新疆甜瓜地方品种资源核心种质构建

新疆甜瓜地方种质资源具有丰富的遗传多样性,是新疆哈密瓜遗传改良的重要基因库。以121份新疆甜瓜地方品种为研究对象,结合按来源分组和系统聚类选择的方法,通过多重比较29个表型性状数据确定适宜的取样比例,筛选出25份地方品种为初选核心种质。在初选核心种质取样量上,人工定向补充5份优异种质和极值材料确定了核心种质,约占地方品种总数量的25%。对表型保留比例、遗传多样性指数、变异系数、表型频率方差、极差符合率、均值符合率、标准差符合率等检验参数进行了检验和评价。结果表明:调整后的核心种质除标准差符合率降低外,其余参数均优于或等于初选核心种质,更能代表原始样品;所构建的核心种质很好地保留了所有地方品种资源的遗传多样性和变异幅度。     

利用表型数据构建陆地棉核心种质

以5963份陆地棉种质资源为材料,根据品种主要突变性状和品种类型分组成11组群,在分组的基础上利用21个表型性状,用非加权类平均聚类分析法,构建了281份陆地棉核心种质,占全部种质资源总量的4.71%。利用不同性状的均值t测验、方差F测验、变异系数、多样性指数t检验、均值、极差、表型方差、变异系数、均值差异百分率、方差差异百分率、极差符合率、变异系数变化率、主成分分析等参数进行核心种质代表性检验和评价。结果表明,所构建的陆地棉核心种质可以代表全部种质的遗传多样性。     

基于农艺性状的山西普通菜豆初级核心种质构建

利用663份山西省普通菜豆资源基于14个农艺性状,采用比较不同分组原则、取样比例和总体取样量不同组合的取样方法,确定了"地理来源+平方根比例+20%总体取样量"为山西省初级核心种质构建的方法。同时,在此基础上对663份资源中一些具有极端性状的资源进行选择,最终确定152份普通菜豆可作为山西省普通菜豆初级核心种质。通过总体与初级核心种质资源多样性分析,数量性状均值比较,数量性状极值、变幅和标准差比较,性状多样性的差异性分析和各性状总体分布的χ2检验,最终得出:152份普通菜豆资源能够代表山西省普通菜豆资源的总体,可作为山西省普通菜豆评价和创新利用的优先样品集。     

中国芒(Miscanthus sinensis)初级核心种质的构建

以555份芒(Miscanthus sinensis)种质资源为研究对象,根据26个表型性状数据,按地理来源、植物区系和单一性状进行分组,分别采用简单比例法、平方根法和多样性指数法确定组内取样数,再根据聚类和随机2种方法进行组内个体选择。依照上述方案共构建出19个具有代表性的芒初选核心种质样本库。通过平均相似系数、性状符合度、数量性状变异系数和遗传多样性指数等4项检测指标对上述19种构建方案进行比较,最终确定了按"植物区划分组+多样性指数确定取样数+聚类选择个体"为芒初级核心种质构建的最佳方案。通过此方法建立起的芒初级核心种质资源共83份,占总资源的14.95%,且新构建的初级种质资源与总资源性状符合度达到100%。     

基于农艺性状的榕江茶（Camellia yungkiangensis）核心种质构建

摘 要：为得出较为可靠的榕江茶初级核心种质群体,以加强榕江茶种质选育、开发利用和分子遗传学研究,解决其种质资源保存成本较高问题,促进榕江茶种质资源的鉴定和有效利用。以118份榕江茶种质资源为材料,对19个表型性状和4个基本品质成分共计23个农艺性状进行分析;基于2种遗传距离(标准化欧氏距离、马氏距离）、4种聚类方法（离差平方和法、非加权组平均法、最长距离法、最短距离法）和7种总体取样规模（10%、15%、20%、25%、30%、35%、40%）构建了56个候选榕江茶核心种质,利用筛选得到的最佳构建方案构建初级核心种质。通过对原种质、保留种质和核心种质的表型遗传多样性和变异程度,以及各种质不同数量性状间的t检验来评价核心种质的代表性,并用主成分分析法对核心种质进行确认。构建榕江茶核心种质时,2种遗传距离中,标准化欧氏距离优于马氏距离;4种聚类方法中,最短距离法优于另外3种;7种总体取样规模中,30%的取样比例较适宜榕江茶核心种质的构建。对构建的38份核心种质进行分析评价,结果表明,核心种质与原种质23个性状的6个特征值一致性较好,并且遗传多样性指数有一定程度的提升;t检验结果表明,核心种质平衡了稀有性状的分布,有效保留了原种质的遗传多样性;主成分分析结果表明,核心种质的主成分累计贡献率高于原种质;对核心种质进一步确认时,发现核心种质均匀分布在原始种质范围内,无重叠现象,有效的避免了核心种质的冗余。所构建的榕江茶核心种质资源可以很好地代表原种质,较好的保留了原种质的性状、遗传多样性和变异。标准化欧氏距离、最短距离法和30%总体取样规模的构建策略,是构建榕江茶核心种质的最佳方法。最终构建了38份榕江茶种质资源的初级核心种质,占原种质32.20%。核心种质评价表明初级核心种质构建有效且质量较高,能够在保证冗余较少的情况下充分代表原种质遗传多样性。     

基于表型及经济性状构建蒜头果初选核心种质

为尽快明确天然林中蒜头果种质资源收集保存的策略和目标,本研究基于21个表型及经济性状,构建蒜头果核心种质,明确了建立蒜头果育种和保存群体的目标材料,为其资源保育提供依据。在系统聚类和优先取样法的基础上,分别利用遗传多样性法、比例法和对数法,设定10%、20%和30%3种取样比例,产生7种构建策略;采用8个参数评价7种策略构建的核心种质,得到参数最优的核心种质;采用4重方法验证核心种质的有效性和代表性。结果表明,(1)“优先取样法+遗传多样性法+30%取样比例”形成的核心种质,8个评价参数最优,核心种质包含28个样本,取样比例为28.87%。(2)4种验证方法均表明,构建的核心种质具有较好的代表性。多样性指数的t检验表明,核心种质与原种质在21个性状上的多样性指数差异均不显著(0.05);符合率检验表明,核心种质与原种质在21个性状上的均值、极大值、极小值和多样性指数的符合率均在80%以上;主成分检验表明,核心种质与原种质具有相近的特征值、贡献率和累计贡献率;核心种质与原种质的样品分布表明,两者具有相似的分布结构。研究认为,构建的蒜头果核心种质具备代表性、有效性和实用性等特征,可作为蒜头果种质资源收集保存和建立育种群体的依据。     

广西地方稻种资源核心种质构建和遗传多样性分析

以丁颖分类体系分组原则与组内逐层聚类取样方法,对8609份广西地方栽培稻资源表型数据信息进行分析,通过对表型保留比例等评价指标的多重比较确定核心种质总体取样比例,构建出占总体样本5%(414份)的广西地方栽培稻资源初级核心种质。初级核心种质能代表总体遗传变异的89%。用34对SSR分子标记对初级核心种质进行遗传多样性分析,结果表明:广西地方栽培稻资源有较高的遗传多样性(等位基因数A为4.91,Nei’s多样性指数为0.574)。就Nei’s遗传多样性指数而言,粳稻高于籼稻,晚稻高于早稻,水稻高于陆稻,糯稻高于粘稻;来自桂中的稻种资源具有最高的遗传多样性。研究最终利用SSR数据,把414份初级核心种质压缩50%后形成209份核心种质,核心种质基因保留比例达到98%以上,有效代表了广西地方栽培稻资源多样性水平。     

中国普通小麦初选核心种质的产生

对中国普通小麦种质资源构建了初选核心种质。地方品种和选育品种分别构建。按栽培区(地理生态区)分组。地方品种按亚区分为28组,选育品种按大区分为10组。各组内在21个表型性状聚类的基础上,按平方根法取样,并依遗传多样性指数与遗传丰富度加以调整。提出在生产上或育种中起过重要作用的品种为必选材料。初步选定的材料经种植核对,淘汰错杂后,产生初选核心种质。地方品种全部供试材料11694份,初选核心种质3283份,取样比例为28．18％。选育品种全部11441份,初选核心种质1684份,取样比例为14．9％。计划经分子标记分析,最后核心种质的比例占全部种质的10％左右。根据全部材料21个性状遗传多样性指数测验,初选核心种质,除芒和壳两性状外,与全部种质的遗传差异均未达到显水平。讨论了初选核心种质的构建方法。指出陕南部西山地和汾渭谷地是中国小麦地方品种遗传变异多样性的富集地。育成品种多样性程度以西南冬麦区和黄淮冬麦区为最高。     

黄瓜多样性固定核心样本集的构建与评价

利用149对具有多态性的In Del引物对473份黄瓜初选核心种质自交系进行遗传多样性分析。采用3种方法 12种取样比例对该初级遗传多样性固定群体进行抽样获得候选多样性固定核心样本集(GDFCC),使用等位基因数(Na)、有效等位基因数(Ne)、Shannon's信息指数(I)、基因多样性指数(gene diversity)、多态性信息含量(PIC)、总等位位点数(total number of loci)、等位位点保留百分率(retention rate of loci)评价候选多样性固定核心样本集的多样性和代表性,结果表明,采用逐级聚类+稀有基因优先取样法并按照15%取样比例构建出的多样性固定核心样本集的效果较好。比较发现,该核心样本集的Ne、I、基因多样性指数和PIC值均接近或高于初级遗传多样性固定群体,且对原始群体的等位位点的保留百分率为99.68%。入选多样性固定核心样本集的材料来自15个国家和国内18个省市。该研究为今后黄瓜优异基因资源的挖掘利用提供了代表性强、覆盖度广、遗传稳定的研究群体,将有利于黄瓜种质资源的高效研究利用。     

白桦核心种质构建的聚类方法研究

以白桦240个家系的胸径、树高、材积和纤维素含量数据为依据,采用马氏距离计算家系间距离、10%的取样比例和优先取样法,研究了最短距离法、最长距离法、中间距离法、重心法、类平均法、加权配对算术平均法、可变法和离差平方和聚类法建构的核心种质与原种质的遗传参数、性状相关性及分布格局.结果表明,最短距离法构建白桦初级核心种质均值差异百分率、极差符合率、方差差异百分率和极差符合率分别为0、100%、75%和143%,4个性状相关性显著、相关系数均超过0.5,保持了原种质资源的空间分布格局,是构建白桦核心种质最佳方法.     

Assessment of Genetic Diversity in Three Subsets Constituted from the ICRISAT Sorghum Collection Using Random vs Non-Random Sampling Procedures B. Using molecular markers

The large size of the sorghum [Sorghum bi-color (L.) Moench] landrace collection maintained by ICRISAT lead to the establishment of a core collection. Thus, three subsets of around 200 accessions were established from: (1) a random sampling after stratification of the entire landrace collection (L), (2) a selective sampling based on quantitative characters (PCS), and (3) a selection based on the geographical origin of landraces and the traits under farmers’ selection (T). An assessment was done of the genetic diversity retained by each sampling strategy using the polymorphisms at 15 microsatellite loci. The landraces of each subset were genotyped with three multiplex polymerase chain reactions (PCRs) of five fluorescent primer-pairs each with semi-automated allele sizing. The average allelic richness for each subset was equivalent (16.1, 16.3 and 15.4 alleles per locus for the subsets PCS, L, and T, respectively). The average genetic diversity was also comparable for the three subsets (0.81, 0.77 and 0.80 for the subsets PCS, L, and T, respectively). Allelic frequency distribution for each subset was compared with a chi-square test but few significant differences were observed. A high percentage of rare alleles (71 to 76% of 206 total rare alleles) was maintained in the three subsets. The global molecular diversity retained in each subset was not affected by a sampling procedure based upon phenotypic characters.     

Genetic Diversity and Core Collection Evaluations in Common Wheat Germplasm from the Northwestern Spring Wheat Region in China

Fluorescence microsatellite markers were employed to reveal genetic diversity of 340 wheat accessions consisting of 229 landraces and 111 modern varieties from the Northwest Spring Wheat Region in China. The 340 accessions were chosen as candidate core collections for wheat germplasm in this region. A core collection representing the genetic diversity of these accessions was identified based on a cluster dendrogram of 78 SSR loci. A total of 967 alleles were detected with a mean of 13.6 alleles (5–32) per locus. Mean PIC was 0.64, ranged from 0.05 to 0.91. All loci were distributed relatively evenly in the A, B and D wheat genomes. Mean genetic richness of A, B and D genomes for both landraces and modern varieties was B > A > D. However, mean genetic diversity indices of landraces changed to B > D > A. As a whole, genetic diversity of the landraces was considerably higher than that of the modern varieties. The big difference of genetic diversity indices in the three genomes suggested that breeding has exerted greater selection pressure in the D than the A or B genomes in this region. Changes of allelic proportions represented in the proposed core collection at different sampling scales suggested that the sampling percentage of the core collection in the Northwest Spring Wheat Region should be greater than 4% of the base collection to ensure that more than 70% of the variation is represented by the core collection. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Assessment of genetic diversity in three subsets constituted from the ICRISAT sorghum collection using random vs non-random sampling procedures A. Using morpho-agronomical and passport data

A large collection, such as the sorghum [Sorghum bicolor (L.) Moench] landrace collection held at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), represents a challenge for the maintenance of both the accessions of and the information documented for the germplasm collection. The accessibility and knowledge of the landrace collection are the essential factors for an efficient utilization of the genetic resources by both breeders and farmers. Different sampling strategies, either random or non-random, were proposed to obtain subsets of reduced size (core collection). Three subsets were established; a random sampling within a stratified collection (logarithmic strategy: L); a sample based upon morpho-agronomic diversity (principal component score strategy: PCS); and a sample based upon an empirical knowledge of sorghum (taxonomic strategy: T). Comparisons of these three samples for morpho-agronomic characterization and passport information were assessed to determine their impact on phenotypic diversity. For their overall diversity, the three subsets did not differ, as shown with the two-dimensional representation of the morpho-agronomic diversity and the Shannon-Weaver diversity indices. When comparisons for morpho-agronomic and passport data were considered, the PCS subset looked similar to the entire landrace collection. The L subset showed differences for characters associated with the photoperiod reaction that was considered in the stratification of the collection. The T subset was the most distinct from the entire landrace collection as it over-represented the landraces selected by farmers for specific uses and covered the widest range of geographical adaptation and morpho-agronomic characteristics. Received: 5 October 1999 / Accepted: 3 November 1999     

Genetic diversity analysis of common beans based on molecular markers

A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5% polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation.     

基于表型数据的辣椒核心种质构建研究

以收集保存的603份辣椒种质为材料,根据果形指数大小将其分成5组。基于28个性状的表型数据,采用简单比例、平方根比例、对数比例及遗传多样性指数比例法计算各组内取样份数,比较4种组内取样比例法、6种总体取样规模和2种取样方法在构建辣椒核心种质中的作用和效果。结果表明:(1)简单比例、平方根比例、对数比例、遗传多样性指数比例法入选的材料份数占预选核心种质份数依次为24.2%、22.2%、21.1%、17.8%,说明遗传多样性指数比例法对各组取样数量的修正能力最强,使取样更加均衡。(2)当总体取样规模为15%时,遗传多样性指数比例法构建的预选核心种质遗传多样性指数(I)达到最大,表型保留比例(RPR)超过98%;当总体取样规模超过20%时,RPR值、变异系数(CV)和极差符合率(CR)虽然平缓增加,但I值反而减小;说明15%为合适的总体取样规模。(3)利用对数比例法和多样性比例法,在15%的总体取样规模下,聚类取样构建的核心种质I值、RPR值、CV值及CR值均高于随机取样。(4)该研究根据所获得的优化方案最终在表型水平建立了包含91份种质的辣椒核心种质。     

A global view of genetic diversity in cultivated sorghums using a core collection.

We report here an analysis of the structure of genetic diversity in cultivated sorghums. A core collection of 210 landraces representative of race, latitude of origin, response to day length, and production system was analysed with 74 RFLP probes dispersed throughout the genome. Multivariate analyses showed the specificity of the subrace guinea margaritiferum, as well as the geographical and racial pattern of genetic diversity. Neighbour-joining analysis revealed a clear differentiation between northern and southern equatorial African accessions. The presence of Asian accessions in these 2 major geographical poles for sorghum evolution indicated two introductions of sorghum into Asia. Morphological race also influenced the pattern of sorghum genetic diversity. A single predominant race was identified in 8 of 10 clusters of accessions, i.e., 1 kafir, 1 durra, 4 guinea, and 2 caudatum clusters. Guinea sorghums, with the exception of accessions in the margaritiferum subrace, clustered in 3 geographical groups, i.e., western African, southern African, and Asian guinea clusters; the latter two appeared more closely related. Caudatum were mainly distributed in 2 clusters, the African Great Lakes caudatum cluster and those African caudatum originating from other African regions. This last differentiation appears related to contrasting photoperiod responses. These results aid in the optimization of sampling accessions for introgression in breeding programs.