Comparative analysis of seeded and vegetative biotype buffalograsses based on phylogenetic relationship using ISSRs,SSRs, RAPDs,and SRAPs

Buffalograss [Buchloe dactyloides (Nutt.) Englem.] is the only native grass that is being used extensively as a turfgrass in the Great Plains region. Its low-growth habit, drought resistance, and low-maintenance requirement make it attractive as a turfgrass species. Our objective was to obtain an overview on the genetic relatedness among and within seeded and vegetative biotype buffalograsses using inter-simple sequence repeats (ISSRs), random amplified polymorphic DNA (RAPDs), sequence-related amplified polymorphisms (SRAPs), and simple sequence repeats (SSRs) markers that were derived from related species (maize, pearl millet, sorghum, and sugarcane). Twenty individuals per cultivar were genotyped using 30 markers from each marker system. All buffalograss cultivars were uniquely fingerprinted by all four marker systems. Mean genetic similarities were estimated at 0.52, 0.51, 0.62, and 0.57 using SSRs, ISSRs, SRAPs, and RAPDs, respectively. Two main clusters separating the seeded-biotype from the vegetative-biotype cultivars were produced using UPGMA analysis. Further subgroupings were unequivocal. The Mantel test resulted in a very good fit (SRAP=0.92, ISSR=0.90) to good fit (RAPD=0.86, SSR=0.88) of cophenetic values. Comparing the four marker systems to each other, RAPD and SRAP similarity indices were highly correlated (r=0.73), while Spearmans rank correlation coefficient between RAPDs and SSRs was r=0.24 and between ISSRs and SSRs was r=0.66. A genotype-assignment analytical approach might be useful for cultivar identification and property rights protection. Polymorphic SRAPs were abundant and demonstrated genetic diversity among closely related cultivars.Communicated by B. FriebeA contribution of the University of Nebraska Agricultural Research Division, Lincoln, Nebraska 68583. Journal Series No. 14398.     

采用RAPD和ISSR标记研究古尔班通古特沙漠东南缘梭梭种群的遗传结构

梭梭(Haloxylon ammodendron(CA Mey.)Bunge)是一种沙漠旱生优势树种,具有重要的生态和经济价值,然而,我们对梭梭种群的遗传多样性和遗传结构所知甚少.本文采用RAPD和ISSR标记对来自古尔班通古特沙漠东南缘的4个天然梭梭种群的遗传多样性和遗传结构进行了检测.5个RAPD引物和8个ISSR引物分别扩增出61和195条带,多态性位点比率分别为83.6%和89.7%,Shannon信息指数分别为0.333和0.367,RAPD和ISSR分析均表明梭梭种群的遗传多样性水平较高.利用分子方差分析(AMOVA)研究梭梭种群的遗传结构,结果表明,大部分遗传变异存在于种群内,通过RAPD分析发现138.2%的遗传变异发生在种群内;通过ISSR分析发现89.4%的遗传变异发生在种群内;而种群间的遗传分化很小.通过RAPD标记没有检测到种群间的遗传分化,ISSR分析表明10.6%的遗传变异发生在种群内.我们推测梭梭种群较高的遗传多样性水平可能源于对异质、高胁迫环境的长期适应,但还需要进一步的研究加以证实.种群间遗传分异低的主要原因是种群间存在强大的基因流.     

Trends in genetic diversity change of spring bread wheat cultivars released in Russia in 1929-2003

Using genealogy analysis, we studied genetic diversity of 340 cultivars of spring bread wheat that were released on the territory of Russia in 1929-2003. Trends in the temporal change of genetic diversity were inferred from analysis of a set of n x m matrices, where n is the number of the released cultivars and m is the number of original ancestors. The pool of original ancestors of the spring bread wheat cultivars for the total period of study included 255 landraces, of which 88 were from the former USSR and modern Russia. The original ancestors showed great differences in their presence in the cultivar sets examined and, consequently, in their importance for the gene pool of Russian spring wheats. The distributions of contributions of dominant original ancestors to cultivar diversity were significantly different in different regions, indicating that the ancestors were specific for the cultivation conditions. During the last 75 years, the genetic diversity of the spring bread wheat cultivars has been increasing owing to the wide use of foreign material in Russian breeding programs. However, our analysis showed that about 60 landraces, including the Russian ones, were lost during the studied time period. The lost part makes up 35% of the gene pool of the Russian original ancestors. It is reasonable to assume that the lost landraces carried a gene complex f or adaptation to specific Russian environments. Specificity of the contributions of the original ancestors in the sets of cultivars produced in different breeding centers was established. A comparative analysis of genetic similarity of cultivars was carried out using coefficients of parentage. Significant differences in this parameter between breeding institutes and regions of cultivation were revealed.     

Trends in Genetic Diversity Change of Spring Bread Wheat Cultivars Released in Russia in 1929–2003

Using genealogy analysis, we studied genetic diversity of 340 cultivars of spring bread wheat that were released on the territory of Russia in 1929–2003. Trends in the temporal change of genetic diversity were inferred from analysis of a set of n × m matrices, where n is the number of the released cultivars and m is the number of original ancestors. The pool of original ancestors of the spring bread wheat cultivars for the total period of study included 255 landraces, of which 88 were from the former USSR and modern Russia. The original ancestors showed great differences in their presence in the cultivar sets examined and, consequently, in their importance for the gene pool of Russian spring wheats. The distributions of contributions of dominant original ancestors to cultivar diversity were significantly different in different regions, indicating that the ancestors were specific for the cultivation conditions. During the last 75 years, the genetic diversity of the spring bread wheat cultivars has been increasing owing to the wide use of foreign material in Russian breeding programs. However, our analysis showed that about 60 landraces, including the Russian ones, were lost during the studied time period. The lost part makes up 35% of the gene pool of the Russian original ancestors. It is reasonable to assume that the lost landraces carried a gene complex f or adaptation to specific Russian environments. Specificity of the contributions of the original ancestors in the sets of cultivars produced in different breeding centers was established. A comparative analysis of genetic similarity of cultivars was carried out using coefficients of parentage. Significant differences in this parameter between breeding institutes and regions of cultivation were revealed.     

Historical changes in population structure during rice breeding programs in the northern limits of rice cultivation

Key message

The rice local population was clearly differentiated into six groups over the 100-year history of rice breeding programs in the northern limit of rice cultivation over the world.

Abstract

Genetic improvements in plant breeding programs in local regions have led to the development of new cultivars with specific agronomic traits under environmental conditions and generated the unique genetic structures of local populations. Understanding historical changes in genome structures and phenotypic characteristics within local populations may be useful for identifying profitable genes and/or genetic resources and the creation of new gene combinations in plant breeding programs. In the present study, historical changes were elucidated in genome structures and phenotypic characteristics during 100-year rice breeding programs in Hokkaido, the northern limit of rice cultivation in the world. We selected 63 rice cultivars to represent the historical diversity of this local population from landraces to the current breeding lines. The results of the phylogenetic analysis demonstrated that these cultivars clearly differentiated into six groups over the history of rice breeding programs. Significant differences among these groups were detected in five of the seven traits, indicating that the differentiation of the Hokkaido rice population into these groups was correlated with these phenotypic changes. These results demonstrated that breeding practices in Hokkaido have created new genetic structures for adaptability to specific environmental conditions and breeding objectives. They also provide a new strategy for rice breeding programs in which such unique genes in local populations in the world can explore the genetic potentials of the local populations.     

Genetic diversity among alfalfa (Medicago sativa) cultivars coming from a breeding program, using SSR markers

Alfalfa (Medicago sativa) is an autotetraploid, allogamous and heterozygous species whose cultivars are synthetic populations. The breeders apply selection pressure for some agronomic traits within a breeding pool to increase the frequency of favorable individuals. The objective of this study was to investigate the differentiation level among seven cultivars originating from one breeding program, and between these cultivars and the breeding pool, with eight SSR markers. These highly polymorphic and codominant markers, together with recent population genetic statistics extended to autotetraploids, offer tools to analyse genetic diversity in alfalfa. The number of alleles per locus varied between 3 and 24. All loci were at a panmictic equilibrium in the cultivars, except one, probably because of null alleles. With seven SSR loci, each cultivar was at panmictic equilibrium. The mean gene diversity was high, ranging from 0.665 to 0.717 in the cultivars. The parameter F _ST indicated a low but significant diversity among cultivars. Among 21 pairs of cultivars, 15 were significantly different. The breeding pool also had a high diversity, and was significantly different from each cultivar except the most recent one. Considering the characteristics of the breeding program and the mode of cultivar elaboration, we found that they were unable to generate a large variety differentiation. Estimation of population genetics parameters at SSR loci can be applied for assessing the differences between cultivars or populations, either for variety distinction or the management of genetic resources.     

Molecular characterization of Greek pepper (Capsicum annuum L) landraces with neutral (ISSR) and gene-based (SCoT and EST-SSR) molecular markers

Thirty landraces were selected from a Gene Bank collection comprising of pepper (Capsicum annuum L.) landraces from across Greece. The genetic variability among the 30 landraces and one commercial greek cultivar, intended for industrial use, was assessed by Inter-Simple Sequence Repeat (ISSR), Start Codon Targeted (SCoT) and Expressed Sequence Tag (EST) - Simple Sequence Repeat (SSR) molecular markers. All genotypes were clearly distinguished in the dendrograms produced, with the ISSR and SCoT dendrograms being the most consistent. Three landraces were grouped together in all dendrogams revealing a possible phylogenetic relationship. Furthermore, EST-SSR markers were combined with High Resolution Melting (HRM) analysis by which the more adequate and confident separation of the landraces was accomplished due to the unique HRM profiles produced. Genotyping the rich Greek pepper germplasm by molecular markers will aid the breeding process towards well adopted Greek pepper cultivars of higher quality and productivity.     

Genotype identification and assessment of genetic relationships in pearl millet [Pennisetum glaucum (L.) R. Br] using microsatellites and RAPDs

 The potential of DNA markers such as microsatellites, minisatellites and RAPDs was investigated in pearl millet [Pennisetum glaucum (L.) R. Br] with respect to their abundance and variability. Southern analysis, using 22 different di-, tri-, tetra- and penta-oligonucleotide probes and five minisatellite probes, identified (GATA)₄ as the most useful probe for the detection of multiple polymorphic fragments among pearl millet cultivars and landraces from India. The clustering patterns of pearl millet cultivars and landraces based on (GATA)₄ and RAPD (randomly amplified polymorphic DNA) markers differed. The landraces, representing eight states in India, could not be grouped based on their geographical distribution with the DNA markers. RAPD analysis revealed a high degree of genetic diversity among the cultivars and landraces employed in this study. The probability of an identical match by chance for any two genotypes using (GATA)₄ and RAPDs was 3.02×10^-20 for cultivars and 5.2×10^-9 for landraces. The microsatellite (GATA)₄ and RAPDs provide useful tools for genotype identification and for the assessment of genetic relationships in pearl millet. Received: 19 October 1997 / Accepted: 9 December 1997     

Comparative analysis on the genetic relatedness of Sorghum bicolor accessions from Southern Africa by RAPDs,AFLPs and SSRs

In order to get an overview on the genetic relatedness of sorghum (Sorghum bicolor) landraces and cultivars grown in low-input conditions of small-scale farming systems, 46 sorghum accessions derived from Southern Africa were evaluated on the basis of amplified fragment length polymorphism (AFLPs), random amplified polymorphic DNAs (RAPDs) and simple sequence repeats (SSRs). By this approach all sorghum accessions were uniquely fingerprinted by all marker systems. Mean genetic similarity was estimated at 0.88 based on RAPDs, 0.85 using AFLPs and 0.31 based on SSRs. In addition to this, genetic distance based on SSR data was estimated at 57 according to a stepwise mutation model (Deltamu-SSR). All UPGMA-clusters showed a good fit to the similarity estimates (AFLPs: r = 0.92; RAPDs: r = 0.88; SSRs: r = 0.87; Deltamu-SSRs: r = 0.85). By UPGMA-clustering two main clusters were built on all marker systems comprising landraces on the one hand and newly developed varieties on the other hand. Further sub-groupings were not unequivocal. Genetic diversity (H, DI) was estimated on a similar level within landraces and breeding varieties. Comparing the three approaches to each other, RAPD and AFLP similarity indices were highly correlated (r = 0.81), while the Spearman's rank correlation coefficient between SSRs and AFLPs was r = 0.57 and r = 0.51 between RAPDs and SSRs. Applying a stepwise mutation model on the SSR data resulted in an intermediate correlation coefficient between Deltamu-SSRs and AFLPs (r = 0.66) and RAPDs ( r = 0.67), respectively, while SSRs and Deltamu-SSRs showed a lower correlation coefficient (r = 0.52). The highest bootstrap probabilities were found using AFLPs (56% on average) while SSR, Deltamu-SSR and RAPD-based similarity estimates had low mean bootstrap probabilities (24%, 27%, 30%, respectively). The coefficient of variation (CV) of the estimated genetic similarity decreased with an increasing number of bands and was lowest using AFLPs.     

Optimization of bulked AFLP analysis and its application for exploring diversity of natural and cultivated populations of red clover.

Landraces and wild populations of red clover (Trifolium pratense L.) may represent a significant yet poorly characterized genetic resource of temperate grasslands. A bulking strategy with amplified fragment length polymorphism (AFLP) markers was optimized to characterize 120 red clover populations in 6 different groups: Swiss wild clover populations, Mattenklee landraces, Mattenklee cultivars, field clover cultivars, Dutch wild clover populations, and Dutch landraces. Analysis of 2 bulked samples/population consisting of 20 plants each with12 AFLP primer combinations was found optimal for determining genetic diversity and relationships within and among red clover populations and groups. Swiss wild clover populations were clearly separated from all other red clover groups and variability within and among populations was shown to be particularly high in wild clover populations and Mattenklee landraces, emphasising their value as genetic resources for improvement of red clover cultivars, as well as for conservation and restoration of biodiversity. This study shows that the ancestry of red clover landraces is primarily found in introduced cultivars rather than in natural wild clover populations. In addition, the methodological considerations presented here may help improve diversity analyses using bulked samples.     

Molecular diversity and genetic relationships in <Emphasis Type="Italic">Secale</Emphasis>

The objective of this study was to quantify the molecular diversity and to determine the genetic relationships among Secale spp. and among cultivars of Secale cereale using RAPDs, ISSRs and sequence analysis of six exons of ScMATE1 gene. Thirteen ryes (cultivated and wild) were genotyped using 21 RAPD and 16 ISSR primers. A total of 435 markers (242 RAPDs and 193 ISSRs) were obtained, with 293 being polymorphic (146 RAPDs and 147 ISSRs). Two RAPD and nine ISSR primers generated more than 80% of polymorphism. The ISSR markers were more polymorphic and informative than RAPDs. Further, 69% of the ISSR primers selected achieved at least 70% of DNA polymorphism. The study of six exons of the ScMATE1 gene also demonstrated a high genetic variability that subsists in Secale genus. One difference observed in exon 1 sequences from S. vavilovii seems to be correlated with Al sensitivity in this species. The genetic relationships obtained using RAPDs, ISSRs and exons of ScMATE1 gene were similar. S. ancestrale, S. kuprijanovii and S. cereale were grouped in the same cluster and S. segetale was in another cluster. S. vavilovii showed evidences of not being clearly an isolate species and having great intraspecific differences.     

Genetic relationship among wild,landraces and cultivars of hazelnut (Corylus avellana) from Portugal revealed through ISSR and AFLP markers

The genus Corylus, a member of the birch family Betulaceae, includes several species that are widely distributed throughout temperate regions of the Northern Hemisphere. This study assesses the genetic diversity in 26 international cultivars and 32 accessions of Corylus avellana L. from Portugal: 13 wild genotypes and 19 landraces. The genetic relationships among the 58 hazelnuts (Corylus avellana L.) were analyzed using inter simple sequence repeat (ISSR) and amplified fragment length polymorphism (AFLP) markers. Eighteen ISSR primers and seven AFLP primer pairs generated a total of 570 unambiguous and repeatable bands, respectively, from which 541 (95.03 %) were polymorphic for both markers. Genetic similarity index values ranged from 0.239 for wild types and cultivars to 0.143 for landraces and wild types. The genetic relationships were presented as a Neighbor-Joining method dendrogram and a two-dimensional principal coordinate analysis (PCoA) plot. The Neighbor-Joining dendrogram showed three main clusters, and the PCoA analysis has shown to be congruent with the hierarchical analysis. Bayesian analysis clustered all individuals into three groups showing a good separation among wild genotypes, landraces and cultivars. The genetic diversity found on wild genotypes and Portuguese landraces may provide relevant information for the diversity conservation and it will be useful in breeding programs and to identify local selections for preservation.     

The use of ISSR and RAPD markers for detecting DNA polymorphism,genotype identification and genetic diversity among barley cultivars with known origin

The potential of bulk analyses of RAPD and ISSR-PCR markers for fingerprinting purposes was evaluated using ten RAPD and ten ISSR primers. The phylogenetic relationships of 16 barley cultivars from different countries, and all having a known pedigree, were analysed using 353 PCR markers (125 RAPDs and 228 ISSRs). The band profiles generated were reproducible in spite of the different DNA extractions, PCR techniques, electrophoretic methods and gel scorings used. The RAPD primer S10 and four ISSR primers (811, 820, 835 and 881) were both able to distinguish all cultivars. A strong and quite linear relationship was observed between Resolving Power (Rp) of a primer and its ability to distinguish genotypes. The dendrograms obtained using these two molecular markers are in agreement with their known origin, showing clusters that separate very well the spring/winter and six-rows/two-rows cultivars. Thus, bulk analyses of RAPD and ISSR PCR markers provides a quick, reliable and highly informative system for DNA fingerprinting and also permit to establish genetic relationships which agree with, by other means, known origin of the cultivars.     

Genetic diversity and geographical differentiation of Iranian landrace,cultivars, and exotic chickpea lines as revealed by morphological and microsatellite markers

Assessment of the extent of genetic variability within chickpea is fundamental for chickpea breeding and conservation of genetic resources and is particularly useful as a general guide in the choice of parents for breeding hybrids. To establish genetic diversity among 60 accessions of chickpea comprising landraces, internationally developed improved lines, and cultivars, genetic distances were evaluated using 14 simple sequence repeat markers. These markers showed a high level of polymorphism; a total of 59 different alleles were detected, with a mean of 4.2 alleles per locus. The polymorphic information content (PIC) value ranged from 0.31 to 0.89. All the markers, with the exception of TAA170, TA110, GA34, and Ts35, were considered to be informative (PIC > 0.5), indicating their potential usefulness for cultivar identification. Based on the UNJ clustering method, all accessions were clustered in five groups, which indicated the probable origin and region similarity of Iranian landraces over the other cultivars. It also represents a wide diversity among available germplasm. The result has firmly established that introduction of genetic materials from exotic sources has broadened the genetic base of the national chickpea breeding program. As further implications of the findings, this study can be useful for selective breeding for specific traits and in enhancing the genetic base of breeding programs.     

Genetic diversity in cultivars and landraces of Oryza sativa subsp. indica as revealed by AFLP markers.

Genetic diversity among 49 Indian accessions of rice (Oryza sativa subsp. indica), including 29 landraces from Jeypore, 12 modern cultivars, and 8 traditional cultivars from Tamil Nadu, was investigated using AFLP markers. In total, nine primer combinations revealed 664 AFLPs, 408 of which were found to be polymorphic. The percentage of polymorphic AFLPs was approximately the same within the cultivars and landraces. Similar results were obtained when genetic diversity values were estimated using the Shannon-Weiner index of diversity. Genetic diversity was slightly higher in the modern cultivars than in the traditional cultivars from Tamil Nadu. Among the landraces from Jeypore, the lowland landraces showed the highest diversity. The present study showed that the process of breeding modern cultivars did not appear to cause significant genetic erosion in rice. Cluster analysis and the first component of principle component analysis (PCA) both showed a clear demarcation between the cultivars and landraces as separate groups, although the genetic distance between them was narrow. The modern cultivars were positioned between the landraces from Jeypore and the traditional cultivars from Tamil Nadu. The second component of PCA further separated medium and upland landraces from lowland landraces, with the lowland landraces found closest to the traditional and modern cultivars.     

Swiss Mattenklee landraces,a distinct and diverse genetic resource of red clover (<Emphasis Type="Italic">Trifolium pratense</Emphasis> L.)

Genetic variability within and among 19 landraces and cultivars of red clover ( Trifolium pratense L.) was investigated by means of amplified fragment length polymorphism (AFLP) analysis in order to assess the potential value of Swiss Mattenklee landraces as genetic resources for plant breeding and the preservation of biodiversity. Populations were classified into three groups according to their origin and agronomic features: Mattenklee landraces (8), Mattenklee cultivars (8) and field clover cultivars (3). Analysis of molecular variance based on 276 polymorphic AFLP markers revealed 80% of total variability to be due to variability within populations while 12% were attributed to variability among groups. Stepwise discriminant analysis identified a subset of 126 AFLP markers which best separated individual plants into the three respective groups. Genetic distances between populations were considerably larger among groups than among populations within the same group, providing further evidence for the genetic distinction between Mattenklee landraces, Mattenklee cultivars and field clover cultivars. AFLP markers identified two landrace clusters, containing three and four populations respectively, which, together with one additional landrace, may sufficiently represent the genetic variability of all eight landraces investigated. The results of this study strongly suggest that Swiss Mattenklee landraces form a genetically distinct group of red clover. The data obtained provide criteria on how to efficiently manage, preserve and exploit Mattenklee germplasm.     

A consensus map of chromosome 6R in rye (Secale cereale L.)

Four F₂ mapping populations derived from crosses between rye inbred lines DS2×RXL10, 541×Ot1-3, S120×S76 and 544×Ot0-20 were used to develop a consensus map of chromosome 6R. Thirteen marker loci that were polymorphic in more than one mapping population constituted the basis for the alignment of the four maps using the JoinMap v. 3.0 software package. The consensus map consists of 104 molecular marker loci including RFLPs, RAPDs, AFLPs, SSRs, ISSRs, SCARs, STSs and isozymes. The average distance between the marker loci is 1.3 cM, and the total map length is 135.5 cM. This consensus map may be used as a source of molecular markers for the rapid development of new maps of chromosome 6R in any mapping population.     

Genetic Diversity inBrassica oleraceaL. (Cruciferae) and Wild Relatives (2n=18) using RAPD Markers

This paper presents the evaluation of genetic diversity in 29populations of wild taxa of theBrassica oleraceaL. group (2n=18)and two cultivars, using RAPDs as molecular markers. In a previouspaper (Lázaro and Aguinagalde,Annals of Botany82: 000–000,1998), 11 isozymes were used for the same purpose. Results obtainedwith the two molecular markers (isozymes and RAPDs) are compared.DNA from ten individuals per population was analysed using sixdifferent primers; the 151 detected bands were polymorphic,11 were common to all species, six to all taxa, only one toevery population; and no bands were shared by every individual.The dendrogram obtained using genetic distances clustersB. oleraceapopulationswithB. bourgeaui, B. alboglabra, B. montanaandB. incana. B.insularis, B. macrocarpa, B. villosaandB. rupestrispopulationsform another cluster. Populations ofB. creticaandB. hilarionisformthe third cluster. Genetic diversity inB. oleraceapopulations,theB. rupestriscomplex andB. creticasubspecies was estimatedusing the AMOVA programme; the latter was the most diverse.Copyright1998 Annals of Botany Company. Brassica oleraceaL., wild relatives, genetic diversity, genetic resources, RAPD markers, AMOVA.     

Molecular and morphological diversity of on-farm hazelnut (Corylus avellana L.) landraces from southern Europe and their role in the origin and diffusion of cultivated germplasm

Hazelnut (Corylus avellana L.) is a traditional nut crop in southern Europe. Germplasm exploration conducted on-farm in five countries (Portugal, Spain, Italy, Slovenia, and Greece) identified 77 landraces. The present work describes phenotypic variation in nut and husk traits and investigates genetic relationships using ten simple sequence repeat (SSR) markers among these landraces, 57 well-known references cultivars, and 19 wild accessions. Among the 77 landraces, 42 had unique fingerprints while 35 showed a SSR profile identical to a known cultivar. Among the 42 unique landraces, morphological observations revealed high phenotypic diversity, and some had characteristics appreciated by the market such as nut round and caliber. Analysis of genetic relationships and population structure allowed investigation of the origin and spread of the cultivated germplasm in southern Europe. Our results indicate the existence of three primary centers of diversity in the Mediterranean basin: northwestern Spain (Tarragona) and southern Italy (Campania) in the West and Black Sea (Turkey) in the East. Moreover, the data suggest the existence of secondary gene pools in the Iberian (Asturias) and Italian (Liguria and Latium) Peninsulas, where local varieties were recently domesticated from wild forms and/or from introduced ancient domesticated varieties.     

Molecular markers reveal little genetic differentiation among Aconitum noveboracense and A. columbianum (Ranunculaceae) populations

Aconitum noveboracense, a rare, herbaceous perennial, is restricted to recently unglaciated areas in Iowa, Wisconsin, Ohio, and New York, and federally classified as a threatened species. These populations may be disjuncts of the common congener, A. columbianum Nutt., which occurs in the mountains of the western United States. Morphological characters do not reliably separate these taxa. The identity of Black Hills populations, located between the ranges of the rare and common species, is also uncertain. We characterized genetic variation within and among the Aconitum populations in question using isozymes and randomly amplified polymorphic DNA (RAPDs). Isozymes indicate a high degree of similarity among all populations and a high level of genetic diversity in Black Hills populations. Of 97 scorable RAPD loci, 89.7% are polymorphic and clearly resolve most populations. Like isozymes, RAPDs indicate high levels of genetic diversity in the Black Hills and very strong similarity of these populations to A. columbianum from the Bighorn Mountains. Aconitum noveboracense populations show >80% similarity to A. columbianum populations. A population of A. uncinatum from Ohio shows the greatest differentiation from other populations. Therefore, both isozyme and RAPD data concur with the recent treatment of A. noveboracense and A. columbianum as a single species.