Chloroplast and nuclear DNA studies in a few members of the <Emphasis Type="Italic">Brassica oleracea</Emphasis> L. group using PCR-RFLP and ISSR-PCR markers: a population genetic analysis

A population genetic analysis of chloroplast and nuclear DNA was performed covering nine wild populations of Brassica oleracea. Three members of the n = 9 group, all close to B. oleracea, Brassica alboglabra Bailey, Brassica bourgeaui (Webb) O. Kuntze and Brassica montana Pourret, were also studied to better understand their relationship with B. oleracea. Chloroplast DNA was analysed using the PCR-RFLP (polymerase chain reaction - restriction fragment length polymorphism) method. The ISSR-PCR (inter-simple sequence repeat - polymerase chain reaction) technique was adopted to study nuclear DNA. Twelve primer pairs of chloroplast DNA showed very good amplification. The amplified product of each primer pair, digested by three restriction enzymes, revealed no variation of cpDNA among the taxa studied. This indicates they may have the same chloroplast genotype. Seven selected ISSR primers have detected genetic variation, both within and among the populations/taxa surveyed. The information obtained on the intra- and inter-populational genetic diversity of wild populations of B. oleracea neatly defined the individual plants. It could provide important guidelines for backing management and conservation strategies in this species. The study confirms a close relationship between B. alboglabra, B. bourgeaui and B. montana, which is parallel to their morphological similitude.     

Chloroplast DNA variation within prairie cordgrass (Spartina pectinata Link) populations in the U.S.

Chloroplast DNA (cpDNA) is most often maternally inherited and highly conserved leading to previous observation of little to no sequence variation. Comparing cpDNA haplotypes have provided valuable insight into the establishment and migration of polyploid populations. However, to use chloroplast haplotypes to their full potential intrapopulational variation needs to be addressed. In this study, cpDNA haplotype variation was surveyed within 16 natural populations of prairie cordgrass (Spartina pectinata Link) located east of the 100th west meridian and north of the 35th north parallel in the U.S.A. using two non-coding, polymorphic chloroplast regions. Two main clades were defined with subclades as follows: haplotype 1 and haplotype 2A and 2B. It was discovered that seven populations showed intrapopulational chloroplast genome variation. Of the total amount of variation, 95.5% occurred within the octoploid populations and 4.5% occurred within the tetraploid populations. Both variant haplotypes, 2A and 2B, were found in a larger sampling of one of the natural populations, but no variation was found in a mixed ploidy population. The intrapopulational cpDNA variation we found in this study cannot directly be related to mechanisms of introduction of the non-native populations into native populations. Therefore, this cpDNA variation could be novel natural variation that has been fixed as the octoploid populations were established and moved northwest. This analysis provides insight into determining the usefulness of indels and single nucleotide polymorphisms for population identification and may provide information in regards to the origin of chloroplast variation and its subsequent fixation and establishment in natural prairie cordgrass populations.     

基于叶绿体DNA变异的湖北梨属种质系统进化及遗传多样性分析

利用trnL intron、trnL-trnF、trnS-psbC和accD-psa I等4个叶绿体DNA片段对来自湖北省的88份梨属种质资源进行系统进化和遗传多样性分析。结果表明,4个cpDNA片段共检测到变异位点11个,其中单一突变位点6个,插入/缺失(Indel)位点5个。acc D-psa I多态性最高,其变异位点数、核苷酸多态性和单倍型多样性均为最高。供试梨种质的核苷酸多样性和单倍型多样性分别为0.00112和0.769;Tajima's D检验值在P0.10水平上均不显著,表明所检测的4个区域以及合并后的片段均遵循中性进化模型;4个序列合并共检测到叶绿体单倍型10个,其中兴山梨种质中检测到的单倍型最多,荆门其次;Hap2和Hap5是2个主要单倍型,分别占总样本数的31.82%和30.68%;中介邻接网络图显示东方梨和西洋梨独立进化,而较为原始的稀有单倍型Hap8和Hap9均位于荆门,暗示该地区可能为砂梨的起源中心或多样性中心之一。     

High‐throughput multiplex cpDNA resequencing clarifies the genetic diversity and genetic relationships among Brassica napus,Brassica rapa and Brassica oleracea

Brassica napus (rapeseed) is a recent allotetraploid plant and the second most important oilseed crop worldwide. The origin of B. napus and the genetic relationships with its diploid ancestor species remain largely unresolved. Here, chloroplast DNA (cpDNA) from 488 B. napus accessions of global origin, 139 B. rapa accessions and 49 B. oleracea accessions were populationally resequenced using Illumina Solexa sequencing technologies. The intraspecific cpDNA variants and their allelic frequencies were called genomewide and further validated via EcoTILLING analyses of the rpo region. The cpDNA of the current global B. napus population comprises more than 400 variants (SNPs and short InDels) and maintains one predominant haplotype (Bncp1). Whole‐genome resequencing of the cpDNA of Bncp1 haplotype eliminated its direct inheritance from any accession of the B. rapa or B. oleracea species. The distribution of the polymorphism information content (PIC) values for each variant demonstrated that B. napus has much lower cpDNA diversity than B. rapa; however, a vast majority of the wild and cultivated B. oleracea specimens appeared to share one same distinct cpDNA haplotype, in contrast to its wild C‐genome relatives. This finding suggests that the cpDNA of the three Brassica species is well differentiated. The predominant B. napus cpDNA haplotype may have originated from uninvestigated relatives or from interactions between cpDNA mutations and natural/artificial selection during speciation and evolution. These exhaustive data on variation in cpDNA would provide fundamental data for research on cpDNA and chloroplasts.     

Chloroplast and mitochondrial molecular tests identify European×Japanese larch hybrids

Hybrids between European and Japanese larches combine the properties of both parental species (drought resistance, canker resistance, stem straightness) and exhibit a fast growth rate. They are produced in seed orchards, generally by natural pollination. Seeds are collected and used for afforestation as interspecific hybrids. However, there are no convenient tests to assess the interspecific hybrid proportion. In the present study, we developed diagnostic molecular markers suitable for the individual identification of hybrids, whatever their developmental stage. Our strategy involved testing a combination of maternally inherited markers from the mitochondrial genome (mtDNA) and paternally inherited markers from the chloroplast genome (cpDNA). Hybrids were then identified by the presence of a mitochondrial sequence inherited from one parental species and a chloroplast sequence inherited from the other parental species. To achieve this aim, markers discriminating both parental species were first sought. Amplifications of mitochondrial and chloroplast sequences were performed using specific PCR primers. After testing 33 primer pairs in combination with nine restriction enzymes, we detected one mitochondrial marker, f13 which was amplified in Japanese larch and absent in European larch, and one chloroplast marker, ll-TaqI which showed different restriction patterns depending on the species. A restriction fragment of 601 bp was obtained in Japanese larch while two fragments of 120 bp and 481 bp were observed in European larch. These patterns were found in all 197 individuals tested from the two pure species. These markers were then used for the evaluation of the hybrid proportion in a seed lot produced from seed orchards; this was assessed as between 43% and 53% depending on the parental species. The male and female parental species could be determined for each progeny.Communicated by D.B. Neale     

Chloroplast and mitochondrial SSR help to distinguish allo-cytoplasmic male sterile types in cabbage (Brassica oleracea L. var. capitata)

The profiles of single sequence repeat (SSR) in six distinct allo-cytoplasmic male sterile (CMS) types of cabbage (Brassica oleracea L. var. capitata) were generated using 32 SSR primer pairs derived from the Arabidopsis thaliana chloroplast (cp) genome and another 21 SSR primers from the B. napus mitochondrial (mt) genome sequences. In total, 11 cpSSR and 4 mtSSR primers revealed polymorphism among the six cabbage CMS types, namely NigCMS, OguCMSR₁, OguCMSR₂, OguCMSR₃, OguCMSHY and PolCMS. Through cluster analysis, six cabbage CMS types could be unambiguously differentiated with just three sets of primers (ACP43, ACP47, mtSSR2). Analysis of the selected amplicon sequences showed high identity to that of the corresponding sequences in A. thaliana, B. rapa and B. napus. The aligned cluster analysis revealed that the polymorphism mainly included SSR number variation, single nucleotide polymorphism (SNP), and sequence insertion or deletion (InDel). Our results demonstrated that specific mitochondrial or chloroplast SSR analysis could be a feasible alternative means for cabbage CMS type identification.     

Detection of single nucleotide polymorphism (SNP) controlling the waxy character in wheat by using a derived cleaved amplified polymorphic sequence (dCAPS) marker

We investigated a single nucleotide polymorphism (SNP) in the Wx-D1 gene, which was found in a mutant waxy wheat, and which expressed the Wx-D1 protein (granule-bound starch synthase I) as shown by immunoblot analysis. We also assayed starch synthase activity of granule-bound proteins. Using 22 doubled-haploid (DH) lines and 172 F(5) lines derived from the wild type x the mutant, we detected SNP via a PCR-based (dCAPS) marker. Amplified PCR products from Wx-D1 gene-specific primers, followed by mismatched primers designed for dCAPS analysis, were digested with the appropriate restriction enzyme. The two alleles, and the heterozygote genotype were easily and rapidly discriminated by gel-electrophoresis resolution to reveal SNP. All progeny lines that have the SNP of the mutant allele were waxy. Integrating the results of dCAPS analysis, immunoblot analysis and assays of starch synthase activity of granule-bound proteins indicates that the SNP in the Wx-D1 gene was responsible for its waxy character. This dCAPS marker is therefore useful as a marker to introduce the mutant allele into elite breeding lines.     

High throughput genome-specific and gene-specific molecular markers for erucic acid genes in <Emphasis Type="Italic">Brassica napus</Emphasis> (L.) for marker-assisted selection in plant breeding

A single base change in the Bn-FAE1.1 gene in the A genome and a two-base deletion in the Bn-FAE1.2 gene in the C genome produce the nearly zero content of erucic acid observed in canola. A BAC clone anchoring Bn-FAE1.1 from a B. rapa BAC library and a BAC clone anchoring Bn-FAE1.2 from a B. oleracea BAC library were used in this research. After sequencing the gene flanking regions, it was found that the dissimilarity of the flanking sequences of these two FAE1 homologs facilitated the design of genome-specific primers that could amplify the corresponding genome in allotetraploid B. napus. The two-base deletion in the C genome gene was detected as a sequence-characterized amplified region (SCAR) marker. To increase the throughput, one genome-specific primer was labeled with four fluorescence dyes and combined with 20 different primers to produce PCR products with different fragment sizes. Eventually, a super pool of 80 samples was detected simultaneously. This dramatically reduces the cost of marker detection. The single base change in the Bn-FAE1.1 gene was detected as single nucleotide polymorphic (SNP) marker with an ABI SNaPshot kit. A multiplexing primer set was designed by adding a polyT to the 5' primer end to increase SNP detection throughput through sample pooling. Furthermore, the Bn-FAE1.1 and Bn-FAE1.2 were integrated into the N8 and N13 linkage groups of our previously reported high-density sequence-related amplified polymorphism (SRAP) map, respectively. There were 124 SRAP markers in a N8 bin in which the Bn-FAE1.1 gene-specific SCAR marker was located and 46 SRAP markers in a N13 bin into which the Bn-FAE1.2 SNP marker was integrated. These three kinds of high throughput molecular markers have been successfully implemented in our canola/rapeseed breeding programs.     

Hybridization between European and Asian dandelions ( Taraxacum section Ruderalia and section Mongolica)2. Natural hybrids in Japan detected by chloroplast DNA marker

Natural hybridization in Taraxacum between native sexual diploids and introduced agamospermous triploids occurring in Japan was studied by means of chloroplast DNA (cpDNA) marker. We first determined the nucleotide sequences between trnT (UGU) and trnF (GAA) of cpDNA for 22 plants obtained from Japan and Europe. The sequences analyzed were about 1,574 base pairs long. Among all accessions, the total numbers of polymorphic characters were 56 nucleotide substitutions, three insertions/deletions (ins/dels), and one repeat number polymorphism of mononucleotide motif. Of these polymorphic characters, four nucleotides and one ins/del were applicable in the discrimination between Japanese and European taxa of dandelions. We selected the ins/del in an intergenic region between trnL (UAA) 3′ exon and trnF (GAA) as a cpDNA marker. Using a newly developed cpDNA marker, 225 plants of putative Taraxacum officinale collected from 11 populations in Niigata City were investigated. Eighty-two percent of them showed a Japanese haplotype of cpDNA, and they were regarded as hybrids. Compared with the previous studies, it is likely that the prevalence of the hybrid plants is a general phenomena at least in urban areas in Japan. The validity of the cpDNA marker for screening Taraxacum hybrids is discussed. Electronic Publication     

Characterization and primer development for amplification of chloroplast microsatellite regions of Fraxinus excelsior

This study reports the characterization of chloroplast DNA (cpDNA) variation of Fraxinus excelsior at five loci and the successful development of primer pairs for the amplification of three of these containing mononucleotide microsatellites. We detected high levels of haplotype variation among provenances of Fraxinus around Europe and within Ireland.     

Sequencing cucumber (Cucumis sativus L.) chloroplast genomes identifies differences between chilling-tolerant and -susceptible cucumber lines.

Chilling injury in cucumber (Cucumis sativus L.) is conditioned by maternal factors, and the sequencing of its chloroplast genome could lead to the identification of economically important candidate genes. Complete sequencing of cucumber chloroplast (cp)DNA was facilitated by the development of 414 consensus chloroplast sequencing primers (CCSPs) from conserved cpDNA sequences of Arabidopsis (Arabidopsis thaliana L.), spinach (Spinacia oleracea L.), and tobacco (Nicotiana tabacum L.) cpDNAs, using degenerative primer technologies. Genomic sequence analysis led to the construction of 301 CCSPs and 72 cucumber chloroplast-specific sequencing primers (CSSPs), which were used for the complete sequencing of cpDNA of Gy14 (155 525 bp) and 'Chipper' (155 524 bp) cucumber lines, which are, respectively, susceptible and tolerant to chilling injury (4 degrees C for 5.5 h) in the first leaf stage. Comparative cpDNA sequence analyses revealed that 1 sequence span (located between genes trnK and rps16) and 2 nucleotides (located in genes atpB and ycf1) differed between chilling-susceptible and -tolerant lines. These sequence differences correspond to previously reported maternally inherited differences in chilling response between reciprocal F1 progeny derived from these lines. Sequence differences at these 3 cpDNA sites were also detected in a genetically diverse array of cucumber germplasm with different chilling responses. These and previously reported results suggest that 1 or several of these sequences could be responsible for the observed response to chilling injury in cucumber. The comprehensive sequencing of cpDNA of cucumber by CCSPs and CSSPs indicates that these primers have immediate applications in the analysis of cpDNAs from other dicotyledonous species and the investigation of evolutionary relationships.     

药食同源植物薤白的谱系地理学研究

对我国14个地区的药食同源植物薤白（Allium macrostemon）的叶绿体基因片段（psbA-trnH、rps16和trnL-F）与核基因片段（ITS）进行测序分析,揭示薤白的遗传变异分布式样、单倍型地理分布格局,并推断其在第四纪冰期的避难所。结果表明：薤白叶绿体基因（cpDNA）遗传多样性低于核基因（nrDNA）遗传多样性（cpDNA：H_T=0.868;nrDNA：H_T=0.890）。cpDNA和nrDNA的分子变异分析（AMOVA）结果显示：薤白遗传变异主要发生在居群间（cpDNA：92.84%;nrDNA：98.40%）,存在遗传分化（cpDNA：N_st=0.918,G_st=0.866,F_st=0.928;nrDNA：N_st=0.984,G_st=0.855,F_st=0.984）,且N_st均大于G_st,表明该物种具有明显的谱系地理结构。在薤白居群中,共检测到11个叶绿体单倍型和14个nrDNA基因型;单倍型网络图及地理分布图表明,叶绿体单倍型H3、核DNA基因型H1频率最高,位于网络结构图的中心位置,可能为古老单倍型。此外,冰期避难所假说认为遗传多样性高、拥有古老单倍型和较多特有单倍型的区域可能是该物种的冰期避难所,因此推测薤白在第四纪冰期时可能在大盘山、天水和通化地区存在多个冰期避难所。这些分析可为类似草本植物的进化提供参考,丰富对东亚草本植物分子系统与生物地理学的认识。     

Conversion of barley SNPs into PCR-based markers using dCAPS method

Molecular genetic research relies heavily on the ability to detect polymorphisms in DNA. Single nucleotide polymorphisms (SNPs) are the most frequent form of DNA variation in the genome. In combination with a PCR assay, the corresponding SNP can be analyzed as a derived cleaved amplified polymorphic sequence (dCAPS) marker. The dCAPS method exploits the well-known specificity of a restriction endonuclease for its recognition site and can be used to virtually detect any SNP. Here, we describe the use of the dCAPS method for detecting single-nucleotide changes by means of a barley EST, CK569932, PCR-based marker.     

The genus Crataegus L.: an ecological and molecular study

This study aimed at the indentification of the species and genotypes of the genus Crataegus in Syria and determination of the genetic relationships among them based on the analysis of genomic and chloroplast DNA (cpDNA) using ISSRs and CAPS techniques. Morphological characterization carried out on 49 Crataegus samples collected from different geographical regions of Syria revealed four Crataegus species: C. monogyna, C. sinaica, C. aronia and C. azarolus. In the dendrogram constructed for those samples based on ISSRs (20 primers), all samples that belong to C. monogyna were clustered in one cluster. Samples of the other three species were overlaped in another cluster. Two samples of these were the most distant from all other samples in the dendrogram and were suggested to represent hybrid species or subspecies. When CAPS technique was applied on four Crataegus samples that represent the four suggested species using 22 cpDNA regions and 90 endonucleases, no polymorphism was detected neither in amplification products sizes nor in restriction profiles. The inability of detection of variation in cpDNA among species suggested can be attributed to the low level of evolution of the cpDNA in the genus, and to the possibility that some of these species are either subspecies or hybrids since the cpDNA is inherited through one parent only.     

水稻单核苷酸多态性及其应用现状

单核苷酸多态性（single nucleotide polymorphisms, SNPs）在水稻中数量多,分布密度高,遗传稳定性高。水稻SNPs的发现方法主要有对样本DNA的PCR产物直接测序、从SSR区段检测SNPs和从基因组序列直接搜索等。目前已有多种基因分型技术运用到了水稻SNPs检测,SNPs检测的高度自动化使水稻SNPs基因分型非常方便。单核苷酸多态性在水稻遗传图谱的构建、基因克隆和功能基因组学研究、标记辅助选择育种、遗传资源分类及物种进化等方面的应用具有巨大潜力。     

Geographic distribution of chloroplast variation in Italian populations of beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.)

The distribution of chloroplast DNA (cpDNA) variation in Italian beech (Fagus sylvatica L.) populations was studied using PCR-RFLP and microsatellite markers. In total, 67 populations were analysed, and 14 haplotypes were identified by combining the two marker types. A remarkable subdivision of cpDNA diversity in Italian beech was found, as indicated by a high level of genetic differentiation (G_st=0.855). The highest level of total haplotype diversity (h_t=0.822) was estimated for southern Italian populations. The highest number of haplotypes was found in the central-southern region of the peninsula. The nested clade analysis provided evidence for past fragmentation events that may have been occurred during the Quaternary glaciations and had a major role in defining the genetic structure of the central-southern Italian beech populations. Only one haplotype apparently spread towards the north of Italy along the Apennine chain and reached the Italian slope of the western part of the Alps (Maritime Alps, Liguria). All haplotypes found along the Apennines remained trapped in the Italian peninsula. Southern and central Italy represent hotspots of haplotype diversity for Italian beech.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by O. Savolainen     

Taxonomic status and relationships of bracken ferns (Pteridium: Dennstaedtiaceae) of Laurasian affinity in Central and North America

Detailed quantitative comparisons confirm and extend the discrimination of four major morphotypes amongst brackens of Laurasian affinity in Central and North America. These are recognized here at subspecies level as: Pteridium aquilinum sspp. feei , pubescens , latiusculum , and pseudocaudatum . Measurements of spore size indicate that sporophytes of P. aquilinum ssp. feei are diploid (2 n  = 104), as are sspp. pubescens , latiusculum , and pseudocaudatum . Phenetic cluster analysis based on DNA fingerprinting by arbitrarily primed polymerase chain reaction groups these four subspecies as genomically more similar to each other than to any taxa from other geographical regions. The chloroplast haplotype of ssp. feei is the same as that of sspp. latiusculum , pseudocaudatum , and pubescens with respect to the absence of both of the short direct repeats in the rps 4– trn S region (haplotype A), whereas the European ssp. aquilinum (haplotype B) has one of these repeats, and the Southern Hemisphere brackens P. arachnoideum and P. esculentum (haplotype C) have the other.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 1–17.     

Associations among cytoplasmic molecular markers,gender, and components of fitness in Silene vulgaris,a gynodioecious plant

It has been suggested that the dynamics of chloroplast DNA (cpDNA) or mitochondrial DNA (mtDNA) genetic markers used in studies of plant populations could be influenced by natural selection acting elsewhere in the genome. This could be particularly true in gynodioecious plants if cpDNA or mtDNA genetic markers are in gametic disequilibrium with genes responsible for sex expression. In order to investigate this possibility, a natural population of the gynodioecious plant Silene vulgaris was used to study associations among mtDNA haplotype, cpDNA haplotype, sex and some components of fitness through seed. Individuals were sampled for mtDNA and cpDNA haplotype as determined using restriction fragment length polymorphism (RFLP) methods, sex (female or hermaphrodite), fruit number, fruit set, seeds/fruit and seed germination. The sex of surviving germinating seeds was also noted. All individuals in the population fell into one of two cytoplasmic categories, designated haplotypes f and g by a unique electrophoretic signature in both the mtDNA and cpDNA. The subset of the population carrying haplotype g included a significantly higher proportion of females when compared with the sex ratio of the subset carrying the f haplotype. Haplotype g had a significantly higher fitness when measured by fruit number, fruit set and seeds/fruit, whereas haplotype f had significantly higher fitness when measured by seed germination. Offspring of individuals carrying haplotype g included a significantly greater proportion of females when compared with offspring of individuals carrying the f haplotype. Other studies of gynodioecious plants have shown that females generally have higher fitness through seed than hermaphrodites, but in this study not all fitness differences between haplotypes could be predicted from differences in haplotype-specific sex ratio alone. Rather, some differences in haplotype-specific fitness were due to differences in fitness between individuals of the same sex, but carrying different haplotypes. The results are discussed with regard to the potential for hitchhiking selection to influence the dynamics of the noncoding regions used to designate the cpDNA and mtDNA haplotypes.     

Genetic analysis of <Emphasis Type="Italic">Vrn-B1</Emphasis> for vernalization requirement by using linked dCAPS markers in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

To identify a molecular marker closely linked to Vrn-B1, the Vrn-1 ortholog on chromosome 5B, sequence polymorphism at four orthologous RFLP loci closely linked to the Vrn-1 gene family was analyzed by using near-isogenic lines of ”Triple Dirk.” At Xwg644, a RFLP locus, three types of nucleotide sequence differing by the number of (TG) repeats, two or three times, and base changes were detected. A (TG)₃-type sequence proved to be specific to chromosome 5B by nulli-tetrasomic analysis, and substitution of single nucleotide (C/T) was detected between TD(B) carrying the former Vrn2 allele and TD(C) carrying the vrn2 allele. A mismatch primer was designed for dCAPS analysis of this single nucleotide polymorphism (SNP). Polymorphism was successfully detected between two NILs, through nested PCR by using a (TG)₃-specific primer (1st) and a dCAPS primer (2nd) followed by a NsiI digest. The analysis of a BF₂ population [(TD(B)//TD(C)] revealed the close linkage (1.7 cM) between WG644–5B and Vrn2. It was therefore concluded that the former Vrn2 locus is located on chromosome 5B and equivalent to Vrn-B1. Received: 3 May 2001 / Accepted: 19 July 2001     

Distribution of chloroplast DNA diversity within and among populations in gynodioecious Beta vulgaris ssp. maritima (Chenopodiaceae)

With the recent technical advances in molecular biology, chloroplast DNA (cpDNA) has become a marker used for the study of cytoplasmic differentiation of natural populations of plants. As chloroplasts are maternally inherited in most plant species, the seed component of gene flow is thus made accessible. We present here a study of cpDNA polymorphism within the maritima subspecies of the gynodioecious Beta vulgaris in which we try to assess the impact of such a reproductive system on seed flow. One hundred and eighty-eight wild beets were sampled from 20 hermaphroditic and 20 gynodioecious (i.e. containing both hermaphroditic and female plants) populations from the Atlantic coast of Europe. cpDNA variability in these populations was characterized with a rapid restriction fragment length polymorphism (RFLP) method. Eight cpDNA haplotypes were found. Strong differentiation among populations was observed ( F _ST = 0.43) and was consistent with isolation by distance, although most of the cpDNA haplotypes were ubiquitous. Gynodioecy seems to affect the distribution of cpDNA diversity: gynodioecious populations of Beta vulgaris ssp. maritima contained a greater number of cpDNA types but were less differentiated among themselves than hermaphroditic ones.