Genetic assessment of local apple cultivars from La Palma,Spain, using simple sequence repeats (SSRs)

Apple cultivars from Canary Islands can possibly be valuable genetic resources for subtropical areas. We localised 31 accessions considered by growers to be local, and confirmed by historical references that apple crop was introduced in XV century. These accessions were compared with 77 Spanish and 26 commercial cultivars in order to detect synonyms. A set of 10 SSRs were studied, and 2 of them presented 2 loci. Cultivars from La Palma (Canary Islands) presented five specific alleles not found in other Spanish regions. Those polymorphisms allowed detecting one introgressant in La Palma from non-native cultivars, and the other 30 accessions were classified into 14 genotypes. Some accessions derived from non-native cultivars such as Golden Delicious. A main cultivar could be detected, Del País, with 14 accessions. Secondary ones were Camuesa and Pero. Genetic differentiation was small between regions (Fst = 0.057) but significant, confirmed by analysis of molecular variance (AMOVA). Major genetic differentiation was found between non-native cultivars and cultivars from Asturias and Basque Country. Bayesian method and admixture analysis reconstructed three ancestral groups (RPP), Asturian and Basque cultivars grouped in RPPI (mainly those used for cider production), a mixture of cultivars from Galicia and La Palma in RPPII and non-native cultivars were in RPPIII. This genetic differentiation was also confirmed by factorial correspondence analyses (FCA). AMOVA over RPPs increased the genetic differentiation. Allelic variation found in this study showed that Spanish local cultivars represent a differentiated genetic pool that will provide original genotypes to diversify the reduced number of cultivars used in commercial production. In addition, differentiated genotypes localised in La Palma will be preserved in the local Germplasm Bank.     

Commercial Iranian olive cultivars: morphological traits,molecular diversity,and genetic structure

Iran is considered to have a unique gene pool of different fruit and nut species including olive (Olea europaea L.). In this study, we used 22 previously developed microsatellite (simple sequence repeat; SSR) markers for olive to evaluate the level of genetic variation and to produce identification keys for 63 Iranian accessions of olive belonging to 17 groups of cultivars. Based on morphological features, the number of flowers per inflorescence, fruit weights, endocarp weights, oil percentages, and flesh weights per endocarp had the highest coefficient of variation values, indicating the large extent of morphological variability among the 63 Iranian olive cultivars studied. All 22 microsatellite (SSR) markers revealed a high level of polymorphism, with a mean polymorphic information content (PIC) value of 0.511. Analyses of genetic structure among the 63 olive accessions were carried out using model-based methods, which showed a tendency for geographical clustering. Ten SSRs out of the 22 were successful for the identification of unique ID keys for 52 of the 63 accessions. In most cases, there was disagreement between the molecular data and the morphological data. These results could be used to reconstruct and maintain a collection of olive for future breeding programmes.     

SSR markers reveal the uniqueness of olive cultivars from the Italian region of Liguria

Twenty-three important Ligurian olive accessions corresponding to 16 cultivars were studied using 12 SSR markers and 40 Mediterranean cultivars were included in the study in order to investigate the relationships between Ligurian and Mediterranean germplasm. All SSRs produced polymorphic amplifications. One hundred and forty-nine alleles were found in the 63 accessions analysed. Twenty-two alleles were specific to germplasm from Liguria and of these 12 were unique to single cultivars. Heterozygosity and discriminating power calculated in this regional germplasm were high on average (0.70 and 0.74) and not so much lower than the values in the total sample that includes cultivars from different Mediterranean countries (0.77 and 0.88 respectively). No cases of genetic identities were found between Ligurian and Mediterranean accessions. Several cases of homonyms and synonyms within the Ligurian germplasm were explained. Cluster analysis generally revealed a clear discrimination of the profiles from Liguria and Italy with respect to the cultivars from other Mediterranean countries. Only one Ligurian cultivar, “Negrea”, appeared to have a different origin, grouping with the Mediterranean cultivars.     

SSR-based DNA fingerprints reveal the genetic diversity of Sicilian olive (Olea europaea L.) germplasm

Summary

Twelve published simple sequence repeat (SSR; microsatellite) markers, belonging to the ssrOeUA-DCA, GAPU and UDO series, were tested in a panel of 46 accessions of olive germplasm belonging to 30 unique cultivars collected in seven Provinces of Sicily. Four well-known reference olive cultivars were also added. The analysis was carried out on an automatic capillary sequencer using fluorescent dyes, and fragment sizes were determined using internal standards. The results allowed us to rank the SSRs assayed according to their information content and reproducibility. Up to 115 alleles were identified (119, if those unique to sport mutations were included), the frequency of which allowed genetic relationships among accessions to be investigated. The probability that two unrelated genotypes displayed the same SSR pattern at all loci examined was calculated to be as low as 1.18 10^–11. Sixteen accessions were identified as synonyms. Of these, eight matched perfectly with another accession at all SSR loci examined. The others showed one or two allelic differences from the reference accession. These were interpreted as mutations. Otherwise, all accessions were clearly separated from each other. Two likely parentages were also identified (‘Giarfara’ = ‘Nocellara del Belice’

‘Cacaridduni’; and ‘Pizzo di Corvo’ = ‘Nocellara Etnea’ ‘Tonda Iblea’). The genetic diversity of the pool represented by the unique accessions was very high, reflecting the richness of the olive germplasm accumulated in Sicily. A database of the accessions is available to the scientific community (http://www.unipa.it/germolive/ssr.html) to facilitate comparisons of data.     

Genetic diversity of Iranian and some European grapes as revealed by nuclear and chloroplast microsatellite and SNP molecular markers

Genetic and chloroplast haplotype variations of 35 Iranian genotypes and 10 European grape cultivars were investigated using 9 nuclear simple sequence repeats (nSSRs), 4 chloroplast simple sequence repeats (cpSSRs) and 46 single nucleotide polymorphism (SNP) markers. In total, 83 alleles were detected at nine nSSRs, giving a mean of 15.66 alleles per locus and polymorphism information content (PIC) values ≥0.75 ranged from 0.75 to 0.90. For SNP markers, PIC values varied from 0.30 to 0.39 with an average of 0.34. Analysis of molecular variance revealed 97 and 93% of partitioned genetic diversity within populations using nSSRs and SNPs markers, respectively. Un-weighted neighbour-joining (NJ) cluster analysis grouped grapes into 10 and 9 major clusters using SSR and SNP markers, respectively. Synonyms and homonyms were identified among the Iranian genotypes. Close genetic relationship among Farkhi and Bidane-Sefid genotypes may probably propose a common ancestor and mutational evolution. Most European cultivars were differentiated from Iranian genotypes, however, clustering of some Iranian genotypes with European cultivars in the same clusters suggests that clonally propagated materials have probably been exchanged from the Middle East to West or vice versa. C and D chloroplast haplotypes were the most frequent within the Iranian genotypes, while A chloroplast haplotype was exclusively observed among European cultivars.     

Genetic assessment of apple germplasm in Bosnia and Herzegovina using microsatellite and morphologic markers

Traditional apple cultivars from Bosnia and Herzegovina (B&H), potentially diverse due to specific geographic location and history of the country, represent a possible source of valuable traits for future breeding efforts and sustainable fruit growing. A total of 39 accessions, 24 traditional B&H cultivars and 15 modern international cultivars, maintained at the ex situ apple collection “Srebrenik” in Northeast Bosnia were, investigated using 10 SSR (simple sequence repeats) markers and 23 morphologic characteristics. All the used primer pairs manage to amplify clearly distinguishable and highly polymorphic SSR alleles, in average 10.4 alleles per locus. More than two different alleles per locus were detected for seven accessions (five traditional B&H cultivars and two international cultivars). Forty one unique alleles were exclusively present within the B&H cultivars, while seven unique alleles were only detected within international cultivars. The differentiation between traditional B&H and international cultivars (Fst = 0.060; P < 0.0001) was significant, also confirmed by analyses of molecular variance (AMOVA) (f_CT = 0.092; P < 0.001). Cluster analyses of 39 apple accessions, based on 10 SSR loci, revealed that only two traditional B&H cultivars grouped tightly with international cultivars (Ljepocvjetka and Bobovec Jon), while the rest formed separate clusters. Multivariate analyses of variance (MANOVA), nonparametric multivariate analyses of variance (NPMANOVA) and analyses of similarity (ANOSIM) showed statistically significant difference in morphologic characteristics between traditional B&H cultivars and the international cultivars. Cluster analyses of 39 apple accessions, based on the morphologic data, displayed less differentiation between traditional and international accessions, in comparison to the cluster analyses based on molecular data. No correlation between the molecular and morphologic data set was detected using the Mantel test. Many of the morphologic characteristics which have been analyzed in this study have significant commercial importance, we can assume that unlike the microsatellites these traits have been under agronomic selection pressure.     

Intra-cultivar variability of three major olive cultivars grown in different areas of central-southern Italy and studied using microsatellite markers

A collection of 70 olive samples, originating from diverse areas in central-southern Italy (Abruzzo, Apulia, Calabria, and Umbria) and corresponding to 3 major cultivars denominations (‘Carolea’, ‘Coratina’ and ‘Frantoio’), was genotyped at 10 microsatellite loci. In total, 44 alleles with a mean number of 4.4 alleles per locus were detected. The molecular analysis, allowed the study to show a clear genetic diversity between the three cultivars ‘Carolea’, ‘Coratina’ and ‘Frantoio’ and to state that ‘Carolea’ is a polyclonal cultivar, while ‘Coratina’ and ‘Frantoio’, are probably monoclonal ones. The analysis of intra-varietal polymorphism, through the SSR analysis, proved to be very useful both for varietal identification and for intra-varietal ones. Our work shows that the current designations of olive cultivars fall short of describing the genetic variability among economically important plant material. A thorough investigation of the existing variability will prove of major importance for both management and economic production of olive trees.     

Wide genetic diversity of Rosa damascena Mill. germplasm in Iran as revealed by RAPD analysis

The genetic relationships among 41 Rosa damascena accessions from various cultivation areas of Iran and one accession from Bulgaria were analyzed using 31 RAPD (Randomly Amplified Polymorphic DNA) primers. Each primer exhibited 3–12 banding patterns for a total of 343 scorable and 184 polymorphic bands. The combination of 11 primers was found optimal for discrimination of 42 accessions with very low values of cumulative confusion probability (9.7 × 10⁻⁵); indicating that only one pair from over 10,000 distinct pairs of accessions would be indistinguishable. Unweighted pair group method cluster analysis based on similarity values revealed 10 groups at the distance of 0.85. The Bulgarian genotype grouped with the majority of the Iranian genotypes in a main cluster. Results of molecular variance analysis (AMOVA) indicated that the major proportion (65.7%) of the total genetic variation was within collecting provinces rather than between them. The wide genetic variation seen for R. damascena in Iran indicates that Iran is a center of genetic diversity for this species and that there is a promising future for the breeding.     

Use of chloroplast microsatellite markers as a tool to elucidate polymorphism,classification and origin of Tunisian grapevines

Chloroplast microsatellite markers were used in this study to genotype 43 grapevines accessions grown in Tunisia. Size variation was observed for the three cpSSR loci, both in the sample of cultivars and in wild accessions. The seven alleles observed in the sample of cultivars for the three loci are present in wild accessions except that their distribution is different. Levels of genetic diversity obtained for the Tunisian grapevines either in wild or cultivated gene pools are high and comparable with values obtained with other studied samples of Vitis vinifera. The distribution of haplotypes within the two samples is differential. Indeed, the chlorotype A is most abundant in the wild sample, whereas the chlorotype C is majority in the sample of cultivars. Haplotypes frequencies for cultivated grapevine distinguish haplotypes B and C as the most frequent (28% and 44% respectively) and haplotypes A and D as the least frequent (16% and 12% respectively). For wild grapevines, the seven alleles combined in three haplotypes, A, C and D. The haplotype A is the most frequent (44%) in the analyzed sample of wild accessions while haplotypes C and D show a frequency of 28%. Chlorotype distribution in Tunisian cultivars is comparable with that of cultivars in the Eastern Region representing the primary centre of domestication of the species. These results agree with the higher relevance of table grape cultivars in Tunisian viticulture and support an oriental origin of a large part of autochthons cultivars. Our results agree with other studies based in nuclear and chloroplast microsatellite markers and suggest independent domestication events for V. vinifera L. species.     

Microsatellite marker-based identification of mother plants for the reliable propagation of olive (Olea europaea L.) cultivars in Australia

Summary

Olive production in Australia has continued to increase in recent years, however there remains a high degree of confusion on the genetic identities of the cultivars being grown. In the present study, seven microsatellite (simple sequence repeat; SSR) loci were used to identify a set of 53 olive tree samples from different sources. The microsatellite DNA profiles of all 53 tree samples, including seven unknown trees, were compared with the SSR profiles of 14 reference olive cultivars. A total of 60 fragments (alleles), averaging 8.57 alleles per microsatellite locus, were amplified. High average values were found for the observed heterozygosity, the expected heterozygosity, and the polymorphic information content (0.73, 0.74, and 0.72, respectively). While all seven microsatellite markers proved useful for characterisation and identification purposes, a combination of three SSR primer pairs (DCA9, DCA18, and EM030) was sufficient to distinguish all 53 olive samples. The microsatellite allelic profiles allowed the 53 tree samples to be grouped into 23 genotypes. The allelic profiles of 14 of these genotypes matched with their reference cultivars, while the genetic identities of the remaining nine genotypes could not be confirmed. Some of these unknown genotypes may have been derived from feral olive trees, or were due to mislabelling and/or planting errors among Australian olive cultivars. Our results confirm the usefulness of microsatellite markers as a tool for cultivar differentiation and identification, and indicate the need for reliable identification of mother plants for commercial propagation.     

DNA fingerprinting of olive varieties in Istria (Croatia) by microsatellite markers

The Istria region, where olives have been cultivated for many centuries, is characterized by a considerable variety of microclimates. The study of varieties traditionally cultivated in Croatian Istria and their relationships with varieties in historically and geographically connected regions is very important in order to identify native olive germplasm, well adapted to local conditions, and to characterize the oil of regional origin. Twelve olive microsatellite markers were used for identification and differentiation of a set of 27 olive accessions grown in Istria (Croatia). Among the 27 accessions, 18 different SSR profiles were discriminated. All 12 microsatellite markers analysed were polymorphic, revealing a total of 81 alleles. The number of alleles per locus ranged from four to nine. This is the first molecular characterization of olive germplasm in Croatian Istria. The analysis clarified the genetic relationships of varieties native to Croatian Istria with introduced olive varieties, as well as with varieties in the neighbouring Slovene Istria region. Numerous varieties in neighbouring regions showed high similarity and a few cases of synonymy (‘Bilica’-‘Bjankera’; ‘Buga’-‘?rna’) and one Croatian-Slovenian homonymy (‘Bu?a’-‘Buga’) were observed. The results provide useful information for a native germplasm survey and can be used for the construction of a unique database comprising all olive varieties in the Istrian region of Croatia and Slovenia.     

Germplasm diversity and genetic relationships among walnut (Juglans regia L.) cultivars and Greek local selections revealed by Inter-Simple Sequence Repeat (ISSR) markers

Inter-Simple Sequence Repeat (ISSR) markers were used for the assessment of genetic diversity among walnut (Juglans regia L.) selections from Greek native populations in comparison to internationally cultivated walnut genotypes. Similarity coefficient values from 0.13 to 0.93 (with an average of 0.48) were found among the 56 accessions examined, which indicated the presence of a high degree of genetic variability. Most international cultivars were grouped together while most Greek native populations could not be placed into a distinct group. The Greek native population genotypes were found more diverse than the international cultivars. The mean similarity coefficient values for the former and latter were 0.44 and 0.56, respectively. In the cultivar group, two subgroups were distinguished; one consisted of genotypes involving ‘Payne’ and the other ‘Franquette’ in their pedigrees. Some cultivars and populations could not be grouped according to their pedigrees or collection area. Analysis of molecular variance (AMOVA) revealed that a larger part of the genetic variation exists among Greek walnut populations within a collection region (89%) than among the regions (11%). The pairwise regional PhiPT values indicated that the most geographically distant regions are the most genetically differentiated. The high variability existing in the Greek germplasm in combination with their valuable agro-morphological traits suggested that it would be beneficial to utilize this native germplasm pool in walnut breeding programs and germplasm management activities to maximize genetic diversity in cultivated walnut.     

Genetic diversity and relationships of wild and cultivated olives at regional level in Spain

Genetic diversity and relationships between local cultivars and wild olive trees from three important Spanish olive-growing regions, Andalusia (South), Catalonia and Valencia (from Eastern Mediterranean Coastal area), were studied by means of eight SSR loci. Distinct allelic composition and heterozygosity levels were found in wild olive populations and cultivars. The observed patterns of genetic variation revealed: a) the independent clustering of Andalusian wild olives in a separate gene pool, b) the belonging of wild populations and most cultivars from Catalonia to another gene pool, c) the joined clustering of Andalusian and a set of Valencian cultivars in a third gene pool, and d) clustering of wild individuals from Valencia to the three different gene pools. These results suggest that wild populations of Andalusia may represent true oleasters, the ones from Catalonia may be feral forms derived from cultivar seed spreading, while the population of Valencia seems to be the most admixed one. The significant differentiation between Andalusian and most Catalonian cultivars is indicating an independent selection of olive cultivars in the two regions. The detection of a certain wild genetic background in some Catalonian and Valencian cultivars and the similarity found between wild and cultivated forms may suggest the use of local wild trees in olive domestication. The proposed scenario for the development of olive cultivars in Andalusia includes an empirical selection of outstanding local wild genotypes followed by various generations of crosses and various replanting campaigns, as well as possible introductions of ancestral cultivars. Therefore, our findings would lead us to support the hypothesis that the current diversity found in Spanish olive cultivars may be regionally differentiated and due to both, autochthonous and allochthonous origin. The information obtained in this work gives insights into the genetic resources of the main olive producing country, demonstrating that wild olive populations and local cultivars both represent potential sources of useful variability for olive breeding programs.     

Genome composition and genetic diversity of Musa germplasm from China revealed by PCR-RFLP and SSR markers

Banana (Musa spp.) is one of the most important crops in the world. In this study, 216 banana accessions, 184 from the National Banana Germplasm Collection of China (NBGCC) and 32 from the International Network for the Improvement of Banana and Plantain (INIBAP), were used to determine the genome composition of banana plants in these collections and to estimate their genetic diversity. The genome composition was examined using PCR-RFLP markers. The molecular data for all but one accession (ITC 1231) from INIBAP were in agreement with the initial records based on phenotypic characteristics. Microsatellite (SSR) markers were used to investigate the genetic variability and relationships among these banana accessions. Ten of the 47 primer pairs tested consistently produced reproducible and discrete fragments. We identified a total of 92 alleles, ranging from 5 to 15 per locus. The genetic similarity between the accessions ranged between 0.1 and 1, when estimated using Jaccard's coefficient. The UPGMA method based on genetic similarities, grouped the NBGCC accessions according to those containing the ‘A’ and ‘B’ genomes. However, this analysis could not separate all the accessions, especially the somatic mutations, using the primers in this study. These data indicated that limited genetic variation exists within these accessions and the collections of NBGCC should include a much wider range of banana plant material.     

Molecular characterization and genetic relationship among almond cultivars assessed by RAPD and SSR markers

RAPDs and SSRs were used to study the genetic diversity of Iranian almond cultivars and their relationship to important foreign cultivars and three related species. Eight unidentified almond Shahrodi cultivars and three wild almonds (Prunus communis, Prunus orientalis and Prunus scoparia) were also included. Of the primers tested, 42 (out of 80) RAPD and 18 (out of 26) SSR primers were selected for their reproducibility and high polymorphism. A total of 664 polymorphic RAPD bands were detected out of 729 bands. The number of presumed alleles revealed by the SSR analysis ranged from 3 to 10 alleles per locus with a mean value of 6.64 alleles per locus. Both techniques discriminated the genotypes very effectively, but only RAPDs were able to discriminate the cultivars Monagha and Sefied. Results demonstrated an extensive genetic variability within the tested cultivars as well as the value of SSR markers developed in peach for characterization of almond and related species of Prunus. Dice similarity coefficient was calculated for all pair wise comparisons and was used to construct a UPGMA dendrogram. For both markers a high similarity in dendrogram topologies was obtained although some differences were observed. All dendrograms, including that obtained by the combined use of both the marker data, depicted the phenetic relationships among the cultivars and species, depending upon their geographic region and/or pedigree information. Almond cultivars clustered with accession of P. communis showing their close relationship. P. orientalis and P. scoparia were clustered out of the rest of P. dulcis.     

Molekulargenetische Analyse des ‘Maschanzker’/‘Borsdorfer’‐Sortenkomplexes

‘Maschanzker’ is one of the best-known old apple cultivars in Austria and in the 19th century this variety also played an important role in the fruit production of South Tyrol (Northern Italy). ‘Maschanzker’ is believed to originate from one of the oldest German apple vari­eties ‘Borsdorfer’, which is even considered a synonym. However, since the denomination ‘Maschanzker’ is part of the name of a number of more or less similar types of apple, this study aimed at investigating the synonymy and homonymy as well as the relationships within and between different accessions of ‘Maschanzker’, ‘Borsdorfer’ and ‘Edelborsdorfer’ by employing 14 microsatellite DNA markers. A total of 38 accessions from several collections in Europe were analysed and 14 different genotypes were identified, which were assigned to three groups. Our data suggest a series of parent-offspring connections within the here defined Maschanzker group and the Edelborsdorfer group, while no closer relationship was evident to or among the accessions of the Borsdorfer group. Molecular genetic analyses thus provide fundamental data which can serve as a basis for the pomological revision of the ‘Maschanzker’/‘Borsdorfer’ cultivar complex.     

紫丁香天然群体遗传多样性的AFLP分析

 抽取内蒙古大黑山、辽宁北票和山西五老峰3个紫丁香(Syringa oblata Lindl. ) 天然群体为拟似群体, 用筛选出的8对引物, 对群体家系组成的72个样品进行AFLP分析。Nei (1973) 基因多样性指数h = 0.2287, Shannon's信息指数I = 0.3464; 种级遗传多样性Ht = 0.3522, 群体内遗传多样性Hs =0.2287, 群体间遗传多样性Dst = 0.1235, 群体分化系数Gst = 0.3508, 群体间总的基因流的估算值Nm =0.9253, 群体遗传变异的AMOVA分析表明群体的遗传多样性主要分布在群体间, 群体间方差分量的贡献率占51.53%。基于Nei (1972) 遗传距离的UPGMA聚类分析显示群体间的遗传距离与群体的地理距离关系一致。结果表明: 紫丁香群体间的遗传分化较大, 其天然群体缺失造成的现有分布的间断性和地理隔离以及高自交率是导致其群体间的高度分化的主要因素。在目前分布残缺, 群体丢失严重的情况下, 紫丁香种质资源保护和利用策略应为采取优先保存尽可能多的群体。