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...     

180份玉米自交系亲缘关系的分子评价

利用覆盖玉米全基因组的22对SSR引物,对180份玉米自交系的亲缘关系进行分子评价.结果显示:22对SSR引物共检测到129个等位基因,每一位点平均等位基因数5.9,变幅2～13;平均基因多样性指数和平均多态性信息含量分别为0.583和0.528.基于模型的群体结构分析将所有材料分为5个类群,与国内自交系划分的杂种优势...     

辣椒优良自交系间遗传差异的分子分析

作物自交系间遗传差异的分析与评价是杂种优势育种和杂交育种成功的基础。鲜食尖椒类(Capsicum an-nuumvar.longum)品种是我国辣椒生产的主要品种类型之一。针对我国鲜食尖椒的育种目标,以国内外10份尖椒优良自交系为材料,利用相关序列扩增多态性(SRAP)和简单序列重复(SSR)标记技术对其进行了遗传差异分析。结果显示:SRAP技术具有较高的位点和多态性检测能力,平均每次检测的位点数和多态性位点数分别为34个和10个,是SSR的10倍和5倍;辣椒自交系间基于SRAP标记的遗传距离和基于SSR标记的遗传距离之间的相关程度较低(r=0.144);基于SRAP标记和SSR标记联合数据计算的遗传距离,10个尖椒自交系被分为3大类,这种分类结果与辣椒杂种优势育种实践相一致。本研究结果表明,SRAP具有较高的遗传分析效力;基于不同分子标记遗传分析结果的差异与标记间共享位点的多少有关;10个尖椒自交系的分类结果可用于指导育种实践。     

120份欧美玉米自交系的遗传多样性分析

为了拓宽黄淮海区玉米自交系的遗传基础,加快欧美优异种质的融入与利用,本研究利用SSR分子标记对120份来自美国和塞尔维亚及2份中国的玉米自交系进行遗传多样性和聚类分析。结果表明:29个多态性SSR标记共检测到115个等位位点,平均3.97个,位点多态性信息指数(PIC)平均为0.50,较好地揭示了自交系间的遗传多样性;观测杂合度(Ho)仅为0.03,表明参试自交系遗传稳定、纯合度高;美国SS、美国NSS、塞尔维亚和中国骨干自交系4个群之间相比,美国NSS群的等位位点数(3.55)、Shannon信息指数(0.93)最高,而塞尔维亚群的有效等位位点数(2.37)最高,表明美国NSS和塞尔维亚自交系群比其他两个群遗传多样性高;4个自交系群间的遗传距离介于0.1403~0.4695之间,美国NSS群与美国SS群、塞尔维亚群之间较小(0.1419,0.1403),与中国骨干自交系群之间最大(0.4695),4个群的遗传一致度介于0.6253~0.8691之间,美国NSS群与美国SS、塞尔维亚两个群之间的遗传一致度较高,表明美国与塞尔维亚自交系之间基因交流频繁,亲缘关系较近;聚类分析将122份玉米自交系分为9大主要类群,美国SS种质、NSS种质自交系被明显的区分开,并且SS种质被分为2个主要类群(Ⅰ和Ⅸ),NSS种质被分为6个主要类群(Ⅱ-Ⅶ),来自塞尔维亚的材料分散在美国NSS种质类群。本研究结果为来自欧美的自交系在玉米育种中合理利用提供可靠依据。     

不同杂种优势群玉米籽粒脱水速率分析

研究不同杂种优势群玉米自交系籽粒脱水速率的特性,筛选脱水速率快的自交系,为选育适应机械化作业的玉米杂交种提供借鉴。本试验采用烘干测定173份玉米自交系的籽粒的脱水速率及其相关性状,利用覆盖玉米全基因组的210对SSR标记对实验材料进行全基因组扫描,通过Structure V2.3.4 软件揭示其群体结构。对不同杂种优势群平均籽粒脱水速率进行方差分析,并筛选出各个群中籽粒灌浆速率快的自交系。研究结果如下：籽粒脱水速率在不同自交系间存在显著差异,与苞叶、穗轴及籽粒的含水率等性状间存在显著相关性。试验共筛选到脱水速率大于1%的自交系20个;授粉后40天时籽粒的含水率低于21%的自交系10个。参试自交系分成P、旅大红骨、瑞德、兰卡斯特和塘四平头5个杂种优势群;授粉后40天脱水速率依次是Reid群0.92%、Lancaster群0.85%、旅大红骨群0.82%、混合群0.80%、P群0.76%、塘四平头群0.56%。     

玉米抗腐霉茎腐病种质标记基因型鉴定与遗传多样性分析

腐霉茎腐病(Pythium stalk rot)是玉米生产上的重要病害。本研究利用14个与8个抗玉米茎腐病基因连锁的分子标记对196份抗腐霉茎腐病玉米种质进行抗病标记基因型鉴定,并采用42对多态性SSR标记对54份抗病自交系进行遗传多样性分析,以期阐明玉米抗腐霉茎腐病种质的标记基因型和遗传背景,并为资源的有效利用、新基因的挖掘和杂种优势模式确定提供参考信息。14个与抗病基因连锁的分子标记将196份抗性种质鉴定为128种标记基因型,表明存在多样的抗性基因组合方式。191份种质获得与齐319、X178或1145中一个或多个的相同的扩增,表明97.45%种质可能含有与3个抗玉米茎腐病材料相同的抗病基因;粤61、郑653、赤L136、白53和18--14共5份种质均未扩增出与齐319、X178和1145相同的标记基因型,可能携带其他抗茎腐病基因;遗传背景相近的抗性种质分属不同的标记基因型,表明抗病种质携带的抗病基因可能在育种选择中发生了分离。42对多态性SSR引物在54份抗病材料中共检测出119个等位基因(Na),多态位点百分率(PPB)为99.17%,平均有效等位基因数(Ne)为1.7070,平均Nei′s基因多样性(H)为0.3999,平均Shannon′s信息指数(I)为0.5844,平均多态信息含量(PIC)为0.5527,变幅为0.2061～0.7844;通过UPGMA聚类分析,54份抗病材料被划分为2个类群,共6个亚群中,分别是旅大红骨亚群、BSSS亚群、塘四平头亚群、PA亚群、PB亚群、Lan亚群,表现出较高的遗传多样性。结果表明,我国6个杂种优势群中均含有较为丰富的抗腐霉茎腐病种质资源,其中PA亚群包含的抗病种质最多。     

SSR标记用于玉米自交系遗传变异与优势类群划分的研究

采用SSR和杂种优势聚类方法分析我国15个玉米骨干自交系的遗传变异,并初步进行了杂种优势类群划分,从62个SSR引物中筛选的40对有效引物对15个玉米自交系进行了分析,共检测到188个等位基因变异,每个SSR座位的等位基因数2－9个,平均为4．7个,SSR位点的多态信息含量PIC值平均为0．675,分布范围在0．360－0．851之间,根据SSR数据对供试材料进行遗传相似性分析,Nei氏相似性系数分布在0．574－0．777之间,10对多态性高的SSR引物可有效区分15个自交系,应用SSR聚类分析的结果与系谱关系相一致,与杂种优势类法相比较,SSR方法具有效率高,结果可靠,可标准化的特点,对SSR方法在玉米育种实践上的应用进行了初步探讨。     

不同杂种优势群玉米子粒脱水速率分析

采用烘干法测定170份玉米自交系的子粒的脱水速率及其相关性状,利用覆盖玉米全基因组的210对SSR标记对试验材料进行全基因组扫描,通过Structure V2.3.4软件揭示其群体结构。对不同杂种优势群平均子粒脱水速率进行方差分析,并筛选出各个类群中子粒脱水速率快的自交系。结果表明:子粒脱水速率在不同自交系间存在显著差异,与穗轴和子粒的含水率等性状间存在显著相关性。试验共筛选到子粒脱水速率大于1%的自交系20个;授粉后40 d子粒含水率低于21%的自交系10个。参试自交系分成P、旅大红骨、瑞德、兰卡斯特和唐四平头5个杂种优势群;授粉后40 d子粒脱水速率依次是瑞德群0.92%、兰卡斯特群0.85%、旅大红骨群0.82%、混合群0.80%、P群0.76%、唐四平头群0.56%。本文旨在通过研究不同杂种优势群玉米自交系子粒脱水速率的特性,筛选子粒脱水速率快的自交系,为选育适应机械化作业的玉米杂交种提供借鉴。     

喀斯特高海拔山区玉米骨干自交系遗传多样性RAPD标记分析

以代表我国玉米6个主要杂种优势群旅大红骨、Lancaster、Reid、苏湾、墨白和塘四平头的标准测验种丹340、自330、7922、苏37、449、黄早四和适应我国喀斯特高海拔山区的玉米骨干自交系为材料,利用RAPD标记对其进行遗传多样性和杂种优势群划分.从90个随机引物中筛选出21个多态性好的引物扩增材料,共产生146条谱带,其中124条谱带有多态性,占86.3%,说明喀斯特高海拔山区的玉米骨干自交系具有较丰富的遗传多样性.通过UPGMA聚类分析,以遗传相似系数为0.632,可将我国喀斯特高海拔山区玉米种质资源的16个骨干自交系划分为5个类群.     

二十八份玉米自交系的RAPD亲缘关系分析

采用RAPD技术,对28份玉米自交系的亲缘关系进行分析。旨在DNA水平上揭示玉米自交系之间的亲缘关系,为进一步提高玉米杂种优势利用水平提供有益的信息从100个10bp随机引物中筛选出24个多态性较好的引物,对28份玉米自交系DNA进行扩增,扩增出24张DNA指纹图谱,其中多态性DNA谱带106条,占总扩增带数的64％。利用DNA扩增结果进行聚类分析,建立了28个玉米自交系的亲缘天系树状图,将供试材料划分为五个类群,RAPD分析结果与已知系谱的亲缘关系基本一致。     

节瓜自交系遗传多样性的ISSR分析

利用ISSR分子标记技术对36份节瓜自交系进行遗传多样性分析。从100条ISSR引物中筛选出14条多态性明显、条带清晰、反应稳定的引物,对36份节瓜材料基因组DNA进行扩增,共扩增出76条清晰稳定的条带,其中多态性条带45条,多态性比例为59.21%。36份材料间遗传相似系数在0.57~0.96之间,表明材料间遗传多样性较为狭窄。聚类分析结果显示,以遗传相似系数0.76为阈值时,可将36份节瓜自交系材料聚为3类,分类结果与供试材料的地理来源较为吻合。基于聚类分析结果,可为今后节瓜的新品种选育、遗传改良以及分子遗传连锁图谱构建的杂交亲本选择提供科学依据。     

Genetic diversity of African maize inbred lines revealed by SSR markers

Knowledge of genetic diversity (GD) and relationships among maize inbred lines is indispensable in a breeding program. Our objectives were to (1) investigate the level of genetic diversity among maize inbred lines and (2) assess their genetic structures by applying simple sequence repeat (SSR) markers. Fifty-six highland and mid-altitude maize inbred lines obtained from CIMMYT programs in Ethiopia and Zimbabwe were genotyped using 27 SSR loci. All of the genotypes studied could unequivocally be distinguished with the combination of the SSRs used. In total, 104 SSR alleles were identified, with a mean of 3.85 alleles per locus. The average polymorphism information content (PIC) was 0.58. GD expressed as Euclidean distance, varied from 0.28 to 0.73 with an average of 0.59. Cluster analysis using unweighted pair group method with arithmetic average (UPGMA) suggested five groups among the inbred lines. Most of the inbred lines adapted to the highlands and the mid-altitudes were positioned in different clusters with a few discrepancies. The pattern of groupings of the inbred lines was mostly consistent with available pedigree information. The variability detected using SSR markers could potentially contribute towards effective utilization of the inbred lines for the exploitation of heterosis and formation of genetically diverse source populations in Ethiopian maize improvement programs.     

Analysis of genetic diversity and relationships among waxy maize inbred lines in Korea using SSR markers

Information regarding the genetic diversity and genetic relationships among elite inbred lines is necessary to improve new cultivars in maize breeding programs. In this study, genetic diversity and genetic relationships were investigated among 84 waxy maize inbred lines using 50 SSR markers. A total of 269 alleles were identified at all the loci with an average of 5.38 and a range between 2 and 13 alleles per locus. The gene diversity values varied from 0.383 to 0.923 with an average of 0.641. The cluster tree generated using the described SSR markers recognized two major groups at 32% genetic similarity. Group I included 33 inbred lines while group II included 51 inbred lines. The clustering patterns of most of the waxy maize inbred lines did not clearly agree with their source, pedigree or geographic location. The average GS among all inbred lines was 35.7 ± 10.8. Analysis of waxy maize inbred lines collected from Korea and China at 50 SSR loci revealed higher values of average number of alleles (4.9) and gene diversity (0.638) in Korean inbred lines as compared to Chinese inbred lines (3.5 and 0.563, respectively). The information obtained from the present studies would be very useful for maize breeding programs in Korea.     

Genetic structure and linkage disequilibrium pattern of a rapeseed (Brassica napus L.) association mapping panel revealed by microsatellites

Understanding the population structure and linkage disequilibrium (LD) is a prerequisite for association mapping of complex traits in a target population. In this study, we assessed the genetic diversity, population structure and the extent of LD in a panel of 192 inbred lines of Brassica napus from all over the world using 451 single-locus microsatellite markers. The inbred lines could be divided into P1 and P2 groups by a model-based population structure analysis. Out of the 142 inbred lines in the P1 group, 126 lines were from China and Japan, and the remaining 16 lines were from Europe, Canada and Australia. In the P2 group, 33 out of the 50 lines were from Europe, Canada, and Australia, and the remaining 17 lines were from China. Structure analysis further divided each group into two subgroups. AMOVA, pairwise F (ST) and neutrality analyses confirmed the differentiation between groups and subgroups. More than 80 % of the pairwise kinship estimates between inbred lines were <0.05, indicating that relative kinship is weak in our panel. Only 6 % linked marker pairs showed LD, suggesting the low level of LD in this association panel. The LD decayed within 0.5-1 cM at the genome level, and varied considerably across each group and subgroup, due to the population size, genetic background and genetic drift. The characterization of the population structure and LD patterns would be useful for performing association studies for complex agronomic traits in rapeseed.     

Genetic structure and diversity among maize inbred lines as inferred from DNA microsatellites

Two hundred and sixty maize inbred lines, representative of the genetic diversity among essentially all public lines of importance to temperate breeding and many important tropical and subtropical lines, were assayed for polymorphism at 94 microsatellite loci. The 2039 alleles identified served as raw data for estimating genetic structure and diversity. A model-based clustering analysis placed the inbred lines in five clusters that correspond to major breeding groups plus a set of lines showing evidence of mixed origins. A "phylogenetic" tree was constructed to further assess the genetic structure of maize inbreds, showing good agreement with the pedigree information and the cluster analysis. Tropical and subtropical inbreds possess a greater number of alleles and greater gene diversity than their temperate counterparts. The temperate Stiff Stalk lines are on average the most divergent from all other inbred groups. Comparison of diversity in equivalent samples of inbreds and open-pollinated landraces revealed that maize inbreds capture <80% of the alleles in the landraces, suggesting that landraces can provide additional genetic diversity for maize breeding. The contributions of four different segments of the landrace gene pool to each inbred group's gene pool were estimated using a novel likelihood-based model. The estimates are largely consistent with known histories of the inbreds and indicate that tropical highland germplasm is poorly represented in maize inbreds. Core sets of inbreds that capture maximal allelic richness were defined. These or similar core sets can be used for a variety of genetic applications in maize.     

Studying Genetic Diversity in Inbred Sunflower Lines by RAPD and Isozyme Analyses

Genetic diversity of 30 inbred sunflower lines was examined by RAPD and isozyme analyses. The inbred lines were shown to be highly polymorphic by RAPD markers. The line distribution on genetic similarity dendrograms based on the RAPD and isozyme data was analyzed. High effectiveness of RAPD analysis for differentiating genotypes of inbred sunflower lines was demonstrated.     

RFLP Detection of Genetic Variation of Maize Inbred Lines

Genetic similarities of 13 inbred lines of maize (Zea mays L.) were analyzed by restriction fragment length polymorphisms (RFLPs). The objectives of the study were to detect genetic similarities among 13 inbreds and to assign them to heterotic groups. By means of 24 probe-enzyme combinations (PECs) selected for locus specificity, clear patterns and reproducibility, 85 alleles were found with an average of 3.3 alleles per locus. The allelic frequency data were used to estimate genetic similarities among lines, and as a result the diversity index of 0.499 was obtained. Genetic similarities between the pairs of 13 lines ranged from 0.523 up to 0.802 with an average of 0.649. The UPGMA clustering algorithm analysis classified the 13 lines into five groups, which generally corresponded to known maize heterotic groups based on pedigree information. The authors concluded that RFLP-based markers could be used for investigating genetic relationships between maize inbred lines and assigning them to heterotic groups, but it seemed that a large number of PECs were needed to obtain reliable estimates of genetic similarity.     

玉米自交系遗传变异的RFLP分析

利用ＲＦＬＰ标记研究了１３个玉米（Ｚｃａ ｎａｙｓ Ｌ．）自交系的遗传变异。从３０对探针／酶组合中筛选出杂交带型清晰、稳定、重复性好的２４对组合,在１３个自交系中获得８５个等位基因杂交片段,平均每个位点为３．３条,平均多态性指数为０．４９９。１３个自交系之间的遗传相似系数为０．５２３－０．８０２,平均为０．６４９。ＵＰＧＭＡ聚类分析表明,供试自交系共分为５个类群,分群结果与其系谱关系基本吻合;表明     

宁夏水稻选育品种遗传多样性和亲缘关系分析

选择31份宁夏近年来育成或审定的水稻品种(系),利用分布于12条染色体的36对SSR引物进行遗传多样性和遗传距离分析.共检测到159个等位基因,品种间不同位点等位基因数目不等,平均4.4个.Nei基因多样性指数变幅为0.031 7～0.844 4,平均为0.508 8.按育成或审定年份,把31份水稻分为3组,SSR分析...