The influence of European and American wild germplasm in hop (<Emphasis Type="Italic">Humulus lupulus</Emphasis> L.) cultivars

Microsatellite variation at the nuclear and chloroplast genomes was evaluated for wild European and wild American hops, in order to assess the genetic diversity and origin of cultivated hops. Seven nuclear loci and 32 chloroplast loci were used in the analysis of 182 hop accessions including wild European (68), wild American (48), and cultivars (66). A total of 116 alleles were identified using 7 nuclear microsatellites showing different averages of polymorphism and distribution in the wild American and European accessions and cultivars. Two main groups were established as revealed by several statistical analyses; one including European wild accessions and cultivars and a second group consisting of American wild accessions. Three polymorphic chloroplast microsatellite loci were detected, six alleles were scored which defined a total of five haplotypes that were exclusive or presented different distribution between American and European wild accessions. A major influence of the wild European haplotypes was detected among hop cultivars. To the best of our knowledge, this is the first work reporting the use of chloroplast microsatellites in hops.     

Microsatellite DNA Analysis of Wild Hops, Humulus lupulus L.

To study the relationships and genetic diversity among wild hops, Humulus lupulus, we analyzed 133 samples of wild hops collected from Europe, Asia and North America using polymorphism on 11 microsatellite loci. Although only three primers showed bands in Japanese hops, all other samples showed polymorphic bands at most loci. There were no duplicate genotypes among samples of European, Chinese and North American hops, and each individual hop could be distinguished completely. The phylogenetic tree constructed from DA distance with the UPGMA method showed a large cluster comprised of European hops, although Russian hops from the Caucasus and Altai regions were separate from the European cluster. Chinese and North American samples gave distinct clusters suggesting genetic differentiation. This study has indicated that hop microsatellite DNA is differentiated, and is dependent upon the origin in regions of Europe, Asia and North America.     

Genetic diversity and relationships between wild and cultivated olives (<Emphasis Type="Italic">Olea europaea</Emphasis> L.) in Sardinia as assessed by SSR markers

The genetic relationships within and between wild and cultivated olives were examined and clarified in an isolated and restricted area, such as the Mediterranean island of Sardinia. Wild (21 individuals) and cultivated olive trees (22 local cultivars from a germplasm collection and 35 ancient trees) were genotyped by means of 13 SSR loci. Five cases of synonymy were observed and nine distinct genotypes were identified in the collection. Five novel genotypes were also detected among the ancient trees. Differences on the allelic composition and heterozygosity levels were found between wild and cultivated trees. Model-based clustering method classified the olive trees into two major gene pools: (a) wild genotypes and (b) local cultivars from the collection and from heritage olives. Regarding the cultivated plant material, we observed that: (a) most of the Sardinian cultivars shared the same allelic profiles with the ancient cultivated trees and (b) the majority of these cultivars and all the novel genotypes were not related to any other cultivars included in this study. These findings as well as the detection of unique alleles and a certain wild genetic background at some cultivars revealed by the Bayesian analysis may indicate their autochthonous origin. The synonymy cases found between local cultivars and Italian mainland cultivars indicate interchange of genetic material among these growing areas, suggesting thus a possible allochthonous origin. The information obtained can assist in the management of an olive collection and sheds some light on the survival of true oleasters and the origin of Sardinian cultivars.     

Genic SSRs for European and North American hop (Humulus lupulus L.)

Eight genic SSR loci were evaluated for genetic diversity assessment and genotype identification in Humulus lupulus L. from Europe and North America. Genetic diversity, as measured by three diversity indices, was significantly lower in European cultivars than in North American wild accessions. Neighbor Joining cluster analysis separated the hop genotypes into European and North American groups. These eight SSRs were useful in uniquely identifying each accession with the exception of two sets of European landraces and a pair of Japanese cultivars, ‘Shinshuwase’ and ‘Kirin II’. An accession from Manitoba grouped with the European (EU) cluster reflecting the group’s genetic similarity to older Manitoba germplasm used to develop ‘Brewer's Gold’ and the gene pool arising from this cultivar. Cultivars grouped closely with one of their immediate parents. ‘Perle’ grouped with its parent ‘Northern Brewer and ‘Willamette’ grouped with its parent ‘Fuggle H’. Wild American accessions were divided into two subgroups: a North Central group containing mostly H. lupulus var. lupuloides and a Southwestern group containing H. lupulus var. neomexicanus accessions. These eight SSRs will be valuable for genotype identification in European and wild American germplasm and may potentially prove useful for marker-assisted selection in hop. PCR products from four previously reported primer pairs that amplify the same intronic SSR regions as do the genic SSRs in this study were compared in eight common cultivars. Different primer pairs generated robust markers at the chs2 and chi loci. However, only the HLC-004B and HLC-006 primer pairs amplified successfully at the chs3 and chs4 loci. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Genetic diversity of cultivated and wild Ussurian Pear (<Emphasis Type="Italic">Pyrus ussuriensis</Emphasis> Maxim.) in China evaluated with M13-tailed SSR markers

Eight genomic SSR markers with a M13 tail attached were used to assess the genetic diversity of 72 Ussurian Pear accessions (Pyrus ussuriensis Maxim.) in China. The M13-tailed method was effective in discriminating all the 32 wild accessions. All the 40 Ussurian Pear cultivars could be successfully discriminated with the exception of 4 sets of synonymies or spots. A total of 108 alleles were obtained with an average of 13.5 per locus. The expected heterozygosity, observed heterozygosity, and power of discrimination were 0.78, 0.63, and 0.86 respectively. Three triploid cultivars (‘Anli’, ‘Ruan’er’, and ‘Pitaiguo’), and one wild accession, P. ussuriensis ‘Xilin-3’, showed three alleles at some SSRs. The number of alleles and observed heterozygosity per locus for 40 Ussurian Pear cultivars were 9.1 and 0.62, respectively, lower than the values of 32 wild accessions which were 11.3 and 0.65, respectively. A dendrogram based on the SSR genotypes was obtained, showing two major groups corresponding to cultivated group and wild group. All the cultivars fell into the cultivated group. Some subgroups (Nanguoli subgroup, Zhibazi subgroup, Xiangshuili subgroup, Balixiang subgroup, Anli subgroup) could be found in the cultivated group. A very close relationship between ‘Huagaili’ and ‘Miansuan’, and a close relationship between ‘Anli’ and a wild accession, P. ussuriensis ‘Huangshanli’ could be found in Anli subgroup. ‘Nanguoli’ and ‘Xiaowuxiang’ showed a close relationship with at least one identical allele at each locus with the exception of NH015a.     

Genetic structure and differentiation among grapevines (<Emphasis Type="Italic">Vitis vinifera</Emphasis>) accessions from Maghreb region

Three gene pools representative of Vitis vinifera L. subsp. vinifera (=subsp. sativa Beger) growing in the Maghreb regions (North Africa) from Tunisia (44), Algeria (31) and Morocco (18) and 16 wild grape accessions (Vitis vinifera L. subsp. sylvestris (Gmelin) Beger) from Tunisia were analysed for genetic diversity and differentiation at twenty nuclear microsatellites markers distributed throughout the 19 grape chromosomes. 203 alleles with a mean number of 10.15 alleles per locus were observed in a total of 109 accessions. Genetic diversities were high in all populations with values ranging from 0.6775 (Moroccan cultivars) to 0.7254 (Tunisian cultivars). F _st pairwise values between cultivated grapevine populations were low but found to be significantly different from zero. High F _st pairwise values were shown between wild and cultivated compartments. Two parent offspring relationships, two synonyms and two clones of the same cultivar were detected. The rate of gene flow caused by vegetative dissemination of cultivated grapevine plants was not sufficient to genetically homogenise the pools of cultivars grown in different regions. The Neighbour Joining cluster analysis showed a clear separation according to geographical origins for the cultivated grapevines gene pools and revealed a high dissimilarity between cultivated and wild grapevine. However, three cultivars (Plant d’Ouchtata 1, Plant de Tabarka 3 and Plant d’Ouchtata 3) are very close to wild accessions and may result from a hybridisation between cultivated and wild accessions. The high level of differentiation between cultivated and wild accessions indicates that the cultivated accessions do not derive directly from local wild populations but could mostly correspond to imported materials introduced from others regions during historical times or derived from crossing between them.     

Processes affecting genetic structure and conservation: a case study of wild and cultivated <Emphasis Type="Italic">Brassica rapa</Emphasis>

When planning optimal conservation strategies for wild and cultivated types of a plant species, a number of influencing biological and environmental factors should be considered from the outset. In the present study Brassica rapa was used to illustrate this: to develop Scandinavian conservation strategies for wild and cultivated B. rapa, DNA-marker analysis was performed on 15 cultivated and 17 wild accessions of B. rapa plus 8 accessions of the cross compatible B. napus. The B. rapa cultivars were bred in Sweden and Finland in 1944–1997 and the wild B. rapa material was collected from Denmark, Sweden and United Kingdom. The B. napus accessions were bred within the last 20 years in the Scandinavian countries. Results were based on scoring of 131 polymorphic ISSR markers in the total plant material. A Bayesian Markov chain Monte Carlo (MCMC) approach implemented in NewHybrids demonstrated a clear distinction of B. rapa and B. napus individuals except for three individuals that seemed to be backcrosses. The backcrossed hybrids descended from two Swedish populations, one wild and one escaped. The overall pattern of genetic variation and structure in B. rapa showed that cultivated and wild B. rapa accessions formed two almost separated clusters. Geographical origin and breeding history of cultivars were reflected in these genetic relationships. In addition, wild populations from Denmark and Sweden seemed to be closely related, except for a Swedish population, which seemingly was an escaped cultivar. The study point to that many processes, e.g. spontaneous introgression, naturalisation, breeding and agricultural practise affected the genetic structure of wild and cultivated B. rapa populations.     

Germplasm sources of protective glandular leaf trichomes of hop (<Emphasis Type="Italic">Humulus lupulus</Emphasis>)

We report here that small but numerous foliar glands are present near the base of the abaxial leaf blades of hop (Humulus lupulus L.) at about 2.6 times the density found in the more distal regions, and this concentration of glands appear to protect the basal region from damage by insects. Distinctive wild taxa of H. lupulus are native to distinctive regions of the north temperate world. The much higher presence of protective glands in the three native North American Humulus taxonomic varieties in comparison with the varieties native to Europe and Asia suggests specialized leaf feeders in North America have been responsible for the evolution of greater gland density. Commercial domesticated hop cultivars trace most of their germplasm to the European hop (H. lupulus var. lupulus), which possesses a much lower concentration of leaf glands than the native hops of all other regions of the world, and therefore is likely relatively susceptible to damage. We suggest that breeding for increased density of protective foliage glands may be a non-chemical way of alleviating foliar feeding damage in cultivated hops.     

Genetic variation among populations of wild safflower, <Emphasis Type="Italic">Carthamus oxyacanthus</Emphasis> analyzed by agro-morphological traits and ISSR markers

Wild species of safflower, Carthamus oxyacanthus Bieb., is highly crossable with cultivated species, C. tinctorius L. and could be directly exploited in broadening safflower gene pool and improving the crop for biotic and abiotic stress environments. In this study, genetic diversity among accessions of C. oxyacanthus and their relationships with cultivated safflower were evaluated using agro-morphological traits and polymorphic inter-simple sequence repeats (ISSR) markers. Significant variation was observed among accessions particularly for seeds per capitulum, seed yield per plant, harvest index and capitula per plant. Cluster analysis based on agro-morphological traits classified the wild accessions in two groups according to their geographical regions, and separated them from the cultivated genotypes. ISSR marker also revealed a high genetic variation among the accessions, and cluster analysis based on this marker divided genotypes into four groups, with cultivated ones in a separate clade. Genetic variation observed among the wild safflower germplasm at the DNA level was higher than the agro-morphological traits, indicating that ISSR is an effective marker system for detecting diversity among safflower genotypes and their genetic relationships. Accessions of C. oxyacanthus with high genetic relationship to cultivated species could be used for interspecific hybridization in breeding programs of safflower.     

The coexistence of oleaster and traditional varieties affects genetic diversity and population structure in Algerian olive (<Emphasis Type="Italic">Olea europaea</Emphasis>) germplasm

The present work was aimed at assessing the genetic diversity of 42 local cultivars and oleaster genotypes from the area of Bejaia in Algeria. Fifteen highly polymorphic Simple Sequence Repeat markers were evaluated and proved to be very informative, producing a total number of 160 alleles with an average value of 10.7 per locus; the SSRs DCA09 and DCA16 were the most informative, distinguishing 17 and 19 genotypes, respectively. Phylogenetic and population structure analysis split the accessions in two main groups corresponding to most of oleasters and most of traditional varieties, respectively. Interestingly, ten traditional varieties resulted strictly related to the oleasters, indicating hybridization between the two botanical varieties. Genetic parameters and private alleles of groups confirmed this observation and indicated a wide genetic variability in Algerian olive germplasm. The results suggest the need to preserve and characterize this germplasm in order to limit the risk of losing potential important genetic traits present in the crop wild relatives.     

Diversity of the European indigenous wild apple (Malus sylvestris (L.) Mill.) in the East Ore Mountains (Osterzgebirge), Germany: II. Genetic characterization

In the present study genetic diversity and hybridization with cultivars were investigated in a population of the endangered European wild apple species Malus sylvestris (L.) Mill. with the aim to establish a basis for the implementation of conservation activities and to ensure its long-term preservation. A total of 284 putative M. sylvestris trees located in the East Ore Mountains were investigated along with a standard set of reference apple genotypes proposed by the European Cooperative Program for Plant Genetic Resources (ECPGR) and 13 old apple cultivars often cultivated in Saxony. The genetic analysis was performed using 12 microsatellite markers also recommend by the ECPGR. To differentiate ‘true type’ M. sylvestris individuals, hybrids and apple cultivars (Malus × domestica Borkh.) a model-based cluster analysis was performed using STRUCTURE. Two clusters were identified consisting of M. sylvestris and M. × domestica genotypes. About 40 % of the putative M. sylvestris showed an admixture of the species-specific allele frequencies and were defined as hybrids. The genetic diversity of the ‘true type’ M. sylvestris population was still high but slightly lower than in the apple cultivars especially since some SSR loci were fixed on one or few alleles in the M. sylvestris population. The differentiation parameters between ‘true type’ wild apple and cultivars indicated a clear discrimination between the wild and cultivated apple individuals. This fact confirms our expectation of the existence of ‘true type’ M. sylvestris individuals in the East Ore Mountains and argues for the realization of preservation measures in this area.     

Genetic diversity in wild and cultivated black raspberry (Rubus occidentalis L.) evaluated by simple sequence repeat markers

Breeding progress in black raspberry (Rubus occidentalis L.) has been limited by a lack of genetic diversity in elite germplasm. Black raspberry cultivars have been noted for showing very few phenotypic differences and seedlings from crosses between cultivars for a lack of segregation for important traits. Despite these challenges, little molecular work has been done to explore genetic diversity and relationships in wild and cultivated black raspberry germplasm. Microsatellite, or simple sequence repeat (SSR), markers are highly polymorphic codominant markers useful for studying genetic diversity, population genetics, genetic fingerprinting and other applications. We examined genetic diversity in 148 wild and cultivated black raspberry accessions using 21 polymorphic SSR markers. Black raspberry cultivars clustered tightly and showed higher than expected heterozygosity while that of wild accessions was low. Relationships between wild black raspberry accessions were poorly resolved and regional clusters were mostly absent from our analysis. Our results indicated that wild black raspberry germplasm is a relatively untapped resource available for future breeding.     

Phenotypic diversity in wild barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L. ssp. <Emphasis Type="Italic">spontaneum</Emphasis> (C. Koch) Thell.) accessions collected in Jordan

Wild barley, Hordeum vulgare L. ssp. spontaneum (C. Koch) Thell., is the progenitor of cultivated barley. Almost unanimously the center of diversity is considered to be in the Fertile Crescent of the Near East, where wild barley grows under a wide range of environmental and climatic conditions. Jordanian wild barley is expected to harbor genes useful for the improvement of cultivated barley, particularly those associated with tolerance to drought. This study evaluated 103 wild barley accessions collected from different areas of Jordan along with 29 cultivated barley genotypes for several morphological and agronomical traits. The Hordeum vulgare ssp. spontaneum C. Koch accessions were grouped into six populations according to the longitude, latitude, altitude, and rainfall zone of the collection site, and the cultivated barley in one population. The evaluation was conducted during the 2004–2005 growing season under field conditions in three locations in Jordan; namely, Khanasri, Ramtha, and Maru with 123.0, 222.9, and 429.2 mm annual rainfall, respectively. We used an unreplicated design with two systematic checks (the cultivars Rum and Mu’ta) each repeated 15 times. The results showed the existence of high variability among the Hordeum vulgare ssp. spontaneum C. Koch accessions for most of the traits, especially for plant height, tiller number, days to heading, days to anthesis, peduncle length, and peduncle extrusion. Plant height, earliness, peduncle length, and peduncle extrusion were found to be adaptive traits under drought conditions and several superior genotypes for each trait were identified. Genetic variation within population was much higher than between populations. Clustering of populations was according to their ecological geographical pattern.     

Genetic diversity of wild soybean (<Emphasis Type="Italic">Glycine soja</Emphasis> Sieb. et Zucc.) and Japanese cultivated soybeans [<Emphasis Type="Italic">G. max</Emphasis> (L.) Merr.] based on microsatellite (SSR) analysis and the selection of a core collection

Wild soybeans, Glycine soja, are a source of genetic variation to improve soybeans. To improve the efficiency evaluation of conserved germplasm a core or mini-core collection approach that maximizes allelic diversity in a proportion of the whole collection has frequently been advocated. The genetic diversity of a wild soybean collection (1,305 accessions) plus Japanese cultivated soybeans (53 accessions) were analyzed at 20 SSR marker loci. Higher levels of allelic diversity were found in wild soybeans (28 alleles per locus) than Japanese cultivated soybean (five alleles per locus). The genetic distance between wild soybeans from different regions reflected their proximity. Accessions from Russia consisted of a diverse array of alleles resulting in accessions being spread further apart in a PCA plot than accessions from other regions. Accessions of wild soybean from Korea included many rare alleles and thus had a high representation in the core collection. The two core collections developed here, traditional and mini, consisted of 192 accessions with 97% of the allelic diversity (14% of the whole collection) and 53 accessions with 62.4% of the allelic diversity (5% of the whole collection), respectively.     

AFLP analysis of genetic diversity in leafy kale (<Emphasis Type="Italic">Brassica oleracea</Emphasis> L. convar. <Emphasis Type="Italic">acephala</Emphasis> (DC.) Alef.) landraces,cultivars and wild populations in Europe

AFLP markers were used to characterize diversity and asses the genetic structure among 17 accessions of kale landraces, cultivars and wild populations from Europe. The range of average gene diversity in accessions was 0.11–0.27. Several landraces showed higher levels of diversity than the wild populations and one cultivar had the lowest diversity measures. The landraces that were most genetically diverse were from areas where kales are known to be extensively grown, suggesting in situ conservation in these areas as a supplement to storage of seeds in gene banks. An analysis of molecular variance (AMOVA) showed that 62% of the total variation was found within accessions. For most accessions, genetic distance was not related to geographic distance. Similarities among accessions were probably not caused by recent gene flow since they were widely separated geographically; more likely the relationship among them is due to seed dispersal through human interactions. Our results indicate that a kale population found in a natural habitat in Denmark was probably not truly wild but most likely an escape from a cultivated Danish kale that had subsequently become naturalized.     

Genetic identity and relationships of Iranian apple (Malus?×?domestica Borkh.) cultivars and landraces, wild Malus species and representative old apple cultivars based on simple sequence repeat (SSR) marker analysis

In order to shed light on the role of Iran in apple evolution and domestication, we chose to investigate the relationships of a collection of 159 accessions of wild and domesticated apples including Iranian indigenous apple cultivars and landraces, selected wild species, and old apple scion and rootstock cultivars from different parts of the world. The majority of the wild species belonged to M. sieversii, which is widely believed to be the main maternal wild ancestor of domestic apples, from Kazakhstan and M. orientalis, which is one of the probable minor ancestors of domestic apples, from Turkey and Russia located on the east and west of Iran, respectively. The accessions were assigned into six arbitrary populations for the purpose of generating information on genetic parameters. Nine simple sequence repeat (SSR) loci selected from previous studies in apple were screened over DNA extracted from all the accessions. Results showed that all SSR loci displayed a very high degree of polymorphism with 11–25 alleles per locus. In total, there were 153 alleles across all loci with an average of 17 alleles per locus. The SSR allelic data were then used for estimation of population genetic parameters, including genetic variation statistics, F-statistics, gene flow, genetic identity, genetic distance and then cluster analysis using POPGENE 1.32 software. The F-statistics and gene flow in particular, showed that there was more intra-population than between population variation. The genetic identity and genetic distance estimates, and the dendrogram generated from the un-weighted pair group arithmetic average (UPGMA) method of cluster analysis showed that the Iranian cultivars and landraces were more closely related to M. sieversii from Central Asia (east of Iran) and M. orientalis native to Turkey and Russia than to other accessions of Malus species. Also, the old apple cultivars from different parts of the world have a closer genetic relationship to M. sieversii, M. orientalis and the Iranian apples, than to other wild species. Based on these results, we suggest that the Iranian apples may occupy an intermediate position between the domesticated varieties and wild species. We propose that Iran could be one of the major players in apples’ domestication and transfer from Central Asia to the western countries.     

Comparison of 4-Mercapto-4-methylpentan-2-one contents in hop cultivars from different growing regions

Contributions of hop-derived thiols were examined. Extremely strong fruity, black currant-like aromas were detected in beers hopped with some U.S. cultivars. 4-Mercapto-4-methylpentan-2-one (4MMP) was supposed to be the main contributor to the fruity aroma, and the contents between cultivars were investigated. In hop pellets, a negative correlation between 4MMP concentration and copper ion content in hops was observed. 4MMP was detected only in U.S., Australian, and New Zealand cultivars, but no European ones, which are treated with copper-containing fungicides (Bordeaux mixture) and therefore have a high content of copper ions. The 4MMP content was highest in Simcoe cultivars, followed by Summit, Apollo, Topaz, Cascade pellets, and also differed between crop years. It was indicated that most 4MMP exists freely in wort or in hop pellets with only small amounts formed from precursors and that the amounts increased during the fermentation process.     

Genetic diversity in European accessions of the Barley Core Collection as detected by isozyme electrophoresis

Genetic diversity in 79 European accessions of the Barley Core Collections was surveyed using isozyme electrophoresis. A total of 26 alleles were observed at the ten isozyme loci. All loci were polymorphic except Pgd-1 which was monomorphic. The comparison of the results with those of previous studies indicates that most of the alleles occurring in the European Barley are also observed in this set of the European Barley Core Collections. Only five alleles (Est-1 Al; Est-5 Ag, Te; Pgi-1 C and Ndh-2 B) were absent. Nine of 26 alleles were rare alleles, which were detected only in one or two accessions. Moreover, most of rare alleles were detected in 6-rowed winter barley. It is very important to include rare alleles for maximising the genetic variations in core collections. In the set of European Barley Core Collection, 6-rowed barley contained larger diversity than 2-rowed barley; winter type contained larger diversity than spring type. The cluster analysis separated 79 accessions into three major groups. Group I is more complex and comprised 2-rowed spring, 2-rowed winter and 6-rowed winter barley. In this group, 18 accessions in the cluster A and 14 accessions in the cluster B possessed identical genotypes as judged from the ten isozyme data. Principal coordinate analysis could not clearly separate the spring cultivars from the winter barley lines, as well as not separate 2-rowed from 6-rowed barley.     

Genetic Diversity and Relationships of Japanese Peach (<Emphasis Type="Italic">Prunus persica</Emphasis> L.) Cultivars Revealed by AFLP and Pedigree Tracing

To evaluate the genetic diversity and to clarify the genetic relationships of Japanese peach cultivars, we analyzed the amplified fragment length polymorphism (AFLP) and traced the pedigree of 17 Japanese commercial peach cultivars and six traditional accessions. Sixteen AFLP primer combinations produced a total of 837 fragments and 146 polymorphic bands with a polymorphism percentage of 17.5%. All of the peach accessions could be identified from differences in at least 10 polymorphic bands. A cluster analysis showed that all the Japanese commercial peach cultivars, except ‘Kiyomi’ and ‘Jichigetsuto’, formed a major group consisting of three sub-groups. Of the six traditional accessions, four were genetically distant from the Japanese commercial peach cultivars while two accessions from China were classified into the Japanese commercial peach cultivars group. Both the AFLP analysis and pedigree tracing suggested that Japanese commercial peach cultivars are mainly derived from ‘Shanhai Suimitsuto’, one of the traditional accessions from China. Although the genetic relationships revealed by AFLP were generally in agreement with those shown by the pedigree information, some contradictions were found. Combining the AFLP results and pedigree information can provide a better understanding of the genetic relationships of Japanese peach cultivars.     

Genetic diversity of European pear cultivars (<Emphasis Type="Italic">Pyrus communis</Emphasis> L.) and wild pear (<Emphasis Type="Italic">Pyrus pyraster</Emphasis> (L.) Burgsd.) inferred from microsatellite markers analysis

The aim of this study was to identify the group of highly polymorphic microsatellite markers for the identification of six pear cultivars (P. communis) and two individuals of wild pear (P. pyraster). From among 40 tested SSR markers, 19 were selected to profile genetic diversity in pear genotypes due to high polymorphisms. These markers showed high heterozygosity levels (0.5–1) and, on average, 6.4 alleles per marker were found. The set of microsatellite markers employed in this study demonstrated usefulness of microsatellite markers for the identification of pear genotypes. The examined wild forms were represented in this study by only two individuals of P. pyraster. It can be assumed that these forms were distinctly different from the cultivated pear cultivars.