湖南同名地方稻资源SSR标记及表现型的比较分析

本研究以湖南种质库中保存的不同来源的同名湖南地方稻种质11组(同近名为1组)共136份为研究材料,进行SSR分子标记及农艺性状比较分析,目的是评价湖南同(近)名地方稻的遗传差异程度,为同(近)名地方稻种质资源的保存、供种以及重点利用种质遴选提供理论依据。研究结果表明,各组同名材料的表型遗传距离数值变化较大,各组最大遗传距离变幅1.25(D6/D13)~1.51(G1/G5),最小遗传距离变幅0.16(E7/E9)~0.81(B2/B11)。各组同名材料的SSR标记相似系数差异也大,最小相似系数变幅0.38~0.71,最大相似系数变幅0.86~1.00;同组内同(近)名材料交叉聚类。基于表型性状遗传距离与基于SSR标记遗传相似系数判别组内材料间遗传关系的结果有一致的,也有存在一定差异的。C8/C11、D16/D18、G1/G2、M2/M3、M2/M6、M3/M6、N2/N4、N5/N6、F2/F25、P3/P4的SSR标记相似系数达0.95以上,而其表现型却有1~3个性状存在有统计学意义的差异,说明供试同名材料有明显变异,即使同(近)名但也都值得保存。同时也证实了24对SSR标记分析同名地方稻遗传多样性的不足。     

Determination of the population structure of common bean (Phaseolus vulgaris L.) accessions using lipoxygenase and resistance gene analog markers

The common bean (Phaseolus vulgaris L.) is an important food legume throughout the world. Because of the conservation across different plant species, it is possible to evaluate the degree of genetic diversity in the common bean using gene-based marker techniques. The lipoxygenase (LOX) and resistance gene analog (RGA) genes play an important role in the response to biotic and abiotic stresses. Eighty-six common bean accessions were genotyped using gene-based LOX and RGA markers. The total number of polymorphic bands ranged from 193 for LOX to 17 for RGA markers. We detected considerable diversity with a mean of 8.7 alleles per primer for the LOX analysis. For the RGA markers, the number of alleles per polymorphic locus varied from 1 to 4 with an average allele number of 2.8. The genetic similarity between the accessions based on the LOX and RGA markers ranged from 0.12 to 0.55. Using STRUCTURE, 3 groups were revealed among the accessions. The results of this study should provide valuable information for future studies on the genetic diversity of common bean accessions and for association mapping studies examining the relationships between the genotypic and phenotypic traits related to the stress response.     

Molecular characterization and genetic diversity analysis of soybean (Glycine max (L.) Merr.) germplasm accessions in India

Molecular characterization and genetic diversity among 82 soybean accessions was carried out by using 44 simple sequence repeat (SSR) markers. Of the 44 SSR markers used, 40 markers were found polymorphic among 82 soybean accessions. These 40 polymorphic markers produced a total of 119 alleles, of which five were unique alleles and four alleles were rare. The allele number for each SSR locus varied between two to four with an average of 2.97 alleles per marker. Polymorphic information content values of SSRs ranged from 0.101 to 0.742 with an average of 0.477. Jaccard’s similarity coefficient was employed to study the molecular diversity of 82 soybean accessions. The pairwise genetic similarity among 82 soybean accessions varied from 0.28 to 0.90. The dendrogram constructed based on genetic similarities among 82 soybean accessions identified three major clusters. The majority of genotypes including four improved cultivars were grouped in a single subcluster IIIa of cluster III, indicating high genetic resemblance among soybean germplasm collection in India.

Electronic supplementary material

The online version of this article (doi:10.1007/s12298-014-0266-y) contains supplementary material, which is available to authorized users.     

Comparative study of different molecular markers for classifying and establishing genetic relationships in Coffea canephora

The genetic variability characterization of the accessions of the germplasm collection, using molecular markers, is being applied as a complementary strategy to the traditional approaches to redefine the plant genetic resources. In this study, we compared the informativeness and efficiency of the molecular markers RAPD, AFLP and SSR in the analysis of 94 accessions of Coffea canephora germplasm held by the breeding program of the Brazilian Agricultural Research Corporation (Embrapa), Rondônia State, Brazil. For this, we considered the marker’s discriminatory power and level of polymorphism detected and also the genetic relationships and clustering (dendrogram) analysis. The RAPD marker yielded low-quality data and problems in the discrimination of some accessions, being less recommended for genetic studies of C. canephora. The SSRs had a higher level of information content and yielded high-quality data, while AFLP was the most efficient marker system because of the simultaneous detection of abundant polymorphism markers per few reactions. Our results indicate that AFLP and SSR, allies to the intrinsic characteristics of each technique, are the most suitable molecular markers for genetic studies of C. canephora. However, the choice of AFLP or SSR in the species characterization should be made in agreement with some characteristics that are discussed in this work.     

ISSR分子标记技术在分析玉米自交系遗传关系研究中的适用性

利用ISSR分子标记技术对59份玉米自交系和1份大刍草材料进行遗传多样性分析.21对ISSR引物共扩增出475条不同位置的带,平均22.6条;多态性带469条,平均22.3条,百分率高达98.7%;不同引物的多态性信息指数(PIC)在0.84～0.94之间.60份材料的遗传相似系数在0.23～0.48之间.经聚类分析,可将这些材料分成两大组,共9个亚组,并且在一定程度上与血缘和系谱是一致的,也存在一些例外.结果表明,ISSR标记尽管可以用于进行遗传多样性分析,但并不是最好的分子标记类型.综合考虑不同的分子标记类型的优缺点,认为ISSR标记在遗传研究较少的作物上应用潜力较大.     

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.     

Analysis of the Genetic Structure of a Barley Collection Using DNA Diversity Array Technology (DArT)

Analysis of the extent of genetic variation within genetic resources is important for diversity preservation and also for breeders who exploit it. We investigated the recently introduced molecular marker technique of DNA diversity array technology (DArT), with the objective of characterising diversity in the likely relatively narrow genetic background of Czech malting barley cultivars. A total of 94 obsolete or registered barley cultivars and some hulless barley lines primarily of Czech origin were characterised by DArT analysis. A total of 271 polymorphic marker alleles were revealed across the analysed set of accessions, 37 of which were identified as being overrepresented; the other 234 markers were used for further analysis. The average dissimilarity value within the analysed set of accessions was 0.692. To assess how well DArT is suited for individual barley characteristic evaluation, available agronomical data from three yield field trials were used. Out of 94 barley genotypes used in the field trials that were assessed by DArTs, 41 have been grown over time as malting cultivars in the region. Similarity matrices based on Gower’s coefficient for mixed data and simple matching coefficient were used to compare DaRT and agronomical results. We demonstrate that a DArT-based similarity matrix and an agronomical data-based similarity matrix correlated well. To assess the genetic structure of the entire collection, K-means and simple matching coefficient clustering were used. Statistical analysis confirmed the power of the DArT system, in fact they efficiently grouped old genetic resources and modern cultivars in the expected way. Our results show that the level of genetic diversity has not changed substantially over time, but significant shifts in allelic frequency have occurred. In addition, a DArT-based dendrogram and principal component analysis (PCA) plots clearly demonstrated the impact of breeding practices on the diversity of Czech spring malting barley cultivars over time.     

Uncovering the genetic diversity of yams (Dioscorea spp.) in China by combining phenotypic trait and molecular marker analyses

Yam is an important edible tuber and root plant worldwide; China as one of the native places of yams has many diverse local resources. The goal of this study was to clarify the genetic diversity of the commonly cultivated yam landraces and the genetic relationship between the main yam species in China. In this study, 26 phenotypic traits of 112 yam accessions from 21 provinces in China were evaluated, and 24 simple sequence repeat (SSR) and 29 sequence‐related amplified polymorphism (SRAP) markers were used for the genetic diversity analysis. Phenotypic traits revealed that Dioscorea opposita had the highest genetic diversity, followed by D. alata, D. persimilis, D. fordii, and D. esculenta. Among the 26 phenotypic traits, the Shannon diversity indexes of leaf shape, petiole color, and stem color were high, and the range in the variation of tuber‐related traits in the underground part was higher than that in the aboveground part. All accessions were divided into six groups by phenotypic trait clustering, which was also supported by principal component analysis (PCA). Molecular marker analysis showed that SSR and SRAP markers had good amplification effects and could effectively and accurately evaluate the genetic variation of yam. The unweighted pair‐group method with arithmetic means analysis based on SSR‐SRAP marker data showed that the 112 accessions were also divided into six groups, similar to the phenotypic trait results. The results of PCA and population structure analysis based on SSR‐SRAP data also produced similar results. In addition, the analysis of the origin and genetic relationship of yam indicated that the species D. opposita may have originated from China. These results demonstrate the genetic diversity and distinctness among the widely cultivated species of Chinese yam and provide a theoretical reference for the classification, breeding, germplasm innovation, utilization, and variety protection of Chinese yam resources.     

Joint analysis of phenotypic and molecular diversity provides new insights on the genetic variability of the Brazilian physic nut germplasm bank

The genetic variability of the Brazilian physic nut (Jatropha curcas) germplasm bank (117 accessions) was assessed using a combination of phenotypic and molecular data. The joint dissimilarity matrix showed moderate correlation with the original matrices of phenotypic and molecular data. However, the correlation between the phenotypic dissimilarity matrix and the genotypic dissimilarity matrix was low. This finding indicated that molecular markers (RAPD and SSR) did not adequately sample the genomic regions that were relevant for phenotypic differentiation of the accessions. The dissimilarity values of the joint dissimilarity matrix were used to measure phenotypic + molecular diversity. This diversity varied from 0 to 1.29 among the 117 accessions, with an average dissimilarity among genotypes of 0.51. Joint analysis of phenotypic and molecular diversity indicated that the genetic diversity of the physic nut germplasm was 156% and 64% higher than the diversity estimated from phenotypic and molecular data, respectively. These results show that Jatropha genetic variability in Brazil is not as limited as previously thought.     

Genetic diversity in European Pisum germplasm collections

The distinctness of, and overlap between, pea genotypes held in several Pisum germplasm collections has been used to determine their relatedness and to test previous ideas about the genetic diversity of Pisum. Our characterisation of genetic diversity among 4,538 Pisum accessions held in 7 European Genebanks has identified sources of novel genetic variation, and both reinforces and refines previous interpretations of the overall structure of genetic diversity in Pisum. Molecular marker analysis was based upon the presence/absence of polymorphism of retrotransposon insertions scored by a high-throughput microarray and SSAP approaches. We conclude that the diversity of Pisum constitutes a broad continuum, with graded differentiation into sub-populations which display various degrees of distinctness. The most distinct genetic groups correspond to the named taxa while the cultivars and landraces of Pisum sativum can be divided into two broad types, one of which is strongly enriched for modern cultivars. The addition of germplasm sets from six European Genebanks, chosen to represent high diversity, to a single collection previously studied with these markers resulted in modest additions to the overall diversity observed, suggesting that the great majority of the total genetic diversity collected for the Pisum genus has now been described. Two interesting sources of novel genetic variation have been identified. Finally, we have proposed reference sets of core accessions with a range of sample sizes to represent Pisum diversity for the future study and exploitation by researchers and breeders.     

Promoting Utilization of Saccharum spp. Genetic Resources through Genetic Diversity Analysis and Core Collection Construction

Sugarcane (Saccharum spp.) and other members of Saccharum spp. are attractive biofuel feedstocks. One of the two World Collections of Sugarcane and Related Grasses (WCSRG) is in Miami, FL. This WCSRG has 1002 accessions, presumably with valuable alleles for biomass, other important agronomic traits, and stress resistance. However, the WCSRG has not been fully exploited by breeders due to its lack of characterization and unmanageable population. In order to optimize the use of this genetic resource, we aim to 1) genotypically evaluate all the 1002 accessions to understand its genetic diversity and population structure and 2) form a core collection, which captures most of the genetic diversity in the WCSRG. We screened 36 microsatellite markers on 1002 genotypes and recorded 209 alleles. Genetic diversity of the WCSRG ranged from 0 to 0.5 with an average of 0.304. The population structure analysis and principal coordinate analysis revealed three clusters with all S. spontaneum in one cluster, S. officinarum and S. hybrids in the second cluster and mostly non-Saccharum spp. in the third cluster. A core collection of 300 accessions was identified which captured the maximum genetic diversity of the entire WCSRG which can be further exploited for sugarcane and energy cane breeding. Sugarcane and energy cane breeders can effectively utilize this core collection for cultivar improvement. Further, the core collection can provide resources for forming an association panel to evaluate the traits of agronomic and commercial importance.     

Genetic diversity analysis of Zingiber Officinale Roscoe by RAPD collected from subcontinent of India

The present investigation was undertaken for the assessment of 12 accessions of Zingiber officinale Rosc. collected from subcontinent of India by RAPD markers. DNA was isolated using CTAB method. Thirteen out of twenty primers screened were informative and produced 275 amplification products, among which 261 products (94.90%) were found to be polymorphic. The percentage polymorphism of all 12 accessions ranged from 88.23% to 100%. Most of the RAPD markers studied showed different levels of genetic polymorphism. The data of 275 RAPD bands were used to generate Jaccard’s similarity coefficients and to construct a dendrogram by means of UPGMA. Results showed that ginger undergoes genetic variation due to a wide range of ecological conditions. This investigation was an understanding of genetic variation within the accessions. It will also provide an important input into determining resourceful management strategies and help to breeders for ginger improvement program.     

Assessment of genetic diversity and morpho-physiological traits related to drought tolerance in Stylosanthes scabra

Among the many Stylosanthes species, Stylosanthes scabra, a range fodder legume, performs better under limited water condition. In the present investigation, thirty-four accessions of S. scabra were assessed under limited water condition, for various morpho-physiological characters associated with drought. In general, S. scabra exhibited better tolerance to drought, as evidenced by high leaf thickness and greater accumulation of proline, and malondialdehyde (MDA) in water stress condition. Transpiration efficiency (TE) was high, in both control and water stress conditions and positively correlated with root, shoot, and total dry matters, in both control and stress conditions (r ² = ranged from 0.589 to 0.961 in control and from 0.351 to 0.985 in stress). Of these, 25 accessions were assessed for estimation of genetic diversity, employing random amplified polymorphic DNA (RAPD) markers. A total of 210 RAPD bands, obtained with 32 primers, revealed high polymorphic information content (0.49) and marker index (4.41). Dendrogram analysis indicated close proximity among the accessions of S. scabra. These accessions were clustered in high similarity range (84.01–98.36 %). Accession IG-366A separated from other clusters at 85.62 % similarity level. RAPD marker system revealed 13 accessions exhibiting >90 % genetic similarity while the other accessions exhibited similarity ranging from 68 to 90 %. A higher level of genetic similarity which was also evident from the similar levels of TE, biomass production, root/shoot ratio, MDA, proline contents and drought tolerance index, indicated a cause–effect relationship among them. Results also indicated that among the accessions, S. scabra rate-reducing resistance allo-tetraploid lines were better suited for hard and cracking soils, under complete rain-fed condition.     

Morphological and molecular genetic variations of oat genotypes grown in Kermanshah,Iran

Morphological traits and molecular markers are two common methods for genetic variation studies. Molecular markers, morphological traits methods and relationship between the two were used to study genetic variation among 43 oat genotypes and varieties. For this purpose, an augmented design was conducted in three replicates at 2008–2009 cropping season in the experimental field of Campus of Agriculture and Natural Resources of Razi University, Kermanshah, Iran. Four wild oat accessions (Avena sterilis) were added to evaluated genotypes in molecular experiment. Results showed a significant variation among genotypes for all morphological traits and they were classified based on this variation in four groups by WARD cluster analysis. In molecular experiment, 28 inter simple sequence repeat (ISSR) primers amplified 206 polymorph bands. Based on Jaccard similarity matrix, similarity among genotypes was varied from 0.23 to 0.66 and cluster analysis classified genotypes in seven groups by complete linkage method. The correlation between ISSR marker and morphological traits classifications was not significant. ISSR showed to be a helpful marker for genotype identity and separation as it put wild accessions in a group.     

Use of simple sequence repeat markers for DNA fingerprinting and diversity analysis of sugarcane (Saccharum spp) cultivars resistant and susceptible to red rot

Red rod is an economically important disease of sugarcane caused by the fungus Colletotrichum falcatum. We used a simple sequence repeat (SSR)-based marker system to identify and analyze genetic relationships of red rot resistant and susceptible sugarcane cultivars grown in Pakistan. Twenty-one highly polymorphic SSR markers were used for DNA fingerprinting and genetic diversity analysis of 20 sugarcane cultivars. These SSR markers were found to be highly robust; we identified 144 alleles, with 3-11 alleles per marker and a mean of 6.8. Three SSR markers were able to identify all 20 cultivars. DNAMAN(?)-generated homology tree was used to analyze genetic diversity among these cultivars; all cultivars shared 58% or more similarity. We correlated polymorphism information content and resolving power values with marker effectiveness in the process of sugarcane cultivar identification. We concluded that a small number of SSR-derived DNA markers will allow breeders to identify red rot resistant and susceptible cultivars.     

Detection of favorable alleles for yield and yield components by association mapping in upland cotton

Association mapping based on linkage disequilibrium provides a promising tool for dissecting the genetic basis underlying complex traits. To reveal the genetic variations of yield and yield components traits in upland cotton, 403 upland cotton accessions were collected and analyzed by 560 genome-wide simple sequence repeats (SSRs). A diverse panel consisting of 403 upland cotton accessions was grown in six different environments, and the yield and yield component traits were measured, and 560 SSR markers covering the whole genome were mapped. Association studies were performed to uncover the genotypic and phenotypic variations using a mixed linear model. Favorable alleles and typical accessions for yield traits were identified. A total of 201 markers were polymorphic, revealing 394 alleles. The average gene diversity and polymorphism information content were 0.556 and 0.483, respectively. Based on a population structure analysis, 403 accessions were divided into two subgroups. A mixed linear model analysis of the association mapping detected 43 marker loci according to the best linear unbiased prediction and in at least three of the six environments(??lgP?>?1.30, P?<?0.05). Among the 43 associated markers, five were associated with more than two traits simultaneously and nine were coincident with those identified previously. Based on phenotypic effects, favorable alleles and typical accessions that contained the elite allele loci related to yield traits were identified and are widely used in practical breeding. This study detected favorable quantitative trait loci’s alleles and typical accessions for yield traits, these are excellent genetic resources for future high-yield breeding by marker-assisted selection in upland cotton in China.     

Analysis of Genetic Diversity of Persea bombycina “Som” Using RAPD-Based Molecular Markers

The utility of RAPD markers in assessing genetic diversity and phenetic relationships in Persea bombycina, a major tree species for golden silk (muga) production, was investigated using 48 genotypes from northeast India. Thirteen RAPD primer combinations generated 93 bands. On average, seven RAPD fragments were amplified per reaction. In a UPGMA phenetic dendrogram based on Jaccard’s coefficient, the P. bombycina accessions showed a high level of genetic variation, as indicated by genetic similarity. The grouping in the phenogram was highly consistent, as indicated by high values of cophenetic correlation and high bootstrap values at the key nodes. The accessions were scattered on a plot derived from principal correspondence analysis. The study concluded that the high level of genetic diversity in the P. bombycina accessions may be attributed to the species’ outcrossing nature. This study may be useful in identifying diverse genetic stocks of P. bombycina, which may then be conserved on a priority basis.     

Assessment of genetic variation within Indian mustard (Brassica juncea) germplasm using random amplified polymorphic DNA markers

Genetic diversity among 45 Indian mustard (Brassica Juncea L.) genotypes comprising 37 germplasm collections, five advance breeding lines and three improved cultivars was investigated at the DNA level using the random amplified polymorphic DNA (RAPD) technique. Fifteen primers used generated a total of 92 RAPD fragments, of which 81 (88%) were polymorphic. Of these, 13 were unique to accession 'Pak85559'. Each primer produced four to nine amplified products with an average of 6.13 bands per primer. Based on pairwise comparisons of RAPD amplification products, Nei and Li's similarity coefficients were calculated to evaluate the relationships among the accessions. Pairwise similarity indices were higher among the oilseed accessions and cultivars showing narrow ranges of 0.77-0.99. An unweighted pair-group method with arithmetic averages cluster analysis based on these genetic similarities placed most of the collections and oilseed cultivars close to each other, showing a low level of polymorphism between the accessions used. However, the clusters formed by oilseed collections and cultivars were comparatively distinct from that of advanced breeding lines. Genetically, all of the accessions were classified into a few major groups and a number of individual accessions. Advanced breeding lines were relatively divergent from the rest of the accessions and formed independent clusters. Clustering of the accessions did not show any pattern of association between the RAPD markers and the collection sites. A low level of genetic variability of oilseed mustard was attributed to the selection for similar traits and horticultural uses. Perhaps close parentage of these accessions further contributed towards their little diversity. The study demonstrated that RAPD is a simple and fast technique to compare the genetic relationship and pattern of variation among the gene pool of this crop.     

Development and characterization of microsatellite markers in Indian sesame (Sesamum indicum L.)

The genetic characterization of Indian sesame cultivars and related wild species was analysed using 102 simple sequence repeat (SSR; microsatellite) markers. Of these, 62 were novel sesame-specific microsatellites isolated in the course of the present investigation by constructing genomic libraries. Characterization of the 68 sesame accessions and three related wild species using 72 polymorphic SSR primers resulted in the detection of 170 alleles. The number of alleles ranged from two to four with an average of 2.5 alleles per locus. Polymorphic information content of the markers ranged from 0.43 to 0.88 with an average of 0.66. UPGMA cluster analysis grouped all the accessions into two major clusters with a genetic similarity ranging from 0.40 to 0.91. A moderate to high level of genetic variability was observed. The three wild accessions used in the study formed separate clades and distant genetic relationships were observed between the cultivar lines and wild species. Differentiation of genotypes according to geographical region was not observed. Analysis of molecular variance (AMOVA) analysis revealed that a high percentage of variation was within populations (87.1 %). An overall F _st of 0.11 among the populations indicated low population differentiation. The SSR markers developed will be useful for further genetic analysis, linkage mapping and selection of parents in future breeding programmes.