement of yield and its component traits in bottle gourd. Proportion of genes (Ĥ2/4Ĥ1) in the parents were less than 0.25 for all the traits which showed asymmetrical distribution of loci showing dominance in the inheritance of these characters. The ratio of (4 Ĥ1)1/2 + / (4 Ĥ1)1/2- indicated the excess of dominant genes among the parental strains for most of the characters. The ratio of ĥ2/Ĥ2, provides information about groups of gene exhibiting that minor genes mainly governed the characters except days to first pistillate flower anthesis, node number to first staminate flower anthesis, days to first fruit harvest and fruit weight under study, which may be due to concealing effects of dominant gene with positive and negative effects.

Crossbreeding capitalizes on heterosis effects and results in increased performance of crossbred animals. Dominance hypothesis and overdominance hypothesis are 2 common models proposed to explain heterosis. Differential gene expression between parents and hybrids is hypothesized to be responsible for heterosis. This study aimed to investigate the heat tolerance and inheritance patterns of leukocyte transcriptomics in F1 hybrid cattle (Angus males × Droughtmaster females) and their parents Red Angus (AN) and Droughtmaster (DR) under heat stress. According to the respiratory rate and heat tolerance coefficient index, DR was better adapted to heat stress than AN. The physiological responses to heat stress of F1 hybrids were similar to AN. We identified 802 differentially expressed genes in leukocytes between AN and DR under heat stress using mRNA sequencing. Compared with AN, upregulated genes in DR were enriched in biological processes of response to stress, external and chemical stimulus, and cytokine, cell surface receptor signaling pathway, and cardiovascular system development. In contrast, upregulated genes in AN were enriched in B cell activation and regulation of B cell activation. Gene expression levels can be inherited additively or nonadditively and are classified into additive (35%), dominance (44%), and overdominance and underdominance (18%) modes in F1 hybrids and their parents. Inheritance patterns of gene expression showed that 97% (249/255) of the dominant genes were classified as paternal AN dominant in hybrids. The paternal imprinted PEG10 gene and its regulatory transcription factor MYC showed an AN dominant expression pattern. The MYC interacted with most AN dominant genes. These transcriptomic analyses revealed that DR and AN had specific cellular and humoral immunity and cardiovascular systems development function under heat stress. Inheritance pattern analyses from gene expression partly explained phenotypic differences between parents and F1 hybrids. The paternal imprinted PEG10 gene interaction with transcription factor MYC may contribute to explaining paternal dominant gene expression in hybrids.

The main collection of allelic variants for breeding tomato (Solanum Lycopersicum L.) is represented by its wild relatives, which evolved independently. It is important to study different sources of variation that are useful in breeding; therefore, the aim of this study was to evaluate S. habrochaites Knapp & Spooner as a source of different alleles by estimating the average degree of dominance, heterosis with respect to the mid-parent, and narrow-sense heritability of an interspecific cross with S. lycopersicum L. An S8 line derived from the LOR95 collection, the LA1223 accession of S. habrochaites Knapp & Spooner and the F1 generation from crossing the two materials were used. Genotypes were evaluated in a randomized complete block design during two greenhouse cycles in a hydroponic production system. Of 14 evaluated traits, total soluble solids concentration, stem diameter, total number of fruits and plant height showed an overdominance of LA1223, as well as heterosis of 17.2, 32.3, 55 and 49.2 % each, and heritability of 35, 93, 72 and 66 %, respectively. F1 generation had an increase of 2 mm in stem diameter, 30 cm in plant height, 4 fruits and 1.1 °Brix, with respect to the best parent for each variable; this suggests that it would be possible to use LA1223 to broaden the genetic base in the improvement of this vegetable.

The 6 × 6 half-diallel crossings among six parental lines for twelve traits were investigated to estimate different genetic parameters and identify superior lentil line combinations. The significant results of the analysis of variance for all the traits except RW proved the parental lines genetically different from each other. Dominance and additivity were studied and over dominance was found in NPBFF, CAMF, NPdPP, NSPP, SWPP and IPW through Wr/Vr and (Wr + Vr′)/Yr′ graphs. The degree of dominance (H1/D)1/2 supported the result of over dominance for all the traits. The asymmetry in the proportion of genes with positive and negative effects in the parents was studied for all the traits and the presence of an excess dominant gene in most of the traits was noted. General combining ability (GCA) for DFF, PHFF, NSBFF, CAMF, NSBMF, NPdPP and NSPP, as well as specific combining ability (SCA) for all the traits except NPBFF and RW were significant indicating the importance of additive and non-additive gene action, respectively. Parents P3, P4 and P5 were assessed as good general combiner from this investigation and the crosses viz. P1 × P2, P1 × P3, P2 × P5, P4 × P5 and P5 × P6 were the best combiners as judged from the specific combining ability effects. So, these parents and crosses need special consideration for the improvement of lentil.

The present study was carried out at Sakha farm, Sakha Agricultural Research Station (SARS), Kafr El-Sheikh, Egypt, during the three summer seasons of 2017, 2018 and 2019. Four crosses of soybean, each with six populations (P1, P2, F1, Bc1, Bc2 and F2) were tested for yield and some growth attributes. The results showed that: Over dominance was observed for flowering date in crosses I and II, for maturity date and plant height in cross II and seed yield per plant in all crosses, while partial dominance was observed for the remaining crosses for most traits. Significant negative heterosis were detected for flowering date for mid-parent in the first cross, significant positive heterotic effects were detected for other traits. The additive effect (a) was highly significant in positive or negative direction in all crosses for all traits, except in the four crosses for number of seeds per pod and 100 seed weight, crosses I and II for flowering date. Additive x additive types of gene action were found to be significant for most traits of all crosses, also additive x dominance and dominance x dominance types of gene effects were found to be significant for most traits. High narrow sense heritability values were obtained for plant height and number of seeds per pod in the first cross. While, the lowest estimates was resulted for number of seeds per pod in the second cross, number of branches per plant in the first cross and seed yield per plant in the fourth cross.

To determine the genetic components of various agro-morphological and grain quality traits in rice, nine genotypes were crossed in diallel mating design. Vr–Wr graphical analysis and average degree of dominance revealed that presence of overdominance for all the studied traits, suggest that selection may be effective in a later generation. Estimates of genetic components such as D, H1 and H2 on traits under study were controlled by both additive and non-additive gene action. Narrow sense heritability was low for all the traits due to preponderance of non-additive gene action. These findings could help rice breeders to improve grain yield and contributing traits along with grain quality by appropriate selection.

The present investigation was performed at Horticulture Research Farm (V.R.C.), Department of Horticulture, Naini Agricultural Institute, Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS) Prayagraj. The experimental material comprised of 8 genetically diverse genotypes of tomato, 28 crosses diallel mating design (excluding reciprocals) which was evaluated in a Randomized Block Design (RBD). Pant cherry tomato (PCT-1) was identified as a best general combiner for maximum number of traits followed by PPT-2, PBT-22 and PBT-23. The best specific combiner were PBT-15 x PBT-23 followed by PPT-2 x PBT-18, PBT-20 x PBT-19, PCT-1 x PBT-19, PBT-20 x PBT-18, PBT-19 x PBT-23, PBT-15 x PBT-18 and PPT-2 x PBT-23. Hence, these crosses can be utilized in heterosis breeding for improvement in fruit quality characters. The estimates of σ2GCA/σ2SCA indicated number of locules per fruit, pericarp thickness, TSS, pH of fruit juice and ascorbic acid were under the control of non-additive gene action with over dominance effect. Hence, these characters are suitable for hybrid breeding.

The effects of selection on variability at linked sites have an important influence on levels and patterns of within-population variation across the genome. Most theoretical models of these effects have assumed that selection is sufficiently strong that allele frequency changes at the loci concerned are largely deterministic. These models have led to the conclusion that directional selection for selectively favorable mutations, or against recurrent deleterious mutations, reduces nucleotide site diversity at linked neutral sites. Recent work has shown, however, that fixations of weakly selected mutations, accompanied by significant stochastic changes in allele frequencies, can sometimes cause higher diversity at linked sites when compared with the effects of fixations of neutral mutations. This study extends this work by deriving approximate expressions for the mean conditional times to fixation and loss of mutations subject to selection, and analyzing the conditions under which selection increases rather than reduces these times. Simulations are used to examine the relations between diversity at a neutral site and the fixation and loss times of mutations at a linked site that is subject to selection. It is shown that the long-term level of neutral diversity can be increased over the purely neutral value by recurrent fixations and losses of linked, weakly selected dominant or partially dominant favorable mutations, or linked recessive or partially recessive deleterious mutations. The results are used to examine the conditions under which associative overdominance, as opposed to background selection, is likely to operate.

Purpose. To find out the inheritance pattern of plant height in the F1 hybrids from crossing varieties of Triticum aestivum L. which are carriers of wheat-rye translocations (WRT). Methods. The research was conducted in 2016-2017 at the V. M. Remeslo Myronivka Institute of Wheat (MIW) on 30 hybrid combinations of varieties-carriers of wheat-rye translocations. The degree of phenotypic dominance of plant height was determined by the formula B. Griffing; grouping was by G. M. Beil, & R. E. Atkins; manifestation of heterosis was by D. F. Matzinger et al. and S. Fonseca, F. Patterson. Results. The manifestation of depression in plant height in dry season of 2017 was established for almost quarter (seven) of hybrids, while in more favorable meteorological conditions of 2016 there was overdominance of short-stem in hybrid combinations: Kalynova 1BL.1RS / Lehenda Myronivska 1BL.1RS, Zolotokolosa 1AL.1RS / Kolumbiia 1AL.1RS, and Kolumbiia 1AL.1RS / Zolotokolosa 1AL.1RS. In 2017, one hybrid combination was characterized by partial negative inheritance. Regardless of the weather conditions of the year, positive overdominance (increase in plant height) was observed in six hybrid combinations which had high values of the coefficients of both true and hypothetical heterosis. The excess of the height of hybrid plants above the average value of this indicator of both parents was noted in 2016 in 73.3 % of the studied hybrid combinations, and in the unfavorable 2017 it was in 63.3 %. More cases were noted in the 1AL.1RS / 1BL.1RS and 1BL.1RS / 1AL.1RS crosses. Heterosis in plant height was determined for almost half of the hybrid combinations in the groups of crosses 1AL.1RS / 1BL.1RS (for two years) and 1BL.1RS / 1AL.1RS (in 2016). For two years depression of the trait “plant height” was found in hybrids created by using the variety Kolumbiia 1AL.1RS as maternal form when crossing with the variety Zolotokolosa 1AL.1RS, as well as in the hybrid combination Kalynova 1BL.1RS / Lehenda Myronivska 1BL.1RS. Conclusions. The use in crosses of varieties-carriers of WRT differing in plant height made it possible to obtain a different degree of dominance in F1: from overdominance (heterosis) to depression.

Heterosis describes the phenomenon whereby a hybrid population has higher fitness than an inbred population, and has previously been explained by either Mendelian dominance or overdominance, where it is generally assumed that one gene controls one trait. How-ever, recent studies have demonstrated that genes interact through a complex gene regulatory network (GRN). Furthermore, phenotypic variance due to noise is reportedly lower for heterozygotes, whereas the origin of such variance-related heterosis remains elusive. There-fore, a theoretical analysis linking heterosis to GRN evolution and stochastic gene expression dynamics is required. Here, we investigate heterosis related to fitness and phenotypic variance in a system with interacting genes, by numerically evolving diploid GRNs. According to the results, the heterozygote population exhibited higher fitness than the homozygote population, that is, fitness-related heterosis resulting from evolution. In addition, the heterozygote population expressed lower noise-related phenotypic variance in expression levels than the homozygous population, implying that the heterozygote population is more robust to noise. Furthermore, the distribution of the ratio of heterozygote phenotypic variance to homozygote phenotypic variance exhibited quantitative agreement with previous experimental results. By applying dominance and over-dominance to the gene expression pattern rather than only a single gene expression, we confirmed the correlation between heterosis and overdominance. We explain our results by proposing that the convex high-fitness region is evolutionarily shaped in the genetic space to gain noise robustness under genetic mixing through sexual reproduction.Significance StatementHeterosis, that is higher fitness in hybrid populations than inbred populations, is a long-standing problem in genetics, evolution, and breeding studies. Heterosis is not necessarily the result of a trait uniquely determined by a single gene, but likely involves stochasticity and interactions among genes. Through numerical evolution of the gene regulatory network, we demonstrate that heterosis is shaped by evolution to achieve robustness against noise and genetic mixing by sexual recombination in gene expression dynamics. That is, a mixed population is more robust to noise than inbred populations, as revealed experimentally by reduced phenotypic variance. The observed link between heterosis and phenotypic robustness, Mendelian dominance, and the convex single-humped fitness landscape represents a novel avenue in evolution and genetics research.

The Khangchendzonga Landscape (KL), a part of ‘Himalayan Biodiversity Hotspot’, is known for its unique biodiversity assemblage. In recent years, the KL is experiencing threats to biodiversity due to the biological overdominance of native Maling bamboo (Yushania maling). In the present study, we investigated the impacts of the overdominance of Y. maling on the forest composition of Singalila National Park (SNP), Eastern Himalaya, India. Elevational habitats 2400 to 3400 m asl were sampled by laying 69 (10 m × 10 m) forest plots including 51 bamboo plots and 18 non-bamboo plots. Bamboo plots showed significantly (p Y. maling has a significant negative impact on forest structure and composition. Therefore, management of invasiveness of Y. maling is essential through its optimized removal from the protected areas and utilization in making handicrafts, paper industries etc. to create ecological and economic benefits. Further long-term studies assessing the impacts of Y. maling overdominance on forest ecosystems and soil dynamics are recommended.

Postharvest losses are a significant concern for tomato breeding associated with their short fruit shelf life. Sletr1-2 is a new ethylene receptor mutant that has a prominent character in a prolonged fruit shelf life. This research aimed to estimate the combining ability of Sletr1-2 mutant and determine the selection method for future breeding associated with the fruit shelf-life and yield. Four lines of tropical tomato, i.e., 'Intan,' 'Mirah,' 'Ratna' and 'Mutiara,' were crossed with the wild type Micro-Tom (WT-MT) and Sletr1-2 mutant tomato using a line x tester mating design. A randomized complete block design with four replications was used to evaluate twelve F1 and their parents. The study revealed significant differences in the GCA of the line and tester but not for SCA. The lines and testers contributed more to total variance than their interaction. 'Intan' and Sletr1-2 mutants had the greatest fruit shelf-life combiners, with additive gene action being the most prevalent. Simple phenotypic selection or pure line selection from selected crosses in advanced generations would be preferable. 'Mutiara' was the best combiner for yield and plant growth, with non-additive gene action was the most common. The breeding strategy that considered dominance, overdominance, and epistasis was preferred.

The exploitation of heterosis through hybrid breeding is one of the major breeding objectives for productivity increase in crop plants. This research analyzes the genetic basis of heterosis in Brassica juncea by using a doubled haploid (DH) mapping population derived from F1 between two heterotic inbred parents, one belonging to the Indian and the other belonging to the east European gene pool, and their two corresponding sets of backcross hybrids. An Illumina Infinium Brassica 90K SNP array-based genetic map was used to identify yield influencing quantitative trait loci (QTL) related to plant architecture, flowering, and silique- and seed-related traits using five different data sets from multiple trials, allowing the estimation of additive and dominance effects, as well as digenic epistatic interactions. In total, 695 additive QTL were detected for the 14 traits in the three trials using five data sets, with overdominance observed to be the predominant type of effect in determining the expression of heterotic QTL. The results indicated that the design in the present study was efficient for identifying common QTL across multiple trials and populations, which constitute a valuable resource for marker-assisted selection and further research. In addition, a total of 637 epistatic loci were identified, and it was concluded that epistasis among loci without detectable main effects plays an important role in controlling heterosis in yield of B. juncea.

The Dallol protovolcanic area on the Danakil Depression (Afar region, Ethiopia) exhibits unique hydrothermal manifestations in hypersaline context, yielding varied polyextreme physicochemical conditions. Previous studies identified a wide archaeal diversity in less extreme brines but failed to identify microorganisms thriving in either high-chaotropicity, low-water-activity brines or hyperacidic-hypersaline Na-Fe-rich brines. Recently, we accessed several small lakes under intense degassing activity adjacent to the Round Mountain, west to the Dallol dome (Western Canyon Lakes; WCL1-5). They exhibited intermediate parameter combinations (pH~5, 34-41% NaCl-dominated salts with relatively high levels of chaotropic Mg-Ca salts) that should allow to better constrain life limits. These lakes were overwhelmingly dominated by Archaea, encompassing up to 99% of prokaryotic 16S rRNA gene amplicon sequences in metabarcoding studies. The majority belonged to Halobacteriota and Nanohaloarchaeota, the latter representing up to half of prokaryotic sequences. Optical and epifluorescence microscopy showed active cells in natural samples and diverse morphotypes in enrichment cultures. Scanning electron microscopy coupled with energy-dispersive x-ray spectroscopy revealed tiny cells (200-300 nm diameter) epibiotically associated with somewhat larger cells (0.6-1 μm) but also the presence of silica-dominated precipitates of similar size and shape, highlighting the difficulty of distinguishing microbes from mineral biomorphs in this kind of low-biomass systems. This article is protected by copyright. All rights reserved.

Genomes of high latitude killer whales harbour signatures of post-glacial founding and expansion. Here, we investigate whether reduced efficacy of selection increased mutation load in founder populations, or whether recessive deleterious mutations exposed to selection in homozygous genotypes were purged. Comparing the accumulation of synonymous and non-synonymous mutations across pairs of globally sampled genomes reveals that the most significant outliers are high latitude North Atlantic genomes, which have accumulated significantly fewer non-synonymous mutations than all other populations. Comparisons with the genome of a 7.5-Kyr-old North Atlantic killer whale, inferred to be closely related to the population directly ancestral to present-day Icelandic and Norwegian populations, calibrates the timing of the action of selection on non-synonymous mutations predominantly to the mid-late Holocene. Non-synonymous mutations purged in modern Norwegian killer whale genomes are found as globally shared standing variation in heterozygote genotypes more often than expected, suggesting overdominance. Taken together, our findings are consistent with purging of recessive non-synonymous mutations exposed to selection in founder-associated homozygous genotypes.

Loss of heterozygosity is a common mode of adaptation in asexual diploid populations. Because mitotic recombination frequently extends the full length of a chromosome arm, the selective benefit of loss of heterozygosity may be constrained by linked heterozygous mutations. In a previous laboratory evolution experiment with diploid yeast, we frequently observed homozygous mutations in the WHI2 gene on the right arm of Chromosome XV. However, when heterozygous mutations arose in the STE4 gene, another common target on Chromosome XV, loss of heterozygosity at WHI2 was not observed. Here we show that mutations at WHI2 are partially dominant and that mutations at STE4 are overdominant. We test whether beneficial heterozygous mutations at these two loci interfere with one another by measuring loss of heterozygosity at WHI2 over 1,000 generations for ∼300 populations that differed initially only at STE4 and WHI2. We show that the presence of an overdominant mutation in STE4 reduces, but does not eliminate, loss of heterozygosity at WHI2. By sequencing 40 evolved clones, we show that populations with linked overdominant and partially dominant mutations show less parallelism at the gene level, more varied evolutionary outcomes, and increased rates of aneuploidy. Our results show that the degree of dominance and the phasing of heterozygous beneficial mutations can constrain loss of heterozygosity along a chromosome arm, and that conflicts between partially dominant and overdominant mutations can affect evolutionary outcomes.SIGNIFICANCE STATEMENTIn diploid populations, it is beneficial for partially dominant beneficial mutations to lose heterozygosity, but it is deleterious for overdominant beneficial mutations to do so. Because loss-of-heterozygosity tracts often encompass entire chromosome arms, a conflict will arise when a partially dominant beneficial mutation and an overdominant beneficial mutation exist in close proximity. We demonstrate that this conflict occurs, and that it restricts loss of heterozygosity, resulting in more variable evolutionary outcomes.

Despite heterosis contributing to genetic improvements in crops, root growth heterosis in rapeseed plants is poorly understood at the molecular level. The current study was performed to discover key differentially expressed genes (DEGs) related to heterosis in two hybrids with contrasting root growth performance (FO, high hybrid and FV, low hybrid) based on analysis of the root heterosis effect. Based on comparative transcriptomic analysis, we believe that the overdominance at the gene expression level plays a critical role in hybrid roots’ early biomass heterosis. Our findings imply that a considerable increase in up-regulation of gene expression underpins heterosis. In the FO hybrid, high expression of DEGs overdominant in the starch/sucrose and galactose metabolic pathways revealed a link between hybrid vigor and root growth. DEGs linked to auxin, cytokinin, brassinosteroids, ethylene, and abscisic acid were also specified, showing that these hormones may enhance mechanisms of root growth and the development in the FO hybrid. Moreover, transcription factors such as MYB, ERF, bHLH, NAC, bZIP, and WRKY are thought to control downstream genes involved in root growth. Overall, this is the first study to provide a better understanding related to the regulation of the molecular mechanism of heterosis, which assists in rapeseed growth and yield improvement.

Heterosis denotes the superiority of a hybrid plant over its parents. The use of heterosis has contributed significantly to yield improvement in crops. However, the genetic and molecular bases on heterosis are not fully understood. A large number of heterotic loci were identified for 12 yield-related traits in one parental population of chromosome segment substitution lines (CSSLs) and two test populations, which were interconnected by CSSLs derived from two rice genome-sequenced cultivars, Nipponbare and Zhenshan 97. Seventy-five heterotic loci were identified in both homozygous background of Zhenshan 97 and heterogeneous background of an elite hybrid cultivar Shanyou 63. Among the detected loci, at least 11 were colocalized in the same regions encompassing previously reported heterosis-associated genes. Furthermore, a heterotic locus Ghd8NIP for yield advantage was verified using transgenic experiments. Various allelic interaction at Ghd8 exhibited different heterosis levels in hetero-allelic combinations of five near-isogenic lines that contain a particular allele. The significant overdominance effects from some hetero-allelic combinations were found to improve yield heterosis in hybrid cultivars. Our findings support the role of allelic interaction at heterotic loci in the improvement of yield potential, which will be helpful for dissecting the genetic basis of heterosis and provide an optional strategy for the allele replacement in molecular breeding programs in hybrid rice.

Hybrids account for nearly all commercially planted varieties of maize and many other crop plants because crosses between inbred lines of these species produce first-generation [F(1)] offspring that greatly outperform their parents. The mechanisms underlying this phenomenon, called heterosis or hybrid vigor, are not well understood despite over a century of intensive research. The leading hypotheses—which focus on quantitative genetic mechanisms (dominance, overdominance, and epistasis) and molecular mechanisms (gene dosage and transcriptional regulation)—have been able to explain some but not all of the observed patterns of heterosis. Abiotic stressors are known to impact the expression of heterosis; however, the potential role of microbes in heterosis has largely been ignored. Here, we show that heterosis of root biomass and other traits in maize is strongly dependent on the belowground microbial environment. We found that, in some cases, inbred lines perform as well by these criteria as their F(1) offspring under sterile conditions but that heterosis can be restored by inoculation with a simple community of seven bacterial strains. We observed the same pattern for seedlings inoculated with autoclaved versus live soil slurries in a growth chamber and for plants grown in steamed or fumigated versus untreated soil in the field. In a different field site, however, soil steaming increased rather than decreased heterosis, indicating that the direction of the effect depends on community composition, environment, or both. Together, our results demonstrate an ecological phenomenon whereby soil microbes differentially impact the early growth of inbred and hybrid maize.

The lack of knowledge of the genetic parameters and the type of gene action results in difficulties to obtain varieties that combine agronomic and functional characteristics. The objective of this study was to determine the type of gene action associated with the contents of chlorophyll and agronomic characteristics in lettuce populations. The research was conducted at the Experimental Station of Vegetables, Monte Carmelo, Brazil. To perform the crosses and obtain the generations P1, P2, F1, F2, Bc1 and Bc2 the genotypes UFU-Albina#2, UFU-Albina#3, UFU-Lisa124#2#1, UFU-Crespa199#1#1 and UFU-Lisa217#5#2 were used as parents. The generations were evaluated for three characteristics: number of leaves, plant diameter and chlorophyll content. The parameters: genetic, phenotypic, environmental and additive variance, the dominance in F2, heritability in the broad and narrow-sense, the average degree of dominance based on averages, number of genes, the measure of the dominance deviations, additive effects and all interactions of ‘additive x additive’, ‘additive x dominant’ and ‘dominant x dominant’ type, were evaluated. Chlorophyll content was the most influenced by the environment. Plant diameter had the highest narrow-sense heritability for the cross UFU-Lisa-124#2#1 x UFU-Albina#3 (82.1%). The number of genes for the number of leaves varied from inconclusive to a minimum of 9 genes. The gene interactions for number of leaves were of overdominance type, while for plant diameter and for chlorophyll content the gene interactions were of partial dominance. The characteristics are suggested as being of polygenic or oligogenic nature. RESUMO O desconhecimento dos parâmetros genéticos e o tipo de ação gênica resultam em dificuldades na obtenção de variedades que combinam características agronômicas e funcionais. O objetivo deste estudo foi determinar o tipo de ação gênica envolvida com o conteúdo de clorofila e características agronômicas em populações de alface. A pesquisa foi realizada na Estação Experimental de Hortaliças, Monte Carmelo, Brasil. Para realizar os cruzamentos e obter as gerações P1, P2, F1, F2, Bc1 e Bc2, os genótipos UFU-Albina#2, UFUAlbina#3, UFU-Lisa124#2#1, UFU-Crespa199#1 e UFU-Lisa217#5#2 foram usados como parentais. As gerações foram avaliadas para três características (número de folhas, diâmetro das plantas e teor de clorofila) e analisados os seguintes parâmetros: variância genética, ambiental, fenotípica, aditiva, dominância em F2, herdabilidade no sentido amplo, herdabilidade no sentido restrito, grau médio de dominância baseado em médias, número de genes, medida dos desvios da dominância, medida dos efeitos aditivos, medida de todas interações do tipo aditiva x aditiva, aditiva x dominante e dominante x dominante. O teor de clorofila foi a característica mais influenciada pelo ambiente. O diâmetro de planta apresentou a maior herdabilidade no sentido restrito para o cruzamento UFU-Lisa-124#2#1 x UFU-Albina#3 (82,1%). O número de genes para a característica de número de folhas oscilou desde valores inconclusivos até um máximo de 9 genes. As interações gênicas para número de folhas demonstraram ser do tipo sobredominância enquanto que para diâmetro de plantas e teor de clorofila do tipo dominância parcial. Sugere-se que as características avaliadas são de natureza poligênica ou oligogênica.

The aim of this study was to determine the gene action and combining ability of durum wheat for grain protein content. During the three year period a diallel cross was carried out with five modern parents of durum wheat – ‘Victoria’, ‘Deni’, ‘Superdur’, ‘Progres’ and ‘Predel’. Ten hybrid combinations and the parents were grown in the experimental field of the Field Crops Institute, Chirpan. The experiment was performed by the randomize block method design in three replications. It was found that in the inheritance of grain protein content dominance and overdominance in positive and negative directions were observed. Statistical processing of the results showed that both additive and non-additive genetic effects have influenced on inheritance. Non-additive gene effects (SCA) had a greater role in inheritance. This suggests that an effective selection for this trait could begin in later generations. The combining ability analysis has identified two good general combinators (Predel and Superdur varieties) that could be used as donors to increase the values of the trait protein content in grain. Several crosses showing positive and significant SCA effects have also been identified, suitable for achieving reliable transgressive genotypes.

Purpose and objectives. To establish the gene interaction types in the performance inheritance, to evaluate the combining abilities and effects of genes for this trait in spring barley accessions. Materials and methods. We investigated 75 F1 spring barley hybrid combinations derived from crossing 25 female forms with three male ones (chaffy and naked). Crossing was conducted in accordance with topcross design. F1 seeds and parents were sown with a cassette breeding planter SKS-6A. Grain pea was the forecrop. The plot area was 0.20 m2. The interrow distance was 0.20 m; the inter-plot tracks were of 0.50 m. Crossings were performed in two replications. Plants were harvested manually, with roots. For structural analysis, 20 typical plants were chosen from each F1 hybrid population, and the performance inheritance was determined by dominance degree (hp). The obtained data were grouped and gene interaction types were determined as per G.M. Beil and R.E. Atkins’s classification. Using two-factor analysis of variance in STATISTICA 10, we found significant differences between the GCA and SCA variances for the performance and evaluated the combining ability effects. Results and discussion. In 2019–2020, the features of 22 spring barley cultivars and three lines were described in terms of the gene interaction types in the performance inheritance and combining ability. On this basis, the prospects of biotype selections were evaluated. In the arid conditions of 2019, F1 only showed positive over dominance, while in favorable 2020 the inheritance types varied from positive to negative overdominance. In the two years, the general combining ability was high in female cultivars Khors and Troian. The male components did not show consistently high GCA for the both years. Hybrids between accessions with a high GCA and accessions with a lower or intermediate GCA may be promising in breeding due appearance of positive transgressions in the offspring. In 2019, the SCA effects were significantly strong in female forms Troian, Datcha, Gladys, Grace, Gatunok, Modern, and Herkules and in male forms Ahrarii and Scrabble. Conclusions. The study found that the gene interaction types in the spring barley performance inheritance depended on cross combinations and growing conditions. In unfavorable 2019, F1 only showed positive overdominance (heterosis), while in favorable 2020, positive overdominance, positive dominance and intermediate inheritance were observed. In 2019–2020, the high GCA was seen in female cultivars Khors and Troian. The strong SCA effects were noticed in female components Troian, Datcha, Gladys, Grace, Gatunok, Modern, and Herkules and male forms Agrarii and Scrabble. The hybrid combinations with the maximum probability of producing transgressive segregants have been selected, Цель и задачи исследования. Целью исследования было установление типа взаимодействия генов при наследовании продуктивности, комбинационной способности и эффектов действия генов по этому признаку у образцов ячменя ярового. Материалы и методы. Изучали 75 гибридных комбинаций F1 ячменя ярового, исходным материалом были 25 материнских и три отцовских компонента разных разновидностей (пленчатые и голозерные), скрещивания проведены по типу топкроссов. Посев семян первого поколения и родительских образцов проведен кассетной селекционной сеялкой СКС-6А. Предшественник – горох на зерно, площадь делянки – 0,20 м2, междурядие – 0,20 м, межделяночные дорожки – 0,50 м. Повторение – двухразовое. Растения собирали вручную с корнями. Для структурного анализа с каждой гибридной популяции F1 отбирали по 20 типичных растений, наследование продуктивности определяли по степени доминантности (hр). Группирование полученных данных и определение типов взаимодействия генов проводили по классификации G.M. Beil и R.E. Atkins. При помощи двухфакторного дисперсионного анализа по программе STATISTICA 10 установлены достоверные различия между вариансами ЗКЗ и СКЗ по признаку продуктивность и определены эффекты комбинационной способности. Обсуждение результатов. У 2019–2020 гг. установлены особенности 22 сортов и трех линий ячменю ярового по типу взаимодействия генов при наследовании продуктивности и комбинационной способности, на основании чего определены перспективы эффективности отбора биотипов. У засушливых условиях 2019 г. у F1 проявилось только положительное сверхдоминирование, в благоприятном 2020 г. – от положительного до отрицательного сверхдоминирования. За два года изучения установлена высокая общая комбинационная способность материнских сортов Хорс и Троян. У отцовских компонентов стабильно высокой ОКС за оба года изучения не установлено. Гибриды между образцами с высоким уровнем ОКС и образцами с более низким или средним уровнем ОКС могут быть перспективными для селекции посредством появлении в потомстве положительных трансгрессий. Достоверно высокие эффекты специфической комбинационной способности были в 2019 р. у материнских компонентов Троян, Datcha, Gladys, Grace, Ґатунок, Модерн, Геркулес и у отцовских Аграрій та Scrabble. Выводы. В результате исследования установлено, что тип взаимодействия генов при наследовании продуктивности у ячменя ярового зависит от комбинации скрещивания и условий года выращивания. В неблагоприятном 2019 г. у F1 проявилось только положительное сверхдоминирование (гетерозис), в благоприятном 2020 г. – положительное сверхдоминирование, положительное доминирование и промежуточное наследование. В 2019–2020 гг. установлена высокая ОКС материнских сортов Хорс и Троян, высокие эффекты СКС материнских компонентов Троян, Datcha, Gladys, Grace, Ґатунок, Модерн, Геркулес и отцовских Аграрій и Scrabble. Выделены гибридные комбинации с наибольшей вероятностью появления трансгрессивных сегрегантов, Мета і задачі дослідження. Метою дослідження було встановлення типу взаємодії генів при успадкуванні продуктивності, комбінаційної здатності та ефектів дії генів за цією ознакою у зразків ячменю ярого. Матеріали та методи. Досліджували 75 гібридних комбінацій F1 ячменю ярого, вихідним матеріалом були 25 материнських та три батьківських компоненти різних різновидностей (плівчасті та голозерні), схрещування проведено за типом топкросів. Сівбу насіння першого покоління та батьківських зразків проведено касетною селекційною сівалкою СКС-6А. Попередник – горох на зерно, площа ділянки – 0,20 м2, міжряддя – 0,20 м, міжділянкові доріжки – 0,50 м. Повторення – дворазове. Рослини збирали вручну з корінням. Для структурного аналізу з кожної гібридної популяції F1 відбирали по 20 типових рослин, успадкування продуктивності визначали за ступенем домінантності (hр). Групування одержаних даних і визначення типів взаємодії генів проводили за класифікацією G.M. Beil і R.E. Atkins. За допомогою двофакторного дисперсійного аналізу по програмі STATISTICA 10 установлено достовірні відмінності між варіансами ЗКЗ і СКЗ за ознакою продуктивність та визначили ефекти комбінаційної здатності. Обговорення результатів. У 2019–2020 рр. установлено особливості 22 сортів і трьох ліній ячменю ярого за типом взаємодії генів при успадкуванні продуктивності та комбінаційною здатністю, на основі чого визначено перспективи ефективності добору біотипів. У посушливих умовах 2019 р. у F1 проявилося лише позитивне наддомінування, в сприятливому 2020 р. – від позитивного до негативного наддомінування. За два роки вивчення встановлено високу загальну комбінаційну здатність материнських сортів Хорс і Троян. У батьківських компонентів стабільно високої ЗКЗ за обидва роки вивчення не встановлено. Гібриди між зразками з високим рівнем ЗКЗ і зразками з більш низьким чи середнім рівнем ЗКЗ можуть бути перспективними для селекції через прояв у потомстві позитивних трансгресій. Достовірно високі ефекти специфічної комбінаційної здатності були в 2019 р. у материнських компонентів Троян, Datcha, Gladys, Grace, Ґатунок, Модерн, Геркулес та у батьківських Аграрій та Scrabble. Висновки. В результаті дослідження встановлено, що тип взаємодії генів при успадкуванні продуктивності у ячменю ярого залежать від комбінації схрещування та умов року вирощування. В несприятливому 2019 р. у F1 проявилось лише позитивне наддомінування (гетерозис), у сприятливому 2020 р. – позитивне наддомінування, позитивне домінування та проміжне успадкування. В 2019–2020 рр. установлено високу ЗКЗ материнських сортів Хорс і Троян, високі ефекти специфічної СКЗ материнських компонентів Троян, Datcha, Gladys, Grace, Ґатунок, Модерн, Геркулес та батьківських Аграрій і Scrabble. Виділено гібридні комбінації з найбільшою вірогідністю виділення трансгресивних сегрегантів

Heterosis is a widely distributed phenomenon in mollusks. It is vital in aquaculture by bringing beneficial traits into hybrids. People have utilized the heterosis theory in aquaculture for years. However, the molecular basis of heterosis remains elusive. Evident growth and survival heterosis were shown in the hybrid (“Dongyou-1”) of two Haliotis diversicolor geographic genotypes (Japan and Taiwan). To explore the molecular basis underlying the hybrid abalone’s heterosis, we conducted comparative mRNA and miRNA transcriptional analysis in the hybrid and parental genotypes. Differentially expression analysis identified 5,562 differentially expressed genes (DEGs) and 102 differentially expressed miRNAs (DEMs) between the three genotypes. 1,789 DEGs and 71 DEMs were found to be non-additively expressed in the hybrid. Meanwhile, both the expression level dominance pattern (ELD) and expression level overdominance pattern (ELOD) were found in the DEGs and DEMs, showing the existence of dominance and overdominance models in the hybrid’s transcriptome and post-transcriptional regulation. Functional analysis showed the non-additively expressed genes, ELD genes, and ELOD genes were significantly enriched in growth, immunity, and stress response related pathways, while some of the pathways were regulated by the mRNA-miRNA interactions. The expression levels of FGF, C1Q, HC, CAT, SEGPX, and MGST were significantly up-regulated in the hybrid compared to the middle parent value. In conclusion, we identified the existence of non-additivity, dominance, and overdominance models in the transcriptome and miRNAome of the H. diversicolor hybrid; these models facilitate the advantageous parental alleles’ integration into the hybrid, contributing to the hybrid’s growth and survival heterosis.

Most flowering plants are hermaphroditic and experience strong pressures to evolve self-pollination (automatic selection and reproductive assurance). Inbreeding depression (ID) can oppose selection for selfing, but it remains unclear if ID is typically strong enough to maintain outcrossing. To measure the full cost of sustained inbreeding on fitness, and its genomic basis, we planted highly homozygous, fully genome-sequenced inbred lines of yellow monkeyflower (Mimulus guttatus) in the field next to outbred plants from crosses between the same lines. The cost of full homozygosity is severe: 65% for survival and 86% for lifetime seed production. Accounting for the unmeasured effect of lethal and sterile mutations, we estimate that the average fitness of fully inbred genotypes is only 3-4% that of outbred competitors. The genome sequence data provide no indication of simple overdominance, but the number of rare alleles carried by a line, especially within rare allele clusters nonrandomly distributed across the genome, is a significant negative predictor of fitness measurements. These findings are consistent with a deleterious allele model for ID. High variance in rare allele load among lines and the genomic distribution of rare alleles both suggest that migration might be an important source of deleterious alleles to local populations.

International audience; Conditioned both by environment, genotype and the interaction of the genotype itself with the environment, some phenotypic plasticity lies between individuals. This phenomenon allows an adaptive potential of individuals, and may depend on various mechanisms as overdominance, epistasis, pleiotropy, gene linkage and epigenetics. Depending on studied characters, some genotypes or cultivars may be more and less plastic and, in some cases, more and less stable. Considered as powerful anti-oxidants, carotenoids have large applications in medical fields as cancer preventive compounds and precursors of vitamin A and there is an interest for guaranteed carotenoid content in crops. Even if carotenoid accumulation seems to depend on a high genetic component for climacteric fruits as tomato, there is a large effect of G×E interaction overall. Thus, the genetic determinism alone does not explain carotenoid accumulation among most vegetables. Carrot is depicted as a healthy vegetable, thanks to its ability to accumulate carotenoids at high level in roots. However a large variation is observed. In spite of a well-known carotenoid biosynthesis pathway and recent progress on the genetic control, carotenoid accumulation in an underground reserve tissue remains unclear. Regulation can occur at several scales and can result from environmental influences. This article deals with the implication of genotype by environment interaction on carotenoid accumulation and the underlying mechanisms.

Genetics components analysis exhibited over dominance for all the characters in both the generations except plant height which showed partial dominance in F1 and complete dominance in F2. The value of genetic component ( Fˆ ) were found positive for all the characters in both generations except number of primary branches and plant height in both the generations. The positive and significant values of Fˆ indicated that the dominant genes were more frequent than recessive ones in the parents for concerned character. The correlation coefficient (r) between parental order of dominance and parental measurement was not found to be negative for any character.

—The results of breeding using transgressive variability during 1985–2018 on the Don are presented. The location is a chernozem steppe with frequent frosts and insufficient and unstable moistening over the years. The technology of breeding was common: the pedigree and bulk methods were used. When laying a breeding nursery, the following approaches were new: sowing up to 45 000 untreated ears of a designed planter (to eliminate weeding during threshing ears), determining the frost resistance of plants that have been hardened in the field in bundles placed in plastic bags in low temperatures, and determining their viability for 3 days after freezing by the Don method. A large layer of studies (more than 11 000 populations) was analyzed, starting with the F1 population and ending with the completion of formation for each one. It is confirmed that transgression that is the result of the recombination is observed in populations whose parents do not have extreme expression of the trait. It is established that populations should be heterogeneous with long-term formation. This happens when parents have very few common genes and when there is no restriction on recombination due to too large differences in components. With the presence of overdominance in F1 in many studied populations, it is possible to predict the appearance of transgressions (for frost-resistance and productivity in our case) with an average frequency of 0.25-4.36%. They are also possible, but an order of magnitude less than when overdominated, with the incomplete and complete dominance of the trait of the best parent, the excess of parents in F2 on average for the population, or with an intermediate inheritance in F2. This should be accompanied by large volumes of studying the breeding material in the first stages and the presence of various stresses. Of the 38 varieties that were included in the State Register of Russia, 29 were transgressive recombinants for winter hardiness and productivity. They all withstand –18°С on the tillering knot.

BackgroundUtilization of heterosis in maize could be critical in maize breeding for boosting grain yield. However, the genetic architecture of heterosis is not fully understood. To dissect the genetic basis of yield-related traits and heterosis in maize, 301 recombinant inbred lines derived from 08 to 641 × YE478 and 298 hybrids from the immortalized F2(IF2) population were used to map quantitative trait loci (QTLs) for nine yield-related traits and mid-parent heterosis.ResultsWe observed 156 QTLs, 28 pairs of loci with epistatic interaction, and 10 significant QTL × environment interactions in the inbred and hybrid mapping populations. The high heterosis in F1and IF2populations for kernel weight per ear (KWPE), ear weight per ear (EWPE), and kernel number per row (KNPR) matched the high percentages of QTLs (over 50%) for those traits exhibiting overdominance, whereas a notable predominance of loci with dominance effects (more than 70%) was observed for traits that show low heterosis such as cob weight per ear (CWPE), rate of kernel production (RKP), ear length (EL), ear diameter (ED), cob diameter, and row number (RN). The environmentally stable QTLqRKP3–2was identified across two mapping populations, whileqKWPE9, affecting the trait mean and the mid-parent heterosis (MPH) level, explained over 18% of phenotypic variations. Nine QTLs,qEWPE9–1,qEWPE10–1,qCWPE6,qEL8,qED2–2,qRN10–1,qKWPE9,qKWPE10–1, andqRKP4–3, accounted for over 10% of phenotypic variation. In addition, QTL mapping identified 95 QTLs that were gathered together and integrated into 33 QTL clusters on 10 chromosomes.ConclusionsThe results revealed that (1) the inheritance of yield-related traits and MPH in the heterotic pattern improved Reid (PA) × Tem-tropic I (PB) is trait-dependent; (2) a large proportion of loci showed dominance effects, whereas overdominance also contributed to MPH for KNPR, EWPE, and KWPE; (3) marker-assisted selection for markers at genomic regions 1.09–1.11, 2.04, 3.08–3.09, and 10.04–10.05 contributed to hybrid performance per se and heterosis and were repeatedly reported in previous studies using different heterotic patterns is recommended.

Rice can form not only white, but also red, brown and black kernels. In black rice pericarp contains anthocyanin pigment, which has antioxidant activity and is beneficial to human health. The article is devoted to the development of new rice lines with black pericarp on the basis of the hybrid ‘Svetly × Mavr’. The purpose of the work is to develop rice new lines with black seed vessel on the genetic background of the variety ‘Svetly’. There has been carried out a genetic analysis of varying quantitative traits that affect rice productivity. Cleavage by pericarp color occurred according to the dihybrid scheme according to the type of recessive epistasis in the ratio 9:3:4. The black color of the pericarp was formed with the presence of two dominant Pb and Pp genes in the genotype, the brown one was determined by the Pb gene, and the white one was determined by the other combinations of genes. Inheritance of plant height occurred according to the overdominance of large values of the trait. Parental forms differed in the allelic state of two pairs of genes. Along the panicle length, there has been determined partial negative dominance and monogenic differences of the hybridized varieties. According to ‘number of spikelets per panicle’, there has been identified an overdominance of a larger value of the trait and the interaction of two pairs of genes. According to ‘1000-kernel weight’, there has been established partial dominance of large values of the trait and monogenic differences of the initial parental forms. There have been selected the best recombinant forms combining a compact erect panicle and grains with a black seed vessel, and there has been developed starting material for practical breeding. The study was carried out on the fields of the Experimental Station “Proletarskaya” of the Rostov Region in 2018.

Summary Heterosis, or hybrid vigour, is a predominant phenomenon in plant genetics, serving as the basis of crop hybrid breeding, but the causative loci and genes underlying heterosis remain unclear in many crops. Here, we present a large‐scale genetic analysis using 5360 offsprings from three elite maize hybrids, which identifies 628 loci underlying 19 yield‐related traits with relatively high mapping resolutions. Heterotic pattern investigations of the 628 loci show that numerous loci, mostly with complete–incomplete dominance (the major one) or overdominance effects (the secondary one) for heterozygous genotypes and nearly equal proportion of advantageous alleles from both parental lines, are the major causes of strong heterosis in these hybrids. Follow‐up studies for 17 heterotic loci in an independent experiment using 2225 F2 individuals suggest most heterotic effects are roughly stable between environments with a small variation. Candidate gene analysis for one major heterotic locus (ub3) in maize implies that there may exist some common genes contributing to crop heterosis. These results provide a community resource for genetics studies in maize and new implications for heterosis in plants.

In order to study the inheritance pattern of morpho-physiological traits in bread wheat, a 10×10 diallel cross, excluding reciprocals was made and grown in a randomized complete block design (RCBD) with three replications. Observations were recorded on Days to 75% flowering (DF), Days to maturity (DM), Duration of reproductive phase (DRP), Plant height (cm) (PH), Effective tiller/plant (TLS), No. of spikelets per spike (SLS), No. of grains per spike (GS), Grain weight per spike (g) (GW), Spike length (cm) (SL), Biological yield per plant (g) (BY), Harvest index (%) (HI), 1000-Grain weight (g) (TGW), Spike density (SD), Canopy temperature depression (°C) (CTD), Chlorophyll intensity (%) (CI), Chlorophyll fluorescence (Fv/Fm) (CF), Protein content (%) (PC), Grain yield per plant (g) (GY). Highly significant differences were observed among the genotypes for all traits. The resulted 45 F1s and their F2s used for study the nature of gene for grain yield and its contributing traits in bread wheat. The result indicated that considerable gene action and average degree of dominance respond to achieving significant result for grain yield and its component traits. In both the generations F1s and F2s, grain yield per plant (g) was governed by non-additive gene action based on combining ability analysis, (σ2 g/σ2 s)0.5 [GCA and SCA variance ratio] and (H1/D)0.5 [Degree of dominance] were exhibited over dominance type average degree of dominance for grain yield and its component traits in both generations. Genetic analyses of the traits confirm the involvement of both additive and non-additive gene effects in governing the inheritance.