Transcriptome Analysis of Heterosis in Survival in the Hybrid Progenies of‘Haida No.1’and Orange-Shelled Lines of the Pacific Oyster Crassostrea gigas

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.

Heterosis Analysis in Endogenous Substances in Root Bleeding Sap of Sorghum

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.

Dissection of two QTL clusters underlying yield-related heterosis in the cabbage founder parent 01–20

Cabbage has significant heterosis and most commercial cultivars are hybrids.To explore genetic basis of cabbage heterosis and promote cabbage heterosis utilization,we constructed two populations by crossing 100 DH lines derived from a cabbage hybrid 01–20×96–100 with two female parents.Hybrids exhibited different extents of heterosis,the mean value of economic yield was 2.6 times bigger than parents.We identified 66 and 73 QTLs associated with mid-parent heterosis and transgressive heterosis of twelve yield-related traits,respectively.Some QTLs could be detected under the two-year experiment existed in two populations with different testers,showing relatively high phenotypic contribution rate(15.8%–20.0%).Heterosis QTLs exhibited clustered distribution in several cabbage chromosome regions.Two dominant genetic regions,mk300–316 and mk258–268,originated from the elite parent 01–20,exhibited significant genetic effects for yield-related heterosis,which were first identified.Three elite DH lines(D22,D46,D83)harboring these two dominant regions were selected as having strong heterosis in cabbage production.Candidate gene analysis revealed that some genes participating in biosynthetic processes of carbohydrates and some responses to auxin might affect cabbage yield heterosis.QTL identification and genetic dissection of yield-related traits provide new insights into the genetic effects of cabbage heterosis.

Comparative DNA-methylome and transcriptome analysis reveals heterosis-and polyploidy-associated epigenetic changes in rice

Heterosis and polyploidy have an overwhelming influence on plant evolution.Recently,polyploid rice hybrids have been used to breed new rice varieties because they combine the advantages of both heterosis and polyploidy.In this study,we generated six rice lines:autotetraploid rice hybrids and their autotetraploid parents,diploid donors,and hybrids of the diploid donors.To investigate the molecular mechanism controlling the effects of both hybridization and polyploidization,we performed bisulfite and RNA sequencing on young panicles at the pollen meiosis stage to compare the DNA metabolomes and transcriptomes among the six rice lines.The hybrids lines were hypermethylated compared to their corresponding parents and the autotetraploid lines showed globally increased DNA methylation of their transposable elements compared to the diploid donors.The alteration in DNA methylation level corresponded to the differential gene expressions among the rice genotypes,suggesting that methylation changes induced by polyploidization and hybridization may affect gene expression.Groups of gene candidates were identified that may be associated with heterosis and polyploidy.Our results provide DNA information that can be used to investigate epigenetic modification during heterosis and polyploidy in rice.

Heterosis of Vine Decline Disease Resistance Caused by the Fungus Monosporascus cannonballus in Melons (Cucumis melo L)

Vine decline disease (VDD) constitutes a menace to melons worldwide. Especially, the one caused by the fungus Monosporascus cannonballus. Thus, resistant plant material must be released to help growers. Hence, our goal was to develop resistant plant material to VDD. More than 600 melon accessions are expected to be tested for disease resistance in M. cannonballus infested soil in Weslaco, Texas, USA, to identify resistance to VDD, and other important traits. So far, at most 7 lines were found to be resistant to VDD and some of them were used to develop elite, muskmelon inbred lines by pedigree breeding following single or double backcrosses. These elite parents were crossed to each other to develop the hybrids M3 and M4. They were also tested in the same infested field in Weslaco. The hybrids were grown using standard commercial practices followed by growers and when their fruits were ready, their roots were sampled as well as scored for disease severity to estimate high and mid-parent heterosis Our results indicate the existence of heterosis regarding resistance to VDD. Thus, resistant plant material can be developed and selection for resistance can be accomplished.

The Relation between Genetic Difference for Parents of Hybrid Rice and Heterosis

Exploring the indica-japonica differentiation in parents of hybridization can provide theoretical bases for utilizing inter-subspecific heterosis. In this study, 5 sterile lines and 18 self-bred restorer lines were used as female parents and male parents respectively. Then 90 combinations were constructed by incomplete diallel cross followed by relationship analysis between parental Cheng’s index difference value and Euclidean distance and heterosis. The results showed a significant correlation between several phenotype values, super male parent heterosis and control heterosis and Euclidean distance or Cheng’s index difference value. However, it was no significant correlation for yield. Further analysis found a common interval, 3.41 - 3.46 for Euclidean distance and 3 - 4 for cheng’s index difference value of parents, which was significant or high significant positive correlated with phenotype value, super male parent and control heterosis of main yield traits. This illustrates that the larger the genetic difference of parents was, the stronger the heterosis combinations were, when the genetic differences of parents were in an appropriate range.

燕麦F_(1)代杂种优势及F_(2)代遗传变异分析

为了探讨燕麦正、反交杂种后代的杂种优势及遗传变异,本研究以引进品种爱沃和国产品种陇燕5号为亲本配制正、反交组合,对其F_(1)和F_(2)代的性状进行了观测,分析了其表型差异及杂种优势,探讨了F_(2)群体的遗传变异情况。结果表明,正、反交对F_(1)代的表型和杂种优势有显著影响,正交(爱沃(♀)×陇燕5号(♂),AL5)F_(1)代比反交(陇燕5号(♀)×爱沃(♂),L5A)早熟6 d,其株高、主穗粒数、千粒重和穗下节长显著大于反交,而旗叶长宽、倒二叶长均显著小于反交(P<0.05);正、反交F_(1)主穗长的超亲优势最大,分别为41.33%和31.92%,茎粗的超亲优势分别为−45.53%和−36.92%。F_(2)群体遗传变异幅度较大,分离现象明显。分蘖数和有效分蘖数的遗传变异系数和相对遗传进度最大,株高和茎粗的广义遗传率最高。叶片数和主穗粒数在正交和反交F_(2)中的遗传变异系数较为接近,但广义遗传率和相对遗传进度差异却很大。在F_(1)代超亲优势显著的茎粗和主穗长在F_(2)呈近似正态分布,正交F_(2)群体中有6.50%的个体主穗长的超亲优势大于30.00%,而反交主穗长的最大超亲优势为23.30%。总体而言,分蘖数、有效分蘖数具有较大的选择空间,株高、茎粗、主穗长等性状可在早代进行选择♂。

蓖麻Lm型雌性系及其杂交组合的杂种优势分析

为了解Lm型雌性系蓖麻的配合力遗传基础,以5个蓖麻Lm型雌性系为母本,3个蓖麻两性系为父本,根据NC-Ⅱ不完全双列杂交组配15个杂交组合,对蓖麻杂交组合的配合力、遗传力以及杂种优势进行分析。结果表明:雌性系A1和两性系B2的GCA和杂交组合SCA在蓖麻大部分农艺性状中均表现优秀,可在提高蓖麻产量的亲本选育中作为优异亲本进行杂交组合的构建。对亲本杂种优势研究发现,两性系B2参与组配的杂交组合在多个农艺性状上表现为强杂种优势,而Lm型雌性系则表现为在单个性状上具有较强的杂种优势。从遗传力分析结果来看,蓖麻的主茎蒴果数、一级分枝蒴果数、主茎穗长、主茎节数、一级分枝百粒质量和产量受加性效应和非加性效应共同影响,且受环境影响较小,适宜在早代进行选择。

‘YY021’烘烤特性及其杂种优势

为研究烤烟杂交种‘YY021’的烘烤特性及杂种优势,以‘YY021’及其母本‘MSY106’、父本‘LY1306’为研究对象,采用暗箱试验研究上部烟、中部烟和下部烟的变黄、变褐特性;采用电烤箱试验,研究中部烟烘烤过程中烟叶的失水特性、叶绿素降解特性和多酚氧化酶(PPO)活性变化,评价‘YY021’易烤性和耐烤性及其杂种优势。结果表明,上、中、下部位叶片变黄速率均表现为‘YY021’>‘LY1306’>‘MSY106’,下部和中部烟叶变褐速率表现为‘LY1306’>‘MSY106’>‘YY021’,上部烟叶变褐速率表现为‘LY1306’>‘YY021’>‘MSY106’。‘YY021’及其父母本变黄指数和变褐指数均随着叶片部位升高而减小。中部烟叶失水均衡性表现为‘LY1306’显著高于‘MSY106’,‘YY021’介于父母本中间,有中亲优势。‘YY021’中部烟叶绿素降解速率与父母本差异不显著,无杂种优势。中部烟PPO活性均值表现为‘MSY106’>‘YY021’>‘LY1306’,品种间差异显著,‘YY021’有中亲优势。综合上述各指标并参考生产实际表现‘,YY021’中部烟叶易烤性和耐烤性中等,有中亲优势,无超亲优势。

新疆冬麦区AL型三系杂交小麦亲本配合力、杂种优势和聚类分析

为了解新疆AL型三系杂交小麦亲本间配合力及其杂种优势关系,利用稳定不育系8份,恢复力强的恢复系9份,按照NCⅡ不完全双列杂交(8×9)设计配制72个F 1杂交组合,对亲本及杂交组合的7个农艺性状进行配合力效应和杂种优势分析,再根据亲本性状和一般配合力划分杂种优势类群。结果表明,三系小麦杂交组合中普遍存在产量和产量性状杂种优势,针对强优势组合的亲本选择,双亲之一一般配合力(GCA)或双亲GCA之和为正值且相对较大;相关性分析表明,中亲优势与父本和母本GCA值之和呈极显著正相关,父本和母本的GCA相关性大于特殊配合力(SCA)相关性。针对6个性状的GCA效应值和性状表型值分别进行聚类分析表明,配合力距离远的亲本组配可能出现强优势杂交组合的几率较大,性状表型值距离较远的两个亲本同一性状之间的优势互补也可以在后代中表现出较强的杂种优势。将17个亲本划分为4个和5个类群,为后续AL型杂交小麦强优势杂交组合的配制提供了依据。

电生理快速定量菜心杂种优势

本研究以温室培养的14个品种的菜心为材料,测定了饱水与不饱水状态下菜心的基本电生理参数,并基于能斯特(Nernst)方程计算得到叶片相对持水量(LIWHC)、叶片胞内水分转移速率(LIWTR)、叶片胞内持水时间(LIWHT)、叶片营养主动传输能力(NAT)、叶片营养被动传输能力(NPT)、耐低营养能力(RLN)、营养利用效率(NUE)和植物相对代谢活力(MA)等电生理指标,探究其与杂种优势的关系。结果表明,杂交50的胞内水分传输效率均显著低于其他品种的菜心,其RLN和NUE值则显著高于其他品种,但MA则显著高于其他品种。采用隶属函数法对供试品种水分及养分代谢进行综合评价,结果表明,参试的4个品种中,菜心杂交50的综合评价优于其他3个品种。因此,可以通过测定植物的电生理信息来计算水分、养分代谢状况以及植物的相对代谢活力等来鉴定植物的杂种优势。

Heterosis Analysis of Nitrogen Use Efficiency for Grain Production of Brassica napus L.

[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.

Genetic Effects and Heterosis in Plant Height and Internode Traits of Japonica-Indica Hybrid Rice

[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.

Analysis of the Evolutionary Significance of Heterosis——taking the contribution of fitness to the genetic diversity in random mating population as an example

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.

Relationship Between Heterosis and Endogenous Plant Hormones in Liriodendron

To investigate the possible involvement of endogenous plant hormones in heterosis of Liriodendron interspecific hybrid, growth traits and contents of endogenous GA 1/3 (gibberellin A 1, A 3), IAA (indole_3_acetic acid) and iPA (isopentenyl adenine) of tulip tree ( L. chinense (Hemsl.) Sarg.), yellow poplar ( L. tulipifera L.) and their interspecific hybrid ( L. chinense × L. tulipifera ) were examined. Results showed that: (1) the heterosis in height growth trait of the interspecific hybrid was mainly caused by the reletively greater elongation of internodes. Although the uppermost three internodes had the potential of elongation, the first one, which had the greatest elongation amount, contributed to the heterosis of the height growth trait; (2) the contents of endogenous GA 1/3 , IAA and iPA were greatly different among tulip tree, yellow poplar and their interspecific hybrid. All of the three interspecific hybrid families studied significantly contained higher amount of endogenous GA 1/3 and iPA in the uppermost first internode than their parental species. And thus, a correlation between the contents of endogenous GA 1/3 and iPA, and hybrid vigor for height growth trait in Liriodendron was observed; (3) the rankings of endogenous GA 1/3 and iPA contents in the uppermost first internode of three hybrid families studied were not similar to the ranking for height of 3_year_old trees. Therefore, the contents of endogenous GA 1/3 and iPA in the uppermost first internode could not be used in predicting hybrid vigor among hybrid families.

一种绿豆柱头外露突变体的转录组分析

柱头外露作为提高作物异交率、制种纯度和降低制种成本的优良性状,在杂交制种中得到了广泛的利用。绿豆是一种闭花授粉的作物,被报道的柱头外露突变体很少。通过对冀绿7号的化学诱变,发现了1个柱头外露突变体se2,为明确该突变体柱头外露的分子机制,对该突变体及其野生型冀绿7号即将开放的花蕾进行了转录组测序(RNA-seq)分析。根据差异倍数|log2(Fold Change)|≥1,P≤0.05的标准筛选,在se2中共得到572个差异表达基因(differentially expressed genes,DEGs),其中262个DEGs上调,310个DEGs下调。在基因本体(gene ontology,GO)数据库中,差异表达基因显著富集到代谢和生物合成等生物过程,定位在质外体和细胞壁、细胞膜等区域,与结合、氧化还原等分子功能有关。在京都基因与基因组百科全书(kyoto encyclopedia of genes and genome,KEGG)数据库中,差异表达基因显著富集在植物激素信号传导、次生代谢物生物合成等通路。功能注释发现许多有关细胞壁合成和代谢、细胞分裂和细胞扩张、植物激素相关的基因,因此推测se2突变体中龙骨瓣的细胞分裂、细胞扩张以及植物激素信号传导过程受到影响,从而导致了柱头外露。本研究为今后探究绿豆柱头外露的分子机制以及该性状在绿豆杂种优势中的利用奠定了基础。

22份玉米自交系主要农艺性状配合力及应用潜力分析

【目的】分析利用具有国外种业公司背景的玉米杂交种(组合)选育的自交系主要农艺性状的配合力及应用潜力,为玉米种质资源的科学引进与合理利用提供参考依据。【方法】以先21A、SP221、桂39722及桂兆18421等4个广西玉米骨干自交系为测验种,采用4×22 NCⅡ遗传交配设计对22个玉米自交系的株高、穗位高、穗长、穗粗及穗行数等10个重要农艺性状进行配合力、遗传效应和应用潜力分析。【结果】在22个自交系中,大多数重要农艺性状的一般配合力(GCA)表现较好的自交系为B1、B8和B22。不同血缘背景自交系的GCA各有特点,铁岭先锋种子研究有限公司和三北种业有限公司品种(组合)二环系的穗长和穗粗GCA效应值较高,中种国际种子公司二环系的穗行数、三北种业有限公司二环系的百粒重、铁岭先锋种子研究有限公司二环系的行粒数和出籽率等的平均GCA效应值较高。在不同杂交组合中,除株高与穗位高外,其他农艺性状的SCA效应值均较好的杂交组合有T1×B20和T1×B15。株高的广义遗传力和狭义遗传力分别为94.45%和63.72%,其他9个农艺性状的狭义遗传力均小于50.00%。根据配合力评价杂交优势类群,明确其育种的应用潜力,结果显示选自铁岭先锋种子研究有限公司的自交系B12、B13、B15、B19、B22与T2(桂39722,桂单0810的母本)为同一类群;选自其他公司的自交系与4个广西骨干自交系间均可能是杂交优势类群。【结论】自交系B1、B8和B22的农艺性状综合表现优良,可重点育种利用,而杂交组合T1×B20(先21A×正大808的二环系)和T1×B15(先21A×先玉1173的二环系)的产量相关性状表现优良,可参加品种区域试验。在育种工作中,可根据不同国外公司品种选育的二环系在穗长、穗粗、百粒重、穗行数及出籽率等方面的表型优势,有针对性地进行利用或改良。在自交系选育过程中,株高适宜早代选择,穗位高、穗长、穗粗、穗行数、行粒数、百粒重、出籽率和单株产量应晚代选择。

杂种优势形成机制和预测方法及其在猪生产中的应用与展望

杂种优势是指杂种后代的性能优于双亲群体的现象。杂交能有效提高后代的生长发育性能、繁殖性能和抗病性,因此被广泛应用于动植物生产。研究人员利用杂交育种技术培育了超优千号杂交水稻、小偃6号杂交小麦、杜蒙羊、山下黑猪等优秀的农牧新品系和配套系。然而当前的杂种优势研究仍存在一些亟待解决的问题:现有杂种优势理论只能部分解释动植物杂种优势现象,动物杂种优势理论研究较少,且现有的杂种优势预测方法准确性有限。我国是世界上最大的猪肉生产消费国,杂种优势能够有效提高生猪生产性能,在生猪产业的应用方面具有重要的经济和研究价值。但目前有关猪杂交生产研究还处于起步阶段,亟待进一步深入。本文综述了现有的杂种优势理论、杂种优势预测方法,及其在猪生产中的应用研究,以期为杂种优势在生猪育种中的应用提供借鉴与参考。

宁夏引黄灌区春小麦品种(系)抗倒伏相关性状杂种优势及配合力分析

【目的】小麦常规育种实质是对杂种F1性状杂种优势连续多代选择和保持的过程,探究宁夏引黄灌区春小麦品种(系)间抗倒伏相关性状的杂种优势、配合力,明确与小麦抗倒伏性状显著相关的农艺性状指标,为宁夏春小麦抗倒伏性状的杂种优势利用及其后代筛选与保持提供一定的理论依据。【方法】以14份宁夏引黄灌区春小麦品种(系)为亲本,按NCⅡ不完全双列杂交设计配制45个杂交组合,分析亲本及其杂交种F1株高、秆型指数等13个抗倒伏相关性状杂种优势、配合力及其相关性。【结果】不同品种(系)间抗倒伏性存在显著差异,杂种F1代抗倒伏相关性状存在一定的杂种优势。NZ42、M6445和M8887主茎抗推力的一般配合力较高,分别为11.68、8.00和10.67,且其他性状的一般配合力也表现较为优异。主茎抗推力强优势组合有M6445×M8887、M6445×MJ48、NZ42×N2038、NZ42×M7723、NZ42×NZ39、H3015×宁春50号。与此同时,相关性分析发现株高与第一节间长和第二节重成显著正相关,与第二节间长和第四节间长成极显著正相关。其次,主茎抗推力与主茎鲜重、茎粗、弯曲力矩和秆型指数成极显著正相关,与第四节间长成显著负相关,与第二节重和第二节间充实度相关性不显著。【结论】NZ42、M6445和M8887为本研究的优良亲本,且NZ42×NZ39、M6445×MJ48、M6445×M8887为本研究抗倒伏育种的优良组合。同时,供试材料不同组合倒伏性状间存在杂种优势利用潜力,但超亲优势不突出,且杂交组合的抗倒伏能力既受加性效应影响又受非加性效应影响,其中,受母本遗传背景影响更大。与此同时,第四节间长、弯曲力矩和秆型指数与株高和主茎抗推力相关性较高,可作为抗倒性育种后代选择的重要参考。

Production traits and fertility of reciprocal hybrids between Argopecten irradians irradians and A.i.concentricus

The two bay scallop subspecies,Argopecten irradians irradians(NN)and A.i.concentricus(SS),are fast growing and major cultured bivalves in China.However,their relatively small sizes and decreasing production traits caused by long-term inbreeding have been major concerns to the industry in the last two decades.Hybridization between the two bay scallop subspecies may provide a new approach to breed a new variety with superior production traits for the industry.For this end,in this study,we hybridized the two bay scallop subspecies in order to obtain a new strain that incorporates the genes of both subspecies.No significant difference was found in fertilization rate,hatching rate and metamorphosis rate between the purebred and crossbred cohorts(NN♀×SS♂,denoted as NS;SS♀×NN♂,denoted as SN).Both mating strategy(intra-vs.inter-population crosses)and egg origin had significant effects on growth and survival at the larval stage.Heterosis was observed in the crossbred and was more pronounced in older stages.Genetic diversity of the reciprocal hybrids,especially that of SN,was increased compared with the purebred cohorts.Almost all hybrids were completely fertile and able to reproduce by selffertilization or by backcrossing with either parent.Apparently,male sterile individuals whose gonads were fully occupied by the ovary part at mature stage were found in the hybrids for the first time.The hybrids,especially SN,may provide precious germplasm resources for the production of ternary hybrids with the Peruvian scallop,A.purpuratus.