Molecular characterization and similarity relationships among apricot ( Prunus armeniaca L.) genotypes using simple sequence repeats

A collection of 48 apricot genotypes, originated from diverse geographic areas, have been screened with 37 SSR primer pairs developed in different species of Prunus in order to identify and characterize the genotypes and establish their genetic relations. Thirty one of those primer pairs resulted in correct amplifications and 20 produced polymorphic repeatable amplification patterns with the 48 genotypes studied. A total of 82 alleles were detected for the 20 loci. All the genotypes studied could be unequivocally distinguished with the combination of SSRs used. The results obtained evidence for the cross-species transportability of microsatellite sequences, allowing the discrimination among different genotypes of a given fruit-tree species with sequences developed in other species. UPGMA cluster analysis of the similarity data grouped the genotypes studied according to their geographic origin and/or their pedigree information. Received: 5 April 2001 / Accepted: 4 May 2001     

QTL analysis of an advanced backcross of Lycopersicon peruvianum to the cultivated tomato and comparisons with QTLs found in other wild species

 A BC₃ population previously developed from a backcross of Lycopersicon peruvianum, a wild relative of tomato, into the cultivated variety L. esculentum was analyzed for QTLs. Approximately 200 BC₄ families were scored for 35 traits in four locations worldwide. One hundred and sixty-six QTLs were detected for 29 of those traits. For more than half of those 29 traits at least 1 QTL was detected for which the presence of the wild allele was associated with an agronomically beneficial effect despite the inferior phenotype of the wild parent. Eight QTLs for fruit weight could be followed through the BC₂, BC₃, and BC₄, generations, supporting the authenticity of these QTLs. Comparisons were made between the QTLs found in this study and those found in studies involving two other wild species; the results showed that while some of these QTLs can be presumed to be allelic, most of the QTLs detected in this study are ones not previously discovered. Received: 9 April 1997 / Accepted: 20 May 1997     

Description and analysis of genetic diversity between commercial bean lines (Phaseolus vulgaris L.)

The effectiveness of RFLP, DAMD-PCR, ISSR and RAPD markers in assessing polymorphism and relationships between 24 commercial lines of Phaseolus vulgaris L.was evaluated. We have used a Phaseolus-specific minisatellite sequence as a probe, which enabled 23 of the bean lines tested to be fingerprinted. Based on the sequence information obtained, primers corresponding to the bean-specific minisatellite core sequence were used in subsequent PCR amplifications. Our observations indicated that while the DAMD-PCR was sensitive in detecting genetic variation between bean species and between accessions of P. vulgaris, when used alone it may be limited in its ability to detect genetic variation among cultivated bean lines due to the low number of loci amplified. Only one out of the five ISSR primers tested was efficient in generating multiple band profiles, which was insufficient to distinguish all the different bean lines. Reproducible RAPD profiles were obtained, and these allowed us to differentiate all the genotypes tested with seven primers. We ultimately used only results from RFLP and RAPD markers to explore the genetic diversity among commercial bean lines. Both analyses led to the same clustering of the bean lines according to their geographical origins (United States or Europe). With respect to the European lines, the results obtained from RAPD data also enable the lines to be clustered according to their creators. Received: 15 January 2000 / Accepted: 21 March 2000     

Advanced backcross QTL analysis of tomato. II. Evaluation of near-isogenic lines carrying single-donor introgressions for desirable wild QTL-alleles derived from Lycopersicon hirsutum and L. pimpinellifolium

 Improved-processing tomato lines were produced by the molecular breeding strategy of advanced backcross QTL (AB-QTL) analysis. These near-isogenic lines (NILs) contained unique introgressions of wild alleles originating from two donor wild species, Lycopersicon hirsutum (LA1777) and L. pimpinellifolium (LA1589). Wild alleles targeted for trait improvement were selected on the basis of previously published replicated QTL data obtained from advanced backcross populations for a battery of important agronomic traits. Twenty three NILs were developed for 15 genomic regions which were predicted to contain 25 quantitative trait factors for the improvement of seven agronomic traits: total yield, red yield, soluble solids, brix×red yield, viscosity, fruit color, and fruit firmness. An evaluation of the agronomic performance of the NILs in five locations worldwide revealed that 22 out of the 25 (88%) quantitative factors showed the phenotypic improvement predicted by QTL analysis of the BC₃ populations, as NILs in at least one location. Per-location gains over the elite control ranged from 9% to 59% for brix×red yield; 14% to 33% for fruit color; 17% to 34% for fruit firmness; 6% to 22% for soluble-solids content; 7% to 22% for viscosity; 15% to 48% for red yield, and 20% to 28% for total yield. The inheritance of QTLs, the implementation of the AB-QTL methodology for characterizing unadapted germplasm and the applicability of this method to other crops are discussed. Received: 27 October 1997 / Accepted: 25 November 1997     

Advanced back-cross QTL analysis of tomato. II. Evaluation of near-isogenic lines carrying single-donor introgressions for desirable wild QTL-alleles derived from Lycopersicon hirsutum and L. pimpinellifolium

 Improved-processing tomato lines were produced by the molecular breeding strategy of advanced backcross QTL (AB-QTL) analysis. These near-isogenic lines (NILs) contained unique introgressions of wild alleles originating from two donor wild species, Lycopersicon hirsutum (LA1777) and L. pimpinellifolium (LA1589). Wild alleles targeted for trait improvement were selected on the basis of previously published replicated QTL data obtained from advanced backcross populations for a battery of important agronomic traits. Twenty three NILs were developed for 15 genomic regions which were predicted to contain 25 quantitative trait factors for the improvement of seven agronomic traits: total yield, red yield, soluble solids, brix×red yield, viscosity, fruit color, and fruit firmness. An evaluation of the agronomic performance of the NILs in five locations worldwide revealed that 22 out of the 25 (88%) quantitative factors showed the phenotypic improvement predicted by QTL analysis of the BC₃ populations, as NILs in at least one location. Per-location gains over the elite control ranged from 9% to 59% for brix×red yield; 14% to 33% for fruit color; 17% to 34% for fruit firmness; 6% to 22% for soluble-solids content; 7% to 22% for viscosity; 15% to 48% for red yield, and 20% to 28% for total yield. The inheritance of QTLs, the implementation of the AB-QTL methodology for characterizing unadapted germplasm and the applicability of this method to other crops are discussed. Theor Appl Genet (1998) 97 : 170–180 Received: 27 October 1997 / Accepted: 25 November 1997     

Fifty new microsatellite loci for the wheat genetic map

 Hexaploid bread wheat (Triticum aestivum) has low levels of RFLP. Simple sequence repeats, however, show high levels of polymorphism and are therefore especially useful in intervarietal breeding applications. We present 53 newly mapped microsatellite loci for the wheat genetic map, 41 primary loci and 12 additional loci from these same primer pairs. Markers have been accredited with a quality score on a scale of 1–5 which describes the complexity of the amplification product profile from each primer pair. Received: 29 June 1997 / Accepted: 4 February 1998     

Advanced backcross QTL analysis in tomato. I. Identification of QTLs for traits of agronomic importance from Lycopersicon hirsutum

 Advanced backcross QTL (AB-QTL) analysis is a new strategy for studying the effect of unadapted alleles on the agronomic performance of elite cultivated lines. In this paper we report results from the application of the AB-QTL strategy to cultivated tomato using the wild species Lycopersicon hirsutum LA1777 as the donor parent. RFLP genomic fingerprints were determined for 315 BC₂ plants and phenotypic data were collected for 19 agronomic traits from approximately 200 derived BC₃ lines which were grown in replicated field trials in three locations worldwide. Between 1 and 12 significant QTLs were identified for each of the 19 traits evaluated, with a total of 121 QTLs identified for all traits. For 25 of the QTLs (20%) corresponding to 12 traits (60%), the L. hirsutum allele was associated with an improvement of the trait from a horticultural perspective, despite the fact that L. hirsutum is overall phenotypically inferior to the elite parent. For example, L. hirsutum has fruit that remains green when ripe (lack of red pigment) yet alleles were found in this species that significantly increase red color when transferred into cultivated tomatoes. Wild alleles were also associated with increases in total yield and soluble solids (up to 15%) and brix×red yield (up to 41%). These results support the idea that one cannot predict the genetic potential of exotic germplasm based on phenotype alone and that marker-based methods, such as the AB-QTL strategy, should be applied to fully exploit exotic germplasm. Received: 27 October 1997 / Accepted: 25 November 1997     

RFLP and RAPD markers linked to the rosy leaf curling aphid resistance gene (Sd1) in apple

 Sd ₁ is a dominant gene for resistance to biotypes 1 and 2 of the rosy leaf curling aphid, Dysaphis devecta Wlk., which can cause economic damage to apple trees. This report describes the identification of three RFLP and four RAPD markers linked to Sd ₁ in a cross between the D. devecta susceptible variety ‘Prima’ (sd ₁ sd ₁) and the resistant variety ‘Fiesta’ (Sd ₁ sd ₁). Potted trees were artificially infested in the glasshouse, and the ratio of resistant:susceptible plants supported the hypothesis that the resistance was under the control of a single dominant gene. The position of the gene was mapped to a single locus on a ‘Fiesta’ chromosome, within 2 cM of three tightly linked RFLP markers (MC064a, 2B12a and MC029b); the four RAPD markers were located further away (between 13 and 46 cM). This is the first report of molecular markers for an aphid resistance gene in tree fruit crops. The potential application of these markers in a marker-assisted resistance breeding programme is discussed. Received: 1 July 1996/Accepted: 23 August 1996     

Microsatellite analysis of Aegilops tauschii germplasm

The highly polymorphic diploid grass Aegilops tauschii isthe D-genome donor to hexaploid wheat and represents a potential source for bread wheat improvement. In the present study microsatellite markers were used for germplasm analysis and estimation of the genetic relationship between 113 accessions of Ae. tauschii from the gene bank collection at IPK, Gatersleben. Eighteen microsatellite markers, developed from Triticum aestivum and Ae. tauschii sequences, were selected for the analysis. All microsatellite markers showed a high level of polymorphism. The number of alleles per microsatellite marker varied from 11 to 25 and a total of 338 alleles were detected. The number of alleles per locus in cultivated bread wheat germplasm had previously been found to be significantly lower. The highest levels of genetic diversity for microsatellite markers were found in accessions from the Caucasian countries (Georgia, Armenia and the Daghestan region of Russia) and the lowest in accessions from the Central Asian countries (Uzbekistan and Turkmenistan). Genetic dissimilarity values between accessions were used to produce a dendrogram of the relationships among the accessions. The result showed that all of the accessions could be distinguished and clustered into two large groups in accordance with their subspecies taxonomic classification. The pattern of clustering of the Ae. tauschii accessions is according to their geographic distribution. The data suggest that a relatively small number of microsatellites can be used to estimate genetic diversity in the germplasm of Ae. tauschii and confirm the good suitability of microsatellite markers for the analysis of germplasm collections. Received: 8 September 1999 / Accepted: 7 October 1999     

Evaluation of inter-simple sequence repeat analysis for mapping in Citrus and extension of the genetic linkage map

Inter-simple sequence repeat (ISSR) analysis was evaluated for its usefulness in generating markers to extend the genetic linkage map of Citrus using a backcross population previously mapped with restriction fragment length polymorphism (RFLP), random amplified polymorphic DNA (RAPD) and isozyme markers. ISSR markers were obtained through the simple technique of PCR followed by analysis on agarose gels, using simple sequence repeat (SSR) primers. Optimization of reaction conditions was achieved for 50% of the SSR primers screened, and the primers amplified reproducible polymorphic bands in the parents and progeny of the backcross population. Mendelian segregation of the polymorphic bands was demonstrated, with an insignificant number of skewed loci. Most of the SSR primers produced dominant loci; however co-dominance was observed with loci derived from three primers. A new genetic map was produced by combining the segregation data for the ISSR markers and data for the RFLP, RAPD and isozyme markers from the previous map and creating genetic linkages among all the markers using JoinMap 2.0 mapping software. The new map has an improved distribution of markers along the linkage groups with fewer gaps, and marker order showed partial or complete conservation in the linkage groups. The incorporation of ISSR markers into the genetic linkage map demonstrates that ISSR markers are suitable for genetic mapping in Citrus. Received: 3 February 2000 / Accepted: 12 May 2000     

Simple sequence repeat (SSR) markers survey of the cassava (Manihot esculenta Crantz) genome: towards an SSR-based molecular genetic map of cassava

The development of PCR-based, easily automated molecular genetic markers, such as SSR markers, are required for realistic cost-effective marker-assisted selection schemes. This paper describes the development and characterization of 172 new SSR markers for the cassava genome. The placement of 36 of these markers on the existing RFLP framework map of cassava is also reported. Two similar enrichment methods were employed. The first method yielded 35 SSR loci, for which primers could be designed, out of 148 putative DNA clones. A total of 137 primer pairs could be designed from 544 putative clones sequenced for the second enrichment. Most of the SSRs (95%) were di-nucleotide repeats, and 21% were compound repeats. A major drawback of these methods of SSR discovery is the redundancy – 20% duplication; in addition, primers could not be designed for many SSR loci that were too close to the cloning site – 45% of the total. All 172 SSRs amplified the corresponding loci in the parents of the mapping progeny, with 66% of them revealing a unique allele in at least one of the parents, and 26% having unique alleles in both of the parents. Of the 36 SSRs that have been mapped, at least 1 was placed on 16 out of the 18 linkage groups of the framework map, indicating a broad coverage of the cassava genome. This preliminary mapping of the 36 markers has led to the joining of a few small groups and the creation of one new group. The abundance of allelic bridges as shown by these markers will lead to the development of a consensus map of the male- and female-derived linkage groups. In addition, the relatively higher number of these allelic bridges, 30% as against 10% for RFLPs in cassava, underscores SSR as the marker of choice for cassava. The 100% primer amplification obtained for this set of primers also confirms the appropriateness of SSR markers for use in cassava genome analysis and the transferability of the technology as a low-cost approach to increasing the efficiency of cassava breeding. Current efforts are geared towards the generation of more SSR markers to attain a goal of 200 SSR markers, or 1 SSR marker every 10 cM. Received: 15 November 1999 / Accepted: 14 April 2000     

Chimerism in grapevines: implications for cultivar identity,ancestry and genetic improvement

In the course of DNA profiling of grapevine cultivars using microsatellite loci we have occasionally observed more than two alleles at a locus in some individuals and have identified periclinal chimerism as the source of such anomalies. This phenomenon in long-lived clonally propagated crops, such as grapevine, which contains historically ancient cultivars, may have a role in clonal differences and affect cultivar identification and pedigree analysis. Here we show that when the two cell layers of a periclinal chimera, Pinot Meunier, are separated by passage through somatic embryogenesis the regenerated plants not only have distinct DNA profiles which are different from those of the parent plant but also have novel phenotypes. Recovery of these phenotypes indicates that additional genetic differences can exist between the two cell layers and that the Pinot Meunier phenotype is due to the interaction of genetically distinct cell layers. It appears that grapevine chimerism can not only modify phenotype but can also impact on grapevine improvement as both genetic transformation and conventional breeding strategies separate mutations in the L1 and L2 cell layers. Received: 14 March 2001 / Accepted: 22 May 2001     

Molecular-marker analysis of quantitative traits for growth and development in juvenile apple trees

Random amplified polymorphic DNAs (RAPDs) were used in combination with a double pseudo-testcross mapping strategy to estimate the position and effects of quantitative trait loci (QTLs) for traits influencing juvenile tree growth and development in two apple cultivars. The mapping population consisted of 172 F₁ trees from a cross between the columnar mutant ‘Wijcik McIntosh’ and a standard form disease-resistant selection NY 75441-58. Significant associations were found between markers and height increment, internode number, internode length, base diameter increment, base diameter after 9 years of growth, branch number, and leaf break. The number of genomic regions associated with each trait varied from one to eight. The amount of variation explained by linear regression on individual marker loci (R²) ranged from 3.9 to 24.3%, with an average of 7%. Multiple regression using markers for each putative QTL explained from 6.6 to 41.6% of the phenotypic variation, with an average value of 24.3%. A large number of traits had significant variation associated with the map position of the dominant columnar gene, Co. QTL stability over years was estimated by comparing the locations of putative QTLs for traits measured in multiple years. The majority of genomic regions were associated with a trait in only a single year, although regions associated with a trait in more than 1 year were also detected. The limitations of dominant markers and an outbred mapping pedigree for QTL analysis are discussed. Received: 27 August 1997 / Accepted: 10 February 1998     

The use of microsatellite markers for detection of genetic diversity in barley populations

 A barley lambda-phage library was screened with (GA)n and (GT)n probes for developing microsatellite markers. The number of repeats ranged from 2 to 58 for GA and from 2 to 24 for GT. Fifteen selected microsatellite markers were highly polymorphic for barley. These microsatellite markers were used to estimate the genetic diversity among 163 barley genotypes chosen from the collection of the IPK Genebank, Germany. A total of 130 alleles were detected by 15 barley microsatellite markers. The number of alleles per microsatellite marker varied from 5 to 15. On average 8.6 alleles per locus were observed. Except for GMS004 all other barley microsatellite markers showed on average a high value of gene diversity ranging from 0.64 to 0.88. The mean value of gene diversity in the wild forms and landraces was 0.74, and even among the cultivars the gene diversity ranged from 0.30 to 0.86 with a mean of 0.72. No significant differences in polymorphism were detected by the GA and GT microsatellite markers. The estimated genetic distances revealed by the microsatellite markers were, on average , 0.75 for the wild forms, 0.72 for landraces and 0.70 among cultivars. The microsatellite markers were able to distinguish between different barley genotypes. The high degree of polymorphisms of microsatellite markers allows a rapid and efficient identification of barley genotypes. Received: 26 November 1997 / Accepted: 19 January 1998     

Identification of simple sequence repeats (SSRs) in olive ( Olea europaea L.)

A small insert genomic library of Olea europaea L., highly enriched in (GA/CT)n repeats, was obtained using the procedure of Kandpal et al. (1994). The sequencing of 103 clones randomly extracted from this library allowed the identification of 56 unique genomic inserts containing simple sequence repeat regions made by at least three single repeats. A sample of 20 primer pairs out of the 42 available were tested for functionality using the six olive varieties whose DNA served for library construction. All primer pairs succeeded in amplifying at least one product from the six DNA samples, and ten pairs detecting more than one allele were used for the genetic characterisation of a panel of 20 olive accessions belonging to 16 distinct varieties. A total of 57 alleles were detected among the 20 genotypes at the ten polymorphic SSR loci. The remaining primer pair allowed the amplification of a single SSR allele for all accessions plus a longer fragment for some genotypes. Considering the simple sequence repeat polymorphism, 5.7 alleles were scored on average for each of the ten SSR loci. A genetic dissimilarity matrix, based on the proportion of shared alleles among all the pair-wise combinations of genotypes, was constructed and used to disentangle the genetic relationships among varieties by means of the UPGMA clustering algorithm. Graphical representation of the results showed the presence of two distinct clusters of varieties. The first cluster grouped the varieties cultivated on the Ionian Sea coasts. The second cluster showed two subdivisions: the first sub-cluster agglomerated the varieties from some inland areas of Calabria; the second grouped the remaining varieties from Basilicata and Apulia cultivated in nearby areas. Results of cluster analysis showed a significant relationship between the multilocus genetic similarities and the geographic origin of the cultivars. Received: 2 February 2001 / Accepted: 1 June 2001     

The use of microsatellites for detecting DNA polymorphism, genotype identification and genetic diversity in wheat

A set of 20 wheat microsatellite markers was used with 55 elite wheat genotypes to examine their utility (1) in detecting DNA polymorphism, (2)in the identifying genotypes and (3) in estimating genetic diversity among wheat genotypes. The 55 elite genotypes of wheat used in this study originated in 29 countries representing six continents. A total of 155 alleles were detected at 21 loci using the above microsatellite primer pairs (only 1 primer amplified 2 loci; all other primers amplified 1 locus each). Of the 20 primers amplifying 21 loci, 17 primers and their corresponding 18 loci were assigned to 13 different chromosomes (6 chromosomes of the A genome, 5 chromosomes of the B genome and 2 chromosomes of the D genome). The number of alleles per locus ranged from 1 to 13, with an average of 7.4 alleles per locus. The values of average polymorphic information content (PIC) and the marker index (MI) for these markers were estimated to be 0.71 and 0.70, respectively. The (GT)_n microsatellites were found to be the most polymorphic. The genetic similarity (GS) coefficient for all possible 1485 pairs of genotypes ranged from 0.05 to 0.88 with an average of 0.23. The dendrogram, prepared on the basis of similarity matrix using the UPGMA algorithm, delineated the above genotypes into two major clusters (I and II), each with two subclusters (Ia, Ib and IIa, IIb). One of these subclusters (Ib) consisted of a solitary genotype (E3111) from Portugal, so that it was unique and diverse with respect to all other genotypes belonging to cluster I and placed in subcluster Ia. Using a set of only 12 primer pairs, we were able to distinguish a maximum of 48 of the above 55 wheat genotypes. The results demonstrate the utility of microsatellite markers for detecting polymorphism leading to genotype identification and for estimating genetic diversity. Received: 15 May 1999 / Accepted: 27 July 1999     

Utility of barley and wheat simple sequence repeat (SSR) markers for genetic analysis of Hordeum chilense and tritordeum

A selection of 36 wheat and 35 barley simple sequence repeat markers (SSRs) were studied for their utility in Hordeum chilense. Nineteen wheat and nineteen barley primer pairs amplified consistent H. chilense products. Nine wheat and two barley SSRs were polymorphic in a H. chilense mapping population, producing codominant markers that mapped to the expected homoeologous linkage groups in all but one case. Thirteen wheat and 10 barley primer pairs were suitable for studying the introgression of H. chilense into wheat because they amplified H. chilense products of distinct size. Analysis of wheat/H. chilense addition lines showed that the H. chilense products derived from the expected homoeologous linkage groups. The results showed that wheat and barley SSRs provide a valuable resource for the genetic characterization of H. chilense, tritordeums and derived introgression lines. Received: 20 November 2000 / Accepted: 12 April 2001     

AC/GT and AG/CT microsatellite repeats in peach [Prunus persica (L) Batsch]: isolation, characterisation and cross-species amplification in Prunus

 We report the sequences of 17 primer pairs of microsatellite loci, which we have cloned and sequenced from two genomic libraries of peach [Prunus persica (L) Batsch] ‘Redhaven’, enriched for AC/GT and AG/CT repeats respectively. For ten of these microsatellite loci we were able to demonstrate Mendelian inheritance in a segregating back-cross population; the remainder did not segregate. The polymorphism of the microsatellites was evaluated in a panel of ten peach genotypes, including true-to-type peaches, nectarines and one canning-peach. Fifteen microsatellites (88%) were polymorphic showing 2–4 alleles each. The mean heterozygosity, averaged over all loci, was 0.32 and significantly higher than that reported in the literature for isozymes and molecular markers, such as RFLPs and RAPDs. We have also assayed the cross-species transportability and found that ten microsatellite (59%) gave apparently correct amplification in all Prunus species surveyed, namely P. domestica (European plum), P. salicina (Japanese plum), P. armeniaca (apricot), P. dulcis (almond), P. persica var. vulgaris (peach), P. persica var. laevis (nectarine), P. avium (sweet cherry) and P. cerasus (sour cherry), with three of them also being amplified in Malus (apple). The remaining microsatellites gave less-extensive amplification. Because of their appreciable polymorphism and wide cross-species transportability, most of these new markers can be integrated into the linkage maps which are currently being constructed in peach, as well as in other stone fruit crops, such as almond, apricot, cherry and plum. Received: 3 September 1998 / Accepted: 28 November 1998     

Comparative analysis of genetic diversity in the mangrove species Avicennia marina (Forsk.) Vierh. (Avicenniaceae) detected by AFLPs and SSRs

Avicennia marina is an important mangrove species with a wide geographical and climatic distribution which suggests that large amounts of genetic diversity are available for conservation and breeding programs. In this study we compare the informativeness of AFLPs and SSRs for assessing genetic diversity within and among individuals, populations and subspecies of A. marina in Australia. Our comparison utilized three SSR loci and three AFLP primer sets that were known to be polymorphic, and could be run in a single analysis on a capillary electrophoresis system, using different- colored fluorescent dyes. A total of 120 individuals representing six populations and three subspecies were sampled. At the locus level, SSRs were considerably more variable than AFLPs, with a total of 52 alleles and an average heterozygosity of 0.78. Average heterozygosity for AFLPs was 0.193, but all of the 918 bands scored were polymorphic. Thus, AFLPs were considerably more efficient at revealing polymorphic loci than SSRs despite lower average heterozygosities. SSRs detected more genetic differentiation between populations (19 vs 9%) and subspecies (35 vs 11%) than AFLPs. Principal co-ordinate analysis revealed congruent patterns of genetic relationships at the individual, population and subspecific levels for both data sets. Mantel testing confirmed congruence between AFLP and SSR genetic distances among, but not within, population comparisons, indicating that the markers were segregating independently but that evolutionary groups (populations and subspecies) were similar. Three genetic criteria of importance for defining priorities for ex situ collections or in situ conservation programs (number of alleles, number of locally common alleles and number of private alleles) were correlated between the AFLP and SSR data sets. The congruence between AFLP and SSR data sets suggest that either method, or a combination, is applicable to expanded genetic studies of mangroves. The codominant nature of SSRs makes them ideal for further population-based investigations, such as mating-system analyses, for which the dominant AFLP markers are less well suited. AFLPs may be particularly useful for monitoring propagation programs and identifying duplicates within collections, since a single PCR assay can reveal many loci at once. Received: 3 October 2000 / Accepted: 19 February 2001