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Maize (Zea mays L.) Fusarium ear rot (FER), which is caused by the fungal pathogen Fusarium verticillioides, is a major ear disease affecting maize production in China. Developing resistant maize hybrids is a cost‐effective and environmentally friendly method of reducing yield losses due to FER. Using the nail punch inoculation method, 17 highly resistant and 16 highly susceptible inbred lines were identified in this study, and a large‐scale maize hybrid consisting of 528 F1's was produced using a half‐diallel cross model. The hybrids were inoculated with F. verticillioides in 6 year–location environment combinations during 2020–2022. Our results showed that estimates of genotypic, environmental, and genotype × environment interaction variance components were very significant (p < 0.001). All the crosses generated from highly resistant inbred lines exhibited high kernel resistance, whereas those generated from highly susceptible inbred lines mostly exhibited high susceptibility to FER. Crosses between resistant and susceptible inbred lines showed intermediate resistance to FER. The general combining ability (GCA) effect was greater than the specific combining ability effect across multiple environments, indicating that the inheritance of FER resistance was mainly influenced by additive genetic effects. The correlation coefficient between the expected GCA value and hybrid resistance was 0.789, whereas that between the mid‐parent value and hybrid resistance was only 0.644. Inbred performance per se and their corresponding hybrids across multiple environments were significantly correlated (r = 0.823). However, no relationship was observed between the FER resistance of F1's and that of their parental heterotic groups. Core Ideas: In breeding, selecting parents with Fusarium ear rot (FER) resistance is more crucial than selecting the hybrids themselves.The additive effect is the main genetic component of ear rot in maize, whereas the non‐additive effect is minor.Additional inoculation tests for FER resistance are required for specific hybrid combinations.Hybrid resistance can be inferred based on the general combining ability of parental inbred lines.The additive effects of resistance genes in highly inbred lines are minor. [ABSTRACT FROM AUTHOR]

In the past 60 years, China's hybrid rice has developed from a three‐line system to a two‐line system: This has enriched the knowledge of heterosis and crop breeding. At the same time, the large‐scale commercialization of hybrid rice has made great contributions to China's rice production. [ABSTRACT FROM AUTHOR]

Soil salinization and alkalization are important abiotic stresses that affect crop growth and yield. Development of salt and alkali tolerant varieties is still dominated by the following conventional breeding method: The salt and alkali tolerant traits from screened germplasm are introduced into elite varieties by means of hybridization and backcrossing. In recent years, the breeding of salt and alkali tolerant rice has also made great progress. For example, the yield of Chao‐You 1000, a two‐line rice hybrid, has reached 12.04 t/ha growing in fields with salinity between 0.2% and 0.6%. This review is an update on the progress of salt and alkali tolerant rice germplasm screening and new salt and alkali tolerant varieties in development. By reviewing the performance of current rice hybrids in China's National Regional Variety Trials of Saline‐Alkali Tolerant Rice, we proposed the technical approach of developing saline–alkali tolerant rice hybrids using the third‐generation hybrid rice technology and furthermore the trend of developing salt and alkali tolerant rice hybrids. [ABSTRACT FROM AUTHOR]

This study evaluated the performance of various grape hybrids for yield and quality traits, and to identify hybrid vigor for specific traits that can be utilized in future breeding programs. The research involved evaluating 76 hybrids derived from two diverse parents i.e., Pinot Noir and Marselan, during 2021 and 2022. Multiple fruit yield and biochemical traits were examined and quality traits of peel, flesh, and seeds were recorded. Two-way analysis of variance for parents was performed for all the traits under study to understand the significance of these traits over two years. Likewise, statistical analysis, such as the coefficient of variation, combined transmissibility rate, heterosis, and heterobeltiosis were computed to compare the performance of the hybrids against mid and better parents. The highest CV and Ta values were observed for fruit yield and peel phenolic contents respectively, across both years. The two-year data suggested that certain hybrids displayed superior heterosis and heterobeltiosis for numerous individual traits. Hybrid number 7 exhibited negative hybrid vigor for most of the traits and must be avoided for general cultivation. while hybrid number 25 showed increased hybrid vigor fruit yield and total flavonoids in peel, flesh, and seeds as well as a higher concentration of tannins in seeds. This research underscores the potential of hybrid number 25 for grape farmers and the wine industry in China, hinting at the untapped potential of hybrid grapes in producing superior wines. The study's insights aim to aid the development of indigenous grape varieties, reducing China's reliance on imports and fostering a unique Chinese wine identity in the global market. The data derived from this two-year evaluation can guide future breeding programs and further exploration of grape hybrid vigor to optimize both yield and wine-making quality. [ABSTRACT FROM AUTHOR]

The whiteleg shrimp (Litopenaeus vannamei) is one of the most economically important aquaculture species in China. Genetic diversity is crucial for maintaining the gene pool of farmed shrimp. In this study, the effects of artificial selection on the genetic structure of four whiteleg shrimp strains were evaluated using microsatellite sequences. The results showed that the observed heterozygosity (Ho), expected heterozygosity (He), and the polymorphism information content (PIC) of the four selected strains ranged from 0.446 to 0.574, 0.450 to 0.566, and 0.435 to 0.509, respectively. All the selected strains maintained a moderate level of genetic diversity. Most inbreeding coefficients (Fis) in the four strains were positive but not significantly different from zero, indicating a relatively low degree of inbreeding within each strain. However, He and PIC in line 5 showed a decreasing trend from the 2017 to the 2019 generations, and Fis in line 10 showed a significant increasing trend across generations, indicating that measures must be taken to maintain the level of genetic diversity for lines 5 and 10. UPGMA cluster trees showed that the four breeding lines had apparent genetic differences, which could provide a genetic basis for studying crossbreeding between selective lines and the utilization of heterosis. This study will be useful for population genetic research and the breeding strategies of whiteleg shrimp. [ABSTRACT FROM AUTHOR]

Rice heterosis has played a significant role in improving rice yields in China since the 1970s. The utilization of heterosis between the indica and japonica subspecies of rice is especially important in this regard. However, inter-subspecies hybridization between indica and japonica rice is hampered by the inadequate seed-setting rate and inferior rice quality of hybrid offspring, which has limited its development. The discovery and cloning of wide-compatibility gene S5-n and the granular starch synthase gene Wx have provided a solution to this problem, paving the way for the breeding of inter-subspecies hybrid rice. Here we demonstrated the breeding process of Zheyou810 and its performances in regional trials. Employing marker-assisted selection through the utilization of KASP (Kompetitive Allele-Specific PCR), a high-yielding and superior-quality indica–japonica hybrid rice variety named Zheyou810 was developed. Zheyou810 achieved an average yield of 10,737.75 kg/ha (12.58% higher than control Jiayou5) in the national regional trials across 2019 and 2020, and 11,777.25 kg/ha (13.36% higher than Jiayou5) in the production trial in 2020, respectively. The quality of rice has also been improved, reaching the standards set by the Ministry of Agriculture of the People's Republic of China for Grade 3 premium rice (NY/T593). In 2021, Zheyou810 was approved by the national examination showing broad application prospects. [ABSTRACT FROM AUTHOR]

Future breeding is likely to involve the detection and removal of deleterious alleles, which are mutations that negatively affect crop fitness. However, little is known about the prevalence of such mutations and their effects on phenotypic traits in the context of modern crop breeding. To address this, we examined the number and frequency of deleterious mutations in 350 elite maize inbred lines developed over the past few decades in China and the United States. Our findings reveal an accumulation of weakly deleterious mutations and a decrease in strongly deleterious mutations, indicating the dominant effects of genetic drift and purifying selection for the two types of mutations, respectively. We also discovered that slightly deleterious mutations, when at lower frequencies, were more likely to be heterozygous in the developed hybrids. This is consistent with complementation as a potential explanation for heterosis. Subsequently, we found that deleterious mutations accounted for more of the variation in phenotypic traits than nondeleterious mutations with matched minor allele frequencies, especially for traits related to leaf angle and flowering time. Moreover, we detected fewer deleterious mutations in the promoter and gene body regions of differentially expressed genes across breeding eras than in nondifferentially expressed genes. Overall, our results provide a comprehensive assessment of the prevalence and impact of deleterious mutations in modern maize breeding and establish a useful baseline for future maize improvement efforts. [ABSTRACT FROM AUTHOR]

The photosynthetic capacity of flag leaf plays a key role in grain yield in rice. Nevertheless, there are few studies on the heterosis of the rice flag leaf. Therefore, this study focuses on investigating the genetic basis of heterosis for flag leaf in the indica super hybrid rice combination WFYT025 in China using a high-throughput next-generation RNA-seq strategy. We analyzed the gene expression of flag leaf in different environments and different time periods between WFYT025 and its female parent. After obtaining the gene expression profile of the flag leaf, we further investigated the gene regulatory network. Weighted gene expression network analysis (WGCNA) was used to identify the co-expressed gene sets, and a total of 5000 highly expressed genes were divided into 24 co-expression groups. In CHT025, we found 13 WRKY family transcription factors in SDGhps under the environment of early rice and 16 WRKY family genes in SDGhps of under the environment of middle rice. We found nine identical transcription factors in the two stages. Except for five reported TFs, the other four TFs might play an important role in heterosis for grain number and photosynthesis. Transcription factors such as WRKY3, WRKY68, and WRKY77 were found in both environments. To eliminate the influence of the environment, we examined the metabolic pathway with the same SDGhp (SSDGhp) in two environments. There were 312 SSDGhps in total. These SSDGhps mainly focused on the phosphorus metallic process, phosphorylation, plasma membrane, etc. These results provide resources for studying heterosis during super hybrid rice flag leaf development. [ABSTRACT FROM AUTHOR]

Tomato is an important vegetable crop in China, and its yield ranks the top among vegetables in the world. It has important nutritional value, with rich and varied tastes. Plant male sterility is caused by the abnormal development of stamens, which cannot produce pollen with normal function, while pistils develop normally and can be fertilized by foreign normal pollen. Tomato is a typical self-pollinated plant with obvious heterosis and strong disease resistance and stress resistance. At present, the production of tomato F1 hybrid seeds in China basically depends on artificial emasculation and pollination, therefore, a lot of manpower and material resources are needed in the process of seed production. In the use of tomato male sterile seed production, the seed production process can be simplified, costs be greatly reduced and and seed purity be improved, in this case, tomato yield and quality will be increased significantly. Therefore, the research and utilization of tomato male sterility is of great practical significance to tomato genetic breeding, and has always been an important research topic for the domestic and foreign scholars. This paper mainly outlines the current situation of male sterility of tomato in recent years, summarizes the types of tomato male sterility, the application of genetic engineering technology of tomato male sterility, the fine positioning and functional study of tomato male sterility gene, and the analysis of cell biological mechanism of tomato male sterility. The effect of temperature on tomato male sterility is expounded from the perspective of genetics, and the physiological and biochemical mechanism and the gene function and regulation mechanism in response temperature changes are discussed. Then, the heterosis of tomato male sterility and its utilization value in production and application are analyzed. On this basis, the problems existing in the current research work are put forward, and the innovation and basic research of tomato male sterility technology in the future are prospected. [ABSTRACT FROM AUTHOR]

Macrobrachium nipponense, an important economic aquaculture species in China, is experiencing degradation of shrimp germplasm resources. Hybridization is a means of genetic improvement and can contribute to overcoming this serious problem. However, the molecular mechanisms of heterosis resulting from hybridization is unknown. In this study, LC–MS/MS combined with TMT tags were used for comparative proteomics analyses of the broodstock populations (Dianshan, DS) and hybrid offspring (DS ♀ × CD [Changjiang, CJ ♂ × Dongting, DT ♀], SCD) in M. nipponense. A total of 57 differentially expressed proteins (DEPs) were identified, of which 35 proteins were up‐regulated and 22 proteins were down‐regulated. The results showed that the 57 differential proteins correspond to three functional types, including 431 biological processes, 458 cellular components and 762 molecular functions. KEGG pathway analyses identified growth‐ and immunity‐related pathways, including alanine, aspartate and glutamate metabolism (ko00250), arginine biosynthesis (ko00220), arginine and proline metabolism (ko00330), hippo (ko04390), apoptosis (ko04215), p53 (ko04115) and complement system (ko04610). The expression of genes encoding the differentially expressed proteins were verified using real‐time quantitative PCR, and the results showed that the hybrid population was superior to the parent population in terms of growth and immunity. This study provided important data for genetic and breeding research of Macrobrachium nipponense. [ABSTRACT FROM AUTHOR]

SUMMARY: Heterosis is extensively used to improve crop productivity, yet its allelic and chromatin regulation remains unclear. Based on our resolved genomes of the maternal TGY and paternal HD, we analyzed the contribution of allele‐specific expression (ASE) and chromatin accessibility of JGY and HGY, the artificial hybrids of oolong tea with the largest cultivated area in China. The ASE genes (ASEGs) of tea hybrids with maternal‐biased were mainly related to the energy and terpenoid metabolism pathways, whereas the ASEGs with paternal‐biased tend to be enriched in glutathione metabolism, and these parental bias of hybrids may coordinate and lead to the acquisition of heterosis in more biological pathways. ATAC‐seq results showed that hybrids have significantly higher accessible chromatin regions (ACRs) compared with their parents, which may confer broader and stronger transcriptional activity of genes in hybrids. The number of ACRs with significantly increased accessibility in hybrids was much greater than decreased, and the associated alleles were also affected by differential ACRs across different parents, suggesting enhanced positive chromatin regulation and potential genetic effects in hybrids. Core ASEGs of terpene and purine alkaloid metabolism pathways with significant positive heterosis have greater chromatin accessibility in hybrids, and were potentially regulated by several members of the MYB, DOF and TRB families. The binding motif of CsMYB85 in the promoter ACR of the rate‐limiting enzyme CsDXS was verified by DAP‐seq. These results suggest that higher numbers and more accessible ACRs in hybrids contribute to the regulation of ASEGs, thereby affecting the formation of heterotic metabolites. Significance Statement: The regulation of alleles and chromatin accessibility in plant heterosis formation remains unclear. Here, we explored the contribution of allele‐specific expression and chromatin accessibility to heterosis formation in two of the largest cultivated oolong tea hybrids in China compared with their parents, which will provide new insights into the formation and regulation of plant heterosis. [ABSTRACT FROM AUTHOR]

Background: Since its development and wide adoption in China, hybrid rice has reached the yield plateau for more than three decades. To understand the genetic basis of heterosis in rice and accelerate hybrid rice breeding, the yield performances of the elite rice hybrid, Quan-you-si-miao (QYSM) were genetically dissected by whole-genome sequencing, large-scale phenotyping of 1061 recombined inbred lines (RILs) and 1061 backcross F1 (BCF1) hybrids derived from QYSM's parents across three environments and gene-based analyses. Results: Genome-wide scanning of 13,847 segregating genes between the parents and linkage mapping based on 855 bins across the rice genome and phenotyping experiments across three environments resulted in identification of large numbers of genes, 639 main-effect QTLs (M-QTLs) and 2736 epistatic QTLs with significant additive or heterotic effects on the trait performances of the combined population consisting of RILs and BCF1 hybrids, most of which were environment-specific. The 324 M-QTLs affecting yield components included 32.7% additive QTLs, 38.0% over-dominant or dominant ones with strong and positive effects and 29.3% under-dominant or incomplete recessive ones with significant negative heterotic effects. 63.6% of 1403 genes with allelic introgression from subspecies japonica/Geng in the parents of QYSM may have contributed significantly to the enhanced yield performance of QYSM. Conclusions: The parents of QYSM and related rice hybrids in China carry disproportionally more additive and under-dominant genes/QTLs affecting yield traits. Further focus in indica/Xian rice breeding should shift back to improving inbred varieties, while breaking yield ceiling of Xian hybrids can be achieved by one or combinations of the three strategies: (1) by pyramiding favorable alleles of additive genes, (2) by eliminating or minimizing under-dominant loci, and (3) by pyramiding overdominant/dominant genes polymorphic, particularly those underlying inter-subspecific heterosis. [ABSTRACT FROM AUTHOR]

The relationship between parental genetic differences and the quality and yield of japonica hybrid rice strongly influences japonica hybrid rice breeding. In this study, 137 parental lines of japonica hybrid rice were genotyped using 8K rice SNP-Chips to characterize their genetic diversity, population structure, and indica-genotype proportion. The genetic diversity of total parental lines averaged 0.264, with values of 0.287 for restorer lines and 0.148 for the sterile lines. The introduction of indica lineage increased the genetic diversity of restorer lines relative to that of sterile lines. By model-based population structure analysis, the 137 lines were divided into 14 groups. According to the grouping results, eight restorer lines and five sterile lines were selected from different groups for cross breeding, yielding 40 japonica hybrid rice combinations (F1). Investigation of the yield and quality of these combinations showed that highyield combinations could be obtained by increasing parental genetic distance to 0.8-0.9, a result accomplished largely by the introduction of indica genomic components of restorer lines. To further improve grain quality, the genetic distance between parents should be reduced to 0.4-0.5, suggesting an indicagenotype proportion of 30%-40% for restorer lines. This study may provide a reference for breeding of japonica hybrid rice. [ABSTRACT FROM AUTHOR]

The nitrogen use efficiency (NUE) of modern maize hybrids has been greatly improved, but for decades, little was known on whether the NUE heterosis of maize hybrids had increased. A two-year field study was conducted on eight maize hybrids and their parental inbred lines from the 1970s to 2000s under two N levels (0, 150 kg N ha−1). These were the most popular hybrids in China's main maize-growing areas at the time. The results showed that the yield of the maize hybrids increased significantly at an average rate of 37.5% every 10 years. The evolution of NUE heterosis was mainly related to the increased kernel number per ear. The absolute NUE heterosis (AHNUE) and the mid-parent NUE heterosis (MPHNUE) of maize hybrids increased by 151.4% and 76.4% in the past four decades, or an average rate of 2.11 kg kg−1 and 19.1% every 10 years. Based on the coefficient of determination, the contribution of the mid-parent nitrogen internal efficiency heterosis (MPHNIE) to MPHNUE (43–57%) was significantly higher than that of the mid-parent nitrogen recovery efficiency heterosis (MPHNRE) (19–32%), indicating that the evolution of maize NUE heterosis was mainly derived from its NIE heterosis evolution. The increase of NIE heterosis in the past 40 years was closely related to the increased heterosis of kernel number per ear, the pre-silking N accumulation and the post-silking N remobilization. Therefore, the enhancement of maize NUE heterosis can be attributed to (i) heterosis improvement in post-silking N remobilization, which results mainly from greater heterosis in pre-silking N accumulation; (ii) heterosis improvement in carbon and nitrogen sink capacity, which exhibit as heterosis enhancement in grain yield and grain nitrogen concentration. To further improve yield and NUE, the pre-silking N and carbon accumulation and post-silking N remobilization should both continue to increase in maize breeding. Our results will provide new insights into NUE and help breeders select genotypes with both higher yields and higher NUE for the future. [ABSTRACT FROM AUTHOR]

This study evaluates the impact of varying planting densities on hybrid winter wheat (Triticum aestivum L.) varieties in the eastern Huang-Huai-Hai region, an area critical to China’s wheat production. Focusing on ‘Jingmai 17’, a hybrid variety, and ‘Jimai 22’, a conventional type, across three planting densities (150, 300, and 450 plants·m−2) during the 2021–2023 growing seasons, the investigation centered on key agronomic metrics such as leaf area per culm (LAC), SPAD values for chlorophyll content, dry matter, nitrogen accumulation and remobilization, alongside grain yield and its components. The results highlight ‘Jingmai 17’’s superior performance over ‘Jimai 22’, notably in maintaining a larger LAC post-anthesis, a slower decline in SPAD values during grain filling, and an extended green leaf area duration. These characteristics are conducive to higher biomass accumulation and efficient post-anthesis remobilization. Importantly, a planting density of 300 plants·m−2 emerged as optimal, enhancing canopy structure for maximal light interception and promoting a higher nitrogen use efficiency (NUE) and yield for both varieties. The NUE of Jingmai 17 and Jimai 22 in both years increased by 2.2%, 0.4% and 1.7%, 1.4%, respectively, relative to the 450 plants·m−2 treatment; and the yield increased by 10%, 4%, 9%, 4%, and 10%, 5%, 8%, 2%, relative to the 150 plants·m−2 and 450 plants·m−2 treatments, respectively. This optimal density represents a strategic balance, enabling robust wheat growth while maximizing resource use efficiency. For the eastern Huang-Huai-Hai region, these findings suggest a potent strategy to augment wheat yields and improve agricultural sustainability. Adopting a planting density of 300 plants·m−2 could significantly enhance the productivity of hybrid winter wheat varieties, tapping into their heterosis advantages for substantial yield improvements. By refining planting density practices, the eastern Huang-Huai-Hai region stands to achieve marked gains in wheat yield efficiency, contributing to the broader goals of food security and sustainable farming practices. [ABSTRACT FROM AUTHOR]

Since the development of indica hybrid rice in the 1970s, great success has been achieved in hybrid rice production in China and around the world. The utilization of inter-subspecific indica–japonica hybrid rice has always been considered due to its stronger heterosis characteristics. However, indica – japonica hybrids face a serious problem of sterility, which hinders the exploitation of their heterosis. In the past decades, the genetic basis of indica – japonica hybrid sterility has been well studied. It was found that in sterile indica – japonica hybrids, female sterility was mainly controlled by the S5 locus and male sterility by the Sa , Sb , Sc , Sd , and Se loci. In this study, we developed wide-compatible indica lines (WCILs) by pyramiding multiple neutral (n) alleles of the hybrid sterility loci. First, we identified Sn alleles of the loci in single-segment substitution lines (SSSLs) in the genetic background of indica Huajingxian 74 (HJX74). Then, the Sn alleles of S5 , Sb , Sc , Sd , and Se loci in SSSLs were pyramided in the HJX74 genetic background. The WCILs carrying Sn alleles at the S5 , Sb , Sc , Sd , and Se loci showed wide compatibility with indica and japonica rice varieties. Therefore, the WCILs will be used to develop inter-subspecific indica–japonica hybrid rice with normal fertility. [ABSTRACT FROM AUTHOR]

Super hybrid rice genotypes have transformed the rate of genetic yield gain primarily due to intersubspecific heterosis, although the physiological basis underpinning this yield transformation has not been well quantified. We assessed the radiation use efficiency (RUE) and nitrogen use efficiency (NUE) of novel hybrid rice genotypes under four management practices representative of rice cropping systems in China. Y-liangyou 900 (YLY900), a new super hybrid rice widely adopted in China, was examined in field experiments conducted in Jingzhou and Suizhou, Hubei Province, China, from 2017 to 2020. Four management practices were conducted: nil fertilizer (CK), conventional farmer practice (FP), optimized cultivation with reduced nitrogen (OPT–N), and optimized cultivation with increased nitrogen (OPT+N). Yield differences across the treatment regimens were significant (p < 0.05). Grain yield of OPT+N in Jingzhou and Suizhou were 11 and 12 t ha–1, which was 14 and 27% greater than yields obtained under OPT–N and FP, respectively. Relative to OPT–N and FP, OPT+N had greater panicle numbers (9 and 18%), spikelets per panicle (7 and 12%), spikelets per unit area (17 and 32%), and total dry weight (9 and 19%). The average RUE of OPT+N was 2.7 g MJ–1, which was 5 and 9% greater than that of OPT–N and FP, respectively, due to higher intercepted photosynthetically active radiation (IPAR). The agronomic efficiency of applied N (AEN) of OPT+N was 17 kg grain kg–1 N, which was 9 and 68% higher than that of OPT–N and FP. These results show that close correlations exist between yield and both the panicles number (R 2 = 0.91) and spikelets per panicle (R 2 = 0.83) in OPT+N. We conclude that grain yields of OPT+N were associated with greater IPAR, RUE, and total dry matter. We suggest that integrated cropping systems management practices are conducive to higher grain yield and resource use efficiency through expansion of sink potential in super hybrid rice production. [ABSTRACT FROM AUTHOR]

Identification of the right parental combinations to maximize heterosis is the major goal of hybrid breeding, which could be achieved through identification of heterotic groups. The main objective of this study was to identify promising heterotic groups for future rice breeding programs. A collection of 359 rice genotypes of diverse origins of China and abroad, composed of inbreds, maintainers, restorers, and temperature-sensitive genic male sterile (TGMS) lines were genotyped using 10K SNP chips. The SNP data set was subjected to genomic analyses for estimation of genetic divergence and diversity. Significant variations were observed in the germplasm with the identification of six different genetic groups. These lines were assigned to the genetic groups independent of their origin. Taking an account of commercially used heterotic groups present in each cluster, three cytoplasmic male sterile (CMS) lines and 14 inbred and restorer lines with moderate to high genetic distances selected from five heterotic patterns were crossed and obtained 42 F1 hybrids. A total of 14 hybrids were found with significant maximum mid- and better-parent heterosis, namely, TaifengA × Guang122, TaifengA × Wushansimiao, and TaifengA × Minghui63 for earliness; Guang8A × Huazhan for dwarf stature; and Guang8A × Huanghuzhan-1, TaifengA × Yuexiangzhan, Guang8A × Minhui3301, TianfengA × Guang122, Guang8A × Yahui2115, TianfengA × Huanghuazhan, TianfengA × Minghui63, TianfengA × Minhui3301, TaifengA × Gui99, and Guang8A × Yuenongsimiao for yield and yield-related traits. Mid-parent and better-parent heterotic F1 hybrids were in positive correlation with the genetic distances as that manifested by commercially used heterotic groups, encouraging the use of genotypic data for identification of heterotic groups. Our study provides an informative strategy for the development of early maturing, lodging resistant and high-yielding commercial hybrids and cultivars in future heterosis breeding programs. [ABSTRACT FROM AUTHOR]

Seed deterioration during rice seed storage can lead to seed vigor loss, which adversely affects agricultural production, the long-term preservation of germplasm resources, and the conservation of species diversity. However, the mechanisms underlying seed vigor maintenance remain largely unknown. In this study, 16 hybrid rice combinations were created using four sterile lines and four restorer lines that have been widely planted in southern China. Following artificial aging and natural aging treatments, germination percentage and metabolomics analysis by gas chromatography–mass spectrometry was used to identify the metabolite markers that could accurately reflect the degree of aging of the hybrid rice seeds. Significant differences in the degree of seed deterioration were observed among the 16 hybrid rice combinations tested, with each hybrid combination having a different germination percentage after storage. The hybrid rice combination with the storage-resistant restorer line Guanghui122 exhibited the highest germination percentage under both natural and artificial storage. A total of 89 metabolic peaks and 56 metabolites were identified, most of which were related to primary metabolism. Interestingly, the content of galactose, gluconic acid, fructose and glycerol in the seeds increased significantly during the aging process. Absolute quantification indicated that galactose and gluconic acid were highly significantly negatively correlated with the germination percentage of the seeds under the different aging treatments. The galactose content was significantly positively correlated with gluconic acid content. Additionally, glycerol showed a significant negative correlation with the germination percentage in most hybrid combinations. Based on the metabolomics analysis, metabolite markers that could accurately reflect the aging degree of hybrid rice seeds were identified. Galactose and gluconic acid were highly significantly negatively correlated with the germination percentage of the seeds, which suggested that these metabolites could constitute potential metabolic markers of seed vigor and aging. These findings are of great significance for the rapid and accurate evaluation of seed aging degree, the determination of seed quality, and the development of molecular breeding approaches for high-vigor rice seeds. [ABSTRACT FROM AUTHOR]

Macrobrachium nipponense is an important aquaculture species widespread in China, but it is currently facing the threat of genetic degradation. Hybridization is one of the methods used for genetic improvement in order to counteract this serious problem. At present, the underlying molecular mechanism of heterosis is unclear. In this study, next‐generation sequencing (NGS) was used to sequence the transcriptome (RNA‐Seq) of hybrid offspring and female parent. A total of 1479 DEGs were identified, of which 267 were up‐regulated and 1212 were down‐regulated. These DEGs were mainly enriched in signal transduction, transport and catabolism, infectious diseases, immune system, endocrine system, cellular community eukaryotes, cancers, carbohydrate metabolism, cell growth and death, amino acid metabolism and neurodegenerative diseases. Pathways and genes related to growth and development, immunity and anti‐oxidation were identified, and the related genes in these pathways were verified by real‐time quantitative PCR. These findings provided new insights into potential strategies targeting growth traits, stress resistance and selective breeding. [ABSTRACT FROM AUTHOR]

Heterosis, which has greatly increased maize yields, is associated with gene expression patterns during key developmental stages that enhance hybrid phenotypes relative to parental phenotypes. Before heterosis can be more effectively used for crop improvement, hybrid maize developmental gene expression patterns must be better understood. Here, six maize hybrids, including the popular hybrid Zhengdan958 (ZC) from China, were studied. Maize hybrids created in-house were generated using an incomplete diallel cross (NCII)-based strategy from four elite inbred parental lines. Differential gene expression (DEG) profiles corresponding to three developmental stages revealed that hybrid partial expression patterns exhibited complementarity of expression of certain parental genes, with parental allelic expression patterns varying both qualitatively and quantitatively in hybrids. Single-parent expression (SPE) and parent-specific expression (PSE) types of qualitative variation were most prevalent, 43.73 and 41.07% of variation, respectively. Meanwhile, negative super-dominance (NSD) and positive super-dominance (PSD) types of quantitative variation were most prevalent, 31.06 and 24.30% of variation, respectively. During the early reproductive growth stage, the gene expression pattern differed markedly from other developmental stage patterns, with allelic expression patterns during seed development skewed toward low-value parental alleles in hybrid seeds exhibiting significant quantitative variation-associated superiority. Comparisons of qualitative gene expression variation rates between ZC and other hybrids revealed proportions of SPE-DEGs (41.36%) in ZC seed DEGs that significantly exceeded the average proportion of SPE-DEGs found in seeds of other hybrids (28.36%). Importantly, quantitative gene expression variation rate comparisons between ZC and hybrids, except for transgressive expression, revealed that the ZC rate exceeded the average rate for other hybrids, highlighting the importance of partial gene expression in heterosis. Moreover, enriched ZC DEGs exhibiting distinct tissue-specific expression patterns belonged to four biological pathways, including photosynthesis, plant hormone signal transduction, biology metabolism and biosynthesis. These results provide valuable technical insights for creating hybrids exhibiting strong heterosis. [ABSTRACT FROM AUTHOR]

Background: Heterosis has been exploited for decades in different animals and crops due to it resulting in dramatic increases in yield and adaptability. Hybridization is a classical breeding method that can effectively improve the genetic characteristics of organisms through heterosis. Abalone has become an increasingly economically important aquaculture resource with high commercial value. However, due to changing climate, abalone is now facing serious threats of high temperature in summer. Interspecific hybrid abalone (Haliotis gigantea ♀ × H. discus hannai ♂, SD) has been cultured at large scale in southern China and has been shown high survival rates under heat stress in summer. Therefore, SD has become a good model material for heterosis research, but the molecular basis of heterosis remains elusive. Results: Heterosis in thermal tolerance of SD was verified through Arrhenius break temperatures (ABT) of cardiac performance in this study. Then RNA-Sequencing was conducted to obtain gene expression patterns and alternative splicing events at control temperature (20 °C) and heat stress temperature (30 °C). A total of 356 (317 genes), 476 (435genes), and 876 (726 genes) significantly diverged alternative splicing events were identified in H. discus hannai (DD), H. gigantea (SS), and SD in response to heat stress, respectively. In the heat stress groups, 93.37% (20,512 of 21,969) of the expressed genes showed non-additive expression patterns, and over-dominance expression patterns of genes account for the highest proportion (40.15%). KEGG pathway enrichment analysis showed that the overlapping genes among common DEGs and NAGs were significantly enriched in protein processing in the endoplasmic reticulum, mitophagy, and NF-κB signaling pathway. In addition, we found that among these overlap genes, 39 genes had undergone alternative splicing events in SD. These pathways and genes may play an important role in the thermal resistance of hybrid abalone. Conclusion: More alternative splicing events and non-additive expressed genes were detected in hybrid under heat stress and this may contribute to its thermal heterosis. These results might provide clues as to how hybrid abalone has a better physiological regulation ability than its parents under heat stress, to increase our understanding of heterosis in abalone. [ABSTRACT FROM AUTHOR]

The bay scallop southern subspecies, A. irradians concentricus , is an important cultured bivalve in southern China. However, the demand for superior stocks with faster growth and larger size has been increasing. To improve the stock of this scallop, interspecific hybridization was carried out between A. purpuratus (PP) and A. irradians concentricus (SS). The results showed that both reciprocal crosses developed normally and exhibited significant heterosis in important production traits such as growth and survival. At harvest, the heteroses in the SP and PS cohorts were 34.97 and 21.74 in shell height, 138.35 and 79.48 in wet weight, 155.12 and 40.60 in soft-body weight, and 349.60 and 214.40 in adductor muscle weight, respectively. The crossbred cohorts PS and SP outperformed the purebred cohort SS by 30.68% and 82.05% in whole body weight, and by 94.55% and 178.22% in adductor muscle weight, respectively. Morphological and molecular evidence indicated that the derived offspring were true hybrids between the two Argopecten scallops. The gonads of most hybrids were fully feminized and functionally male-sterile, although only 0.79–4.66% of the spawned eggs were able to hatch and resulted in normal backcross offspring. The results from this study indicate that hybridization between A. purpuratus and A. irradians concentricus may provide a promising way for genetic improvement of existing A. irradians concentricus brood stocks in China. • Interspecific hybridization between A. purpuratus and A. i. concentricus resulted in positive heterosis in most traits. • Morphological and molecular evidence confirmed true hybrid offspring from both Argopecten scallops. • Most, but not all hybrids developed feminized gonads that were male- and female-sterile. • The findings have significant implications for the genetic improvement of existing stocks in China. [ABSTRACT FROM AUTHOR]

• The volatile compounds in fresh leaves from 22 major oolong tea cultivars predominantly cultivated in Fujian of China were analyzed using SPME and GC–MS. • The PCA and HCA with leaf volatile compositions notably highlighted the significant distinctions of FS, DHP, SJG, and JMD from the remaining tea cultivars. • The analysis of nonadditive volatiles in tea hybrids revealed a noteworthy positive MPH in JGY and HMG. • JGY exhibited a marked positive MPH in aldehydes, aromatic hydrocarbons, and epoxides, whereas HMG displayed a pronounced positive MPH in aldehydes, epoxides, and esters. Tea is highly esteemed by consumers due to its distinct aroma and the abundance of nutrients that contribute to human well-being. While volatile compounds in fresh tea leaves serve as the essential foundation for tea aroma, the understanding of cultivar-specific aroma constituents and their genetic regulation remains a research gap. In this study, we extracted and profiled the volatile compounds in fresh leaves from 22 major oolong tea cultivars using gas chromatography-mass spectrometry. A total of 140 volatile compounds were identified, of which 61 were consistently found in all tea cultivars. The volatile profiles of the 22 tea cultivars exhibited considerable dissimilarity, with several distinct cultivar-specific volatiles identified. Subsequent analysis of nonadditive volatiles in tea hybrids revealed a noteworthy positive mid-parent heterosis (MPH) in 'Mingke 1' (also known as 'Jinguanyin') and 'Huangmeigui'. Comprehensive heterosis across various volatile compounds was also documented. Our study elucidated the composition of volatile compounds in the fresh leaves from the major oolong tea cultivars and provided an extensive exploration of volatile heterosis in tea plants. These cultivar-specific volatile variations will offer essential insights for enhancing the genetic aspects of tea aroma flavor and deepen our understanding of the molecular mechanisms underlying volatile compound formation in fresh tea leaves. [ABSTRACT FROM AUTHOR]

Background: Heterosis refers to superior traits exhibiting in a hybrid when compared with both parents. Generally, the hybridization between parents can change the expression pattern of some proteins such as non-additive proteins (NAPs) which might lead to heterosis. 'Zhongdan808' (ZD808) and 'Zhongdan909' (ZD909) are excellent maize hybrids in China, however, the heterosis mechanism of them are not clear. Proteomics has been wildly used in many filed, and comparative proteomic analysis of hybrid and its parents is helpful for understanding the mechanism of heterosis in the two maize hybrids. Results: Over 2000 protein groups were quantitatively identified from second seedling leaves of two hybrids and their parents by label-free quantification. Statistical analysis of total identified proteins, differentially accumulated proteins (DAPs) and NAPs of the two hybrids revealed that both of them were more similar to their female parents. In addition, most of DAPs were up-regulated and most of NAPs were high parent abundance or above-high parent abundance in ZD808, while in ZD909, most of DAPs were down-regulated and most of NAPs were low parent abundance or below-low parent abundance. Pathway enrichment analysis showed that more of stress response-related NAPs in ZD808 were high parent abundance or above-high parent abundance, and most of PS related NAPs in ZD909 were high parent abundance or above-high parent abundance. Finally, four stress response-related proteins and eight proteins related to PS were verified by PRM, ten of them had significant differences between hybrid and midparent value. Conclusions: Even though every one of the two hybrids were more similar to its female parent at proteome level, the biological basis of heterosis is different in the two maize hybrids. In comparison with their parents, the excellent agronomic traits of hybrid ZD808 is mainly correlated with the high expression levels of some proteins related to stress responses and metabolic functions, while traits of ZD909 is mainly correlated with high expressed proteins related to photosynthesis. Our proteomics results support previous physiological and morphological research and have provided useful information in understanding the reason of valuable agronomic traits. [ABSTRACT FROM AUTHOR]

Two‐line hybrid rice with high efficiency and yield was successfully and widely being planted in China. HHZ is an elite inbred rice which is widely cultivated in Southern China. The latest developed engineered hybrid is promising for the future of hybrid rice breeding and production. In order to explore its heterosis performance, the main yield traits of two different groups of hybrid rice varieties and a inbred variety were investigated, specifically: (1) a large‐scale extension of high‐yield varieties of two‐line hybrid rice and their parents (restorer lines), (2) a new generation of hybrid rice created by genetic engineered with HHZ as a background genome and its parental lines, and (3) a inbred indica rice variety, HHZ. We postulate that the performance of the main yield traits of genetically engineered hybrid rice may be better than that of commercial high‐yielding hybrid rice in the same paddy field. To test our assumption, field experiments were conducted to investigate the performance of the main yield traits in the different types of hybrid rice and to compare and analyze the differences of the yield heterosis traits. The hybrid rice varieties showed obvious high‐parent heterosis for effective panicle number (EPN) per hill, grain number per panicle (GNP), seed set rate (SSR), and harvest index (HI), but high‐parent heterosis for the 1000‐grain weight (KGW) was negative. Standard heterosis for GNP and KGW was found in the hybrid rice varieties, and the standard heterosis for EPN, SSR, and HI was negative. The grain number per panicle (GNP) is the largest contributor to heterotic performance. The genetically engineered hybrid rice showed similar heterotic performance to but not greater than that of two‐line hybrid rice varieties. This study provides important insights for the breeding, cultivation, and popularization of different types of hybrid rice varieties. [ABSTRACT FROM AUTHOR]

Cross‐breeding has been successfully applied in agriculture and aquaculture industries to improve important production traits. In our previous studies, we produced the F1 hybrids with high heterosis in growth by crossing the bay scallops with the Peruvian scallops and selected a new strain, Bohai Red, from the F1 hybrids. In this study, we selected another new strain from the backcross (BC1) of the F1 hybrids with bay scallops. The base cohort (G0) was size‐selected from the BC1, and the G1, G2, G3 and G4 cohorts were produced with size‐selected brood stocks from the G0, G1, G2 and G3 cohorts respectively. Our results showed that average shell height, shell length, shell width and whole body weight of the G4 cohort were increased by 16.8%, 16.8%, 11.5% and 43.6%, respectively, compared with the unselected control group of bay scallop. This new strain has now become one of the major cultured Argopecten scallops in northern China waters and was later named QN‐2. [ABSTRACT FROM AUTHOR]

Abalones are a group of economically important species of mollusks that represent a source of high-quality protein. China accounts for 90% of the world's abalone production, and make a significant contribution to the aquaculture industry's economic value. With the increasing scale of abalone farming, problems such as the degradation of germplasm resources and a reduced ability to resist environmental changes and stresses have become increasingly prominent. The hybrid breeding technique has significantly ameliorated this situation. The distant hybrid species H. discus hannai ♀ × H. fulgens ♂ (the Lvpan abalone) shows significant heterosis in terms of growth and stress resistance. However, our knowledge of the cytogenetics and molecular mechanisms of heterosis in the hybrid abalone remains limited. In this study, we found significant non-transcribed spacer (NTS) variation of 5S rDNA gene among H. discus hannai , H. fulgens , and the Lvpan abalone, with five, two, and four types of NTSs identified, respectively. These NTSs exhibited genomic polymorphisms within and between species, making them reliable markers for species identification. Furthermore, the sequence alignment of NTSs and genomic resequencing analysis indicated that the hybrid abalone was biased toward H. discus hannai , suggesting a maternal effect. Moreover, numerous mutation sites that were identified only in the hybrid abalone potentially contributed to heterosis. This study provides a valuable molecular data reference for future research on distant hybridization and contributes to a better understanding of the molecular mechanisms underlying heterosis in mollusks. • Variations in the 5S rDNA gene can be used for interspecific identification. • Nucleotide mutations detected in Lvpan abalone potentially contribute to heterosis. • Comparison of variation suggests the presence of maternal effects in Lvpan abalone. [ABSTRACT FROM AUTHOR]

Genetic admixture, the intraspecific hybridization among divergent introduced sources, can immediately facilitate colonization via hybrid vigor and profoundly enhance invasion via contributing novel genetic variation to adaption. As hybrid vigor is short‐lived, provisioning adaptation is anticipated to be the dominant and long‐term profit of genetic admixture, but the evidence for this is rare. We employed the 30 years' geographic‐scale invasion of the salt marsh grass, Spartina alterniflora, as an evolutionary experiment and evaluated the consequences of genetic admixture by combining the reciprocal transplant experiment with quantitative and population genetic surveys. Consistent with the documentation, we found that the invasive populations in China had multiple origins from the southern Atlantic coast and the Gulf of Mexico in the US. Interbreeding among these multiple sources generated a "hybrid swarm" that spread throughout the coast of China. In the northern and mid‐latitude China, natural selection greatly enhanced fecundity, plant height and shoot regeneration compared to the native populations. Furthermore, genetic admixture appeared to have broken the negative correlation between plant height and shoot regeneration, which was genetically‐based in the native range, and have facilitated the evolution of super competitive genotypes in the invasive range. In contrast to the evolved northern and mid‐latitude populations, the southern invasive populations showed slight increase of plant height and shoot regeneration compared to the native populations, possibly reflecting the heterotic effect of the intraspecific hybridization. Therefore, our study suggests a critical role of genetic admixture in accelerating the geographic invasion via provisioning rapid adaptive evolution. [ABSTRACT FROM AUTHOR]

Fibre traits were assessed for 6 × 6 full-diallel families of Eucalyptus urophylla measured at 10 years old. Analysis of variance showed that there were significant combination effects and no block differences on any fibre traits except fibre width. The mean fibre length, fibre width, fine percent, mean curl, fibre kink index and kink angle of controlled crossed families were 0.57 mm, 19.74 µm, 27.38%, 0.039°, 0.64 and 8.24° respectively. The heritability of fibre traits was at low to middle level, and the coefficients of variation ranged from 8.58 (width) to 39.30% (kink angel). Inbreeding depressions of fibre length and width were observed in most families, and the largest inbreeding depressions were estimated at -61.76 and -15.45%. Heterosis ranged from -42.42 to 103.84%. Kink angle had higher general combining ability and fine percent had higher estimation of specific combining ability. Genotypic correlation between fibre length and fibre width were positive, implying these two traits could be selected simultaneously. As an important indicator of pulp yield, fibre traits should be used for breeding E. urophylla. [ABSTRACT FROM AUTHOR]

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Interspecific hybridization has been used as an important tool for genetic manipulation in oyster culture with the aim to produce a new strains having desired traits from both the parental species. A two by two factorial cross between sympatric oyster species, Hong Kong oyster ( Crassostrea hongkongensis ) and Kumamoto oyster ( Crassostrea sikamea ), yielded hybrids that were fast growing (a characteristic of Hong Kong oyster) and had superior meat quality (characteristic to Kumamoto oyster). Reciprocal hybrids were obtained by the acceptable level of fertilization and hatching rate compared to these of two parental species. The survival rate of the hybrids was similar to that of the parental species. The hybrids exhibited fully developed gonads and gametes when sexually mature. Relative to C. sikamea , the hybrids also showed significant growth advantages as in shell height and wet weight. The shell morphology of the hybrid was dictated by maternal inheritance. Our results revealed that reciprocal hybrids exhibited larger growth heterosis and survival advantage (in terms of C. sikamea ), as well as a higher meat weight, showing great potential for application in the oyster aquaculture industry in southern China. Statement of relevance We firstly conducted the interspecific hybridization between the largest ( Crassostrea hongkongensis ) and smallest oysters ( C. sikamea ) in Crassostea genus, and then obtained reciprocal hybrids with obvious the heterosis (in terms of C. sikamea ). These hybrids are very useful as a new stock for the oyster aquaculture industry. [ABSTRACT FROM AUTHOR]

The Chinese soft-shelled turtle ( Pelodiscus sinensis ) is a highly important freshwater aquaculture species in China. The molecular mechanisms underlying changes in immunity and growth in hybrid vigor are not well understood. In the present study, the transcriptomes from significantly different P. sinensis strains (Qingxi black turtle, B and Japanese strain, J) and the resulting hybrid (Zajiao-1, F) were sequenced using an Illumina sequencing platform. Differentially expressed genes (DEGs) between Zajiao-1 and the Qingxi black turtle were enriched mainly in the HTLV-I infection and Hippo signaling pathways, while DEGs between the Zajiao-1 and Japanese strain were enriched mainly in tryptophan metabolism, caner-associated pathways, transcriptional dysregulation in cancer, amebiasis, Fcγ-mediated phagocytosis and the peroxisome pathway. Highly expressed genes involved in the regulation of disorders of the fatty acid biosynthesis, immune and cardiovascular systems in P . sinensis were found among the DEGs. Enrichment categories for gene ontology included cellular processes, metabolic pathways, and the actin cytoskeleton pathway. The reliability of the sequencing data was verified through quantitative real-time polymerase chain reaction analysis of 20 immunity or growth-related genes. These findings offer new insights into heterosis of growth traits and resistance to stresses and potential strategies for selective breeding. [ABSTRACT FROM AUTHOR]

In order to assess the overall progress of our long-term selective breeding program and quantify the effects of inbreeding on production traits in selected line of Pacific oyster Crassostrea gigas , we systematic analyzed the growth, survival and yield of selected, inbreeding and wild populations for 440 days in northern China. During the larval stage, selected line exhibited high superiority in both survival rate and shell height. Compared with wild population, the shell height and survival rate of selected line increased by 19.10% and 57.15% at day 20, respectively. Meanwhile, the shell height and individual weight of the selected line were significantly higher than wild population at whole grow-out stage. Notably, the cumulative survival rate of selected line increased by 71.35% compared with wild population at harvest. Additionally, the final yield of selected line increased by 157.98% compared with wild population and it would be of great benefits to oyster industry. In this study, the effects of inbreeding on shell height were not significant (P > 0.05) at whole larvae stage, ranged from −0.68% to −5.01%. On the contrary, there were significant inbreeding depression (−5.14% to −22.46%) on larvae survival and the estimated coefficient were − 2.06% to −8.98% per 10% increase of inbreeding coefficient of F. During grow-out stage, inbreeding depression on survival were not significant (P > 0.05), ranged from −0.83% to −5.04%. On the contrary, there were significant (P < 0.05) inbreeding depression on growth traits and tend to increase with age. The estimated inbreeding depression coefficient of individual weight ranged from −1.54% to −5.91% per 10% increase of inbreeding coefficient of F, which was higher than the estimate obtained for shell height (−0.64% to −5.52%). For yield, the estimated inbreeding depression coefficient was −8.37% per 10% increase of inbreeding coefficient of F (P < 0.05). The above results indicate that substantial genetic progress was achieved in our selective breeding program, and it is necessary to maintain pedigree records to avoid the harmful effects of inbreeding depression. • Remarkable genetic improvement has been made in the oyster selective breeding in China. • Inbreeding had a negative effect on growth traits and yield at different grow-out stages. • Inbreeding depression on grow-out survival was not significant, which may be due to selection (purging) effects. • Inbreeding population has potential for exploiting inbreeding and heterosis for line development. [ABSTRACT FROM AUTHOR]

Oysters are a keystone species in estuaries and intertidal zones and have important economic and ecological significance; however, worldwide, the dominant aquaculture oyster species suffers from mass mortality owing to anthropogenic impacts and rapid climate change. As a possible solution, inter/intraspecies hybridization is a feasible way to breed new germplasms with genetic improvement and high environmental adaptability. Suminoe oysters (Crassostrea ariakensis) are broadly distributed in the estuaries of China and have evolved strong genetic divergence between the northern and southern populations; therefore, they are ideal candidates to explore intraspecies heterosis and the associated molecular mechanisms. In this study, we performed reciprocal hybridization and examined fitness traits in oysters cultured in both northern and southern habitats. Reciprocal hybrids performed better than inbred populations in both environments, indicating heterosis in Suminoe oysters. Hybrids reared in maternal habitats showed faster growth, higher field survival, and greater aerobic metabolism than alternative hybrid oysters under the same conditions. The transcriptional analysis identified modules related to heterosis and maternal effect, while genes responsible for galactose metabolism, glycolysis/gluconeogenesis, and the tricarboxylic acid cycle were enriched and upregulated in hybrids, especially those in maternal environments. Our findings reveal that accelerated aerobic energy metabolism, which may result from mitonuclear coadaptation, underlies the molecular basis of heterosis and maternal effect in the hybridization of Suminoe oysters. Thus, we provide important insights for the aquaculture management of marine species, revealing that selecting appropriate environments (maternal habitats) is critical for heterosis in cross-breeding. • Hybrids from divergent oyster populations showed heterosis in growth and survival. • Hybrids in maternal habitat exhibited better performance indicating maternal effect. • Accelerated aerobic metabolism underlies heterosis and maternal effect in oyster. • Our findings propose better hybridization breeding of hybrids in maternal habitat. [ABSTRACT FROM AUTHOR]

China is the world's largest abalone farming country, with production reaching 203,000 tons in 2020. In the last few decades, interspecific hybridization has been carried out in China and achieved a certain level of success, and rearing techniques have been rapidly developed. To systematically evaluate the performance of purebred and crossbred strains under different culture modes, we determined the magnitudes of the Genotype by Environment Interactions (GEI) to identify stable and high growth performance strains. Two purebred (Haliotis discus hannai and H. gigantea) and four crossbred abalone strains were evaluated in three representative culture modes (Inland industrial aquaculture mode, Sea-based aquaculture mode and South-North (S-N) relay mode). After 2 years of culture, the growth performance of strains varied with different culture modes. Both H. discus hannai ♀ × H. fulgens ♂ (DF) and H. gigantea ♀ × H. discus hannai ♂ (SD) exhibited significant heterosis in all three culture modes, and H. discus hannai ♀ × (H. discus hannai ♀ × H. fulgens ♂) ♂ (DD × DF) and (H.gigantea ♀ × H. discus hannai ♂) ♀ × H. discus hannai ♂ (SD × DD) showed significant growth advantages compared to the purebred parents of H. discus hannai (DD) and H. gigantea (SS). A combined analysis of variance revealed significant genotype by environment interactions for shell length (14.2%), harvest weight (8.7%), and fullness index (10.4%), indicating that phenotype reranking occurred under different culture modes. The average performance for shell length, harvest weight, and the fullness index followed the pattern: DF > DD × DF > SD > SD × DD > DD > SS. Combining the results of growth assessment and genotype by environment interaction analysis, the following conclusions can be drawn: 1) DF was the highest yielding genotype among the three culture modes and should be promoted. 2) SD and D × DF had notable performance under the S-N relay mode, suggesting that these could be used as suitable strains for S-N relay rearing. 3) In the case of purebred SS, the sea-based aquaculture mode was the best option. 4) The S-N relay mode significantly improved the economically important traits of most of the strains. The results from this study can provide critical advice for different strains as well as guidance for the abalone farming industry in world. • A comprehensive field study on the purebred and hybrid abalone strains cultivated in three culture modes was reported. • The hybrid H. discus hannai ♀ × H.fulgens ♂ exhibited the most growth under South-North relay mode. • South-North relay mode can significantly improve the economical traits of most of the strains. [ABSTRACT FROM AUTHOR]

Hybridization is a widely used and effective method in grouper breeding. In this study, we constructed full-sib families of brown-marbled grouper (Epinephelus fuscoguttatus), Jinhu grouper (E. fuscoguttatus ♀ × E. tukula ♂), and Hulong grouper (E. fuscoguttatus ♀ × E. lanceolatus ♂) and compared the growth characteristics under industrial conditions. The body weight of Jinhu grouper was 1.49 times that of Hulong grouper (P < 0.05) and the body weight of Jinhu grouper was 2.03 times that of E. fuscoguttatus (P < 0.05). Moreover, the survival rate of Jinhu grouper was significantly higher than those of Hulong grouper and E. fuscoguttatus (P < 0.05). The relationships between body length and body weight (W = aLb) in Jinhu grouper, Hulong grouper, and E. fuscoguttatus were similar, and both Jinhu grouper and Hulong grouper may inherit the growth pattern of E. fuscoguttatus. The b values were all <3, indicating allometric relationships at this stage. In a comparison of the low temperature tolerance, E. fuscoguttatus and Jinhu grouper stopped feeding at 19 °C and 16 °C, respectively, and 11 °C and 9 °C were the half-lethal temperatures, respectively. A histopathological analysis showed that the degree of damage in the gill, muscle, and liver tissues increased as the temperature decreased. The activities of total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC), and glutathione peroxidase (GSH-Px) in the liver decreased initially and then increased as the temperature decreased. The malondialdehyde (MDA) contents in the liver increased initially and decreased thereafter. Lysozyme (LZM) activity in the serum increased initially and then decreased, and immunoglobulin M (IgM) levels did not vary significantly with respect to temperature (P > 0.05). In conclusion, Jinhu grouper was characterized by a rapid growth rate, high survival rate, and low temperature resistance. This hybrid grouper is suitable for industrial culture in China, with broad potential applications • Growth and survival were better in Jinhu grouper than in E. fuscoguttatus and Hulong grouper. • Behavioral, histological, and enzyme responses to low temperature stress were studied. • The half-lethal temperature was lower in Jinhu grouper than in E. fuscoguttatus. [ABSTRACT FROM AUTHOR]

• Heredity variation and inheritance tendency were analyzed for eighteen fruit-related traits of F 1 population derived from 'Hongfei' × 'Pujianghonghua' of Chinese cherry for two years. • Significant levels of transgressive heterosis were observed for total soluble solid, anthocyanin content and fruit stalk length, whereas negative heterosis detected in fruit weight and size. • The fruit-related traits were most likely controlled by two pairs of major genes, which exerted both additive effects and dominant effects. • The heritability of major gene controlling maturity date and fruit development period was high, while that of major genes controlling fruit quality traits was low. Chinese cherry [ Cerasus pseudocerasus (Lindl.) G.Don] is one of the important stone fruits in China. To explore the heredity variation of fruit-related traits, we investigated 18 fruit-related traits of the F 1 segregating population around 700 individuals derived from 'Hongfei' × 'Pujianghonghua' of Chinese cherry for two years. The mixed major gene and polygene inheritance model method was also evaluated for their fitness in relating to the traits. The results showed that the main fruit traits had different degrees of variation, with the coefficient of variation ranging from 4.76 to 26.71% (72.23% for anthocyanin content) in 2021, and from 4.71 to 21.57% in 2022. Significant levels of transgressive heterosis were observed for fruit stalk length, total soluble solid and anthocyanin content, whereas negative heterosis was detected in fruit weight and size. The most suitable genetic model for fruit maturity date and fruit development period was 2MG-ADI and 2MG-AD, respectively, and the heritability of major gene was greater than 90%. The optimal genetic model for ten fruit size and flavor related traits was 2MG-AD or 2MG-EA, which were controlled by two pairs of major genes with additive-dominant effect or equal-additive effect, with the major gene heritability being less than 45%. The additive effects of the fruit-related traits were mostly positive, while the dominant effects were mainly negative. These results provide a theoretical basis for quantitative trait locus (QTL) mapping and marker-assisted breeding of fruit-related traits in Chinese cherry. [Display omitted] [ABSTRACT FROM AUTHOR]

Heterotic groups and patterns are extremely important in hybrid breeding. Nine elite inbreds widely used in Chinese rapeseed hybrid breeding programs were crossed in a diallel mating design to develop 36 hybrids. These hybrids and their parents were evaluated for two successive years in northern China. Five different methods, which were based on specific combining ability (SCA) effects, SCA‐Yang's effects, molecular markers, heterotic group specific and general combining ability, and heterotic grouping based on the general combining ability of multiple traits, were compared for their ability to classify the tested inbreds into heterotic groups. With regard to grouping of inbreds, breeding efficiency, and cross‐mean yield variation explained by the cross types, the SCA method was the most promising, followed by the SCA‐Yang's and molecular marker methods. Using the SCA method, three testers (8D129, 8C343, and 8D153) and opposing heterotic groups [(8C108, 8C189, and 8D129), (8C343, 8C360, and 8E001), and (8C272, 8D153, and 8E019)] were identified across environments. Chinese southern and northern rapeseed lines formed a different heterotic group. Four outyielding crosses, 8D129 × 8E001 (high‐check heterosis, 29.52%), 8C343 × 8D129 (24.76%), 8C189 × 8C272 (23.98%), and 8C272 × 8C343 (22.95%), were identified as ideal hybrids for further extensive testing in multilocation trials and are promoted for adoption and commercialization in China. [ABSTRACT FROM AUTHOR]

Development of hybrid rice is an important strategy to increase yields of irrigated rice in China. Day length is a highly important environmental factor for hybrid rice adaptability, productivity and quality. Heterosis of hybrid rice has been utilized under natural- (long) day length conditions in the middle and lower reaches plain of Yangtze River Valley in China for a long time. However, whether the hybrid rice can show heterosis under short-day length conditions is unknown. In this study, we analyzed plant height, grain number per panicle, and other yield related traits of hybrid rice Liangyoupeijiu (LYP9) and its parents (Pei’ai 64S and 93-11) under natural- and short-day length conditions and compared the respective heterosis. Results showed that earlier heading, reduced plant height, and reduced grain number per panicle were found in these three varieties under short-day length conditions relative to those under natural-day length conditions. In either natural- or short-day length conditions, heterosis of LYP9 was mainly displayed in grain number per panicle and plant height. This study may help in breeding and selecting suitable hybrid rice for different regions with natural- or short-day length. [ABSTRACT FROM AUTHOR]

To measure the contributions of parental inbreds per se and heterosis to the genetic gain of single- cross maize (Zea mays L.) hybrids, yield trials of 29 historically important hybrids used in China during 1964 through 2001 and their parental inbreds were conducted. Mean rate of genetic gain for single-cross hybrids when measured across all locations was 55 kg ha-1 yr-1; heterosis contributed 37 kg ha-1 yr-1 (67%) of yield gain. Inbred yields at stressed locations were exceptionally poor and may have inflated measurements of heterosis. At unstressed locations, heterosis contributed 5 kg ha-1 yr-1 (8%) and 16 kg ha-1 yr-1 (39%) or 10 kg ha-1 yr-1 (19%) when locations were combined. For individual characteristics, the highest percent heterosis was for kernel weight per ear (58.6%), corresponding to and emphasizing the historic goal in China of increasing yield on an individual plant rather than on a unit area basis. There are opportunities to further improve the productivity of Chinese maize by increasing inbred parent yields, increasing tolerances to stresses associated with higher planting densities, and also increasing the contribution of heterosis through optimal assignation of inbreds into complementary heterotic groups. [ABSTRACT FROM AUTHOR]

Simple Summary: Hybrid tilapia (Oreochromis niloticus ♀ × O. aureus ♂) are commercially important in China. Because cultured hybrids have superior growth and survival rate relative to the parental stocks, parent species potentially represent model taxa to analyze the molecular mechanisms of hybrid vigor. Comparisons of the growth and hematologic biochemical characters and transcriptional analyses of mRNA and miRNA, approximately 21-nt-long noncoding RNAs that negatively regulate gene expression at the post transcriptional level, were performed in hybrid and parental tilapia stocks to investigate the underlying molecular basis for heterosis. The present study indicated that dominance and overdominance models are widespread in transcriptional and post-transcriptional regulation of genes involved in growth, metabolism, immunity, and antioxidant capacity in hybrid tilapia, thus providing new insights into molecular heterosis in hybrid tilapia and advancing our understanding of the complex mechanisms involved in this phenomenon in aquatic animals. Heterosis is a widespread biological phenomenon in fishes, in which hybrids have superior traits to parents. However, the underlying molecular basis for heterosis remains uncertain. Heterosis in growth and survival rates is apparent in hybrid tilapia (Oreochromis niloticus ♀ × O. aureus ♂). Comparisons of growth and hematological biochemical characteristics and mRNA and miRNA transcriptional analyses were performed in hybrid and parents tilapia stocks to investigate the underlying molecular basis for heterosis. Growth characteristics and hematological glucose and cholesterol parameters were significantly improved in hybrids. Of 3097 differentially expressed genes (DEGs) and 120 differentially expressed miRNAs (DEMs) identified among three stocks (O. niloticus, O. aureus, and hybrids), 1598 DEGs and 62 DEMs were non-additively expressed in hybrids. Both expression level dominance and overdominance patterns occurred for DEGs and DEMs, indicating that dominance and overdominance models are widespread in the transcriptional and post-transcriptional regulation of genes involved in growth, metabolism, immunity, and antioxidant capacity in hybrid tilapia. Moreover, potential negative regulation networks between DEMs and predicted target DEGs revealed that most DEGs from miRNA-mRNA pairs are up-regulated. Dominance and overdominance models in levels of transcriptome and miRNAome facilitate the integration of advantageous parental alleles into hybrids, contributing to heterosis of growth and improved survival. The present study provides new insights into molecular heterosis in hybrid tilapia, advancing our understanding of the complex mechanisms involved in this phenomenon in aquatic animals. [ABSTRACT FROM AUTHOR]

Noble scallop Chlamys nobilis is one of the most important bivalves in China. C. nobilis aquaculture is mainly carried out in coastal areas that vulnerable to high salinity fluctuations. Hyposaline conditions caused by a large volume of freshwater input from rivers in rainy seasons often leads to mass mortalities of farmed C. nobilis. Interspecific hybridization is a promising approach to improve the growth rate, survival rate and environmental adaptability of bivalves. However, it is not clear whether intraspecific hybridization can be used as a management strategy to mitigate the impact of hyposaline on farmed C. nobilis. Therefore, this study compared the effects of hyposaline on the growth rate, survival rate, total carotenoid content (TCC) and transcriptome data of intraspecific inbred and hybrid C. nobilis. The results of this study revealed that intraspecific hybridization of C. nobilis exhibited significant positive heterosis in growth rate, survival rate and adaptation to hyposaline condition. The stronger adaptation to hyposaline condition is mainly attributed to the induction of genes involved in osmoregulation, cell protection and damaged protein repair. Therefore, intraspecific hybridization is a potential management strategy to mitigate the impact of hyposaline on farmed bivalves (at least for C. nobilis). • Hyposaline negatively affects the growth and survival C. nobilis larvae. • Hyposaline has relatively low impact on growth and survival of C. nobilis juvenile. • Intraspecific hybridization can improve adaptability of C. nobilis to hyposaline conditions. • Enhance adaptability to hyposaline condition involved osmoregulation, cell protect and repair of damaged protein. [ABSTRACT FROM AUTHOR]

• Graphical user interfaces offering an accessible way to see and understand trends, patterns, and connotations in breeding data. • Statistical tools providing convenient experimental design and data analysis support which may reduce the professional demand for statistics skills of breeders. • Intelligent decision support tools for heterosis prediction and cultivar evaluation improving the decision-making ability with multi-dimensional breeding data. Plant breeding is an effective guarantee of agriculture production and food security, whereas information technologies are effective ways to promote plant variety improvement. Although breeding information technologies provide a convenient and scientific means for breeding, it also leads to the problem of massive data processing with multidimensional breeding data in multiple granularities across generations. Therefore, decision support tools that help breeders extract relevant and valuable information are necessary and important. This paper introduces the decision support tools of the golden seed breeding cloud platform at three levels: (i) graphical user interfaces; (ii) statistical tools; and (iii) intelligent decision support tools. The advantages have effectively improved the breeding efficiency as well as the data management and application capabilities in more than 150 breeding institutions in China. The successful application of our system confirms the effectiveness of our work and provides data and support for future research. [ABSTRACT FROM AUTHOR]

The Peruvian scallop (Argopecten purpuratus) has been introduced to China and has successfully been hybridized with the bay scallop (A. irradians irradians). The F1 hybrids of these two scallops exhibited a large increase in production traits and some other interesting new characteristics. To understand the genetic basis of this heterosis, nuclear gene and partial mtDNA sequences, and genomic in situ hybridization (GISH) were employed to analyze the genomic organization of the hybrids. Amplification of the ribosomal DNA internal transcribed spacer (ITS) showed that the parental ITS sequences were present in all the hybrid individuals, illustrating that the hybrid offspring inherited nuclear DNA from both parents. Sequence analyses of the ITS region further confirmed that the hybrids harbored alleles from their parents; some recombinant variants were also detected, which revealed some alterations in the nuclear genetic material of the hybrids. The analysis of mitochondrial 16S rDNA showed that the hybrids possessed sequences that were identical to the 16S rDNA of the female parents, proving a matrilineal inheritance of mitochondrial genes in scallops. In addition, GISH clearly discriminated between the parental chromosomes and indicated a combination of haploid genomes of duplex parents in the hybrids. The genetic analyses in our study illustrated that the F1 hybrids inherited nuclear material from both parents and cytoplasmic genetic material maternally, and some variations occurred in the genome, which might contribute to a further understanding of crossbreeding and heterosis in scallop species. [ABSTRACT FROM AUTHOR]

The Peruvian scallop (Argopecten purpuratus) has been introduced to China and has successfully been hybridized with the bay scallop (A. irradians irradians). The F1 hybrids of these two scallops exhibited a large increase in production traits and some other interesting new characteristics. To understand the genetic basis of this heterosis, nuclear gene and partial mtDNA sequences, and genomic in situ hybridization (GISH) were employed to analyze the genomic organization of the hybrids. Amplification of the ribosomal DNA internal transcribed spacer (ITS) showed that the parental ITS sequences were present in all the hybrid individuals, illustrating that the hybrid offspring inherited nuclear DNA from both parents. Sequence analyses of the ITS region further confirmed that the hybrids harbored alleles from their parents; some recombinant variants were also detected, which revealed some alterations in the nuclear genetic material of the hybrids. The analysis of mitochondrial 16S rDNA showed that the hybrids possessed sequences that were identical to the 16S rDNA of the female parents, proving a matrilineal inheritance of mitochondrial genes in scallops. In addition, GISH clearly discriminated between the parental chromosomes and indicated a combination of haploid genomes of duplex parents in the hybrids. The genetic analyses in our study illustrated that the F1 hybrids inherited nuclear material from both parents and cytoplasmic genetic material maternally, and some variations occurred in the genome, which might contribute to a further understanding of crossbreeding and heterosis in scallop species. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge of genetic divergence among inbred lines is essential for cross breeding. The objectives of this study were to (1) analyze the level and character of genetic diversity in C. moschata accessions, and (2) classify the genetic divergence among inbred lines in C. moschata to assist in selection of parent genotypes for genetic improvement. Twenty agronomic characters were investigated and rich diversities were demonstrated among 39 inbred lines of C. moschata from China. Various degree correlations among these characters made it possible to summarize the diversities of the twenty characters into 3 major principal components: leaf, fruit and flesh quality factor. Forty-one inbred lines of pumpkin were clustered into four groups based on principal component data, which is more distinct for classification that based on the original data of the 20 characters. However, parent inbred lines whose hybrids displayed significant heterosis in fruit weight, soluble solid and fruit shape were located in different clusters or sub-clusters based on standardized original data. It was suggested that genotypes in the same clusters may represent members of one heterotic group. [Copyright &y& Elsevier]

Abstract: This study describes the first introduction of the Peruvian scallop, Argopecten purpuratus (P), from Peru to China. Reciprocal hybridization was carried out between the newly introduced Peruvian scallops and the bay scallops, A. irradians irradians (I). Morphological and molecular evidence indicated that the derived offspring were true hybrids between the two Argopecten scallops. At larval stages, when cultured at 23°C, the growth rates of the hybrid cohorts were not different from that of the inbred bay scallop group but significantly higher than that of the Peruvian scallops. The survival rate of the A. purpuratus ♀× A. irradians ♂ (P♀×I♂) cohort was higher than those of both inbred cohorts but the A. irradians ♀× A. purpuratus ♂ (I♀×P♂) cohort survived better than the bay scallop cohort only. Significant maternal effects were noted on growth rate but not on survival rate. Mating strategy and its interaction with egg origin had significant effects on both growth and survival rates. During the adult grow-out stage, the survival rates of the hybrid cohorts were not different from that of the bay scallops but were much higher than that of the Peruvian scallops. The growth rates in both shell height and whole body weight in the hybrid cohorts were much higher than those of the inbred bay and Peruvian scallop cohorts. Compared with the bay scallops, the production traits in the hybrid cohorts were increased by 125.9–138.9% in whole body weight and by 145.4–156.2% in adductor muscle weight. Thus, although it may not be feasible to culture the Peruvian scallops at a large scale in China, hybridizing the Peruvian scallops with bay scallops may be a very effective way in increasing scallop production in China. [Copyright &y& Elsevier]

Abstract: To meet the growing demand for rice production, the Ministry of Agriculture, P. R. China initiated a nationwide project on the development of super rice in 1996. Through efforts in research, super rice breeding in China has gained significant advances in the aspects of breeding theories, creation of breeding materials and selection and promotion of elite rice varieties. A creative super rice breeding path of the construction of harmonious plant type combined with the utilization of heterosis was proposed. Super rice plays more and more important roles in rice production. Totally, 71 super rice varieties in China have been successfully developed and released to production. These varieties have 12 t/hm2 yield potential in on-farm demonstration fields, 8% to 15% higher than the check varieties with high resistance to pest and medium to high level of grain quality, the total growing area of which has reached 23.7 million hectares, and rice grain production increased by 17.7 million tons from 1996 to 2009. This paper reviewed the development and achievements of super rice breeding in aspects of the breeding methodology and breeding practices, summarized the successful experience of super rice breeding in China and proposed the developmental strategies of super rice for the future. [Copyright &y& Elsevier]

Abstract: This study aimed at studying the molecular genetic basis of plant height (PH) heterosis in wheat. From a set of doubled haploid (DH) lines derived from Huapei 3 × Yumai 57, an “immortalized F2” population was constructed with 168 single crosses. The DH lines, IF2 population, and the parents were evaluated for plant height in 3 environments, i.e., in Tai''an, Shandong Province, China, in 2007 and 2008 cropping seasons and in Jiyuan, Henan Province, China in 2008 cropping season. Based on the genetic map of quantitative trait locus (QTL) constructed in a previous study, the heterosis of PH of wheat was analyzed using the composite interval mapping method. A total of 3 additive QTLs, 2 dominance QTLs, 4 pairs of epistatic QTLs (including additive by additive, additive by dominance, dominance by additive, and dominance by dominance), and 20 heterotic loci were detected for PH in the 3 environments. Two QTLs, QPh2D and QPh4D, were detected on chromosomes 2D and 4D with a minor interaction of additive by environment. In addition, several heterotic loci for PH except QPh2D were also identified on chromosome 2D in close regions with similar marker intervals. Of them, QTLs QPh2D-2 and QPh2D-7 explained the PH variance by 29.77% and 55.77%, respectively. Another QTL associated with PH heterosis, QPh7D-2, was mapped in the marker interval between Xwmc273.2 and Xcfd175 on chromosome 7D in the 3 environments. These results indicated that a few QTLs on chromosomes 2D, 4D, and 7D play an important role in PH heterosis in wheat. These loci have potential use for the improvement of PH in wheat breeding assisted with molecular markers. [Copyright &y& Elsevier]