玉米自交系间遗传距离与产量杂种优势,杂种产量的关系

以13个玉米自交系及其按双列杂交配制的78个单交种为材料,研究性状选择、亲本选择对遗传距离与产量杂种优势、杂种产量关系的影响,结果表明:(1)当性状数较少时,遗传距离与产量杂种优势、杂种产量的关系因性状的不同而异;当性状数较多时,遗传距离与产量杂种优势、杂种产量的关系为抛物线,受性状影响较小;(2)当所选亲本材料的遗传差异较大时,遗传距离与产量杂种优势的关系为抛物线;当所选亲本材料的遗传差异较小时,遗传距离与产量杂种优势的关系为直线或不相关。     

RAPD分子标记与玉米杂种产量优势预测的研究

以２４个优良玉米自交系统ＮＣⅡ设计组配成１４３个单杂交种为材料，利用的ＲＡＰＤ分子标记技术研究玉米杂种优势群划分，遗传距离与特殊配合力，杂种产量，杂种产量优势的联系。结果表明：（１）ＲＡＰＤ技术可用于玉米杂种优势群划分。（２）亲本遗传距离杂种产量优势，杂种产量，特殊配合畋有一定相关关系，但决定系数很小，分别是１０％，１０％，１５％，利用ＲＡＰＤ技术预测杂种优势，杂种产量作用有限，应进一步研究与杂     

利用遗传标记预估畜禽杂种优势的研究

本文综述了诸多预估杂种优势方法的优劣,提出了研究和分析亲本间遗传距离是预估杂种优势的突破口。作为基因产物的蛋白质（酶）、及遗传物质ＤＮＡ本身,它们之间的差异能够真实反映不同群体间的遗传差异。根据遗传距离预测杂种优势的准确度较高。     

利用SSR标记分析水稻亲本间遗传距离与杂种优势的关系

利用5个光温敏核不育系与40个恢复系（品种）配制了200个组合,应用SSR标记估算了这5个不育系与40个恢复系之间的遗传距离,分析了遗传距离与杂种优势的关系。结果表明：（1）不同材料、不同遗传距离范围之间,遗传距离与单株产量以及有效穗数、穗长、每穗粒敷、着粒密度、结实率、千粒重、单株产量7个性状超亲优势的相关性有很大差别,表现出很复杂的关系。（2）田丰S与父本遗传距离在0．6286～2．5257之间时,F1单株产量及其超亲优势与遗传距离极显著相关;培矮64S与父本遗传距离在0．8247～1．5315之间时,F1单株产量与遗传距离显著相关。（3）所有两系组合亲本间遗传距离在0．5333～1．5之间时,F1单株产量超亲优势与遗传距离显著相关;遗传距离在0．5333～1．0之间时,F1单株产量与遗传距离显著相关,遗传距离分别在1．0～1．5、0．5333～1．5和0．5333～2．5257之间时极显著相关。（4）另外,F1单株产量与遗传距离的相关程度普遍高于其超亲优势与遗传距离的相关程度。     

AFLP标记在玉米种质资源鉴定中的应用

利用AFLP分子标记技术对55份玉米(Z ea m ay s L.)种质材料进行了研究.结果表明,20对AFLP引物检测到清晰可见的带656条,其中多态性带487条.平均每个引物组合可以检测到24.4条多态性带.将55份玉米材料聚为6组,与材料来源基本一致.结果显示AFLP有利于玉米遗传多样性分析.对来源美国先锋的P ioneer系列与瑞得种群和BSSS种群的关系进行了初步探讨,认为P ioneer系列中有很多材料与瑞得种群有亲缘关系.     

贵州70份玉米自交系的SSR标记遗传多样性及其杂种优势群分析

从251个SSR标记中筛选出均匀分布在玉米基因组上的88个SSR标记,用以分析评价贵州省2000年以来47个审定品种的70份亲本材料的遗传多样性。SSR标记检测的结果:88个标记共检测出466个等位基因,每个标记可检测等位基因2～18个,平均为5.31个;每个标记位点的多态性信息量(PIC)变化为0.213～0.965,平均为0.586,这表明贵州玉米自交系具有较为丰富的遗传多样性。POPTREE聚类分析结果:70份自交系分为Ⅰ、Ⅱ和Ⅲ类群。Ⅰ类群含8个自交系,以瑞德和兰卡斯特等温带种质为主。Ⅱ类群有11个自交系,以PN78599、瑞德和兰卡斯特等温带种质为主。Ⅲ类群拥有51个自交系,可分为A和B 2个亚群,B亚群还可再分为B1和B2 2个次亚群,A亚群中的10个系以我国地方温带种质为主,B1次亚群中的19个系以贵州地方亚热带种质为主,B2次亚群中的22个系以泰国苏湾热带种质为主。杂种优势利用分析的结果表明,贵州近些年在玉米育种中,主要是利用贵州地方亚热带种质和泰国苏湾热带种质2个杂种优势群,这与其多态位点百分率较高有关,与其群内SSR位点的平均等位数较多有关。贵州玉米育种利用的种质类型较少,有必要加强玉米种...     

小麦亲本遗传距离与产量杂种优势间的相关性研究

本文以10个小麦品种和按双列杂交配制的45个组合为材料,对遗传距离与产量杂种优势的关系进行了研究,结果表明:亲本遗传距离与产量杂种优势有极显著的非线性回归关系.遗传距离等于零时,杂种优势等于零;随着遗传距离的增大,杂种优势迅速达到最大值,然后缓慢下降,为通过原点的不对称抛物线.并对玉米、棉花的遗传距离与杂种优势的关系重新进行了探讨,一致表明,非线性回归关系优于抛物线回归关系.     

AFLP标记及在微生物和动物中的应用

AFLP是在PCR和RFLP基础上发展起来的新一代分子标记技术,具有稳定好、分辨率高和效率高等特点。AFLP技术现已广泛应用于微生物和动物方面的研究,在构造遗传图谱、遗传多态性研究、育种辅助选择等多领域中有着其它分子标记技术不可比拟的优势,广泛应用于微生物和动物的研究。     

对生玉米产量性状的杂种优势和配合力分析

本文利用对生基因转育获得的对生与互生自交系及其杂交组合,研究了对生性状对产量性状杂种优势和配合力的遗传效应的影响。结果表明:对生玉米同互生玉米一样具有普遍的杂种优势,在产量性状上F1对生株优势互×互组合大于对×对组合和对×互(互×对)组合;对生性状的转育对产量性状的一般配合力有降低效应,而含有对生基因的互生玉米具有较高的一般配合力效应,因此,在对生玉米育种中可以利用含有不同对生基因的互生自交系作亲本来组配杂交组合(互×互),从而获得较高的制种产量和高产的对生杂交种。     

Use of DNA Markers in Prediction of Hybrid Performance and Heterosis for a Three-Line Hybrid System in Rice

Two Cytoplasmic Male Sterile lines were crossed with fourteen restorer lines of rice widely grown in the western regions of Maharashtra, India, to produce 28 F₁ hybrids which were evaluated for eight agronomically important traits, contributing to yield potential, in replicated field trials. The hybrid performance was recorded along with heterosis and heterobeltiosis. All the rice lines under investigation were subjected to marker-based variability analysis. An attempt was made to correlate genetic distance based on specific markers for each trait individually, as well as average genetic distance based on all specific markers, with hybrid performance and heterosis, by regression analysis. Specific markers could cluster the parental lines in different groups and showed significant correlation with hybrid performance. The data also supports the proposition that epistasis is the basis of heterosis. The analysis, however, revealed a lack of significant predictive values for field application.     

利用微卫星DNA标记法进行5个肉用绵羊品种的多态性分析和杂种优势率预测

研究选择了与产肉性能相关的5个微卫星标记,分析了这5个位点在杜泊、德国美利奴、特克塞尔、道塞特和右玉本地绵羊5个品种中的遗传多态性.通过遗传分析预测了4个国外引进肉用绵羊品种与右玉本地绵羊的杂种优势,并与实际测定结果进行了比较分析.结果表明,利用微卫星DNA多态性进行品种间杂种优势预测是可行的,杜泊羊与右玉本地绵羊杂交的杂种优势最大,与实际测定结果一致.     

Phenotypic Plasticity Contributes to Maize Adaptation and Heterosis

Plant phenotypic plasticity describes altered phenotypic performance of an individual when grown in different environments. Exploring genetic architecture underlying plant plasticity variation may help mitigate the detrimental effects of a rapidly changing climate on agriculture, but little research has been done in this area to date. In the present study, we established a population of 976 maize F₁ hybrids by crossing 488 diverse inbred lines with two elite testers. Genome-wide association study identified hundreds of quantitative trait loci associated with phenotypic plasticity variation across diverse F₁ hybrids, the majority of which contributed very little variance, in accordance with the polygenic nature of these traits. We identified several quantitative trait locus regions that may have been selected during the tropical-temperate adaptation process. We also observed heterosis in terms of phenotypic plasticity, in addition to the traditional genetic value differences measured between hybrid and inbred lines, and the pattern of which was affected by genetic background. Our results demonstrate a landscape of phenotypic plasticity in maize, which will aid in the understanding of its genetic architecture, its contribution to adaptation and heterosis, and how it may be exploited for future maize breeding in a rapidly changing environment.     

The Genomic Impacts of Drift and Selection for Hybrid Performance in Maize

Although maize is naturally an outcrossing organism, modern breeding utilizes highly inbred lines in controlled crosses to produce hybrids. The U.S. Department of Agriculture’s reciprocal recurrent selection experiment between the Iowa Stiff Stalk Synthetic (BSSS) and the Iowa Corn Borer Synthetic No. 1 (BSCB1) populations represents one of the longest running experiments to understand the response to selection for hybrid performance. To investigate the genomic impact of this selection program, we genotyped the progenitor lines and >600 individuals across multiple cycles of selection using a genome-wide panel of ∼40,000 SNPs. We confirmed previous results showing a steady temporal decrease in genetic diversity within populations and a corresponding increase in differentiation between populations. Thanks to detailed historical information on experimental design, we were able to perform extensive simulations using founder haplotypes to replicate the experiment in the absence of selection. These simulations demonstrate that while most of the observed reduction in genetic diversity can be attributed to genetic drift, heterozygosity in each population has fallen more than expected. We then took advantage of our high-density genotype data to identify extensive regions of haplotype fixation and trace haplotype ancestry to single founder inbred lines. The vast majority of regions showing such evidence of selection differ between the two populations, providing evidence for the dominance model of heterosis. We discuss how this pattern is likely to occur during selection for hybrid performance and how it poses challenges for dissecting the impacts of modern breeding and selection on the maize genome.     

玉米不同杂种优势近等基因系及其杂交种的基因表达分析

以自发突变产生的籽粒大小和穗位叶片不同的 3对近等基因系及其杂交种为材料 ,研究了 6个基因在其叶片组织中的表达情况 ,以评价这些基因在杂种优势形成中可否作为“限率性基因”模式存在。结果表明 ,有些基因通过增强或减弱表达在杂种优势现象中起一定作用。将被测基因视为整体时会发现它们依次增强表达趋势为 :近等基因系 4 88 1>4 88 2 >4 78;相应杂交种 4 88 1× 340 >4 88 2× 340 >4 78× 340。对近等基因系及其杂交种个体千粒重和穗粒重的相关分析表明 ,Sus1、Sh1和ZmSps34 3′基因亦可作为适合的限率性候选基因以研究杂种优势分子机理。     

玉米杂种与亲本穗分化期功能叶基因差异表达与杂种优势

为探讨玉米杂种优势的分子机理,以10个玉米自交系及其组配的38个杂交种为材料,利用cDNA-AFLP技术,分析杂种与亲本在玉米雌穗小穗分化期功能叶片的基因差异表达类型与主要农艺性状的杂种表现及杂种优势的关系。研究表明：（1）杂种的基因相对于其双亲,存在质和量的表达差异,其中质的差异表达类型包括：单亲沉默表达,双亲沉默表达,亲本显性表达和杂种特异表达等类型。（2）在雌穗小穗分化期,同一差异表达类型中不同杂交组合间差异很大;从总体平均看,杂种特异表达类型占25.22%,亲本显性表达类型占21.46%,双亲沉默表达类型占8.27%,单亲沉默表达类型占33.49%。（3）单亲沉默表达与株高的杂种表现呈显著正相关;双亲沉默表达与穗粗的杂种优势呈显著负相关,显性表达与行粒数和单株粒重的杂种优势呈显著负相关,其余表达类型与所有农艺性状杂种表现及杂种优势均不相关,并对结果进行了讨论。     

对生玉米籽粒品质性状的杂种优势和配合力分析

本文利用对生基因转育获得的对生与互生自交系及其杂交组合,研究了对生性状对玉米主要品质性状的杂种优势和配合力的遗传效应的影响。结果表明:对生自交系籽粒品质性状的配合力效应一般高于互生玉米,在蛋白质含量上,对生F1杂种优势与普通互生F1无明显差异,而在油份和淀粉含量上对生F1较互生表现出明显的优势。不同组配方式对F1对生群体籽粒品质性状的杂种优势存在差异,在对生组合利用中通过互×互组配较对×对组配能使F1获得更高的蛋白质含量;选育含油量较高的对生系,利用对×对组合有助于选育高油杂交种;选育淀粉含量较高的含有不同对生基因的互生自交系作亲本,利用互×互组配有助于选育高淀粉对生杂交组合。