Genealogical analysis of the diversity of spring barley cultivars released in former Czechoslovakia and modern Czech Republic

Genealogical analysis was employed in studying the time course of changes in genetic diversity of spring barley cultivars released in former Czechoslovakia and the modern Czech Republic. Cultivars from different regions proved to significantly differ in the distribution of dominant ancestor contributions, suggesting a specificity of original ancestors to different cultivation conditions. A comparison of cultivar groups differing in end use showed that the genetic diversity of malting cultivars was significantly lower than that of feed cultivars, although modern malting and feed cultivars of Czechia and Slovakia have virtually the same genetic basis. Temporal analysis showed that diversity tended to increase through decades. While new original ancestors were introduced in pedigrees, especially in the past 30 years, the number of local landraces and old cultivars gradually decreased. The losses accounted for about two-thirds of the local germplasm. Thus, a substantial increase in genetic diversity was accompanied by genetic erosion of the local spring barley gene pool of former Czechoslovakia. A cluster structure was observed for the set of spring barley cultivars released in the postwar period. The coefficient of parentage averaged over all possible pairs of cultivars introduced in the Czech National List was estimated at 0.11. It was concluded that the genetic diversity of modern spring barley cultivars in the Czech Republic is at an acceptable level.     

Genealogical analysis of the diversity of spring barley cultivars released in former Czechoslovakia and modern Czechia

Genealogical analysis was employed in studying the time course of changes in genetic diversity of spring barley cultivars released in former Czechoslovakia and the modem Czech Republic. Cultivars from different regions proved to significantly differ in the distribution of dominant ancestor contributions, suggesting a specificity of original ancestors to different cultivation conditions. A comparison of cultivar groups differing in end use showed that the genetic diversity of malting cultivars was significantly lower than that of feed cultivars, although modern malting and feed cultivars of Czechia and Slovakia have virtually the same genetic basis. Temporal analysis showed that diversity tended to increase through decades. While new original ancestors were introduced in pedigrees, especially in the past 30 years, the number of local landraces and old cultivars gradually decreased. The losses accounted for about two-thirds of the local germplasm. Thus, a substantial increase in genetic diversity was accompanied by genetic erosion of the local spring barley gene pool of former Czechoslovakia. A cluster structure was observed for the set of spring barley cultivars released in the postwar period. The coefficient of parentage averaged overall possible pairs of cultivars introduced in the Czech National List was estimated at 0.11. It was concluded that the genetic diversity of modern spring barley cultivars in the Czech Republic is at an acceptable level.     

Population structure revealed by different marker types (SSR or DArT) has an impact on the results of genome-wide association mapping in European barley cultivars

Diversity arrays technology (DArT) and simple sequence repeat (SSR) markers were applied to investigate population structure, extent of linkage disequilibrium and genetic diversity (kinship) on a genome-wide level in European barley (Hordeum vulgare L.) cultivars. A set of 183 varieties could be clearly distinguished into spring and winter types and was classified into five subgroups based on 253 DArT or 22 SSR markers. Despite the fact, that the same number of groups was revealed by both marker types, it could be shown that this grouping was more distinct for the SSRs than the DArTs, when assigned to a Q-matrix by STRUCTURE. This was supported by the findings from principal coordinate analysis, where the SSRs showed a better resolution according to seasonal habit and row number than the DArTs. A considerable influence on the rate of significant associations with malting and kernel quality parameters was revealed by different marker types in this genome-wide association study using general and mixed linear models considering population structure. Fewer spurious associations were observed when population structure was based on SSR rather than on DArT markers. We therefore conclude that it is advisable to use independent marker datasets for calculating population structure and for performing the association analysis.     

Diversity of North European oat analyzed by SSR, AFLP and DArT markers

Oat is an important crop in Nordic countries both for feed and human consumption. Maintaining a high level of genetic diversity is essential for both breeding and agronomy. A panel of 94 oat accessions was used in this study, including 24 museum accessions over 100- to 120-year old and 70 genebank accessions from mainly Nordic countries and Germany, covering different breeding periods. Sixty-one polymorphic SSR, 201 AFLP and 1056 DArT markers were used to evaluate the past and present genetic diversity of the Nordic gene pool. Norwegian accessions showed the highest diversity, followed by Swedish and Finnish, with German accessions the least diverse. In addition, the Nordic accessions appeared to be highly interrelated and distinct from the German, reflecting a frequent germplasm exchange and interbreeding among Nordic countries. A significant loss of diversity happened at the transition from landraces and old cultivars to modern cultivars. Modern oat originated from only a segment of the landraces and left the remainder, especially black oat, unused. However, no significant overall diversity reduction was found during modern breeding periods, although fluctuation of diversity indices was observed. The narrow genetic basis of the modern Nordic gene pool calls for increasing genetic diversity through cultivar introduction and prebreeding based on neglected sources like the Nordic black oat.     

Genome-Wide Association Mapping for Kernel and Malting Quality Traits Using Historical European Barley Records

Malting quality is an important trait in breeding barley (Hordeum vulgare L.). It requires elaborate, expensive phenotyping, which involves micro-malting experiments. Although there is abundant historical information available for different cultivars in different years and trials, that historical information is not often used in genetic analyses. This study aimed to exploit historical records to assist in identifying genomic regions that affect malting and kernel quality traits in barley. This genome-wide association study utilized information on grain yield and 18 quality traits accumulated over 25 years on 174 European spring and winter barley cultivars combined with diversity array technology markers. Marker-trait associations were tested with a mixed linear model. This model took into account the genetic relatedness between cultivars based on principal components scores obtained from marker information. We detected 140 marker-trait associations. Some of these associations confirmed previously known quantitative trait loci for malting quality (on chromosomes 1H, 2H, and 5H). Other associations were reported for the first time in this study. The genetic correlations between traits are discussed in relation to the chromosomal regions associated with the different traits. This approach is expected to be particularly useful when designing strategies for multiple trait improvements.     

Haplotype diversity and population structure in cultivated and wild barley evaluated for Fusarium head blight responses

Fusarium head blight (FHB) is a threat to barley (Hordeum vulgare L.) production in many parts of the world. A number of barley accessions with partial resistance have been reported and used in mapping experiments to identify quantitative trait loci (QTL) associated with FHB resistance. Here, we present a set of barley germplasm that exhibits FHB resistance identified through screening a global collection of 23,255 wild (Hordeum vulgare ssp. spontaneum) and cultivated (Hordeum vulgare ssp. vulgare) accessions. Seventy-eight accessions were classified as resistant or moderately resistant. The collection of FHB resistant accessions consists of 5, 27, 46 of winter, wild and spring barley, respectively. The population structure and genetic relationships of the germplasm were investigated with 1,727 Diversity Array Technology (DArT) markers. Multiple clustering analyses suggest the presence of four subpopulations. Within cultivated barley, substructure is largely centered on spike morphology and growth habit. Analysis of molecular variance indicated highly significant genetic variance among clusters and within clusters, suggesting that the FHB resistant sources have broad genetic diversity. The haplotype diversity was characterized with DArT markers associated with the four FHB QTLs on chromosome 2H bin8, 10 and 13 and 6H bin7. In general, the wild barley accessions had distinct haplotypes from those of cultivated barley. The haplotype of the resistant source Chevron was the most prevalent in all four QTL regions, followed by those of the resistant sources Fredrickson and CIho4196. These resistant QTL haplotypes were rare in the susceptible cultivars and accessions grown in the upper Midwest USA. Some two- and six-rowed accessions were identified with high FHB resistance, but contained distinct haplotypes at FHB QTLs from known resistance sources. These germplasm warrant further genetic studies and possible incorporation into barley breeding programs.     

Genetic characterization of Iranian safflower (Carthamus tinctorius) using inter simple sequence repeats (ISSR) markers

Safflower (Carthamus tinctorious L.) is valued as a source of high quality vegetable oil. 20 ISSR primers were used to assess the genetic diversity of 18 accessions of safflower collected from different geographical regions of Iran. The ISSR primers combinations revealed 57.6 % polymorphism, among 338 genetic loci amplified from the accessions. The sum of effective number of alleles and observed number of alleles were 29.76 and 36.77, respectively. To understand genetic relationships among these cultivars, Jacquards’ similarity coefficient and UPGMA clustering algorithm were applied to the ISSR marker data set. ISSR markers grouped accessions into two main clusters and four sub clusters. Also, the principal coordinate analysis (PCoA) supported the cluster analysis results. The results showed these genotypes have high genetic diversity, and can be used for alternative safflower breeding program.     

利用RAPD标记分析大麦种质资源的遗传多样性

利用RAPD标记对19份西藏近缘野生大麦材料、33份我国不同省市的地方品种以及8份国外引进大麦品种共60份大麦种质资源的遗传多样性进行检测.结果表明材料间遗传差异明显.32个RAPD引物中,有25个引物(占78.13%)可扩增出清晰且具多态性的条带,另外7个引物能扩增出1～3条清晰但无多态性的条带.每个引物可扩增出1～8条多态性带,平均为3.72条.32个引物共产生119条DNA片段,其中87条具有多态性,多态性比率(PPB)为73.11%,平均多态信息量(PIC)为0.434;每个位点平均有效等位基因数(Ne)为2.304;材料间遗传相似系数GS变化范围为0.757～0.981,平均值为0.871.19份来源于西藏的近缘野生大麦材料间GS值变幅为0.818～0.969,平均为0.892;33份我国栽培大麦地方品种间的GS值变化范围为0.783～0.981,平均为0.879;8份分别来自8个国家的栽培大麦品种间的GS值变幅为0.820～0.956,平均为0.882.根据RAPD标记分析的结果,对60份大麦种质资源进行聚类分析,在平均GS值0.871水平上60份大麦材料可聚为5类,聚类结果能在一定程度上反应材料的地理分布关系,但某些相同地理来源的材料也较分散地分布在整个聚类树中.本研究从分子水平上进一步证明了我国栽培大麦丰富的遗传多样性,是世界栽培大麦的遗传多样性中心之一.     

Assessment of genetic diversity in Brazilian barley using SSR markers

Barley is a major cereal grown widely and used in several food products, beverage production and animal fodder. Genetic diversity is a key component in breeding programs. We have analyzed the genetic diversity of barley accessions using microsatellite markers. The accessions were composed of wild and domesticated barley representing genotypes from six countries and three breeding programs in Brazil. A total of 280 alleles were detected, 36 unique to Brazilian barley. The marker Bmag120 showed the greatest polymorphism information content (PIC), with the highest mean value found on chromosome three, and the lowest on chromosomes four and six. The wild accessions presented the highest diversity followed by the foreign genotypes. Genetic analysis was performed using Principal Coordinates Analysis, UPGMA clustering, and Bayesian clustering analysis implemented in Structure. All results obtained by the different methods were similar. Loss of genetic diversity has occurred in Brazilian genotypes. The number of alleles detected in genotypes released in 1980s was higher, whereas most of the cultivars released thereafter showed lower PIC and clustered in separate subgroups from the older cultivars. The use of a more diverse panel of genotypes should be considered in order to exploit novel alleles in Brazilian barley breeding programs.     

Development and assessment of DArT markers in triticale

Triticale (X Triticosecale Wittm.) is a hybrid derived by crossing wheat (Triticum sp.) and rye (Secale sp.). Till date, only a limited number of simple sequence repeat (SSRs) markers have been used in triticale molecular analyses and there is a need to identify dedicated high-throughput molecular markers to better exploit this crop. The objective of this study was to develop and evaluate diversity arrays technology (DArT) markers in triticale. DArT marker technology offers a high level of multiplexing. Development of new markers from triticale accessions was combined with mining the large collection of previously developed markers in rye and wheat. Three genotyping arrays were used to analyze a collection of 144 triticale accessions. The polymorphism level ranged from 8.6 to 23.8% for wheat and rye DArT markers, respectively. Among the polymorphic markers, rye markers were the most abundant (3,109) followed by wheat (2,214) and triticale (719). The mean polymorphism information content values were 0.34 for rye DArT markers and 0.37 for those from triticale and wheat. High correlation was observed between similarity matrices derived from rye, triticale, wheat and combined marker sets, as well as for the cophenetic values matrices. Cluster analysis revealed genetic relationships among the accessions consistent with the agronomic and pedigree information available. The newly developed triticale DArT markers as well as those originated from rye and wheat provide high quality markers that can be used for diversity analyses and might be exploited in a range of molecular breeding and genomics applications in triticale.     

Evaluation of Genetic Diversity in Chinese Wild Apple Species Along with Apple Cultivars Using SSR Markers

China, one of the primary centers of genetic diversity for the genus Malus, is very rich in wild apple germplasm. In this study, genetic diversity in 29 Malus accessions, including 12 accessions from 7 Chinese Malus species, 4 Chinese landraces, and 13 introduced apple cultivars, was assessed using a set of 19 single-locus simple sequence repeat (SSR) markers distributed across all 17 linkage groups of the apple genome. The number of alleles detected at each locus ranged from 2 to 11, with an average of 5.3 per SSR marker. In some accessions, 16 unique alleles were identified. Ten out of these 16 unique alleles (62.5%) were detected exclusively in wild species, indicating that these Chinese wild apple species have considerable genetic diversity and can be used in breeding programs to increase the genetic diversity of apple cultivars. Using 19 SSRs, an unweighted pair-group method with arithmetic average cluster analysis was conducted, and the resulting dendrogram revealed that all cultivars, except for E??peMeBckoe, were clustered together in the same group. The Russian cultivar E??peMeBckoe was closely related to the Chinese crabapple Baihaitang (M. prunifolia), with a high similarity coefficient value of 0.94. Of the two M. sieversii accessions used, one accession showed a close relationship to apple cultivars, while the other accession was closely related to wild apple species, suggesting the presence of a wider genetic diversity in Chinese M. sieversii species. The influence of SSR marker selection on genetic diversity analysis in this Malus collection was also discussed.     

High-throughput genotyping of hop (Humulus lupulus L.) utilising diversity arrays technology (DArT)

Implementation of molecular methods in hop (Humulus lupulus L.) breeding is dependent on the availability of sizeable numbers of polymorphic markers and a comprehensive understanding of genetic variation. However, use of molecular marker technology is limited due to expense, time inefficiency, laborious methodology and dependence on DNA sequence information. Diversity arrays technology (DArT) is a high-throughput cost-effective method for the discovery of large numbers of quality polymorphic markers without reliance on DNA sequence information. This study is the first to utilise DArT for hop genotyping, identifying 730 polymorphic markers from 92 hop accessions. The marker quality was high and similar to the quality of DArT markers previously generated for other species; although percentage polymorphism and polymorphism information content (PIC) were lower than in previous studies deploying other marker systems in hop. Genetic relationships in hop illustrated by DArT in this study coincide with knowledge generated using alternate methods. Several statistical analyses separated the hop accessions into genetically differentiated North American and European groupings, with hybrids between the two groups clearly distinguishable. Levels of genetic diversity were similar in the North American and European groups, but higher in the hybrid group. The markers produced from this time and cost-efficient genotyping tool will be a valuable resource for numerous applications in hop breeding and genetics studies, such as mapping, marker-assisted selection, genetic identity testing, guidance in the maintenance of genetic diversity and the directed breeding of superior cultivars.     

贵州野生大麦麦芽品质性状的SSR标记分析

采用6对啤酒大麦的麦芽浸提和糖化力紧密连锁引物对103份采自贵州的野生大麦材料进行SSR标记。结果表明,贵州野生大麦麦芽品质性状存在丰富的变异,6对SSR引物共检测出38个等位变异,每个位点平均6.33个等位变异,其中GMS001位点对贵州野生大麦基因组DNA变异检测最有效。UPGMA聚类图显示,该6对与麦芽品质紧密连锁的SSR引物对区分野生大麦在贵州不同的资源产地和棱性是有效的,表现为遵义地区野生大麦遗传多样性丰富,而来自贵州凯里地区的野生大麦资源遗传多样性狭窄。麦芽品质性状标记结果表明贵州野生六棱大麦较四棱大麦的遗传差异更显著,表明进行贵州啤酒大麦人工育种的亲本应在亲缘关系较远的六棱大麦之间选择。     

The use of AFLPs to examine genetic relatedness in barley

The generation of AFLPs in spring barley cultivars provided genetic information relating to the development of the crop in the UK since 1953. Principal co-ordinate (PCO) analysis of genetic similarities (gs) confirmed the marked contrast in the cultivars used in the 1970s and 1980s. The earliest cultivars, many derived from Proctor, were succeeded by tall-strawed, disease-resistant types with high yield but poor malting potential. In the 1980s they were in turn replaced by short-strawed cultivars with excellent yield and good malting quality, which originated from Triumph. A PCO plot of gs provided insight into the effects of selection for disease resistance and the antagonism between malting quality and particular resistance genes. The analysis of gs was more useful than pedigrees and estimates of kinship in revealing the genetic relationship between cultivars. Theoretical considerations for maximising the efficiency of an AFLP genotyping programme are discussed in the context of the number of primer pairs required to distinguish genotypes at varying levels of similarity.     

鸭茅种质资源遗传多样性的SRAP研究

利用SRAP(Sequence-related amplified polymorphism)标记对来自国内外的45份鸭茅（Dactylis glomerata L.）种质资源进行遗传多样性研究。21对引物扩增出438个条带,多态性条带为363条,多态性条带比率为82.08%,每对引物组合的多态性带数平均为17.29条。GS值范围在0.6248-0.9686间,平均GS值为0.7958,显示来源广泛的鸭茅种质资源间存在着丰富的遗传变异。聚类分析及主成分分析能将所有材料聚为4类,能较准确的反映材料的来源分布情况及供试材料的染色体倍性差异,表明鸭茅的遗传多样性与染色体倍性及地理分布密切相关。同时清楚的揭示出国产鸭茅品种遗传基础较为狭窄。本研究为育种和探讨鸭茅种质资源遗传变异奠定了较好的理论基础。     

Inter simple sequence repeat analysis of genetic diversity and relationships in cultivated barley of Nordic and Baltic origin

This study evaluates putative changes of genetic diversity and relationships of barley in the Nordic and Baltic countries that might have taken place during the last century as a result of commercial breeding. Four ISSR primers were used to analyse 227 accessions, yielding a total of 47 polymorphic loci. Shannon-Weaver diversity values for each locus ranged from 0.012 to 0.693. Overall, there were no significant changes of genetic diversity observed over time. A significant decrease of diversity was, however, observed in material from the southern parts of the Nordic and Baltic countries. In material from the northern parts no decrease of diversity was observed. The genetic diversity of six-rowed barley bred in the middle of the 20th century was low, but there was no significant difference between modern accessions and landraces or old cultivars. The magnitude in changes of genetic diversity differed also in material from different countries of origin. A cluster analysis clearly separated the material into two groups. The first cluster included 86.5% of all six-rowed accessions, whereas the second cluster contained 97.4% of all two-rowed accessions.     

新疆甜高粱种质资源遗传多样性的SSR分析

选用50对SSR引物对新疆现有72份甜高粱种质资源进行遗传多样性分析。结果表明:有20对引物在72份甜高粱种质资源中表现为多态性。共检测到91个等位基因,每对引物可检测到的等位基因数目为2～5个,平均为3.45个。多态性信息量(PIC)的变动范围为0.2859～0.6652,平均为0.5057。72份甜高粱种质间的遗传相似系数变化范围为0.2001～1.000,平均值为0.5599。UPGMA聚类分析将72份材料划分为A、B两大类群,A群包括69份材料,而A群又被分成从Ⅰ到Ⅺ共11个亚群,B群包括3份材料,农艺性状近似的大多被聚到同一类群。     

Genetic diversity among barley cultivars assessed by sequence-specific amplification polymorphism

We analyzed the genetic structure and relationships among barley cultivars (Hordeum vulgare L.) with sequence-specific amplification polymorphisms (S-SAPs). Polymorphisms were identified in 824 individual barley plants representing 103 cultivars (eight plants per cultivar) widely grown in Canada and the United States, using PCR primers designed from the long terminal repeat of the barley retrotransposon BARE-1 and a subset of four selective MseI primers. From the 404 bands scored, 150 were polymorphic either within or between cultivars. Genetic structure assessed with analysis of molecular variance attributed the largest component of variation to the within groups of cultivars (69–86%). Within-cultivar genetic variation was estimated as average gene diversity over loci and ranged from 0 (completely homogenous) to 0.076 (most heterogeneous cultivar). Only 17 out of 103 cultivars (16%) were judged to be homogenous by this criterion. Relationships among cultivars were analyzed by cluster analysis using unweighted pair-groups using arithmetic averages and found groups similar to those determined by agriculturally significant phenotypic traits such as spike morphology (two-rowed or six-rowed), cultivar type (malting or feed), seed characteristic (hull-less or hulled), and growth habit (winter or spring), with minor overlaps. Discriminant analysis of groups determined by these phenotypic traits fully supported the different groups with minor overlaps between the malting/feed. S-SAP markers generated from retrotransposons such as BARE-1 are invaluable tools for the study of genetic diversity in organisms with a narrow genetic base such as barley. In this study, S-SAP analysis revealed significant amounts of cryptic variation in closely related cultivars including somaclonal variation, which could not be inferred by the pedigree analysis.     

Mapping new EMBL-derived barley microsatellites and their use in differentiating German barley cultivars

By searching the EMBL DNA sequence database, we were able to develop 39 new, database-derived barley microsatellites. Eighteen of these EMBL microsatellites were mapped either to the interspecific barley map Lerche×BGRC41936 (L×41), the Igri×Franka map (I×F, Graner et al. 1991), or to both maps simultaneously. In addition, all 39 EMBL microsatellites were assigned to individual barley chromosomes by PCR screening of wheat barley addition lines. Both studies verified a random distribution of the microsatellites within the barley genome. Subsequently, 22 EMBL microsatellites were used to assess the genetic similarity among a set of 28, mainly German, barley cultivars and two wild form accessions. Spring and winter cultivars could be easily differentiated using the first coordinate of a principal coordinate analysis. Whereas the group of spring barley cultivars appeared rather homogeneous, winter barley cultivars could be divided into three subgroups. Two H. v. ssp. spontaneum accessions were included in the assessment of genetic similarity. They were placed among the winter barley cultivars. Based on the assessment of the 30 barley cultivars and accessions, the polymorphism information content (PIC) of each EMBL microsatellite has been calculated. The average PIC value among the EMBL microsatellites was equal to 0.38, which ascertains the value of these microsatellites as a genetic tool in barley genome research projects. Received: 6 December 1999 / Accepted: 23 February 2000     

走马胎种质资源遗传多样性的ISSR分析

走马胎( Ardisia gigantifolia)是紫金牛科( Myrsinaceae)紫金牛属( Ardisia)多年生小灌木植物。走马胎作为我国传统中药材,已有多年的药用历史。目前,走马胎不再局限于临床药用,在食疗和保健方面的开发利用崭露头角,大大扩展了其应用范围。随着走马胎市场需求量的增大,野生走马胎植物被过度采挖,导致野生走马胎资源几乎枯竭。人工栽培走马胎逐渐成为供应药用市场的主力军,但是人工栽培走马胎种质、种子来源混杂,常会造成质量和疗效的不稳定,而利用分子标记技术可以从分子水平上对走马胎进行种质的区分和评价。该研究利用ISSR分子标记技术,对来自广西地区的36份走马胎种质资源进行了遗传多样性分析,采用POPGEN32软件进行数据分析,用UPGMA软件绘制聚类图。结果表明：14条ISSR引物共检测到136个清晰的扩增位点,多态性位点112个,多态位点百分率为82.35％;Nei’ s基因多样性指数( H)为0.2965,Shannon多样性指数(I)为0.4417,基因分化系数(Gst)为0.8558。个体间的遗传相似系数为0.6678~0.8382,平均为0.7391。基于聚类分析可知,所有的个体被划分为5类,其中绝大多数来自相同或者邻近地区的个体严格按照地理位置聚为相同的一类或者亚类,只有少数个体在归类上与地理位置相悖。研究证明ISSR分子标记技术在评价走马胎种质资源亲缘关系和遗传变异等方面有很好的适用。该研究结果为该药用植物的种质资源评估和引种栽培提供了科学依据。