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.

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。

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。

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.

不同遗传背景亲本及其杂交种对田间出苗率的影响

为了研究细胞质不同亲本及其杂交种对田间出苗率的影响,以29个AL型不育系和25个恢复系为亲本材料配制了双列杂交组合,以“同母多父”和“同父多母”的方式,对杂交种和亲本的田间出苗率进行比较分析。结果表明,细胞质遗传背景不同的恢复系、保持系、杂交种之间田间出苗率差异不显著。杂交种与双亲的田间出苗率间呈显著正相关,田间出苗率高的亲本所配置杂交种田间出苗率表现出较高杂种优势。杂交种田间出苗率应该作为优异亲本的重要指标得到重视。

优质抗病糯稻种质的性状鉴定及其杂种优势利用

【目的】为有效改良传统糯稻品种的产量、品质及抗性等综合性状,满足当前专用型糯稻市场的发展需求。【方法】采用不完全双列杂交(NC II)方法,构建亲本及20个杂种一代的遗传群体,评价糯稻亲本及杂交组合产量和品质性状的育种利用价值,鉴定出高产、抗病、低直链淀粉含量、高碱消值的糯稻新种质。【结果】7个优良品系的实割产量变幅7744.35~9216.45 kg·hm^(-2),其中X-104实割产量最高,达9216.45 kg·hm^(-2),X-27实割产量达8960.40 kg·hm^(-2),明显优于3个对照;两个株系植株矮壮,且分别携带了Pi-1、Pi-kh和Pi-1、Pi-9、Pi-kh的稻瘟病抗性基因,表现为中抗稻瘟病;直链淀粉含量(amylose content,AC)分别为1.71%和1.68%;碱消值(alkali spreading value,ASV)达6.75级和6.13级,育种价值高。在杂种优势利用上,X-27除了株高性状一般配合力为正效应外,该株系有利提高杂种后代的产量与稻米品质。X-57降低后代的株高和AC,提高后代产量和ASV。X-104虽产量高,品质好,但不利于杂种优势利用。闽糯2S/X-41、闽糯2S/X-107杂交一代在产量、株高、AC及碱消值等性状上具有明显的超亲优势和竞争优势,在杂交糯稻上应用价值高。【结论】杂交糯稻的产量与品质均为复杂性状,其中有效穗数、穗长、千粒重、长宽比、单株产量、AC、ASV主要受糯稻恢复系的控制。各性状的广义遗传率(h2B)变幅14.72%~53.99%,狭义遗传率(h2N)变幅10.25%~43.07%,遗传率较低,易受环境影响。育种上需大量配组,方可培育出不同用途的专用型糯稻杂交稻。

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。

华南型黄瓜相关性状的遗传效应分析

为研究华南型黄瓜自交系及其F1代的遗传效应,以华南型黄瓜4个自交系为父本,5个自交系为母本,采用NCII试验设计配制20个杂交组合,对9个农艺性状、产量和品质指标进行杂种优势分析、相关性分析、配合力分析和遗传力参数分析。杂种优势分析表明,叶面积和产量正向超亲、中亲优势占比60%~100%;相关性分析表明,叶面积与产量呈极显著正相关。特殊配合力分析表明,F1代中09-2-CD×P107、09-2-CD×Gy08、C20×Quanlü在产量中有明显优势,Qc19×Quanlü、LC68×Gy08、LC68×Quanlü、Qc19×138-LC在品质和产量中具有一定优势。一般配合力分析表明,P107可作为总糖含量和产量较高的父本,C20可作为高维生素C含量和高产母本,09-2-CD可作为株高较低和高产母本。遗传力参数分析表明,华南型黄瓜纵径、横径、维生素C含量、单果质量的狭义遗传力和广义遗传力均超过60%,说明这些性状具有较好的遗传稳定性。

强冬性和春性甘蓝型油菜变种间杂种优势分析

为了研究甘蓝型强冬性与春性油菜变种间亲本组配的杂交组合之间的杂种优势表现,选用8个强冬性甘蓝型油菜和4个春性甘蓝型油菜作为研究材料,组配杂交组合,分析亲本及F1的杂种优势强/弱。结果表明,冬×春组合的F1生育期较冬性亲本明显缩短;在冬×春组合中,株高、分枝部位、主花序长度、角果长度和单株有效角果数等方面有较强的杂种优势,其中角果长度(超亲优势:10.61%,杂种优势指数:128.81%)和单株有效角果数(超亲优势:17.31%,杂种优势指数:143.92%)杂种优势最为明显。结合杂种表现和杂种优势结果,说明甘蓝型油菜变种间杂交比种内杂交具有更明显的杂种优势表现,并且角果长度和单株有效角果数的超亲优势和杂种优势指数最高。本研究结果为今后研究甘蓝型油菜变种间杂种优势的研究利用提供了基础。

玉米籽粒胚乳细胞相关性状的杂种优势研究

为了解析玉米粒重性状杂种优势的产生原因,对籽粒胚乳细胞数目、细胞大小开展了研究。以玉米品种‘郑单958’、‘先玉335’及其亲本为试验材料,分析了杂交种与亲本在单籽粒重量、单籽粒胚乳细胞数目及胚乳细胞面积的杂种优势关系。结果表明,‘先玉335’和‘郑单958’胚乳细胞数目的中亲优势分别为40.81%和36.03%,超亲优势分别为33.09%和23.82%;百粒重的中亲优势分别为27.22%和28.89%,超亲优势分别为19.72%和18.34%;而胚乳细胞面积的中亲优势分别为-44.42%和-24.79%,超亲优势分别为-45.75%和-37.30%。单籽粒胚乳细胞数目与粒重呈极显著正相关,相关系数为0.796。综上所述,玉米杂交种籽粒的胚乳细胞数目多于亲本是粒重杂种优势产生的重要原因,选育籽粒胚乳细胞数目多的自交系进行杂交组配利于提高杂交种的粒重。

基于杂交种光合特性解析烟叶生物量杂种优势的形成机制

为从光合生理角度解析烟叶生物量杂种优势的形成机制,本研究以生物量差异较大的6个亲本及其杂交组合为材料,测定其烟叶生物量、光合特性、叶绿素含量及光合相关基因的表达量,分析了烟叶生物量杂种优势与光合特性间的关系,并基于杂交种的光合特性解析烟叶生物量杂种优势形成的基础。结果表明,烟草杂交种的生物量具有普遍的杂种优势,超亲优势、中亲优势组合率分别达到55.56%、77.78%;杂交种净光合速率、胞间CO_(2)浓度、叶绿素a含量等光合相关指标也表现出普遍的杂种优势,超亲优势组合率分别为55.56%、100%、66.67%,中亲优势组合率分别为88.89%、100%、77.78%;生物量杂种优势与净光合速率达到显著相关关系,相关系数为0.73(p<0.05);NtLhcb1、NtLhcb2、NtPsbA、NtatpF、Ntrbcl基因相对表达量在强、弱优势杂交种间达到显著差异,与烟叶生物量杂种优势呈显著或极显著正相关。烟草杂交种中NtLhcb1、NtLhcb2、NtPsbA、NtatpF、Ntrbcl基因上调表达,可能促进了烟草杂交种光合能力增强。

河南省方城县肉羊产业发展现状研究

该文通过采取规模场全覆盖召开座谈会、电话采访小养殖场(户)的方式对方城县当前肉羊杂交利用情况进行调研,阐述了方城县肉羊产业发展现状和养殖现状,发现存在良繁体系、养殖布局不合理、龙头企业带动不足等问题,提出提振种业、发展适度规模养殖、壮大龙头企业、实现肉羊一二三产业融合发展等对策建议,以期为推动方城县绿色畜牧业高质量发展提供参考。