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BackgroundThe additive model of inheritance assumes that heterozygotes (Aa) are exactly intermediate in respect to homozygotes (AA and aa). While this model is commonly used in single-locus genetic association studies, significant deviations from additivity are well-documented and contribute to phenotypic variance across many traits and systems. This assumption can introduce type I and type II errors by overestimating or underestimating the effects of variants that deviate from additivity. Alternative genotype encoding strategies have been explored to account for different inheritance patterns, but they often incur significant computational or methodological costs. To address these challenges, we introduce PAGER (Phenotype Adjusted Genotype Encoding and Ranking), an efficient pre-processing method that encodes each genetic variant based on normalized mean phenotypic differences between diallelic genotype classes (AA, Aa, and aa). This approach more accurately reflects each variant's true inheritance model, improving model precision while minimizing the costs associated with alternative encoding strategies.ResultsThrough extensive benchmarking on SNPs simulated with both binary and continuous phenotypes, we demonstrate that PAGER accurately represents various inheritance patterns (including additive, dominant, recessive, and heterosis), achieves levels of statistical power that meet or exceed other encoding strategies, and attains computation speeds up to 55 times faster than a similar method, EDGE. We also apply PAGER to publicly available real-world data and identify a novel, relevant putative QTL associated with body mass index in rats (Rattus norvegicus) that is not detected with the additive model.ConclusionsOverall, we show that PAGER is an efficient genotype encoding approach that can uncover sources of missing heritability and reveal novel insights in the study of complex traits while incurring minimal costs.

Parental epigenetic asymmetries, which contribute to the monoallelic expression of genes known as imprints, play a critical role in seed development in flowering plants. Primarily, differential DNA methylation patterns and histone modifications on parental alleles form the molecular basis of gene imprinting. Plants predominantly exhibit this non-Mendelian inheritance phenomenon in the endosperm and the early embryo of developing seeds. Imprinting is crucial for regulating nutrient allocation, maintaining seed development, resolving parental conflict, and facilitating evolutionary adaptation. Disruptions in imprinted gene expression, mediated by epigenetic regulators and parental ploidy levels, can lead to endosperm-based hybridization barriers and hybrid dysfunction, ultimately reducing genetic diversity in plant populations. Conversely, imprinting helps maintain genetic stability within plant populations. Imprinted genes likely influence seed development in various ways, including ensuring proper endosperm development, influencing seed dormancy, and regulating seed size. However, the functions of most imprinted genes, the evolutionary significance of imprinting, and the long-term consequences of imprinting disruptions on plant development and adaptation need further exploration. Thus, it is clear that research on imprinting has immense potential for improving our understanding of plant development and ultimately enhancing key agronomic traits. This review decodes the possible genetic and epigenetic regulatory factors underpinning genomic imprinting and their positive and negative consequences on seed development. This study also forecasts the potential implications of exploiting gene imprinting for crop improvement programs. [ABSTRACT FROM AUTHOR]

Apomixis is a reproductive process that produces clonal seeds while bypassing meiosis (or apomeiosis) without undergoing fertilization (or pseudo-fertilization). The progenies are genetically cloned from their parents, retaining the parental genotype, and have great potential for the preservation of genes of interest and the fixing of heterosis. The hallmark components of apomixis include the formation of female gametes without meiosis, the development of fertilization-independent embryos, and the formation of functional endosperm. Understanding and utilizing the molecular mechanism of apomixis has far-reaching implications for plant genetic breeding and agricultural development. Therefore, this study focuses on the classification, influencing factors, genetic regulation, and molecular mechanism of apomixis, as well as progress in the research and application of apomixis-related genes in plant breeding. This work will elucidate the molecular mechanisms of apomixis and its application for plant genetic improvement. [ABSTRACT FROM AUTHOR]

The study quantified breed effects and putative non-additive genetic variation for quantitative and qualitative slaughter and skin traits involving three ostrich breeds: South African Black (SAB), Zimbabwean Blue (ZB), and Kenyan Red (KR) ostriches. Such data from contemporary slaughter groups with all three pure breeds represented were analyzed together (SAB: n = 457; ZB: n = 74; KR: n = 50). Two 2 × 2 diallel crossbreeding designs were used to assess crosses of ZB and KR birds with the SAB strain. Subsequently, the data from SAB, ZB and their reciprocal crosses, slaughtered together; as well as the data from SAB and KR ostriches, along with their reciprocal crosses, respectively, were analyzed separately. ZB and KR birds outperformed SAB birds for most size-related slaughter and skin traits. Linear contrasts were used to distinguish the effects of breed, heterosis, and the dam line. For the ZB x SAB design, additive breed effects were significant for slaughter weight (10.4%), crust skin size (3.9%) and nodule shape score (1.6%) (all P < 0.05). Significant heterosis were found for slaughter weight (4.3%), crust skin size (1.7%) and nodule size score (3.7%) (P < 0.05). Dam line effects were observed for skin weight (4.1%) and hair follicle score (4.1%). In the KR x SAB design, additive breed effects were like outcomes for the ZB x SAB design. Heterosis estimates were significant (P < 0.05) for slaughter weight (5.8%), crust skin size (2.9%), crown length (1.7%) and nodule size score (4.4%). Dam line effects were significant for slaughter weight (3.7%) and nodule size score (3.8%). In conclusion, ZB and KR birds outperformed their SAB contemporaries for size and size-related traits. Crossbreeding with these genotypes could improve some size-related traits over the mid-parent value of purebreds. [ABSTRACT FROM AUTHOR]

Crossbreeding is a widely adopted practice in the livestock industry, leveraging the advantages of heterosis and breed complementarity. The prediction of Crossbred Performance (CP) often relies on Purebred Performance (PB) due to limited crossbred data availability. However, the effective selection of purebred parents for enhancing CP depends on non-additive genetic effects and environmental factors. These factors are encapsulated in the genetic correlation between crossbred and purebred populations (rpc). In this study, a two-way crossbreeding simulation was employed to investigate various strategies for integrating data from purebred and crossbred populations. The goal was to identify optimal models that maximize CP across different levels of rpc. Different scenarios involving the selection of genotyped individuals from purebred and crossbred populations were explored using ssGBLUP (single-step Genomic Best Linear Unbiased Prediction) and ssGBLUP-MF (ssGBLUP with metafounders) models. The findings revealed an increase in prediction accuracy across all scenarios as rpc values increased. Notably, in the scenario incorporating genotypes from both purebred parent breeds and their crossbreds, both ssGBLUP and ssGBLUP-MF models exhibited nearly identical predictive accuracy. This scenario achieved maximum accuracy when rpc was less than 0.5. However, at rpc = 0.8, ssGBLUP, which exclusively included sire breed genotypes in the training set, achieved the highest overall prediction accuracy at 73.2%. In comparison, the BLUP-UPG (BLUP with unknown parent group) model demonstrated lower accuracy than ssGBLUP and ssGBLUP-MF across all rpc levels. Although ssGBLUP and ssGBLUP-MF did not demonstrate a definitive trend in their respective scenarios, the prediction ability for CP increased when incorporating both crossbred and purebred population genotypes at lower levels of rpc. Furthermore, when rpc was high, utilizing paternal genotype for CP predictions emerged as the most effective strategy. Predicted dispersion remained relatively similar in all scenarios, indicating a slight underestimation of breeding values. Overall, the rpc value emerged as a critical factor in predicting CP based on purebred data. However, the optimal model to maximize CP depends on the factors influencing rpc. Consequently, ongoing research aims to develop models that optimize purebred selection, further enhancing CP. [ABSTRACT FROM AUTHOR]

The cost of hybrid tomato (Solanum lycopersicum L.) production, unavailability, and cost of hybrid seeds are constraints to tomato production in developing countries. To overcome this problem, it is important to develop inbred lines through appropriate conventional selection breeding. Three F1 monohybrids crossing followed by conventional selection of advanced segregating generations were done to identify superior recombinant sergeant inbred lines. The inbred lines showed approximately 75% yield improvement, 40% earliness in maturity, and 20% in total soluble solids (TSS) compared to their respective F1 hybrid vigor performances. This indicated the possibility of developing inbred lines with equivalent, or higher, inbred vigor and yield potential than their corresponding hybrid and respective F1 hybrids, thus, helping overcome the problem of hybrid seed unavailability, unaffordability, and cost of hybrid seed production. [ABSTRACT FROM AUTHOR]

Maize is one of the most successful crops in utilizing heterosis which significantly improves maize stresses resistance and yield. Drought is a destructive abiotic stress that significantly reduces crop yield, particularly in maize. Drought stress and rewatering frequently occur during the growth and development of maize; however, themolecular mechanisms of heterosis under drought stress and re-watering have rarely been systematically investigated. Zhengdan7137 and Zhengdan7153 are two maize hybrid varieties with robust heterosis, and separately belongs to the SS×NSS and Reid×Tangsipingtou heterotic groups. 54 transcriptomes of these two hybrids and their parental inbred lines were analyzed under well-watering (WW), waterdeficit (WD), and re-watering (RW) conditions using RNA-Seq. In this study, we identified 3,411 conserved drought response genes (CDRGs) and 3,133 conserved re-watering response genes (CRRGs) between Zhengdan7137 and Zhengdan7153. When comparing CDRGs and CRRGs to overdominance and underdominance genes, we identified 303 and 252 conservative drought response overdominance genes (DODGs) and underdominance genes (DUDGs), respectively, and 165 and 267 conservative re-watering response overdominance genes (RODGs) and underdominance genes (RUDGs), respectively. DODGs are involved in stress response-related processes, such as L-phenylalanine metabolism, carbohydrate metabolism, and heat response, whereas DUDGs are associated with glucose metabolism, pentose-phosphate shunt, and starch metabolism. RODGs and RUDGs contribute to the recovery of hybrids from drought stress by upregulating cell propagation and photosynthesis processes, and repressing stress response processes, respectively. It indicated overdominant and underdominant genes conservatively contributed to hybrid heterosis under drought stress. These results deepen our understanding of the molecular mechanisms of drought resistance, uncover conservative molecular mechanisms of heterosis under drought stress and re-watering, and provide potential targets for improving drought resistance in maize. [ABSTRACT FROM AUTHOR]

Background: Two-line hybrid wheat technology system is one way to harness wheat heterosis both domestically and internationally. Seed vigor is a crucial parameter for assessing seed quality, as enhanced seed vigor can lead to yield increments of over 20% to a certain extent. MicroRNAs (miRNAs) were known to participate in the development and vigor of seed in plants, but its impact on seed vigor in two-line hybrid wheat remains poorly elucidated. Results: The hybrid (BS1453/11GF5135) wheat exhibited superiority in seed vigor and anti-aging capacity, compared to its male parent (11GF5135, MP) and female parent (BS1453, FP). We identified four miRNAs associated with seed vigor, all of which are novel miRNAs. The majority of targets of miRNAs were related to ubiquitin ligases, kinases, sucrose synthases and hydrolases, involving in starch and sucrose metabolism, hydrolysis, catalysis, plant hormone signal transduction, and other pathways, which played crucial roles in seed development. Additionally, we also found miR531 was differentially expressed in both male parent and hybrid, and its target gene was a component of the E1 subunit of α-ketoate dehydrogenase complex, which interacted with dihydrolipoamide acetyltransferase (E2) and dihydrolipoyl dehydrogenase (E3). Finally, We established a presumptive interaction model to speculate the relationship of miR531 and seed vigor. Conclusions: This study analyzed the seed vigor of two-line hybrid wheat, and screened seed vigor-related miRNAs. Meanwhile speculated the genetic relationship of hybrid and parents, in terms of miRNAs. Consequently, the present study provides new insights into the miRNA-mediated gene and protein interaction network that regulates seed vigor. These findings hold significance for enhancing the yield and quality of two-line hybrid wheat, facilitating its future applications. [ABSTRACT FROM AUTHOR]

Nicotine exhibits obvious heterosis, which can be used to create Nicotiana tabacum L. (tobacco) varieties with varying nicotine content. However, the reasons for the formation of nicotine heterosis and its relationship to nicotine transport and accumulation remain unknown. This study conducted a comprehensive analysis of six tobacco hybrids with varying heterosis levels and their parent materials from various aspects, such as phenotype, physiology, and transcriptomics. The results showed that the direct path coefficient of transport heterosis to nicotine heterosis was highest in hybrids, at 0.98, and a highly significant positive correlation between the two. The plant height, thick stalk circumference, large flow of tissue fluid in the stalk, and high nicotine concentration of tobacco were the underlying factors that led to the strong nicotine transport capacity of hybrids. The formation of nicotine transport heterosis in hybrids was mainly influenced by non-additive gene effects (accounting for 89.93%), with over-dominant effects playing a dominant role (accounting for 58.79%). Among non-additive expression DEGs, nicotine transporter related multi antimicrobial extrusion protein, drug/metabolite transporter, ABC family transporter, and glutathione S-transferase were significantly upregulated in hybrid strains. The RT-qPCR results indicated that these genes related nicotine transport also exhibited heterosis at the expression level. Our results revealed that the formation of nicotine heterosis is mainly achieved by enhancing the nicotine transport capacity in hybrids. The results are not only beneficial for promoting the theoretical study of nicotine heterosis in tobacco and the breeding and utilization of hybrids, but are also of great significance for guiding nicotine production and promoting its multipurpose utilization. [ABSTRACT FROM AUTHOR]

The hybrid grouper (Cromileptes altivelas, ♀ × Epinephelus lanceolatus, ♂) is an economically important aquaculture species that exhibits certain growth advantages compared to its female parent, Cromileptes altivelas. However, the current understanding of the molecular mechanisms underlying the growth of hybrid groupers is lacking. Herein, we performed full-length transcriptome sequencing and next-generation sequencing on the hybrid grouper and its parents to identify growth-related genes and comprehensively analyze the regulatory mechanism of growth heterosis in the hybrid grouper. Approximately 44.70, 40.44, and 45.32 Gb of single-molecule real-time sequencing data were generated in C. altivelas (Cal), E. lanceolatus (Ela), and the hybrid (Hyb), which were combined into 204,322 non-redundant isoforms using the PacBio sequencing platform. Differentially expressed genes (DEGs) were identified between Hyb and Cal (3,494, 2,125, and 1,487 in brain, liver, and muscle tissues, respectively) and Hyb and Ela (3,415, 2,351, and 1,675 in brain, liver, and muscle tissues, respectively). Then, 27 DEGs (13 in the brain and 14 in the muscle) related to growth traits were identified using cluster and correlation network analysis. Quantitative RT-PCR validated 15 DEGs consistent with transcriptome sequencing (RNA-seq) trends. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these 15 genes were mainly involved in regulating the actin cytoskeleton, suggesting that this pathway plays an essential role in fish growth. In addition, we found that the phosphatase and tensin homologue (PTEN) is a key regulator of growth heterosis in Hyb. These results shed light on the regulatory mechanism of growth in the Hyb, which is important for marker-assisted selection programs to improve the growth quality of groupers. [ABSTRACT FROM AUTHOR]

The genetic analysis of potato is hampered by the complexity of tetrasomic inheritance. An ongoing effort aims to transform the clonally propagated tetraploid potato into a seed-propagated diploid crop, which would make genetic analyses much easier owing to disomic inheritance. Here, we construct and report the large-scale genetic and heterotic characteristics of a diploid F2 potato population derived from the cross of two highly homozygous inbred lines. We investigate 20,382 traits generated from multi-omics dataset and identify 25,770 quantitative trait loci (QTLs). Coupled with gene expression data, we construct a systems-genetics network for gene discovery in potatoes. Importantly, we explore the genetic basis of heterosis in this population, especially for yield and male fertility heterosis. We find that positive heterotic effects of yield-related QTLs and negative heterotic effects of metabolite QTLs (mQTLs) contribute to yield heterosis. Additionally, we identify a PME gene with a dominance heterotic effect that plays an important role in male fertility heterosis. This study provides genetic resources for the potato community and will facilitate the application of heterosis in diploid potato breeding. An ongoing effort aims to transform the clonally propagated tetraploid potato to a seed-propagated diploid crop, but our understanding of it disomic inheritance is limited. Here, the authors report genetic basis of heterosis in the elite hybrid potato and identify a male fertility-related PME gene with dominance heterotic effect. [ABSTRACT FROM AUTHOR]

High-quality red/dry chilli for spice, pharmaceutical and medicinal purposes is a major goal in chilli breeding. The male sterile lines have greater potential for the exploitation of heterosis in chilli to achieve this objective. Genetic male sterile lines with special traits like destalking and ability to withstand high rainfall were involved in heterosis breeding to identify hybrids for commercial and industrial purposes. Forty F1 hybrids were developed by crossing 4 diverse GMS lines with 10 testers using Line × Tester mating design to estimate heterosis, combing ability and gene action. The experiment involving 14 parents and 40 F1s, along with standard variety 'CH-27' was laid out in α-lattice square design in three replications during summer 2020 and 2021. The GMS lines MS 9-2 and MS 26-1 along with testers DPCh 10, VVG, DPCh 40 and Him Palam Mirch-2 showed significant GCA for marketable red/dry fruit yield and majority of their component traits. Ten F1 hybrids were identified with superiority for fruit yield based on mean performance, significant heterosis and SCA effects, providing an opportunity to utilize them in value-added products and dried spice purposes viz., MS 9-2 × HPM-2, MS 11-2 × DPCh 40, MS 9-2 × DPCh 40 and MS 9-2 × DPCh 101 with erect fruiting habit and that of MS 9-2 × DPCh 10, MS 26-1 × DPCh 10, MS 9-2 × PBC 535, MS 26-1 × VVG, MS 29-2 × DPCh 10 and MS 26-1 × DPCh 22- C with pendent fruits. The non-additive gene action was predominant in the expression of fruit yield, total red fruits/plant, oleoresin and capsanthin. A significant positive correlation among SCA, economic heterosis and per se performance is an indicative to identify superior hybrids. Multi-location testing of these hybrids shall pave way to exploit them commercially by making them available to the farmers. [ABSTRACT FROM AUTHOR]

To evaluate the expression of drought tolerance for bread wheat, six parents diverse in their response to drought i.e., Giza 171 (P1), Sakha 95 (P2), Bohouth 6 (P3), Cham 8 (P4), Gemmiza 12 (P5) and Masr 3 (P6) and their 15 F1 crosses at 100% water requirements, and 70% water requirements sown in randomized complete blocks design season 2023/24 to estimate some genetic parameters for day to heading, days to maturity, chlorophyll pigments, superoxide dismutase activity, the activity of ascorbate peroxidase, proline content, number of spikes/plant, number of grains/spike, 100-kernel weight, and grain yield/plant. slightly significant differences were shown for most studied traits across all water regimes. The ratios of general combining ability to specific combining ability exceeded one for the examined traits, with some exceptions, signifying the influence of additive gene effects on the inheritance. The parental genotypes as good combiners, for earliness were P1 under both treatments, as well as P1, P2, and P3 at 70% water requirements, for physiologic and agronomic traits. The crosses P3 × P4 and P4 × P6 were the best combinations across the two treatments depending on physiological response and yield attributes. Most hybrids had significant heterotic values for agronomic and biophysiological traits. The genotypic and phenotypic coefficients of variation varied from 1.71% for days to maturity to 14.83% for proline content, and from 1.90% for days to maturity to 16.64% for the activity of ascorbate peroxidase under well-watered, respectively; likewise, from 2.03% and 1.80% for days to maturity to 14.69% and 14.05% for chlorophyll a, respectively under water deficit. [ABSTRACT FROM AUTHOR]

Simple Summary: Humans are diploid organisms, carrying one set of chromosomes from our mother and one from our father. Plants can exist as diploid or polyploid, carrying multiple chromosome copies. Plant breeders can cross polyploid crops in unique and beneficial ways that are not possible in diploid crops. It will be necessary to produce food in a more sustainable manner, with less virgin land turned over and fewer resources consumed, therefore the study of hybrid polyploid crops is essential for the improvement of our food system. The improvement in quantitative traits (e.g., yield, size) in F1 offspring over parent lines is described as hybrid vigour, or heterosis. There exists a fascinating relationship between parental genetic distance and genome dosage (polyploidy), and heterosis effects. The contribution of nuclear heterozygosity to heterosis is not uniform across diploid and polyploid crops, even within same species, thus demonstrating that polyploid crops should be part of any discussion on the mechanisms of heterosis. This review examines the records of correlating heterosis with parental genetic distance and the influence of adding supplementary genomes in wide crosses. Increasing nuclear heterozygosity through parental genetic distance has been shown to be an imperfect predictor for heterosis in a variety of commercial crops such as maize, rice, and pepper. However, increasing the ploidy level raises the maximum number of alleles that can be harboured at any one locus, and studies on crops such as oilseed rape, potato, alfalfa, maize, and rice have demonstrated that heterosis may be maximised upon increasing multi-locus nuclear heterozygosity. The novel heterotic phenotypes observed above the diploid level will contribute to our understanding on the mechanisms of heterosis and aid plant breeders in achieving the righteous goal of producing more food with fewer inputs. [ABSTRACT FROM AUTHOR]

Summary: Epistasis refers to nonallelic interaction between genes that cause bias in estimates of genetic parameters for a phenotype with interactions of two or more genes affecting the same trait. Partitioning of epistatic effects allows true estimation of the genetic parameters affecting phenotypes. Multigenic variation plays a central role in the evolution of complex characteristics, among which pleiotropy, where a single gene affects several phenotypic characters, has a large influence. While pleiotropic interactions provide functional specificity, they increase the challenge of gene discovery and functional analysis. Overcoming pleiotropy‐based phenotypic trade‐offs offers potential for assisting breeding for complex traits. Modelling higher order nonallelic epistatic interaction, pleiotropy and non‐pleiotropy‐induced variation, and genotype × environment interaction in genomic selection may provide new paths to increase the productivity and stress tolerance for next generation of crop cultivars. Advances in statistical models, software and algorithm developments, and genomic research have facilitated dissecting the nature and extent of pleiotropy and epistasis. We overview emerging approaches to exploit positive (and avoid negative) epistatic and pleiotropic interactions in a plant breeding context, including developing avenues of artificial intelligence, novel exploitation of large‐scale genomics and phenomics data, and involvement of genes with minor effects to analyse epistatic interactions and pleiotropic quantitative trait loci, including missing heritability. [ABSTRACT FROM AUTHOR]

In the context of rapidly increasing population and diversified market demands, the steady improvement of yield and quality in horticultural crops has become an urgent challenge that modern breeding efforts must tackle. Heterosis, a pivotal theoretical foundation for plant breeding, facilitates the creation of superior hybrids through crossbreeding and selection among a variety of parents. However, the vast number of potential hybrids presents a significant challenge for breeders in efficiently predicting and selecting the most promising candidates. The development and refinement of effective hybrid prediction methods have long been central to research in this field. This article systematically reviews the advancements in hybrid prediction for horticultural crops, including the roles of marker-assisted breeding and genomic prediction in phenotypic forecasting. It also underscores the limitations of some predictors, like genetic distance, which do not consistently offer reliable hybrid predictions. Looking ahead, it explores the integration of phenomics with genomic prediction technologies as a means to elevate prediction accuracy within actual breeding programs. [ABSTRACT FROM AUTHOR]

Heterosis, recognized for improving crop performance, especially in the first filial (F1) generation, remains an area of significant study in the tobacco industry. The low utilization of leaf veins in tobacco contributes to economic inefficiency and resource waste. Despite the positive impacts of heterosis on crop genetics, investigations into leaf-vein ratio heterosis in tobacco have been lacking. Understanding the mechanisms underlying negative heterosis in leaf vein ratio at the molecular level is crucial for advancing low vein ratio leaf breeding research. This study involved 12 hybrid combinations and their parental lines to explore heterosis associated with leaf vein ratios. The hybrids displayed diverse patterns of positive or negative leaf vein ratio heterosis across different developmental stages. Notably, the F1 hybrid (G70 × Qinggeng) consistently exhibited substantial negative heterosis, reaching a maximum of -19.79% 80 days after transplanting. A comparative transcriptome analysis revealed that a significant proportion of differentially expressed genes (DEGs), approximately 39.04% and 23.73%, exhibited dominant and over-dominant expression patterns, respectively. These findings highlight the critical role of non-additive gene expression, particularly the dominance pattern, in governing leaf vein ratio heterosis. The non-additive genes, largely associated with various GO terms such as response to abiotic stimuli, galactose metabolic process, plant-type cell wall organization, auxin-activated signaling pathway, hydrolase activity, and UDP-glycosyltransferase activity, were identified. Furthermore, KEGG enrichment analysis unveiled their involvement in phenylpropanoid biosynthesis, galactose metabolism, plant hormone signal transduction, glutathione metabolism, MAPK signaling pathway, starch, and sucrose metabolism. Among the non-additive genes, we identified some genes related to leaf development, leaf size, leaf senescence, and cell wall extensibility that showed significantly lower expression in F1 than in its parents. These results indicate that the non-additive expression of genes plays a key role in the heterosis of the leaf vein ratio in tobacco. This study marks the first exploration into the molecular mechanisms governing leaf vein ratio heterosis at the transcriptome level. These findings significantly contribute to understanding leaf vein ratios in tobacco breeding strategies. [ABSTRACT FROM AUTHOR]

Background: As blackgram cultivation is majorly spread in rain fed areas, breeding short duration and high yielding blackgram varieties is of profound importance to tackle terminal moisture stress and reap impressive yields by breaking the yield plateau. Hence, the present study was aimed to identify highly heterotic cross combinations for yield and earliness. Methods: Six parents along with 15 F1s were evaluated (rabi, 2019) for seed yield and its component traits along with earliness to estimate the magnitude of heterosis. Result: The cross LBG-752 x TBG-104 exhibited heterosis estimates in desirable direction for yield and earliness. The next best crosses were LBG-752 x PU-31, TU-40 x TBG-104, LBG-752 x TU-40 and IPU-2-43 x TBG-104. Because of its autogamous genetic architecture and biological constraints in large scale economic hybrid seed production, heterosis could be exploited only by isolating the early maturing and high yielding segregants followed by bi-parental or recurrent selection in early segregating generations and single plant selection in subsequent generations that would result in short duration and high yielding blackgram variety that fits well into different ecological niches. [ABSTRACT FROM AUTHOR]

Background: For improvement of quantitative traits the information on nature of gene action is an important asset for plant breeders. However, the information on gene action for yield and its attributes is scanty in pigeonpea crop. Methods: The present experiment was carried out during kharif 2018-2020 at GBPUAT, Pantnagar, Uttarakhand. The experimental material consisted of six generations of three crosses viz., PADT-16 × PUSA 992, PADT-16 × UPAS 120 and PADT-16 × PAU 881. The observations were recorded on nine morphological characters. The gene action was estimated by three parameters model of Jinks and Jones if scaling tests were non significant and six parameters model of Hayman if scaling tests were significant. Result: For majority of traits in all three crosses, epistatic gene action was present as scaling tests were found to be significant. However, for traits number of primary branches, number of secondary branches and number of seeds per pod in cross PADT-16 × UPAS 120 a simple additive/dominance model was found to be adequate. In general, magnitude of dominance was found to be higher as compared to corresponding additive gene action. The high magnitude of dominance indicated that heterosis breeding is rewarding in these characters. [ABSTRACT FROM AUTHOR]

During the recent decades, the scientific community turned its attention towards the dual purpose lines and crosses that might offer a suitable solution for two problems in poultry breeding - the use of male chickens for meat and the use of female chickens for rearing in alternative types of systems for egg production. Hence, a study with four groups of birds: a dual purpose cross „Salmon“, a dual purpose purebred line „BB“, a laying line „L“ and a laying hybrid line „ISA-Brown“ was conducted. The aim was to compare the morphological traits, as well as the fertility and the hatchability of the eggs, obtained from „ISA-Brown“, compared to the dual purpose „Salmon“ reared at IAS-Kostinbrod, and the local dual purpose and laying lines involved in its creation. As a result of the conducted research, we can conclude that the selection for high performance, larger eggs and the presence of heterosis in hybrids has to some extent a positive influence on most of the morphological traits determining the quality of the eggs produced. In addition, negative consequences for their hatchability, embryo survival and some morphological parameters such as increased width of the egg and increased diameter of the yolk were also observed. On the other hand, in the stock hybrids, compared to the purebred lines and the dual purpose crosses, this can also be considered as a sign of deterioration of the nutritional quality of the eggs. [ABSTRACT FROM AUTHOR]

Maize (Zea mays) represents one of the most successful uses of heterosis among crops. Hybrid maize seeds can be produced by crossing a male-sterile female parent with a male parent as the pollen donor to achieve high seed purity at low cost. Cytoplasmic male sterility (CMS) has been widely used for maize hybrid seed production. Recently, several hybrid seed production technologies based on genic male sterility (GMS) genes have been developed. In addition, the identification of environment-sensitive genic male sterility (EGMS) genes provides opportunities for the two-line system to be applied in maize hybrid seed production. In this review, we systematically summarize the male-sterile genes and molecular mechanisms of male sterility in maize. Future prospects for the study of maize male sterility are highlighted. Future research will enhance our understanding of the molecular regulatory networks of male sterility and promote the process of maize hybrid seed production using male sterile lines. [ABSTRACT FROM AUTHOR]

The most important step in plant breeding is the correct selection of parents, and it would be wise to use heterotic groups for this. The purpose of this study is to analyse yield and its components as well as genetic diversity in line × tester wheat populations. It also seeks to present a coherent framework for the isolation of early superior families and the development of heterotic groups in bread wheat. F1 and F2 generations of 51 genotypes, including 36 combinations between 12 lines and three testers and 15 parents, were evaluated for yield and its components in a three-replication experiment according to the randomized block design. Line × tester analysis of variance, general and specific combining abilities, heterosis, heterobeltiosis and inbreeding depression were calculated. Heterotic groups created based on general and specific combining abilities were compared with each other. The results showed that there was sufficient genetic variation in the population and that further genetic calculations could be made. The selections made based on general and specific combining abilities, heterosis values and average performance of genotypes without heterotic grouping indicated different genotypes for each feature. The creation of heterotic groups made it possible to select genotypes that were superior in terms of all the criteria listed. It was concluded that heterotic groups created based on specific combining abilities may be more useful for breeding studies. [ABSTRACT FROM AUTHOR]

SUMMARY: The utilization of rice heterosis is essential for ensuring global food security; however, its molecular mechanism remains unclear. In this study, comprehensive analyses of accessible chromatin regions (ACRs), DNA methylation, and gene expression in inter‐subspecific hybrid and its parents were performed to determine the potential role of chromatin accessibility in rice heterosis. The hybrid exhibited abundant ACRs, in which the gene ACRs and proximal ACRs were directly related to transcriptional activation rather than the distal ACRs. Regarding the dynamic accessibility contribution of the parents, paternal ZHF1015 transmitted a greater number of ACRs to the hybrid. Accessible genotype‐specific target genes were enriched with overrepresented transcription factors, indicating a unique regulatory network of genes in the hybrid. Compared with its parents, the differentially accessible chromatin regions with upregulated chromatin accessibility were much greater than those with downregulated chromatin accessibility, reflecting a stronger regulation in the hybrid. Furthermore, DNA methylation levels were negatively correlated with ACR intensity, and genes were strongly affected by CHH methylation in the hybrid. Chromatin accessibility positively regulated the overall expression level of each genotype. ACR‐related genes with maternal Z04A‐bias allele‐specific expression tended to be enriched during carotenoid biosynthesis, whereas paternal ZHF1015‐bias genes were more active in carbohydrate metabolism. Our findings provide a new perspective on the mechanism of heterosis based on chromatin accessibility in inter‐subspecific hybrid rice. Significance Statement: The utilization of rice heterosis is an essential avenue to overcome the yield bottleneck; however, the underlying molecular mechanism remains unclear. We characterized the more actively accessible chromatin state in the inter‐subspecific hybrid compared to that in its parents, revealing the regulation of chromatin accessibility and DNA methylation. This study offers a novel perspective on ACR as an embodiment of the regulation of hybrid rice. [ABSTRACT FROM AUTHOR]

Heterosis of growth traits in economic fish has benefited the production of aquaculture for many years, yet its genetic and molecular basis has remained obscure. Nowadays, a new germplasm of hybrid Jinhu grouper (Epinephelus fuscoguttatus ♀ × E. tukula ♂), abbreviated as EFT, exhibiting paternal-biased growth heterosis, has provided an excellent model for investigating the potential regulatory mechanisms of heterosis. We integrated transcriptome and methylome to unravel the changes of gene expression, epigenetic modification, and subgenome dominance in EFT compared with maternal E. fuscoguttatus. Integration analyses showed that the heterotic hybrids showed lower genomic DNA methylation levels than the purebred parent, and the up-regulated genes were mostly DNA hypomethylation. Furthermore, allele-specific expression (ASE) detected paternal subgenome dominance-regulated paternal-biased heterosis, and paternal bias differentially expressed genes (DEGs) were wholly up-regulated in the muscle. Multi-omics results highlighted the role of lipid metabolism, particularly "Fatty acid synthesis", "EPA biosynthesis", and "Signaling lipids", in EFT heterosis formation. Coherently, our studies have proved that the eicosapentaenoic acid (EPA) of EFT was greater than that of maternal E. fuscoguttatus (8.46% vs. 7.46%). Finally, we constructed a potential regulatory network for control of the heterosis formation in EFT. Among them, fasn, pparg, dgat1, igf1, pomca, fgf8a, and fgfr4 were identified as key genes. Our results provide new and valuable clues for understanding paternal-biased growth heterosis in EFT, taking a significant step towards the molecular basis of heterosis. [ABSTRACT FROM AUTHOR]

Proper waste management will reduce several pollutions arising out of burning of different agri-wastes such as stubble burning of rice. The lignocellulose in the dry matter, can be converted into various essential products including biofuel through gasification and pyrolysis. This will help to reduce the cost by minimizing the import of petroleum products. A productive sustainable strategy is the development of energy-efficient rice varieties possessing desirable biomass traits without undermining the yield potential. For this sufficient genetic variability should be available to develop suitable dual-purpose varieties. Considering these points, initially, the molecular diversity in popular varieties for biomass traits was explored using cellulose synthase specific markers. An archeopteryx tree constructed thereof indicated the presence of sufficient diversity among the varieties. Eight potential varieties, having sufficient diversity among each other, were selected as parents for developing dual- purpose hybrids. Some of the superior crosses identified concerning both grain and straw yield per plant were Kanchan/Meher, Kanchan/Pratikshya, Pratikshya/Ankit, Hiranmayee/Chandrama and Kanchan/Meher. The crosses including Kanchan/Pratikshya, Meher/Pratikshya, Meher/Ankit, Pratikshya/Hiranmayee, Hiranmayee/Gobinda, Hiranmayee/Pradeep and Gobinda/Pradeep exhibited both positive significant relative heterosis and heterobeltiosis for the biochemical traits. Non-additive gene action was reported to involve in the inheritance of traits viz., plant height, biochemical traits and grain yield, whereas additive gene action played a crucial role in the inheritance of traits viz., leaf area, seed weight and straw yield. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural, Environmental & Veterinary Sciences is the property of Arab Journal of Sciences & Research Publishing (AJSRP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acroceras macrum, a forage grass from Africa, offers potential for enhancing cattle production in subtropical flood-prone regions. Despite its use in Northeast Argentina since the 1980s, the lack of available fertile seeds limits its widespread adoption and large-scale cultivation. We evaluate a germplasm collection of hybrids generated for breeding purposes in Corrientes, Argentina. To assess the feasibility of breeding programs, we examined heterosis and heritability through phenotypic traits. We evaluated growth characteristics (initial vigor, ground cover), plant morphology (leaf and internode size), biomass production (across two sites and years), reproductive stem proportion, flowering peak timing, and seed filling (measured on four dates). Six families were assessed: four full-sibling families compared to the superior parent, and two half-sibling families. The timing of the flowering peak exhibited a correlation with photoperiod. All traits depended on parental combinations, exhibiting significant intra-familial variability ranging from negative heterotic hybrids exceeding 80% to positive hybrids reaching 90%. Correlations between heterosis of the traits and parents' genetic distance must be confirmed. Nevertheless, correlativeness was mainly observed for biomass production for distinct years and seasons. Hence, genetic distance could be a useful tool for the election of the parental combinations to improve this key trait in the species. Furthermore, heritability, was significant for most evaluated traits. It also could be exploited for breeding. This comprehensive assessment sheds light on the phenotypic behavior of A. macrum families, providing valuable insights for future breeding efforts aimed at enhancing its agronomic potential in subtropical regions prone to flooding. [ABSTRACT FROM AUTHOR]

In China, the main breeding objective for maize (Zea mays L.) is increasing the yield of single-cross hybrids. In this regard, developing yield-prediction models based on genetic markers for hybrids can enhance the probability of obtaining hybrid vigour in maize single-cross hybrids and reduce the cycle for germplasm development (inbred lines). In this study, we used simple sequence repeat markers to genotype 257 cross combinations from 97 commonly used maize inbred lines classified into four heterotic groups (Domestic Reid, P78599-type BSSS, Tangsipingtou, and Lvda Red Cob). We calculated the Q values (the probability of each individual's genomic variation coming from each subpopulation) of each inbred line's genetic components. We found that these reflected genetic distances between the parental inbred lines. The parental genetic difference was identified as a key factor influencing heterosis for yield performance of single-cross hybrids, and the interaction factors of Q values between the parents were found to be highly correlated with the accuracy of single-cross hybrid yield predictions. Moreover, we developed a yield-prediction model for maize single-cross hybrids based on our established equation: Y = 9480.2 − 2352.6R1R2 − 1411.8R1L2 + 94.1R1P2 + 1148.0R1S2 − 988.8L1R2 − 1016.9L1L2 − 655.7L1P2 − 1175.4L1S2 − 569.1P1R2 + 371.6P1L2 − 604.2P1P2 + 1684.7P1S2 + 733.1S1R2 + 726.9S1L2 + 924.2S1P2 − 1678.1S1S2 (the correlation coefficient r = 0.4778). Using this model for maize breeding, we achieved prediction accuracies of 66.7% and 76.9% for low and high-yielding single-cross combinations, thereby reducing the workload in field assessment experiments and improving breeding efficiency. [ABSTRACT FROM AUTHOR]

A higher varietal specificity in the manifestation of traits in parental varieties was noted compared to hybrids. Two component traits of ear productivity in a series of generations were analyzed against the background of various factors, shifts in their average values and their impact on yield were predicted and determined. The phenotypic dominance index (hp) in the first generation was determined by the number of grains per ear and the weight of 1000 grains, combinations with a high level of heterosis were identified. Under the conditions of the Apsheron region, the effects of interaction between genotype and environment were determined in nine varieties of spring soft wheat and seven hybrid populations F1...F4 formed with their participation. A reliable effect of environmental conditions on all the studied traits was established. The contribution of the "year" factor to the number of grains per ear in varieties and hybrids was 10.9 and 13.9%, respectively; to the weight of 1000 grains - 5.8 and 19.5%; to the yield - 47.3 and 41.1%. The genetic component made a significant contribution to the weight of 1000 grains in varieties and hybrids (81.5 and 58.8%), as well as to the number of grains in varieties (38.4%). [ABSTRACT FROM AUTHOR]

The way of inheritance, the manifestations of heterosis, transgression and depression, minimal number of genes by which parental forms differ, degree of dominance, manifestations of epistasis and coefficient of heritability and efficiency of selection with regard to plant height and number of leaves, on Burley tobacco samples are established. For the purpose are researched the population of P1, P2, F1 and F2 of seven hybrid combinations. The results show that in the height of plants and number of leaves inheritance is preferably overdominantly and always in the direction of the parent with the higher values of investigated parameters. With respect to the height of the plants was observed and incompletely dominantly, and when the number of leaves and an additive. Manifestations of heterosis and transgression are more pronounced in relation to the number of leaves and have significant values of economic importance, only by this indicator. Data from hybridological analysis showed that the minimal number of genes determining the expression of the trait plant height is greater than the number of leaves. Epistatic interactions are more strongly manifested in the determination of the trait height of plant, but only in the number of leaves negative ones are observed. The relatively low to medium values obtained in terms of the coefficient of heritability in the studied crosses Burley tobacco show that a low share of genotype influence on the manifestation of the studied trait is observed, which means that the selection for plant height will be more effective in the later hybrid generations. The established even lower values for the index number of leaves show the crucial importance of the influence of the environment on the determination of the trait and suggest an effective selection in even later hybrid generations, which makes the selection activity difficult. The study shows that, in general, the selection for the trait number of leaves is more complex and longer than that for the height of the plants. [ABSTRACT FROM AUTHOR]

Heterosis is a crucial factor in enhancing crop yield, particularly in sorghum (Sorghum bicolor). This research utilised six sorghum restorer lines, six sorghum sterile lines, and 36 hybrid combinations created through the NCII incomplete double-row hybridisation method. We evaluated the performance of F1 generation hybrids for leaf photosynthesis-related parameters, carbon metabolism-related enzymes, and their correlation with yield traits during the flowering stage. Results showed that hybrid sorghum exhibited significant high-parent heterosis in net photosynthetic rate (P n), transpiration rate (T r), stomatal conductance (G s), apparent leaf meat conductance (AMC), ribulose-1,5-bisphosphate (RuBP) carboxylase, phosphoenolpyruvate (PEP) carboxylase, and sucrose phosphate synthase (SPS). Conversely, inter-cellular carbon dioxide concentration (C i), instantaneous water uses efficiency (WUE), and sucrose synthase (SuSy) displayed mostly negative heterosis. Traits such as 1000-grain weight (TGW), grain weight per spike (GWPS), and dry matter content (DMC) exhibited significant high-parent heterosis, with TGW reaching the highest value of 82.54%. P n demonstrated positive correlations with T r, C i, G s, RuBP carboxylase, PEP carboxylase, GWPS, TGW, and DMC, suggesting that T r, C i, and G s could aid in identifying high-photosynthesis sorghum varieties. Concurrently, P n could help select carbon-efficient sorghum varieties due to its close relationship with yield. Overall, the F1 generation of sorghum hybrids displayed notable heterosis during anthesis. Combined with field performance, P n at athesis can serve as a valuable indicator for early prediction of the yield potential of the F1 generation of sorghum hybrids and for screening carbon-efficient sorghum varieties. There is limited information on the hybridisation of enzymes linked to these characteristics. Understanding hybrid dominance of photosynthetic traits and their associated enzymes in sorghum is crucial for identifying sorghum hybrids with highly dominant combinations and selecting suitable parents. This study utilised 36 sorghum hybrid F1 generations and their respective parents to assess hybrid dominance in leaf photosynthetic parameters, key enzyme activities during photosynthesis, yield formation, and other relevant factors, while also examining their correlation with yield in field conditions. This article belongs to the Collection Machine Learning for Plant Stress Phenotyping. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The manifestations of heterosis and transgression regarding the length and width of the leaves in ten hybrid combinations of Burley tobacco аre investigated. The results of the study show that in almost all variants and in both indicators, the values of the hypothetical heterosis exceed those of the real one. According to length of leaves heterosis with economic significance is observed only in one of the investigated hybrid combinations. Transgressive manifestations for this indicator are even less pronounced and are not significant in any of the studied options. In contrast to length of leaves the manifestations of heterosis are of economic importance in six of the ten crosses studied and could be successfully used to increase of width of leaves. Transgressive events in width of leaves are less pronounced than heterosis, but much more pronounced than those in the length. Direction of crossing affects the heterosis manifestations only of the length of the leaves but not those concerning their width. In terms to width of leaves, the manifestations of heterosis and transgression are related. Of all the studied variants, the one with the highest selection value regarding sizes of leaves is Hybrid 1555. [ABSTRACT FROM AUTHOR]

Forty F1 crosses obtained from 5 × 8 line by tester mating design methodology were studied. The varieties Chirpan-539, Sirius, Darmi (Bulgarian selection), Nazili 954 (Turkish) and FR-H-1002 (Spanish) were used as female parents, selection lines 449, 489, 639, 535, 550, 572, 578 and 678 were used as male parents. The aim of the study was to identify the best F1 crosses for improving lint percentage and fiber length in new cotton varieties, by applying a new approach to select parents with the highest possible general combining ability (GCA) for both traits. Crosses and their parents were sown in one row, randomized in three replications. The highest values of the GCA effects of the two parental forms for each trait were taken as “ideal” and the Euclidean distances between them and the GCA effects of the two parents for each F1 cross were calculated. Combining ability analysis of variance showed that females and males differed in general and specific combining abilities. The cultivars Chirpan-539 and Nazili-954 from the females, and lines 550 (Tiara variety) and 578, from the males, appeared to be very good general combiners for lint percentage. The cultivar FR-H-1002 and Darmi variety, from the females, and lines 449, 572, and 578, from the males, appeared to be very good general combiners for fiber length. Some crosses showed high positive SCA effects and heterosis for both traits. Cross combinations FR-H-1002 × 578, Darmi × 578 and Nazili 954 × 578 had the highest possible GCA for both studied traits and are most valuable for selection programs. A total of seven crosses with short Euclidean distances to the “ideal” population in which desirable segregates are expected to occur were selected. [ABSTRACT FROM AUTHOR]

An experiment was carried out to evaluate the level of heterosis and combining ability in cotton. Thirty five interspecific hybrids were generated by crossing five lines viz., GMS 14, GMS 17, GMS 19, GMS 21 and GMS 27 with seven testers namely CCB26, CCB51, DB1901, CCB2, CCB6, CO18 and Suvin in line x tester mating fashion. Twelve parents along with 35 hybrids and a standard check (DCH 32) were raised in a randomized block design with two replications to evaluate the combining ability and heterosis to identify good combiners and the best hybrids with high yield and fibre quality. The lines viz., GMS 14 and GMS 17 and the testers viz., CO 18 and Suvin were found to record significant gca effects for yield and fibre quality traits. Out of the 35 hybrids, GMS 14 x CO18, GMS 27 x Suvin and GMS 17 x CO18 recorded highly positive significant sca effects for most of the traits. The ratio between additive and dominant genetic variance was less than one for all the traits, indicating the preponderance of dominant gene action or non-additive gene action. The above three crosses also exhibited high heterosis over mid parent, better parent and standard check. Hence, these hybrids could be harnessed after analyzing their performance in yield trials. [ABSTRACT FROM AUTHOR]

The present research was conducted in Okra to study combining ability and gene action in a set of 28 F1s developed by crossing seven lines and four testers. The experiment was laid out in a Randomized Block Design with three replications and observations were recorded on 12 traits viz. days to 50% flowering, days to first picking, number of internodes, number of branches plant-1, fruit length at maturity and harvest, number of fruits plant-1, number of seeds fruit-1, seed index, fruit weight, yield per plant and plant height. The results revealed that two lines viz., VRO-4 and Sel2 were excellent general combiners for most of the traits in both positive and negative direction as per desirable traits. Cross VRO-6 x Varsha Uphar recorded highly significant SCA effects for eight traits and GAO-5 x GJO-3 for yield trait. Variance due to GCA was less than SCA, and the GCA/SCA ratio was less than unity indicating preponderance of nonadditive gene action for all the traits. This suggested the feasibility of exploitation of heterosis. [ABSTRACT FROM AUTHOR]

Twenty F1 s, parents and checks viz., MTU 1010 and RNR 15048 were assessed for grain yield and its contributing attributes to study combining ability and heterosis. The mean of hybrids was greater than that of the parents except for days to 50% flowering and plant height. For majority of the investigated characters, the analysis of variance indicated considerable variations among parents and hybrids. Degree of dominance was more than unity for majority of traits including grain yield. For the examined characters, SCA variances were equal to GCA variances, indicating the dominance of additive and non-additive gene activity. The traits days to 50 % flowering, plant height, panicle length, test weight, kernel length and kernel length/breadth ratio showed additive gene action whereas the remaining traits showed non-additive gene action. The gca effects revealed that among the lines IR 72 had significant gca effects in desired direction for yield and yield attributing traits. Among the 20 hybrids, MTU 1001 x Akshyadhan was found to be a good specific combiner for grain yield per plant. Similarly, the hybrids NLR 34449 x IR10N270 and IR 72 x IR10N270 were found to be good specific combiners for grain yield and yield contributing characters. The standard heterosis of these three hybrids was positively significant over the check varieties MTU 1010 and RNR 15048. Based on mean, sca and heterosis estimates, MTU 1001 x Akshyadhan, NLR 34449 x IR10N270 and IR 72 x IR10N270 were identified as promising hybrids. [ABSTRACT FROM AUTHOR]

The present investigation was undertaken in brinjal (Solanum melongena L.) to estimate combining ability and gene action following a half diallel mating design using ten parents. The ratio of genetic variance components, σ² gca/σ² sca and σ² D/σ² A, showed dominant gene action, indicating the presence of non-additive genetic variance for days to 50% flowering, fruit yield per plant, total phenol, antioxidant activity and total soluble sugar. The traits fruits per plant, fruit girth, and fruit weight showed additive genetic variance. Among the parental genotypes, AB 15-08, ABSR 2 and AB 20- 13 were found to be good general combiners for fruit yield, fruits per plant, and total soluble solids. The three highestranking hybrids were AB 15-08 × AB 20-13, AB 15-08 × AB 20-03 and AB 20-07 × GP BRJ 224. The above hybrids would be rewarding for harnessing heterosis. [ABSTRACT FROM AUTHOR]

The present investigation was undertaken to study the residual heterosis in F2 and F3 populations of Indian mustard [Brassica juncea (L.) Czern & Coss.]. The study material included eight parents and the 28 crosses of Indian mustard in two generations, namely F2 and F3. The experiment was conducted over two years at Uttar Banga Krishi Viswavidyalaya, Cooch Behar, West Bengal, during Rabi season 2020-21 and 2021-22. Out of the 28 crosses, three crosses namely, Npj-194 × DRMR-15-16, Npj-194 × RW- 85-59 (Sarma) and Npj-194 × SKJM-05 were found to show significantly positive residual standard heterosis over the standard variety (SKJM-05) for both the characters siliquae per plant and seed yield per plant. This provides us evidence that by improving siliquae per plant, the character seed yield per plant can be improved. The promising cross populations which have shown significant standard heterosis for seed yield in F2 and F3, can be utilized for the development of hybrid varieties, which would be very much beneficial to the marginal farmers of our country as they would be able to use the F2 and F3 seeds of the hybrid varieties without any compromise with seed yield. [ABSTRACT FROM AUTHOR]

Exploring the biological potential of maize root architecture is one of the most important ways to improve nitrogen use efficiency (NUE). The NUE and its heterosis in maize hybrids have improved remarkably over decades. Yet, there is little research on maize hybrid heterosis for root architecture and its possible physiological relationship to heterosis for NUE. A field study lasting two years was carried out on four typical maize hybrids from old and new eras, including their parental inbred lines with two levels of nitrogen (0, 150 kg N ha−1). Compared to old-era maize hybrids, the brace root angle (BA) and crown root angle (CA) of new-era maize hybrids increased by 19.3% and 8.0% under 0 N, and by 18.8% and 7.9% under 150 N, which exhibited a steeper root architecture; the crown root number (CN) of new-era maize hybrids increased by 30.5% and 21.4% under 0 N and 150 N, respectively, which showed a denser root system; meanwhile, the depth of 95% cumulative root weight (D95) of new-era maize hybrids separately increased by 10.5% and 8.5% under 0 N and 150 N, which exhibited a deeper root distribution. This steeper-denser-deeper root architecture enhanced pre-anthesis N uptake and provided a premise of greater post-anthesis N remobilization. All maize hybrids displayed significant heterosis for root architecture compared to their parental inbred lines. The brace root branching (BB) and crown root branching (CB) of new-era maize hybrids and D95 have positive heterosis, while the BA, CA, and CB of old-era maize hybrids, brace root number (BN), and CN have negative heterosis. Regardless of whether root architecture heterosis was positive or negative, new-era maize hybrids showed an overall elevated trend compared to old-era maize hybrids. Structural equation modeling (SEM) showed that heterosis for nitrogen internal efficiency (NIE) was the primary reason for NUE heterosis in maize, influenced by heterosis for root architecture, which was steeper, denser, and deeper. Our results indicated that, compared with old-era maize hybrids, new-era maize hybrids had stronger heterosis for root architecture, which was beneficial to pre-silking nitrogen absorption and is an important physiological basis for the higher NIE heterosis and NUE heterosis in new-era maize hybrids. [ABSTRACT FROM AUTHOR]

The preservation of genetic variation is fundamental in biodiversity conservation, yet its importance for population viability remains contentious. Mixed‐source reintroductions, where individuals are translocated into a single vacant habitat from multiple genetically divergent and often depauperate populations, provide an opportunity to evaluate how genetic variation and hybridization influence individual and relative population fitness. Population genetic theory predicts that individuals with higher genetic variation and hybrids among populations should have higher fitness. We tested these two hypotheses by analyzing individual and population‐scale data for westslope cutthroat trout (Oncorhynchus clarkii lewisi) in four mixed‐source reintroductions. We observed more hybrid and fewer nonhybrid offspring than expected across four independent mixed‐source reintroductions. We also found clear evidence that heterozygosity influenced individual reproductive and relative population fitness. Overall, we found a strong, positive relationship between genetic variation, hybridization, and transplant fitness, emphasizing the importance of genetic variation and population mixing in conservation. [ABSTRACT FROM AUTHOR]

Abstract Nicotine exhibits obvious heterosis, which can be used to create Nicotiana tabacum L. (tobacco) varieties with varying nicotine content. However, the reasons for the formation of nicotine heterosis and its relationship to nicotine transport and accumulation remain unknown. This study conducted a comprehensive analysis of six tobacco hybrids with varying heterosis levels and their parent materials from various aspects, such as phenotype, physiology, and transcriptomics. The results showed that the direct path coefficient of transport heterosis to nicotine heterosis was highest in hybrids, at 0.98, and a highly significant positive correlation between the two. The plant height, thick stalk circumference, large flow of tissue fluid in the stalk, and high nicotine concentration of tobacco were the underlying factors that led to the strong nicotine transport capacity of hybrids. The formation of nicotine transport heterosis in hybrids was mainly influenced by non-additive gene effects (accounting for 89.93%), with over-dominant effects playing a dominant role (accounting for 58.79%). Among non-additive expression DEGs, nicotine transporter related multi antimicrobial extrusion protein, drug/metabolite transporter, ABC family transporter, and glutathione S-transferase were significantly upregulated in hybrid strains. The RT-qPCR results indicated that these genes related nicotine transport also exhibited heterosis at the expression level. Our results revealed that the formation of nicotine heterosis is mainly achieved by enhancing the nicotine transport capacity in hybrids. The results are not only beneficial for promoting the theoretical study of nicotine heterosis in tobacco and the breeding and utilization of hybrids, but are also of great significance for guiding nicotine production and promoting its multipurpose utilization.

Abstract Okra (Abelmoschus esculentus L. Moench) is a vital vegetable crop known for its nutritional and economic significance, especially in tropical and subtropical regions. Studying heterosis and combining ability in okra is crucial for enhancing its yield, quality, and resistance to pests and diseases. Heterosis can lead to superior offspring with enhanced traits while understanding combining ability helps in identifying the best parent combinations for breeding programs. Okra is an often cross-pollinated crop; therefore, exploiting heterosis is advantageous. The study was conducted from 2021 to 2022 at the Experimental Farm and Quality Analysis Laboratory, Department of Vegetable Science, College of Horticulture, Dr Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India to evaluate the heterosis and combining ability in okra to facilitate the development of high-yielding, resilient cultivars. The experimental material consisted of an F1 population of 30 crosses obtained from 10 parental lines crossed with three testers in a Line × Tester mating design, plus a standard check (Punjab-8). Estimates of heterosis (heterobeltiosis and standard heterosis) of the cross combinations UHFO-6 × Pusa Bhindi-5, UHFO-6 × Arka Anamika and UHFO-9 × Arka Anamika were high for inter-nodal distance, number of pods per plant, average pod weight, pod yield per plant, harvest duration, hundred seed weight, mucilage content, etc. Higher estimates of general combining ability (GCA) effects for pod yield per plant were observed in the parental lines UHFO-6 (123.47) and UHFO-9 (7.49). Among the cross combinations, UHFO-10 × Hisar Unnat (38.81), UHFO-2 × Pusa Bhindi-5 (38.29), UHFO-2 × Arka Anamika (17.42), and UHFO-5 × Arka Anamika (15.06) demonstrated higher estimates of specific combining ability (SCA) effects for pod yield per plant. The cross UHFO-2 × Hisar Unnat (160.00) exhibited the highest heterobeltiosis for mucilage content, while UHFO-10 × Arka Anamika (562.03) showed the highest standard heterosis for total polyphenol content. These cross combinations could produce okra with enhanced nutritional and medicinal properties. The highest GCA and SCA effects for pod yield per plant were observed in UHFO-6 (123.47) and UHFO-10 × Hisar Unnat (38.81), respectively. Identifying these parental lines and cross combinations based on their combining ability can result in the development of okra hybrids with substantially higher yields. In future, after multi-location trials, these parents and crosses can be released to replace existing okra cultivars (hybrids/varieties). Higher yielding and better quality okra cultivars can enhance the profitability for farmers, contribute to food security, and meet market demands more efficiently.