Genetic differentiation and diversity upon genotype and phenotype in cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> L. Walp.)

The evolution of species is complex and subtle which always associates with the genetic variation and environment adaption during active/passive spread or migration. In crops, this process is usually driven and influenced by human activities such as domestication, cultivation and immigration. One method to discover this process is to analyze the genetic diversity of those crops in different regions. This research first assessed the similarity and differentiation between genetic diversity of genotype and phenotype in 768 world-wild cowpea germplasm which were collected by USDA and US breeding programs. Totally 1048 genotyping by sequencing (GBS) derived single nucleotide polymorphisms (SNPs) and 17 agronomic traits were used to analyze the genetic diversity, distance, cluster and phylogeny. The group differentiation was analyzed based on both the genotype distances from 1048 SNP markers and the phenotypic (Mahalanobis) distance D2 from 11 traits. A consistent result of diversity in genotype (polymorphism information content, PIC) and phenotype (Shannon and Simpson index) indicated that the East Africa and South Asia sub-continents were the original and secondary regions of cowpea domestication. Both dendrograms built by genetic distance present relationship among different regions, and the Mantel coefficient showed medium correlation level (r = 0.58) between genotype and phenotype. The information of both genotypic and phenotypic differentiations may help us to understand evolution and migration of cowpea more comprehensively and also will inform breeders how to use cowpea germplasm in breeding programs.     

谷子核心种质表型遗传多样性分析及综合评价

通过遗传种质的多样性评估可以指导深入研究资源和育种中优异互补亲本的选择进而提高优异基因的交流累加和新品种培育的效率。本研究选用了来自世界各地的份谷子核心种质通过个表型性状的综合鉴定评估遗传多样性和筛选优异种质资源结果表明我国谷子资源的表型遗传多样性丰富单穗粒重、穗长、穗粗、株高、茎节数和生育期均表现了丰富的变异谷子育成品种遗传多样性相比农家品种下降明显育种的遗传增益主要体现在株高和穗长的适度减低,以及茎粗、茎节数、穗粗、单穗粒重、单穗重及生育期的适度增加系统聚类分析将谷子资源分成类第类以来源为东北欧国家的品种为主第类以北美和非洲的品种为主第类以东亚、南亚的品种为主我国种质可划分为春播型、春夏兼播型和南方型类型采用主成分分析法和逐步回归分析法综合评判表明叶鞘色、刚毛长度、粒色、米色、株高、穗长、茎粗和单穗粒重个性状可作为谷子表型鉴定的主要指标。     

Biodiversity in a germplasm collection of durum wheat

Summary Over 7,600 durum wheat accessions belonging to 22 country gene pools were evaluated in Syria, during the seasons 1985–86 through 1987–88 under semi-arid Mediterranean climatic conditions. Data on seven agronomic traits are presented to assess the distinctiveness and the phenotypic diversity of these pools. Univariate statistical analysis revealed differences among materials of diverse origins for all traits. Mean phenotypic diversity within countries was highest in the germplasm from India, lowest in that from Bulgaria. In a canonical variate analysis, the first three canonical variables explained 77.7% of the total variance. A cluster analysis was performed to supplement the generated information by the canonical analysis. The multivariate analyses evidenced the distinctiveness of the Ethiopian germplasm. The gene pools from Syria and Jordan, closely resembling each other, appeared separate from all others. A certain peculiarity was also shown by the germplasms from Greece, Morocco and France, while the remaining countries clustered into four groups. The results of the present evaluation could provide useful information for breeding activities, germplasm collection, and establishment of core collections. Evidence is presented that environment played a major role in creating the overall variation for the considered traits, although germplasm exchange seemed also an important factor.     

水稻核心种质表型性状遗传多样性分析及综合评价

种质资源是水稻遗传育种和解析复杂性状的重要基础,而对遗传多样评估有利于鉴定最优亲本组合以产生遗传变异最大的后代群体和促进不同资源的有利基因渗透到栽培品种。选用14个表型性状对美国农业部水稻核心种质中的6大洲
1 579份水稻种质, 分析与评价其遗传多样性和优良稻种资源,主要结果如下: (1)亚洲、非洲与大洋洲间遗传距离较远,且亚洲、非洲和大洋洲的水稻资源具有较丰富的表型遗传多样性,而不同性状的遗传多样性在洲际间表现不同;粒长宽比、碱消值、株高、粒宽、千粒重和淀粉含量等6个性状具有很高的表型遗传多样性。(2)采用主成分分析法和逐步回归分析法综合评判表明,越南的PI392768的综合性状表现最好,法国的PI281760综合性状表现最差,同时淀粉含量、抽穗期、株高、倒伏性、糙米色和颖壳色等6个性状可作为种质资源综合评价指标。在水稻育种中应注重利用具有丰富遗传多样性的种质资源,并在亲本选配时适当选择遗传距离较远且综合性状表现差异大的种质材料。     

64份苦荞种质资源农艺性状遗传多样性分析与综合评价

采用Shannon-Wienerˊs多样性指数、主成分分析、综合得分F值及聚类分析等方法对干旱地区64份苦荞种质资源的主要农艺性状进行了遗传多样性分析和综合评价。结果表明,单株粒重的遗传多样性指数最高,为13.630,主茎粗的变异系数最高,为30.6%;主成分分析将苦荞种质的11个农艺性状降维为累计贡献率达87.580%的6个主成分;综合得分F值与生育期、株高、主茎节数、千粒重和单株粒重等具有极显著的相关性,可作为苦荞种质资源综合评价的主要指标;根据综合得分F值和聚类分析结果筛选出7份具有不同育种目标选择潜力的优良材料。     

黄麻核心种质的遴选

遴选黄麻核心种质可为黄麻种质创新及新品种选育奠定基础。本研究以300份黄麻种质资源为基础,基于SSR分子标记和农艺性状考察,结合地理来源构建核心种质。结果表明,11个农艺性状变异系数变幅在13.06%～84.87%,表现出丰富的遗传多样性。按农艺性状聚类分析可划分为8个类群,按分子标记聚类可划分为10个类群。结合2个聚类分析、地理位置并按比例取样,建立一个由108份品种(系)组成的预选核心种质。采用44对SSR引物对其进行遗传差异分析,在遗传相似系数为0.65时,可把108份品种(系)分成圆果种和长果种两大类。根据遗传差异分析,剔除遗传相似系数大于或等于0.85的遗传冗余,获得84份品种(系)的核心种质,其中圆果种60份和长果种24份。比较84份核心种质与300份种质的农艺性状变异系数及Shannon-Wiener指数发现,两者之间相差不大,表明遴选的84份核心种质可以最大限度代表300份黄麻种质资源的遗传多样性加以利用和保存。     

120份谷子种质资源的农艺性状表现和遗传多样性分析

对120份谷子种质资源的21个主要农艺性状进行遗传多样性、主成分以及聚类分析。结果表明,遗传多样性指数以主穗重和主穗粒重最高,均为2.02;变异系数以单株干草重最高,为64.12%。根据谷子种质性状间的遗传差异,对21个主要农艺性状进行主成分分析,得到10个主成分因子的累计贡献率达81.777%。通过聚类分析,将谷子种质资源分为6个类群,各类群在生育期、株高、分蘖性、籽粒产量和干草产量等性状间有明显的形态学特征,从早熟、高产和单株干草重3个方面筛选出11份优异谷子种质资源。本研究结果可为甘肃干旱高寒农业区谷子种质资源高效利用和亲本选择提供科学依据。     

Classification of a collection of sesame germplasm using multivariate analysis

Sesame (Sesamum indicum L.) is an important edible oil crop. Meteorological factors such as temperature, rainfall, and the amount of solar radiation determine the yield potential of sesame. To identify phenotypic diversity and to infer genotypic backgrounds in a collection of 250 sesame germplasm accessions, we classified the germplasm based on variation in morphological traits using principal component (PC) and cluster analysis. The sesame germplasm was grouped based on five PCs, which accounted for 82.3% of total variation. The first PC (PC1) was positively correlated with days to flowering, days to maturity, and number of capsules per plant, whereas the second PC (PC2) was negatively correlated with all characteristics except capsule-bearing stem length. The third component (PC3) was highly positively correlated with capsule length and plant height. We constructed a scatter diagram of the first two PCs (PC1 vs. PC2), revealing four distinct groups of eigenvectors. Most sesame germplasm was widely distributed among Groups I, II, III, and IV. Group III showed a wide range of distribution in the diagram. Otherwise, the distribution of the 250 germplasm accessions was more compact in a scatter diagram of PC1 vs. PC3 compared with PC1 vs. PC2. Groups I, II, III, and IV contained 142, 102, 2, and 3 sesame germplasm accessions, respectively. The two germplasm in Group III were collected from different regions, as were the three germplasm in Group IV. The results show that the distribution of sesame origin is wider than the regions examined in view of phenotypic diversity.     

云南稻种资源表型遗传多样性的研究

以5285份云南省地方稻种资源为材料,以<云南稻种资源目录>中记录的31个数量和质量性状为基本数据,研究结果表明:云南稻种资源遗传多样性大,稻种类型多,优异资源丰富.云南稻种资源主要分布于思茅、临沧、文山等滇西南和滇东南地区,占总数的80%;全部稻种资源中粳稻占54%,基本表现籼粳各半;滇西南和滇东南的遗传多样性最大,粳稻     

Allozyme differentiation of European populations and cultivars of Lolium perenne L., and the relation to ecogeographical factors

Summary Sixty Lolium perenne populations were screened for allozyme diversity at five loci. Objective was to determine whether allozyme diversity could be used as selection criterion for genebank accessions of L. perenne. Subsampling of locations was tested with allozyme analysis to determine whether genetically different populations could be collected at one location. Correlations between allelic frequencies and environmental factors and morphological data were established, to find ecogeographical patterns in the observed variation. Results indicated that with few examples each allelic variant could be observed in each population screened; very few unique alleles were found. Differences between populations were largely due to differences in allelic frequencies. Few correlations were found with environmental factors and morphological data. For some allele frequencies a north-south cline was observed. Generally, allozymic data of the five screened loci did not appear to be useful for the selection of accessions for genebank storage. Significant genotypic differences between populations collected at one location could be established. In general these results agreed with earlier results concerning phenotypic variation in the same populations.     

中原牡丹品种初级核心种质构建与代表性检验

以400个中原牡丹品种的形态学和农艺学性状为基本数据,采用花型分组,组内按平方根比例策略确定取样量,并使用类平均聚类法取样,获得了中原牡丹品种初级核心种质,其取样比例占总体样本的30%.经检测,初级核心种质与总体种质的31个性状中仅花期1个性状的多样性指数达到了显著差异水平,初级核心种质多样性指数对总体种质的代表性达99.20%,表型保留比例达到了100%.表明,这个包含120个样本的初级核心种质能在表型性状上很好地代表总体种质的遗传多样性.     

Genetic diversity in red clover (Trifolium pratense L.) revealed by morphological and microsatellite (SSR) markers

The NPGS-USDA core collection with 85 accessions of red clover, an important forage species, is little described. The goal of the present study was to evaluate the diversity of a set of accessions from the core collection at the morphological and molecular level in order to extract some valuable accessions for Brazilian red clover breeding programs. Twenty-one morphological traits, collected in field and greenhouse in South Brazil, and seven SSR markers were used to describe 57 accessions from the U.S. core collection and one population cultivated in Southern Brazil. Variation between accessions was large for most of the 21 morphological traits. A cluster analysis based on the morphological traits revealed five distinct clusters that separated the populations according to flowering earliness, as already described, but also according to persistency, growth habit and dry matter productivity. Over seven SSR loci, the number of alleles averaged 11.1 alleles per locus. Genetic diversity measured with SSR markers was high, with a mean expected heterozygosity of 0.86. An analysis of molecular variance revealed that the largest proportion of variation (83.6%) resided at the within population level. Although the molecular markers also separated accessions into five clusters, there was no coincidence between the composition of groups found with morphological and molecular data. Use of genetic diversity in breeding programs requires to use the most promising populations, to combine positive traits such as persistency and forage yield, and probably to use within population variation to detect valuable genotypes that could be used as parents of synthetic varieties.     

Genetic diversity in cornsalad (Valerianella locusta) and related species as determined by AFLP markers

Fifteen amplified fragment length polymorphism (AFLP) EcoRI/MseI‐based primer combinations with five selective bases (Eco RI‐ANN, MseI‐CN) were used to estimate genetic diversity among 45 line varieties of cultivated cornsalad and 19 genebank accessions classified into nine different species related to cornsalad. Polymorphic fragments were scored for calculation of Jaccard's coefficient of genetic similarity (GS). The average GS estimate in elite germplasm (GS = 0.90) was substantially higher than in exotic germplasm (GS = 0.47). UPGMA‐cluster analysis revealed genetic relationships among recently bred varieties, old varieties and genebank accessions. Analysis of molecular variance indicated almost threefold variability within sets compared with between sets due to a high level of polymorphism among wild species. Sources for increasing genetic diversity in elite germplasm of cornsalad were suggested and a duplicate among the genebank accessions was detected. AFLPs could be considered a powerful tool for genetic diversity estimation in cornsalad germplasm and are recommended for systematic fingerprinting of remaining cornsalad species.     

柚类种质资源表型多样性分析及综合评价

为了建立合理的柚类分类系统并为柚类育种提供参考,本研究以82份柚类种质资源为试材,采用变异系数、Shannon-Weaver多样性指数、方差、相关性、主成分、聚类、回归分析等对其26个表型性状进行多样性分析、差异分析及综合评价。结果表明:这82个品种的26个性状的变异系数为0.26%。其中翼叶面积和果心面积变异较大,其他性状遗传特性较稳定;单果重、果横径、果形指数、果皮厚、囊瓣数、种子数、果心长和宽、叶片长和宽、叶片面积、花瓣宽、花柄长等性状等级分布均匀,翼叶面积、花瓣数、雄蕊长分级较少且分布不均;来源于中国大陆以外品种的果皮厚、叶柄长、翼叶长,明显优于长江流域和珠江流域来源的材料,但雌蕊长则相反;选育品种的叶片长、宽和面积显著大于遗传材料和地方品种;82个品种可聚为大翼叶大果型、大翼叶小果型,小翼叶大果型,小翼叶小果型4个类群;前7个主成分累计贡献率75.57%,包含了柚类表型性状的大部分信息;26个性状F平均值0.45,其中早暹柚得分最高为0.69,红肉琯溪蜜柚最低为0.24;囊瓣数、种子数等12个性状与F值极显著相关;回归方程筛选出单果重、囊瓣数等19个性状。本研究说明柚类种质资源具有较高的表型多样性,筛选出的19个性状可作为柚类综合评价指标,为柚类育种提供科学依据。     

Association analysis of fibre traits in Gossypium arboreum accessions

Advances in the use of diploid Asiatic species in cotton breeding require an understanding of the relatedness and ancestry of diploid cotton accessions, and identification of simple sequence repeat (SSR) markers associated with agronomically important phenotypic traits, for example, fibre quality. Fifty‐six Gossypium arboreum germplasm accessions introduced from nine regions of Africa, Asia and Europe were evaluated for eight fibre characters (lint percentage, lint colour, elongation, micronaire, strength, 50% span length, 2.5% span length and maturity%) and genotyped with 98 SSR markers. When viewed across all accessions most of the SSR markers were polymorphic. Population structure analysis identified six main clusters for the accessions which corresponded to different geographic regions, indicating agreement between genetic and predefined populations. The general linear model method was used to disclose marker–trait associations. Marker–trait associations were investigated by fitting single marker regression models for phenotypic traits on marker band intensities with correction for population structure. This paper illustrates the potential of association mapping in diploid cotton, because existing phenotypic data, a modest number of SSR markers, and a pioneering statistical analysis, identified interesting associations.     

绿豆种质资源农艺性状的因子分析及综合评价

为合理利用绿豆种质资源,本研究以55份绿豆种质资源为材料,通过对其10个农艺性状进行因子分析及聚类分析。结果表明:10个农艺性状的变异系数为8.57%~47.19%,其中单株粒重变异系数最大,生育期变异系数最小。将10个农艺性状简化为结荚数因子、高度因子、粒数因子、粒重因子和生育期因子5个独立的主因子,该5个主因子可以反映原始信息的86.340%。经综合得分排序,评选出10份性状优良的绿豆种质资源。聚类分析将55份种质资源的10个数量性状分为3大类,类群I、类群II、类群III分别包括22份、7份、26份材料。结合综合评价和聚类分析认为,在黑龙江绿豆生产中,‘安绿8号’、‘佳木斯黄绿豆’、‘冀绿1号’可作为品种选育的改良亲本,也可大面积种植利用。     

Genetic diversity for agronomic and fiber traits in day-neutral accessions derived from primitive cotton germplasm

Upland cotton (Gossypium hirsutumL) is an important crop that is cultivated in warm climates through-out the world. Agronomic performance and fiber quality must continually be improved if cotton is to maintain economic viability. Primitive ancestors of cotton contain diversity for trait improvement; however, many of these accessions have a short-day flowering response (photoperiodic) and are not readily useable in breeding programs. In this study, 114 day-neutral derived primitive germplasm lines were evaluated in field trials for two years. Agronomic and fiber trait data were collected and analyzed. Variance components, genotypic values, and genotypic correlations were calculated. Genotypic effects for all traits studied made significant contributions to the phenotypic variation indicating genetic diversity among these lines. The predicted genotypic values showed a wide range of variation for agronomic and fiber traits. Weak genotypic correlations were found between yield and 2.5% span length and fiber strength, two important fiber traits. Although these day-neutral derived accessions had lower lint percentage, they had improved fiber length, strength, micronaire, and comparable yields with two commercial cultivars. Thus, these day-neutral derived accessions are sources of genetic variation that when used in breeding programs offer the potential to improve important traits and expand genetic diversity.Contribution of the USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

Estimation of phenotypic divergence in a collection of <Emphasis Type="Italic">Capsicum</Emphasis> species for yield-related traits

Phenotypic divergence among the 24 accessions belonging to a collection of six species of Capsicum from different geoclimatic regions available in field gene bank of CIMAP, Lucknow, India, was quantified by multivariate analysis for 12 quantitative and qualitative traits. Based on their values, all 24 accessions were grouped into six clusters such that the genetic stocks within cluster had smaller D ² values among themselves than those belonging to different clusters. The accessions of Capsicum annuum were distributed in different clusters in morphotyping representing different species, suggesting that taxonomic characteristics are not always related to agronomic traits. No parallelism/association was found between geographical and phenotypic diversity. Accessions 15 and 23 (clusters V and VI, respectively) had distinct identity. The three characteristics that played the greatest role in differentiation were fruit diameter, number of fruits per plant, and leaf diameter, which can be utilized as conventional/morphological markers for the improvement of chilli yield and obtaining good segregants in chilli breeding programs.