Polyploidization is a commonly employed strategy in crop breeding to augment genetic diversity,particularly leveraging the distinctive benefits of additional progressive heterosis or multi-generation heterosis unique ...Polyploidization is a commonly employed strategy in crop breeding to augment genetic diversity,particularly leveraging the distinctive benefits of additional progressive heterosis or multi-generation heterosis unique to polyploidy.Despite genetic disparities between polyploids and diploids,challenges stem from reproductive anomalies,complicating genetic investigations in polyploid systems.Through nearly two decades of intensive research,our team has effectively generated a series of fertile tetraploid lines known as neo-tetraploid rice(NTR),facilitating comparative genetic studies between diploid and tetraploid rice.In this study,we identified diploid counterparts(H3d and H8d)for two NTR lines[Huaduo 3(H3)and Huaduo 8(H8)]and utilized them to create diploid and tetraploid fertile F_(2) populations to assess genotype segregation ratios,recombination rates,and their impact on QTL mapping via bulked segregant analysis combined with sequencing(BSA-seq).Additionally,we assessed yield heterosis in F_(1) and F_(2) generations of two tetraploid populations(H3×H8 and T449×H1),revealing evidence of multi-generation heterosis in polyploid rice.These findings provide valuable insights into the advantages and challenges of polyploid rice breeding.展开更多
Sexual maturation heterosis has been widely exploited in animal crossbreeding.However,the underlying mechanism has been rarely explored in chicken.In the present study,we performed the reciprocal crossing between Whit...Sexual maturation heterosis has been widely exploited in animal crossbreeding.However,the underlying mechanism has been rarely explored in chicken.In the present study,we performed the reciprocal crossing between White Leghorn and Beijing You chicken to evaluate the phenotypes related to sexual maturation,and profiled the ovary circRNAs of purebreds(WW,YY)and crossbreds(WY,YW)to elucidate the molecular mechanism underlying heterosis for sexual maturation.Pubic space and oviduct length exhibited positive heterosis,and age at first egg(AFE)exhibited negative heterosis in the crossbreds.We identified 3,025 known circRNAs and 624 putative circRNAs,which were mainly derived from the exons.Among these circRNAs,141 and 178circRNAs were specially expressed in WY and YW,respectively.There were 52.38 and 64.63%of total circRNAs in WY and YW exhibited non-additive expression pattern,respectively.GO enrichment and KEGG pathway analysis showed that the host genes of non-additive circRNAs were mainly involved in TGF-beta signaling pathway,oocyte development,ATPase activator activity,oocyte meiosis,progesterone-mediated oocyte maturation and GnRH signaling pathway.Weighted gene co-expression network analysis identified that 4 modules were significantly(P<0.05)correlated with oviduct length and pubic space.The host genes of non-additive circRNAs harbored in the 4 modules were associated with MAPK signaling pathway and Wnt signaling pathway.Furthermore,competing endogenous RNAs(ceRNA)network analysis characterized non-additive circRNAs gal-FGFR2_0005 and galMAPKAP1_0004 could interact with gga-miR-1612 and gga-miR-12235-5p to regulate CNOT6,COL8A1,and FHL2,which were essential for ovary development,indicating that the non-additive circRNAs involved in the formation of sexual maturation heterosis through regulating genes related to the reproductive and developmental process.The findings would provide a deeper understanding of the molecular mechanism underlying sexual maturation heterosis from a novel perspective.展开更多
Background Crossbreeding is widely promoted as an efficient strategy to improve the productivity in agriculture.The molecular mechanism underlying heterosis for egg production is always intriguing in chicken.The trans...Background Crossbreeding is widely promoted as an efficient strategy to improve the productivity in agriculture.The molecular mechanism underlying heterosis for egg production is always intriguing in chicken.The transcriptional dynamic changes play a crucial role in the formation of heterosis,but little is known for the egg production traits.Results In present study,we measured the continuous manifestation of heterosis ranging from 2.67%to 10.24%for egg number in the crossbreds generated by reciprocal crossing White Leghorn and Beijing You chicken.The high-quality transcriptomes of ovary for purebreds(WW and YY)and crossbreds(WY and YW)in 5 laying stages were sequenced and integrated to identify regulatory networks relevant to the heterosis.We found highly conserved transcriptional features among 4 genetic groups.By using weighted gene co-expression network analysis(WGCNA),we obtained multiple gene co-expression modules that were significantly correlated with egg number for each group.The common KEGG pathways including apelin signaling pathway,cell cycle,ribosome,spliceosome and oxidative phosphorylation,were screened for the 2 crossbreds.Then,we identified consensus co-expression modules(CMs)that showed divergent expression pattern among crossbred(WY or YW)and purebreds(WW and YY).The hub genes of CMs were again overrepresented in the cell cycle pathway,and the crossbreds exhibited temporally complementary dominance of hub genes in the 5 laying stages.These results suggested that the crossbreds inherited from both parents to maintain the ovary function by cell cycle-related genes,contributing to the persistent heterosis for egg production.Furthermore,the dominant genes including MAD2L1,CHEK2 and E2F1 were demonstrated to function in ovarian follicle development and maturation and could be the candidate genes for egg production heterosis.Conclusion Our study characterized the dynamic profile of genome-wide gene expression in ovary and highlighted the role of dominant expression of cell cycle pathway genes in heterosis.These findings provided new insights for the molecular mechanism of egg production heterosis,which would facilitate the rational choice of suitable parents for producing crossbred chickens with higher egg production.展开更多
In order to cultivate Manila clam varieties in northern China,we crossed the Dalian wild population(referred to as D)and the Weihai wild population(referred to as W)to create a 2×2 complete diallel hybrid.Ultimat...In order to cultivate Manila clam varieties in northern China,we crossed the Dalian wild population(referred to as D)and the Weihai wild population(referred to as W)to create a 2×2 complete diallel hybrid.Ultimately,we obtained two hybrid groups(D♀×W♂(DW)and W♀×D♂(WD))and two inbred groups(D♀×D♂(DD)and W♀×W♂(WW)).We measured their growth and survival during the larval and juvenile stages and compared the data between hybrid and inbred groups to study the potential heterosis of the hybrid.With the exception of slightly lower values in the WD group,fertilization and hatching rates did not differ significantly among the other groups.However,during the larval stage(days 1–15),we observed significant differences in the growth rate of Manila clam in the hybrid groups at days 1,3,and 6 of age(P<0.05).Among the groups,the clams in the DW group had the highest survival rate,which was indicative of significant heterosis.After entering the juvenile stage(days 30–120),both hybrid groups showed high heterosis in terms of growth and survival.The DW group had the greatest amount of heterosis for survival performance,and the WD group had the greatest amount of heterosis for shell length and height growth.These results indicated that this hybrid combination had great breeding potential,and provided a useful hybrid strategy for producing genetic improvements in R.philippinarum.展开更多
Heterosis,a crucial biological phenomenon,plays a vital role in determining the yield and quality of plants.Radish,an important root vegetable crop,exhibits notable heterosis in terms of root yield and quality.Neverth...Heterosis,a crucial biological phenomenon,plays a vital role in determining the yield and quality of plants.Radish,an important root vegetable crop,exhibits notable heterosis in terms of root yield and quality.Nevertheless,the molecular mechanism underlying the formation of heterosis in radish remains unclear.Herein,both the transcriptome and DNA methylome analyses were performed on the F_(1)hybrids and parental lines.Expression level dominance(ELD)genes and allele-specific expression(ASE)genes together significantly contribute to heterosis,primarily through energy metabolism and plant hormone signal transduction pathway.An increase in average methylation level in the F_(1)hybrids was observed compared to the parental lines.Interestingly,a negative correlation was found between the methylation level of differentially expressed genes(DEGs)in gene body regions and their expression levels in NAU-LB and the F_(1)hybrids.Moreover,the hybrids were more sensitive to the 5-azacytidine than their parents,and the root weight and total sugar content in the F_(1)hybrids were dramatically decreased compared to the control.Immunolocalization results indicated that the auxin content of the F_(1)hybrids were reduced under 5-azacytidine treatment.Proliferating cell nuclear antigen immunolocalization revealed significant inhibition of vascular cambium activity in both the hybrids and parental lines.Notably,the expression profiles of a few differentially methylated DEGs including RsSUS1,RsSUC2a,RsIAA7,and RsIAA18,were significantly increased in the root of hybrids compared to their parents,suggesting a potential role of DNA methylation in yield heterosis.Collectively,these findings would provide valuable insight into the molecular mechanism underlying taproot yield heterosis and facilitate the genetic improvement of taproot yield and quality in radish breeding programs.展开更多
Hybridization remains an important method for breeding new poplar varieties.It results in significant variation in leaf phenotype among parents and offspring,and among offspring themselves.This study aimed to investig...Hybridization remains an important method for breeding new poplar varieties.It results in significant variation in leaf phenotype among parents and offspring,and among offspring themselves.This study aimed to investigate whether leaf shape variations were similar in offspring produced from reciprocal crosses.Specifically,two hybrid combinations were produced:the direct cross with Populus ussuriensis as the maternal parent and P.simonii×P.nigra as the paternal parent(HY53),and the reciprocal cross with P.simonii×P.nigra as the maternal parent and P.ussuriensis as the paternal parent(HY268).Using 3-month-old rooted cuttings from 40 clones(36 F1 hybrids and their parents)growing in a greenhouse,we measured and analyzed 14 leaf morphological traits to assess genetic variation and heterosis.The results showed HY53 clones generally exhibited greater average height than HY268 clones.Leaf phenotypes differed between the two hybrid combinations,with significant differences observed among parents and offspring for almost all traits,as revealed by analysis of variance(ANOVA).The phenotypic coefficient of variation was higher in HY268 clones.Additionally,leaf traits demonstrated high repeatability.Notably,some hybrid offspring exhibited positive or negative mid-parent heterosis,as well as over-parent heterosis for certain leaf phenotypes.The systematic cluster analysis further indicated distinct separation among HY268 clones.This research provides valuable materials for poplar breeding and offers insights into hybrid vigor in wood plants.The findings highlight the importance of reciprocal crossing in influencing leaf phenotype variation and heterosis,offering practical insights for future breeding strategies.展开更多
Heterosis has been widely utilized in agricultural production.Despite over a century of extensive research,the underlying mechanisms of heterosis remain elusive.Most hypotheses and research have focused on the genetic...Heterosis has been widely utilized in agricultural production.Despite over a century of extensive research,the underlying mechanisms of heterosis remain elusive.Most hypotheses and research have focused on the genetic basis of heterosis.However,the potential role of gut microbiota in heterosis has been largely ignored.Here,we carefully design a crossbreeding experiment with two distinct broiler breeds and conduct 16S rRNA amplicon and transcriptome sequencing to investigate the synergistic role of gut microbiota and host genes in driving heterosis.We find that the breast muscle weight of hybrids exhibits a high heterosis,6.28%higher than the mid-parent value.A notable difference is observed in the composition and potential function of cecal microbiota between hybrids and their parents.Over 90%of differentially colonized microbiota and differentially expressed genes exhibit nonadditive patterns.Integrative analyses uncover associations between nonadditive genes and nonadditive microbiota,including a connection between the expression of cellular signaling pathways and metabolism-related genes and the abundance of Odor-ibacter,Oscillibacter,and Alistipes in hybrids.Moreover,higher abundances of these microbiota are related to better meat yield.In summary,these findings highlight the importance of gut microbiota in heterosis,serving as crucial factors that modulateheterosis expression in chickens.展开更多
Heterosis has been exploited to enhance the yield and adaptability in various shellfish species;however,the molecular basis of it remains unclear.The Pacific oyster Crassostrea gigas is one of the most economically im...Heterosis has been exploited to enhance the yield and adaptability in various shellfish species;however,the molecular basis of it remains unclear.The Pacific oyster Crassostrea gigas is one of the most economically important aquaculture species,and its productive traits can be improved by hybridization.Here,an intraspecific cross between orange shell(O,10th generation)and‘Haida No.1’(H,13th generation)of C.gigas was performed to assess the heterosis of survival trait.Survival rates of hybrid family(OH)and inbred families(HH and OO)were compared at larval stage,and eyed-pediveliger larvae of three families were subjected to transcriptome analysis.The analysis results of best-parent heterosis and mid-parent heterosis showed that the hybrid family exhi-bited a high heterosis in survival relative to the parental families.The OH-M(OH vs.OO)and OH-P(OH vs.HH)had 425 and 512 dif-ferentially expressed genes(DEGs),respectively.Functional enrichment analysis of these DEGs revealed that the significantly enrich-ed genes function in virion binding,C-type lectin receptor signaling pathway,cellular defense response and other immune-related pro-cesses,which involves perlucin-like protein,CD209 antigen-like protein,ZNFX1,caspase-3 and acan genes.These differentially ex-pressed genes in OH-M and OH-P,together with the immune-related processes mentioned above may play an important role in the larval survival of C.gigas.In addition,three genes(CYP450,fucolectin and perlucin-like)are associated with the orange shell and low survival of maternal oyster OO.These findings provide support for the application of hybrid with superior survival and will facilitate the understanding of heterosis formation in the Pacific oyster.展开更多
Despite hybrid dominance contributing to the genetic improvement of crops,little is known about heterosis and inheritance patterns of endogenous substances in sorghum(Sorghum bicolor(L.)Moench)root bleeding sap.In thi...Despite hybrid dominance contributing to the genetic improvement of crops,little is known about heterosis and inheritance patterns of endogenous substances in sorghum(Sorghum bicolor(L.)Moench)root bleeding sap.In this study,six sterile and six restorer lines of sorghum and 36 hybrid sorghum combinations formulated as incomplete double-row crosses were selected as test materials,and heterosis,combining ability,heritability,and their interrelationships of root bleeding sap endogenous substances in different hybrid sorghum combinations and their parents were investigated.The results showed that the root bleeding sap of the F1 generation of hybrid sorghum had a high heterosis in both soluble sugar content and amino acid content at the flowering stage,and the average high-parent heterosis was 129.34%and 74.57%,respectively.Indole-3-acetic acid(IAA),cytokinins(CTK),gibberellic acid(GA_(3)),abscisic acid(ABA),soluble sugar,amino acid,and root bleeding intensity were mainly affected by non-additive genetic effects of the genes.Soluble protein was affected by additive genetic effects of the genes and had a high narrow heritability(75.50%),which could be selected at low generations in breeding.The combining ability analyses showed that the sterile lines 521A and 170A,and the restorer lines Ji318R and 0–30 were promising parents with high general combining ability.Correlation analysis showed that all endogenous substances of root bleeding sap were positively correlated with the sum of parental general combining ability(GCA)at highly significant levels,and IAA,CTK,GA_(3),ABA,soluble sugar,amino acid,and root bleeding intensity were positively correlated with male GCA at significant or highly significant levels.Therefore,the GCA of the restorer lines root bleeding sap endogenous material or the sum of both parents’GCA can be used to predict the performance of wounding endogenous material in the F1 generation of hybrid sorghum.Overall,this study results can help elucidate heterosis mechanisms of root bleeding sap endogenous material and improve sorghum quality.展开更多
[Objective]The aim was to study heterosis of N use efficiency for grain production （NUEg） of Brassica napus L. and provide theoretical basis for breeding N-efficient cultivars. [Method]Dry matter production and N co...[Objective]The aim was to study heterosis of N use efficiency for grain production （NUEg） of Brassica napus L. and provide theoretical basis for breeding N-efficient cultivars. [Method]Dry matter production and N content of six B.napus parents （Zheshuang 3,Yangyou 7,ZJ1,Shilijia,Ningyou 14 and Huyou 16） and their F1 combinations from 6 × 6 complete diallel cross in maturity stage under two N levels were measured; heterosis of NUEg,combining ability and heritability size were analyzed and calculated. [Result]The results showed that NUEg has obvious heterosis; combining ability variance analysis indicated that NUEg was mainly controlled by additive,dominant and cytoplasmic effects; genetic variance analysis showed that additive effects and dominance effects were all significant in low nitrogen fertilizer and dominance effects were significant in high nitrogen fertilizer. [Conclusion]NUEg of B.napus has obvious heterosis.展开更多
[Objective] This study aimed to investigate the genetic effects and heterosis of plant height and internode traits of japonica-indica hybrid rice. [Methed] Incomplete diallel crosses were made between six japonica CMS...[Objective] This study aimed to investigate the genetic effects and heterosis of plant height and internode traits of japonica-indica hybrid rice. [Methed] Incomplete diallel crosses were made between six japonica CMS lines and nine indica widecompatibility restorer lines; the genetic effects of plant height and internode traits of japonica-indica hybrid rice were analyzed using the additive-dominance genetic model. [Result] The ple, nt height, panicle length and the length of internode 1 of japonica-in- dica hybrid rice were mainly controlled by the additive effects; but the length of in- ternode 3, internode 4 and internode 5 were mainly controlled by dominance effects. Both the narrow sense heritability and broad sense heritability of plant height, panicle length, number of elongated internodes and length of most internodes reached signifi- cance level. The positive phenotypic correlation, genetic correlation, additive correla- tion and dominance correlation between plant height and panicle length, number of e- longated internodes and internode length were significant; and most of the other paired traits were significantly positively correlated. Heterosis analysis showed that the positive heterosis value over mid-parent and positive heterosis value over better- parent of the length of internode 3, internode 4, internode 5 and internode 6 reached significant level, and the heterosis value over mid-parent of plant height reached extreme significance level. [Conclusion] This study will provide reliable theoretical basis for the genetic improvement and heterosis utilization of plant height and internode traits in japonica-indica hybrid rice.展开更多
Upon the analogy of definition of heterosis and inbreeding depresstion in terms of population genetics, the heterosis is thought to be evaluated overall with fitness. By establishing a mathematical model, the equilibr...Upon the analogy of definition of heterosis and inbreeding depresstion in terms of population genetics, the heterosis is thought to be evaluated overall with fitness. By establishing a mathematical model, the equilibrium status of three genotypes of random mating population （i. e. RR, Rr and rr） under different fitness, which exposes that heterosis is the precondition for multiallele to exist in the population. The heterosis protects the genetic diversity and makes the population owning a stronger self-control and evolution potential by improving the hetemzygote＇s fithess so as not to wash out different types of genes. It deepens Darwin＇s thoughts of individual section by making the individual fitness consonant with population fitness.展开更多
[Objective] This study aimed to predict the heterosis of hot pepper using SSR genetice distance. [Method] Twenty-five hybridized combinations between 10pepper parents were obtained through NCⅡ incomplete diallel cros...[Objective] This study aimed to predict the heterosis of hot pepper using SSR genetice distance. [Method] Twenty-five hybridized combinations between 10pepper parents were obtained through NCⅡ incomplete diallel cross to analyze the relationship between SSR genetic distance and heterosis. [Result] The genetic distance of the parents varied in a range from 0.13 to 0.33, and the average genetic distance was 0.25, indicating that the genetic difference was not obvious among the parents, namely, they shared a close genetic relationship. In addition, the SSR genetic distance was closely related to yield per plant and fruits per plant, but showed no obvious correlation with other traits. [Conclusion] This study proved that in a certain range the combinations between the parents with a distant genetic distance possessed stronger heterosis and a larger possibility to produce a high yield and vice versa.展开更多
To compare the heterosis levels among various groups of parental lines used extensively in China, identify foundational heterotic groups in parental pools and understand the relationship between genetic distance and h...To compare the heterosis levels among various groups of parental lines used extensively in China, identify foundational heterotic groups in parental pools and understand the relationship between genetic distance and heterosis performance, 16 parental lines with extensive genetic variation were selected from various sub-groups, and 39 hybrid combinations were generated and evaluated in Fujian and Hainan Provinces of China. The main results were as follows： （1） The 16 parental lines can be grouped into 7 sub-groups consisting of 1 maintainer sub-group and 6 restorer sub-groups; （2） Mean grain yield of the restorer lines was higher than that of the maintainer lines, and mean yield of parental lines was higher than that of the hybrid combinations; （3） The two best heterotic patterns were II-32A × G5 and II-32A × G6, moreover, the order of restorer sub-groups according to grain yield, from the highest to lowest, was G7, G6, G5, G4, G3 and G2; High specific combining ability values were observed for combinations of II-32A × G5, II-32A × G6 and Tianfeng A × G7; （4） Hybrid combinations derived from II-32A crossed with 13 restorer lines had higher yield trait values （mid-parent heterosis, better-parent heterosis, standard heterosis over check and specific combining ability） than any other combinations; （5） Genetic distance was positively correlated with panicle number, grain length and length-to-width ratio （P 〈 0.05） and negatively correlated with grain width, grain yield, seed-setting rate, as well as mid-parent heterosis, standard heterosis over check, and specific combining ability for grain yield （P 〈 0.01）. These heterotic groups and patterns and their argonomic traits will provide useful information for future hybrid rice breeding programs.展开更多
This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability.The reason is that general combining ability changes with the number and kind of pure strains in...This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability.The reason is that general combining ability changes with the number and kind of pure strains in the foundation stock and hence special combining ability changes also,so that work with different kinds of pure strains in the foundation stock cannot be compared.Hence combining ability is useless as a parameter to predict the amount of heterosis expected in the next generation.On the other hand,since each cross has a separate heritability,it can be applied to a cross population just as successfully as in purebreeding.Since the same concept holds in both cases,resort to any other concept would be superfluous.That's why combining ability must be rejected.Another reason(not given in the full text)is,an infinite number of pure strains would be required in the foundation stock for its results to be comparable with those of the heritability theory,which disposes of its utility altogether.The main content of the thesis is then the centennial enigma of heterosis can be resolved by Descarte's theoretic method of deduction.Accordingly we start from the definition of heterosis.H=F¡-MP,where H is heterosis,F,is the first generation offspring,MP is the mean of the parents or midparent,and from the use of a binomial random variable and its extention to the multinomial case derive the basic relations of heterosis with its components.Starting with second degree statistics,we obtain Vn=Vr,-2cov(F,,MP)+Vup,where V and cov stand for variance and covariance.The equations of heterosis are v„=(1/2)Na²+(1/4)Nd’+Vr(F,)=additive dominance F,epistasis Vup=(1/2)Na’+(1/2)V1,additive parental epistasis V„=(1/4)Nd’+V(F)+(1/2)V1,dominance F,epistasis parental epistasis.where N is number of genes controlling a trait,a=(P1-P,)12,d is deviation from midparent,while the variance components are all indicated by their names under the repective terms.It turns out that all these can be easily computed from the data so that the problem becomes a simple one which any college student may solve.In other words,the right answers are found when the right questions are asked.Who had ever shown that the heritability principle is inapplicable in crossbreeding,e.g.,in a crossing of two pure strains?From this cue arose the realization that the F,of a cross of two pure strains must also be a Mendelian population,with p and q both equal to 1/2 which simplifies the algebra outright.This Heritability Theory of Heterosis,or HTH in capital letters,re-sts on 2 initial anguments:1)Since 0.5+0.5=1,crossing two pure strains gives a population which is only a special case of pure-breeding,thereforea heritability coefficient must exist for the F1;2)Our problem reduces to that of finding that coefficient;the an-swer is given by the additive component divided by Ve.,i.e.,(1/2)No'1 Vp..which is readily found from the solution of the het-erosis equations.Thus the elemnal enigma of heterosis is resolved!This happened at the end of the 20th century.We now come to the second point of the discovery,the new genetic parameter crossheritability which will rise in size with the increase of the number of times it's used and form the link between breeding and evolution.The advent of the Age of Evolution Engineering in the 21st century marks a totally new era,showing that artificial will ultimately supercede natural selection,with the long span of time element eliminated.For agriculture at least,it means there is no limit to the increase of food supply by the new method,with the concentra-tion of desirable genes by hybridization in place of the old theory of their fixation.Genetic gain is achieved through artificial selec-tion,with an 80%saving of time,labor and cost by adoption of the new method.Applied to a further increase in all kinds of agri-cultural products including hybrd rice,it means that a huge eacalation,in fact a New Green Revolution,on a much langer scale than that of any such before,is in view,provided it is adopted in our research and educational institutions as early as possible,ere its spread elsewhere.The possibilities from the evolution point of view can only be pictured by science fiction.展开更多
[Objective] This study aimed to investigate the genetic diversity of Macheng black goat and its correlation with heterosis.[Method] Ten microsatellite markers were selected for polymorphism investigation and statistic...[Objective] This study aimed to investigate the genetic diversity of Macheng black goat and its correlation with heterosis.[Method] Ten microsatellite markers were selected for polymorphism investigation and statistical analysis of Boer goat and Macheng black goat populations.[Result] The results showed that totally 175 alleles were found in 10 microsatellite loci; to be specific,the maximum number of detected alleles was 23,and the minimum number was 10; the effective number of alleles （Ne） was 6.4-18.1,with absolute difference value of 1.6-8.1 from the observed number of alleles.The highest gene frequency was 0.239 1 and the lowest was 0.002 7.The polymorphic information contents of all the ten microsatellite markers were above 0.95.The observed heterozygosity （Ho） ranged from 0.616 7 to 0.984 4 and the expected heterozygosity （He） ranged from 0.844 1 to 0.944 6.The average expected heterozygosity of Boer goat and Macheng black goat was respectively 0.894 0 and 0.906 7.Various body weight and body size indices of Boer goatxMacheng black goat hybrids were improved in varying degrees compared with Macheng black goat （with an increase range of 0.32％-30.06％）.The average heterosis rates of body height and chest girth were relatively high,while average heterosis rate of body weight was relatively low.[Conclusion] The genetic distance between Boer goat and Macheng black goat was 0.379 5,which is consistent with the geographical distribution of Boer goat and Macheng black goat populations and is fully relevant to the heterosis of Boer goat × Macheng black goat hybrids,indicating that investigating polymorphism via microsatellite loci is one of the feasible means to predict and analyze heterosis between varieties.展开更多
The embryo, cytoplasmic, and maternal heterosis for erucic acid content （EAC） and glucosinolate content （GLS） of rapeseed （Brassica napus L.） were studied by using the genetic models for quantitative traits of s...The embryo, cytoplasmic, and maternal heterosis for erucic acid content （EAC） and glucosinolate content （GLS） of rapeseed （Brassica napus L.） were studied by using the genetic models for quantitative traits of seeds in diploid crops. Eight parents were included in a diallel mating design in two years. It was found that the heterosis of EAC and GLS was simultaneously controlled by genetic main effects and genotype×environment （GE） interaction effects. The general heterosis of most crosses for EAC was significantly positive, while it was not for GLS. The general heterosis was more important for two quality traits of rapeseed because of the low GE interaction heterosis in both years, especially for GLS. Among different genetic systems, significant positive embryo general heterosis and the negative maternal general heterosis were found for EAC and GLS in most hybrid crosses. Some hybrids with significant negative interaction heterosis were detected for either of EAC or GLS. In general, maternal general and interaction heterosis was more important for reducing EAC and GLS of rapeseed.展开更多
Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selec...Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.展开更多
F1 potassium heterosis of 8 flue-cured tobacco varieties and 6 self-bred high-potassium new strains were studied. The results showed that the F1 mean het- erosis of potassium content had differences between different ...F1 potassium heterosis of 8 flue-cured tobacco varieties and 6 self-bred high-potassium new strains were studied. The results showed that the F1 mean het- erosis of potassium content had differences between different parts of plants, showing B2F （8.45%）〉X2F （7.59%）〉C3F （5.64%）; the F1 over-parent heterosis of potassium content of various parts was not obvious, showing X2F （0.05%）〉C3F （-0.43%） 〉B2F （-0.48%）; the F, control heterosis of potassium content of different parts showed B2F （17.81%）〉X2F （4.06%）〉C3F （1.12%）. The variance of GCA of potassium content in various parts of the 6 self-bred high-potassium new strains was significant or extremely significant, and all leaves of GK2 had greater GCA effect on potassium content; C3F and X2F of GK7 had good GCA effect on potassium con- tent, but GCA effect was bad in B2F; GK9 preformed well in B2F but badly in C3F. The variance of SCA in all combinations was extremely significant, and the good combinations included Duoye 87xGK7 （17.19%） in B2F, Duoye 87xGK2 （25.63%）, ChangbohuangxGK5 （19.43%）, Yunyan 87xGK7 （22.78%）, and Yunyan 87xGK9 （24.38%） in C3F, Coker176xGK7 （19.87%）, 101xGK9 （15.89%）, Yunyan 85xGK9 （19.15%）, and Yunyan 87xGK9 （20.74%） in X2F.展开更多
Maize （Zea raays L.） is one of the most important crops because of the remarkable properties of its hybrid, which is responsible for the high commercial value of hybrid maize. The genetic basis of heterosis （hybrid...Maize （Zea raays L.） is one of the most important crops because of the remarkable properties of its hybrid, which is responsible for the high commercial value of hybrid maize. The genetic basis of heterosis （hybrid vigor） is not well understood. A differential display technique was performed to identify genes with differential expression across twelve maize inbred lines and thirty-three hybrids during ear development. An incomplete diallel design was used to investigate the relationship between the global framework of differential gene expression and heterosis. It was found that the genes belonging to MONO pattern （i.e., genes expressed in both parental lines and in hybrid） was the highest in percentage among the total five patterns and illustrated that the properties of differentially expressed genes are not entirely responsible for heterosis. Furthermore,a larger number of differentially expressed genes in hybrid, which serves as a major reservoir for generating novel phenotypes that exhibit heterosis of certain agronomic traits during early development and differentiation of maize ear. Moreover, there were some silent genesin hybrids that are responsible for the arrest or abortion of spikelets and for the increase in kernels weight.展开更多
基金supported by the National Key Resarch and Development Program of China(Grant No.2023YFD1200802)the Base Bank of Lingnan Rice Germplasm Resources Project,China(Grant No.2024B1212060009).
文摘Polyploidization is a commonly employed strategy in crop breeding to augment genetic diversity,particularly leveraging the distinctive benefits of additional progressive heterosis or multi-generation heterosis unique to polyploidy.Despite genetic disparities between polyploids and diploids,challenges stem from reproductive anomalies,complicating genetic investigations in polyploid systems.Through nearly two decades of intensive research,our team has effectively generated a series of fertile tetraploid lines known as neo-tetraploid rice(NTR),facilitating comparative genetic studies between diploid and tetraploid rice.In this study,we identified diploid counterparts(H3d and H8d)for two NTR lines[Huaduo 3(H3)and Huaduo 8(H8)]and utilized them to create diploid and tetraploid fertile F_(2) populations to assess genotype segregation ratios,recombination rates,and their impact on QTL mapping via bulked segregant analysis combined with sequencing(BSA-seq).Additionally,we assessed yield heterosis in F_(1) and F_(2) generations of two tetraploid populations(H3×H8 and T449×H1),revealing evidence of multi-generation heterosis in polyploid rice.These findings provide valuable insights into the advantages and challenges of polyploid rice breeding.
基金funded by the National Natural Science Foundation of China(32172721)the China Agriculture Research System(CARS-40)+1 种基金the Central Publicinterest Scientific Institution Basal Research Fund,China(2021-YWF-ZYSQ-12)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(ASTIP-IAS04)。
文摘Sexual maturation heterosis has been widely exploited in animal crossbreeding.However,the underlying mechanism has been rarely explored in chicken.In the present study,we performed the reciprocal crossing between White Leghorn and Beijing You chicken to evaluate the phenotypes related to sexual maturation,and profiled the ovary circRNAs of purebreds(WW,YY)and crossbreds(WY,YW)to elucidate the molecular mechanism underlying heterosis for sexual maturation.Pubic space and oviduct length exhibited positive heterosis,and age at first egg(AFE)exhibited negative heterosis in the crossbreds.We identified 3,025 known circRNAs and 624 putative circRNAs,which were mainly derived from the exons.Among these circRNAs,141 and 178circRNAs were specially expressed in WY and YW,respectively.There were 52.38 and 64.63%of total circRNAs in WY and YW exhibited non-additive expression pattern,respectively.GO enrichment and KEGG pathway analysis showed that the host genes of non-additive circRNAs were mainly involved in TGF-beta signaling pathway,oocyte development,ATPase activator activity,oocyte meiosis,progesterone-mediated oocyte maturation and GnRH signaling pathway.Weighted gene co-expression network analysis identified that 4 modules were significantly(P<0.05)correlated with oviduct length and pubic space.The host genes of non-additive circRNAs harbored in the 4 modules were associated with MAPK signaling pathway and Wnt signaling pathway.Furthermore,competing endogenous RNAs(ceRNA)network analysis characterized non-additive circRNAs gal-FGFR2_0005 and galMAPKAP1_0004 could interact with gga-miR-1612 and gga-miR-12235-5p to regulate CNOT6,COL8A1,and FHL2,which were essential for ovary development,indicating that the non-additive circRNAs involved in the formation of sexual maturation heterosis through regulating genes related to the reproductive and developmental process.The findings would provide a deeper understanding of the molecular mechanism underlying sexual maturation heterosis from a novel perspective.
基金supported by the grants from National Natural Science Foundation of China(32302724 to Jingwei Yuan)the China Agriculture Research System of MOF and MARA(CARS-40 to Yanyan Sun)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences(ASTIP-IAS16 to Jilan Chen)。
文摘Background Crossbreeding is widely promoted as an efficient strategy to improve the productivity in agriculture.The molecular mechanism underlying heterosis for egg production is always intriguing in chicken.The transcriptional dynamic changes play a crucial role in the formation of heterosis,but little is known for the egg production traits.Results In present study,we measured the continuous manifestation of heterosis ranging from 2.67%to 10.24%for egg number in the crossbreds generated by reciprocal crossing White Leghorn and Beijing You chicken.The high-quality transcriptomes of ovary for purebreds(WW and YY)and crossbreds(WY and YW)in 5 laying stages were sequenced and integrated to identify regulatory networks relevant to the heterosis.We found highly conserved transcriptional features among 4 genetic groups.By using weighted gene co-expression network analysis(WGCNA),we obtained multiple gene co-expression modules that were significantly correlated with egg number for each group.The common KEGG pathways including apelin signaling pathway,cell cycle,ribosome,spliceosome and oxidative phosphorylation,were screened for the 2 crossbreds.Then,we identified consensus co-expression modules(CMs)that showed divergent expression pattern among crossbred(WY or YW)and purebreds(WW and YY).The hub genes of CMs were again overrepresented in the cell cycle pathway,and the crossbreds exhibited temporally complementary dominance of hub genes in the 5 laying stages.These results suggested that the crossbreds inherited from both parents to maintain the ovary function by cell cycle-related genes,contributing to the persistent heterosis for egg production.Furthermore,the dominant genes including MAD2L1,CHEK2 and E2F1 were demonstrated to function in ovarian follicle development and maturation and could be the candidate genes for egg production heterosis.Conclusion Our study characterized the dynamic profile of genome-wide gene expression in ovary and highlighted the role of dominant expression of cell cycle pathway genes in heterosis.These findings provided new insights for the molecular mechanism of egg production heterosis,which would facilitate the rational choice of suitable parents for producing crossbred chickens with higher egg production.
基金sponsored by the the Outstanding Young Scientific and Technological Talents Foundation of Dalian(No.2024RJ014)the Research Project of Liaoning Provincial Department of Education(No.LJ212410158027)+1 种基金the Research Projects of Undergraduate Universities in Liaoning Province(No.2024JBZDZ003)the Liaoning Revitalization Talents Program(No.XLYC2403165).
文摘In order to cultivate Manila clam varieties in northern China,we crossed the Dalian wild population(referred to as D)and the Weihai wild population(referred to as W)to create a 2×2 complete diallel hybrid.Ultimately,we obtained two hybrid groups(D♀×W♂(DW)and W♀×D♂(WD))and two inbred groups(D♀×D♂(DD)and W♀×W♂(WW)).We measured their growth and survival during the larval and juvenile stages and compared the data between hybrid and inbred groups to study the potential heterosis of the hybrid.With the exception of slightly lower values in the WD group,fertilization and hatching rates did not differ significantly among the other groups.However,during the larval stage(days 1–15),we observed significant differences in the growth rate of Manila clam in the hybrid groups at days 1,3,and 6 of age(P<0.05).Among the groups,the clams in the DW group had the highest survival rate,which was indicative of significant heterosis.After entering the juvenile stage(days 30–120),both hybrid groups showed high heterosis in terms of growth and survival.The DW group had the greatest amount of heterosis for survival performance,and the WD group had the greatest amount of heterosis for shell length and height growth.These results indicated that this hybrid combination had great breeding potential,and provided a useful hybrid strategy for producing genetic improvements in R.philippinarum.
基金supported by grants from the Jiangsu Seed Industry Revitalization Project[Grant No.JBGS(2021)071]Key Technology R&D Program of Jiangsu Province(Grant No.BE2023366)+3 种基金National Natural Science Foundation of China(Grant No.32172579)the earmarked fund for Jiangsu Agricultural Industry Technology System[Grant No.JATS(2023)421]the Fundamental Research Funds for the Central Universities(Grant No.YDZX2023019)the Project Founded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Heterosis,a crucial biological phenomenon,plays a vital role in determining the yield and quality of plants.Radish,an important root vegetable crop,exhibits notable heterosis in terms of root yield and quality.Nevertheless,the molecular mechanism underlying the formation of heterosis in radish remains unclear.Herein,both the transcriptome and DNA methylome analyses were performed on the F_(1)hybrids and parental lines.Expression level dominance(ELD)genes and allele-specific expression(ASE)genes together significantly contribute to heterosis,primarily through energy metabolism and plant hormone signal transduction pathway.An increase in average methylation level in the F_(1)hybrids was observed compared to the parental lines.Interestingly,a negative correlation was found between the methylation level of differentially expressed genes(DEGs)in gene body regions and their expression levels in NAU-LB and the F_(1)hybrids.Moreover,the hybrids were more sensitive to the 5-azacytidine than their parents,and the root weight and total sugar content in the F_(1)hybrids were dramatically decreased compared to the control.Immunolocalization results indicated that the auxin content of the F_(1)hybrids were reduced under 5-azacytidine treatment.Proliferating cell nuclear antigen immunolocalization revealed significant inhibition of vascular cambium activity in both the hybrids and parental lines.Notably,the expression profiles of a few differentially methylated DEGs including RsSUS1,RsSUC2a,RsIAA7,and RsIAA18,were significantly increased in the root of hybrids compared to their parents,suggesting a potential role of DNA methylation in yield heterosis.Collectively,these findings would provide valuable insight into the molecular mechanism underlying taproot yield heterosis and facilitate the genetic improvement of taproot yield and quality in radish breeding programs.
基金supported by“National Key R&D Program of China(2021YFD2200203)”“the Fundamental Research Funds for the Central Universities(No.2572022AW02 and No.2572023CT19)”。
文摘Hybridization remains an important method for breeding new poplar varieties.It results in significant variation in leaf phenotype among parents and offspring,and among offspring themselves.This study aimed to investigate whether leaf shape variations were similar in offspring produced from reciprocal crosses.Specifically,two hybrid combinations were produced:the direct cross with Populus ussuriensis as the maternal parent and P.simonii×P.nigra as the paternal parent(HY53),and the reciprocal cross with P.simonii×P.nigra as the maternal parent and P.ussuriensis as the paternal parent(HY268).Using 3-month-old rooted cuttings from 40 clones(36 F1 hybrids and their parents)growing in a greenhouse,we measured and analyzed 14 leaf morphological traits to assess genetic variation and heterosis.The results showed HY53 clones generally exhibited greater average height than HY268 clones.Leaf phenotypes differed between the two hybrid combinations,with significant differences observed among parents and offspring for almost all traits,as revealed by analysis of variance(ANOVA).The phenotypic coefficient of variation was higher in HY268 clones.Additionally,leaf traits demonstrated high repeatability.Notably,some hybrid offspring exhibited positive or negative mid-parent heterosis,as well as over-parent heterosis for certain leaf phenotypes.The systematic cluster analysis further indicated distinct separation among HY268 clones.This research provides valuable materials for poplar breeding and offers insights into hybrid vigor in wood plants.The findings highlight the importance of reciprocal crossing in influencing leaf phenotype variation and heterosis,offering practical insights for future breeding strategies.
基金This work was supported by the National Key Research and Development Program of China(2022YFF1000204)the National Natural Science Foundation of China(32102535)+1 种基金the Key Research and Development Program of Hainan province(ZDYF2023XDNY036)the Guangxi Science and Technology Major Program(GK AA23062049).
文摘Heterosis has been widely utilized in agricultural production.Despite over a century of extensive research,the underlying mechanisms of heterosis remain elusive.Most hypotheses and research have focused on the genetic basis of heterosis.However,the potential role of gut microbiota in heterosis has been largely ignored.Here,we carefully design a crossbreeding experiment with two distinct broiler breeds and conduct 16S rRNA amplicon and transcriptome sequencing to investigate the synergistic role of gut microbiota and host genes in driving heterosis.We find that the breast muscle weight of hybrids exhibits a high heterosis,6.28%higher than the mid-parent value.A notable difference is observed in the composition and potential function of cecal microbiota between hybrids and their parents.Over 90%of differentially colonized microbiota and differentially expressed genes exhibit nonadditive patterns.Integrative analyses uncover associations between nonadditive genes and nonadditive microbiota,including a connection between the expression of cellular signaling pathways and metabolism-related genes and the abundance of Odor-ibacter,Oscillibacter,and Alistipes in hybrids.Moreover,higher abundances of these microbiota are related to better meat yield.In summary,these findings highlight the importance of gut microbiota in heterosis,serving as crucial factors that modulateheterosis expression in chickens.
基金supported by the grants from the China Agriculture Research System Project(No.CARS-49)the Earmarked Fund for Agriculture Seed Improvement Project of Shandong Province(No.2020LZGC016).
文摘Heterosis has been exploited to enhance the yield and adaptability in various shellfish species;however,the molecular basis of it remains unclear.The Pacific oyster Crassostrea gigas is one of the most economically important aquaculture species,and its productive traits can be improved by hybridization.Here,an intraspecific cross between orange shell(O,10th generation)and‘Haida No.1’(H,13th generation)of C.gigas was performed to assess the heterosis of survival trait.Survival rates of hybrid family(OH)and inbred families(HH and OO)were compared at larval stage,and eyed-pediveliger larvae of three families were subjected to transcriptome analysis.The analysis results of best-parent heterosis and mid-parent heterosis showed that the hybrid family exhi-bited a high heterosis in survival relative to the parental families.The OH-M(OH vs.OO)and OH-P(OH vs.HH)had 425 and 512 dif-ferentially expressed genes(DEGs),respectively.Functional enrichment analysis of these DEGs revealed that the significantly enrich-ed genes function in virion binding,C-type lectin receptor signaling pathway,cellular defense response and other immune-related pro-cesses,which involves perlucin-like protein,CD209 antigen-like protein,ZNFX1,caspase-3 and acan genes.These differentially ex-pressed genes in OH-M and OH-P,together with the immune-related processes mentioned above may play an important role in the larval survival of C.gigas.In addition,three genes(CYP450,fucolectin and perlucin-like)are associated with the orange shell and low survival of maternal oyster OO.These findings provide support for the application of hybrid with superior survival and will facilitate the understanding of heterosis formation in the Pacific oyster.
基金funded by the Jilin Province Science and Technology Development Plan Project(20210202001NC)of Ziyang Zhouthe Jilin Agricultural Science and Technology Innovation Project(CXGC2021TD011)of Ziyang Zhou。
文摘Despite hybrid dominance contributing to the genetic improvement of crops,little is known about heterosis and inheritance patterns of endogenous substances in sorghum(Sorghum bicolor(L.)Moench)root bleeding sap.In this study,six sterile and six restorer lines of sorghum and 36 hybrid sorghum combinations formulated as incomplete double-row crosses were selected as test materials,and heterosis,combining ability,heritability,and their interrelationships of root bleeding sap endogenous substances in different hybrid sorghum combinations and their parents were investigated.The results showed that the root bleeding sap of the F1 generation of hybrid sorghum had a high heterosis in both soluble sugar content and amino acid content at the flowering stage,and the average high-parent heterosis was 129.34%and 74.57%,respectively.Indole-3-acetic acid(IAA),cytokinins(CTK),gibberellic acid(GA_(3)),abscisic acid(ABA),soluble sugar,amino acid,and root bleeding intensity were mainly affected by non-additive genetic effects of the genes.Soluble protein was affected by additive genetic effects of the genes and had a high narrow heritability(75.50%),which could be selected at low generations in breeding.The combining ability analyses showed that the sterile lines 521A and 170A,and the restorer lines Ji318R and 0–30 were promising parents with high general combining ability.Correlation analysis showed that all endogenous substances of root bleeding sap were positively correlated with the sum of parental general combining ability(GCA)at highly significant levels,and IAA,CTK,GA_(3),ABA,soluble sugar,amino acid,and root bleeding intensity were positively correlated with male GCA at significant or highly significant levels.Therefore,the GCA of the restorer lines root bleeding sap endogenous material or the sum of both parents’GCA can be used to predict the performance of wounding endogenous material in the F1 generation of hybrid sorghum.Overall,this study results can help elucidate heterosis mechanisms of root bleeding sap endogenous material and improve sorghum quality.
基金Supported by Agricultural Science &Technology Project of Jiangsu Province(BE2008369)~~
文摘[Objective]The aim was to study heterosis of N use efficiency for grain production （NUEg） of Brassica napus L. and provide theoretical basis for breeding N-efficient cultivars. [Method]Dry matter production and N content of six B.napus parents （Zheshuang 3,Yangyou 7,ZJ1,Shilijia,Ningyou 14 and Huyou 16） and their F1 combinations from 6 × 6 complete diallel cross in maturity stage under two N levels were measured; heterosis of NUEg,combining ability and heritability size were analyzed and calculated. [Result]The results showed that NUEg has obvious heterosis; combining ability variance analysis indicated that NUEg was mainly controlled by additive,dominant and cytoplasmic effects; genetic variance analysis showed that additive effects and dominance effects were all significant in low nitrogen fertilizer and dominance effects were significant in high nitrogen fertilizer. [Conclusion]NUEg of B.napus has obvious heterosis.
基金Supported by National High Technology Research and Development Program of China(863Program,2010AA101301)Chinese Super Rice Breeding and Experiment Demonstration Program,Ministry of Agriculture+1 种基金the 0406 Program of zhejiang ProvinceScientific Research Fund of China National Rice Research Institute(2009RG001-5)~~
文摘[Objective] This study aimed to investigate the genetic effects and heterosis of plant height and internode traits of japonica-indica hybrid rice. [Methed] Incomplete diallel crosses were made between six japonica CMS lines and nine indica widecompatibility restorer lines; the genetic effects of plant height and internode traits of japonica-indica hybrid rice were analyzed using the additive-dominance genetic model. [Result] The ple, nt height, panicle length and the length of internode 1 of japonica-in- dica hybrid rice were mainly controlled by the additive effects; but the length of in- ternode 3, internode 4 and internode 5 were mainly controlled by dominance effects. Both the narrow sense heritability and broad sense heritability of plant height, panicle length, number of elongated internodes and length of most internodes reached signifi- cance level. The positive phenotypic correlation, genetic correlation, additive correla- tion and dominance correlation between plant height and panicle length, number of e- longated internodes and internode length were significant; and most of the other paired traits were significantly positively correlated. Heterosis analysis showed that the positive heterosis value over mid-parent and positive heterosis value over better- parent of the length of internode 3, internode 4, internode 5 and internode 6 reached significant level, and the heterosis value over mid-parent of plant height reached extreme significance level. [Conclusion] This study will provide reliable theoretical basis for the genetic improvement and heterosis utilization of plant height and internode traits in japonica-indica hybrid rice.
文摘Upon the analogy of definition of heterosis and inbreeding depresstion in terms of population genetics, the heterosis is thought to be evaluated overall with fitness. By establishing a mathematical model, the equilibrium status of three genotypes of random mating population （i. e. RR, Rr and rr） under different fitness, which exposes that heterosis is the precondition for multiallele to exist in the population. The heterosis protects the genetic diversity and makes the population owning a stronger self-control and evolution potential by improving the hetemzygote＇s fithess so as not to wash out different types of genes. It deepens Darwin＇s thoughts of individual section by making the individual fitness consonant with population fitness.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(200903025)Key Technologies Research and Development Program of Guizhou Province[(2011)3028+2 种基金(2011)3029]Special Fund of Guizhou Academy of Agricultural Sciences[(2009)018]Special Fund of Guizhou Province[(2012)2195]~~
文摘[Objective] This study aimed to predict the heterosis of hot pepper using SSR genetice distance. [Method] Twenty-five hybridized combinations between 10pepper parents were obtained through NCⅡ incomplete diallel cross to analyze the relationship between SSR genetic distance and heterosis. [Result] The genetic distance of the parents varied in a range from 0.13 to 0.33, and the average genetic distance was 0.25, indicating that the genetic difference was not obvious among the parents, namely, they shared a close genetic relationship. In addition, the SSR genetic distance was closely related to yield per plant and fruits per plant, but showed no obvious correlation with other traits. [Conclusion] This study proved that in a certain range the combinations between the parents with a distant genetic distance possessed stronger heterosis and a larger possibility to produce a high yield and vice versa.
基金supported by grants from the Hi-Tech Research and Development(863)Program of China(Grant Nos.2014AA10A603 and 2014AA10A604)the Special Foundation of Non-Profit Research Institutes of Fujian Province,China(Grant No.2015R1021-8)
文摘To compare the heterosis levels among various groups of parental lines used extensively in China, identify foundational heterotic groups in parental pools and understand the relationship between genetic distance and heterosis performance, 16 parental lines with extensive genetic variation were selected from various sub-groups, and 39 hybrid combinations were generated and evaluated in Fujian and Hainan Provinces of China. The main results were as follows： （1） The 16 parental lines can be grouped into 7 sub-groups consisting of 1 maintainer sub-group and 6 restorer sub-groups; （2） Mean grain yield of the restorer lines was higher than that of the maintainer lines, and mean yield of parental lines was higher than that of the hybrid combinations; （3） The two best heterotic patterns were II-32A × G5 and II-32A × G6, moreover, the order of restorer sub-groups according to grain yield, from the highest to lowest, was G7, G6, G5, G4, G3 and G2; High specific combining ability values were observed for combinations of II-32A × G5, II-32A × G6 and Tianfeng A × G7; （4） Hybrid combinations derived from II-32A crossed with 13 restorer lines had higher yield trait values （mid-parent heterosis, better-parent heterosis, standard heterosis over check and specific combining ability） than any other combinations; （5） Genetic distance was positively correlated with panicle number, grain length and length-to-width ratio （P 〈 0.05） and negatively correlated with grain width, grain yield, seed-setting rate, as well as mid-parent heterosis, standard heterosis over check, and specific combining ability for grain yield （P 〈 0.01）. These heterotic groups and patterns and their argonomic traits will provide useful information for future hybrid rice breeding programs.
文摘This paper begins with the overthrow of the concept of combining ability in crossbreeding by the concept of heritability.The reason is that general combining ability changes with the number and kind of pure strains in the foundation stock and hence special combining ability changes also,so that work with different kinds of pure strains in the foundation stock cannot be compared.Hence combining ability is useless as a parameter to predict the amount of heterosis expected in the next generation.On the other hand,since each cross has a separate heritability,it can be applied to a cross population just as successfully as in purebreeding.Since the same concept holds in both cases,resort to any other concept would be superfluous.That's why combining ability must be rejected.Another reason(not given in the full text)is,an infinite number of pure strains would be required in the foundation stock for its results to be comparable with those of the heritability theory,which disposes of its utility altogether.The main content of the thesis is then the centennial enigma of heterosis can be resolved by Descarte's theoretic method of deduction.Accordingly we start from the definition of heterosis.H=F¡-MP,where H is heterosis,F,is the first generation offspring,MP is the mean of the parents or midparent,and from the use of a binomial random variable and its extention to the multinomial case derive the basic relations of heterosis with its components.Starting with second degree statistics,we obtain Vn=Vr,-2cov(F,,MP)+Vup,where V and cov stand for variance and covariance.The equations of heterosis are v„=(1/2)Na²+(1/4)Nd’+Vr(F,)=additive dominance F,epistasis Vup=(1/2)Na’+(1/2)V1,additive parental epistasis V„=(1/4)Nd’+V(F)+(1/2)V1,dominance F,epistasis parental epistasis.where N is number of genes controlling a trait,a=(P1-P,)12,d is deviation from midparent,while the variance components are all indicated by their names under the repective terms.It turns out that all these can be easily computed from the data so that the problem becomes a simple one which any college student may solve.In other words,the right answers are found when the right questions are asked.Who had ever shown that the heritability principle is inapplicable in crossbreeding,e.g.,in a crossing of two pure strains?From this cue arose the realization that the F,of a cross of two pure strains must also be a Mendelian population,with p and q both equal to 1/2 which simplifies the algebra outright.This Heritability Theory of Heterosis,or HTH in capital letters,re-sts on 2 initial anguments:1)Since 0.5+0.5=1,crossing two pure strains gives a population which is only a special case of pure-breeding,thereforea heritability coefficient must exist for the F1;2)Our problem reduces to that of finding that coefficient;the an-swer is given by the additive component divided by Ve.,i.e.,(1/2)No'1 Vp..which is readily found from the solution of the het-erosis equations.Thus the elemnal enigma of heterosis is resolved!This happened at the end of the 20th century.We now come to the second point of the discovery,the new genetic parameter crossheritability which will rise in size with the increase of the number of times it's used and form the link between breeding and evolution.The advent of the Age of Evolution Engineering in the 21st century marks a totally new era,showing that artificial will ultimately supercede natural selection,with the long span of time element eliminated.For agriculture at least,it means there is no limit to the increase of food supply by the new method,with the concentra-tion of desirable genes by hybridization in place of the old theory of their fixation.Genetic gain is achieved through artificial selec-tion,with an 80%saving of time,labor and cost by adoption of the new method.Applied to a further increase in all kinds of agri-cultural products including hybrd rice,it means that a huge eacalation,in fact a New Green Revolution,on a much langer scale than that of any such before,is in view,provided it is adopted in our research and educational institutions as early as possible,ere its spread elsewhere.The possibilities from the evolution point of view can only be pictured by science fiction.
文摘[Objective] This study aimed to investigate the genetic diversity of Macheng black goat and its correlation with heterosis.[Method] Ten microsatellite markers were selected for polymorphism investigation and statistical analysis of Boer goat and Macheng black goat populations.[Result] The results showed that totally 175 alleles were found in 10 microsatellite loci; to be specific,the maximum number of detected alleles was 23,and the minimum number was 10; the effective number of alleles （Ne） was 6.4-18.1,with absolute difference value of 1.6-8.1 from the observed number of alleles.The highest gene frequency was 0.239 1 and the lowest was 0.002 7.The polymorphic information contents of all the ten microsatellite markers were above 0.95.The observed heterozygosity （Ho） ranged from 0.616 7 to 0.984 4 and the expected heterozygosity （He） ranged from 0.844 1 to 0.944 6.The average expected heterozygosity of Boer goat and Macheng black goat was respectively 0.894 0 and 0.906 7.Various body weight and body size indices of Boer goatxMacheng black goat hybrids were improved in varying degrees compared with Macheng black goat （with an increase range of 0.32％-30.06％）.The average heterosis rates of body height and chest girth were relatively high,while average heterosis rate of body weight was relatively low.[Conclusion] The genetic distance between Boer goat and Macheng black goat was 0.379 5,which is consistent with the geographical distribution of Boer goat and Macheng black goat populations and is fully relevant to the heterosis of Boer goat × Macheng black goat hybrids,indicating that investigating polymorphism via microsatellite loci is one of the feasible means to predict and analyze heterosis between varieties.
基金supported by the Technology Office of Zhejiang Province, China (2008C22084)the 151 Program for the Talents of Zhejiang ProvinceFoundation for University Key Teacher by the Ministry of Education of China
文摘The embryo, cytoplasmic, and maternal heterosis for erucic acid content （EAC） and glucosinolate content （GLS） of rapeseed （Brassica napus L.） were studied by using the genetic models for quantitative traits of seeds in diploid crops. Eight parents were included in a diallel mating design in two years. It was found that the heterosis of EAC and GLS was simultaneously controlled by genetic main effects and genotype×environment （GE） interaction effects. The general heterosis of most crosses for EAC was significantly positive, while it was not for GLS. The general heterosis was more important for two quality traits of rapeseed because of the low GE interaction heterosis in both years, especially for GLS. Among different genetic systems, significant positive embryo general heterosis and the negative maternal general heterosis were found for EAC and GLS in most hybrid crosses. Some hybrids with significant negative interaction heterosis were detected for either of EAC or GLS. In general, maternal general and interaction heterosis was more important for reducing EAC and GLS of rapeseed.
基金Supported by Youth Fund Project of Sichuan Academy of Agricultural Sciences(2009QNJJ015)~~
文摘Five cytoplasmic male sterile （CMS） lines were used as parents in an incomplete diallet cross and six restorer lines of rice design （Nc II design）. Thirty hybrid combinations with the same growth period were selected as experimental ma- terials to investigate the heterosis, combined ability and heredity of Cd content in brown rice of indica hybrid rice. According to the results, Cd content in brown rice showed a significantly negative heterosis; the general combining ability and specific combination ability of Cd content in CMS and restorer lines both reached extremely significant level （P〈0.01）, indicating that both genetic improvement of parents and e- valuation of combinations are important to the breeding of hybrid combinations with low accumulation of Cd; the broad-sense heritabitity and narrow-sense heritability of Cd content were both relatively high with slight differences, which respectively reached 97.73% and 80.10%, indicating that Cd content in brown rice mainly de- pends on the additive action of genes; in addition, parent improvement showed bet- ter effect on the selection of early generation.
文摘F1 potassium heterosis of 8 flue-cured tobacco varieties and 6 self-bred high-potassium new strains were studied. The results showed that the F1 mean het- erosis of potassium content had differences between different parts of plants, showing B2F （8.45%）〉X2F （7.59%）〉C3F （5.64%）; the F1 over-parent heterosis of potassium content of various parts was not obvious, showing X2F （0.05%）〉C3F （-0.43%） 〉B2F （-0.48%）; the F, control heterosis of potassium content of different parts showed B2F （17.81%）〉X2F （4.06%）〉C3F （1.12%）. The variance of GCA of potassium content in various parts of the 6 self-bred high-potassium new strains was significant or extremely significant, and all leaves of GK2 had greater GCA effect on potassium content; C3F and X2F of GK7 had good GCA effect on potassium con- tent, but GCA effect was bad in B2F; GK9 preformed well in B2F but badly in C3F. The variance of SCA in all combinations was extremely significant, and the good combinations included Duoye 87xGK7 （17.19%） in B2F, Duoye 87xGK2 （25.63%）, ChangbohuangxGK5 （19.43%）, Yunyan 87xGK7 （22.78%）, and Yunyan 87xGK9 （24.38%） in C3F, Coker176xGK7 （19.87%）, 101xGK9 （15.89%）, Yunyan 85xGK9 （19.15%）, and Yunyan 87xGK9 （20.74%） in X2F.
文摘Maize （Zea raays L.） is one of the most important crops because of the remarkable properties of its hybrid, which is responsible for the high commercial value of hybrid maize. The genetic basis of heterosis （hybrid vigor） is not well understood. A differential display technique was performed to identify genes with differential expression across twelve maize inbred lines and thirty-three hybrids during ear development. An incomplete diallel design was used to investigate the relationship between the global framework of differential gene expression and heterosis. It was found that the genes belonging to MONO pattern （i.e., genes expressed in both parental lines and in hybrid） was the highest in percentage among the total five patterns and illustrated that the properties of differentially expressed genes are not entirely responsible for heterosis. Furthermore,a larger number of differentially expressed genes in hybrid, which serves as a major reservoir for generating novel phenotypes that exhibit heterosis of certain agronomic traits during early development and differentiation of maize ear. Moreover, there were some silent genesin hybrids that are responsible for the arrest or abortion of spikelets and for the increase in kernels weight.
