Identification of sweet cherry cultivars (Prunus avium L.) and analysis of their genetic relationships by chloroplast sequence-characterised amplified regions (cpSCAR)

Ten cpSCAR markers that show polymorphism in Prunus avium were used to fingerprint sweet cherry cultivars. The purpose of the study was also to contribute to identification and to help determine their genetic interrelationships. Samples of ‘0900 Ziraat’, a superior Turkish variety, which were collected in several locations all over Turkey, had identical cpSCAR patterns, and they resembled a common European haplotype, A. ‘Sweetheart’, ‘Summit’ and ‘Canada Giant’ and their haplotype are intermediate between the previously described haplotypes A and B, which were originally found in Central and Eastern European sweet and wild cherries, and those from Northern Turkey, respectively. The data therefore suggests a local maternal descent (within Europe and Asia Minor) of the cultivars analysed. Our results show that chloroplast DNA analysis is a straightforward way to classify cherry cultivars. We compare our results to others previously reported for sweet cherry cultivars, and conclude that cpSCAR diversity data could be considered for phylogenetic studies in this group.     

Multivariate analysis of Prunus subgen. Cerasus germplasm in Iran using morphological variables

Knowledge of relationships among the cultivated and wild species of Cerasus, a subgenus of Prunus L., is important for recognizing gene pools, identifying pitfalls in germplasm collections and developing effective conservation and management strategies. In this study, morphological characterization of wild Cerasus subgenus species naturally growing in Iran, including P. avium L. (mazzard), P. mahaleb L., P. brachypetala Boiss., P. incana Pall., P. yazdiana Mozaff., P. microcarpa Boiss. subsp. microcarpa, P. microcarpa Boiss. subsp. diffusa and P. pseudoprostrata Pojark. and three commercial species, sweet cherry (P. avium L.), sour cherry (P. cerasus L.) and duke cherry (P. × gondouinii Rehd.) was investigated. Twenty-nine variables were recorded in 95 accessions of these species to detect similarities among them. All studied characteristics were showing a high degree of variability, but it was highly pronounced for plant height, leaf characters especially for dimensions and pubescence as well as for petiole and peduncle length. The majority of significant correlation coefficients were found in the characteristics representing plant size and growth habit with leaf size. Principal component analysis was performed for phenotypical diversity determination and grouping of species. Characters with high discriminating values were those related to growth habit, height, compactness, trunk diameter, leaf dimensions, petiole length, leaf tip and serration, flower color, peduncle length, fruit shape and stone shape. Based on the cluster analysis, species included in two main clusters, first those with large structure (sweet, sour and duke cherries, mazzard and mahaleb), second the other species with small structure which might be potentially suitable for rootstock breeding programs. Scatter plot using two first factors also confirmed the grouping by cluster analysis. The conservation of the highly diverse native populations of Iranian wild Cerasus species is recommended.     

Molecular evaluation of genetic diversity and S-allele composition of local Spanish sweet cherry (Prunus avium L.) cultivars

A group of 28 sweet cherry (Prunus avium L.) local cultivars from the Jerte Valley in Western Spain were fingerprinted using microsatellites and their self-incompatibility alleles determined using S-RNase conserved primers. A total of 12 microsatellite primer pairs revealed 42 informative alleles that allowed the unequivocal identification of 26 genotypes. UPGMA cluster analysis of the similarity data produced a clear separation between the old traditional cultivars and the most recent introductions. The S-allele analysis showed a low number of different alleles in the older cultivars studied and revealed the presence of three new S-alleles not described previously. The combined information obtained from SSR fingerprinting and S-allele identification will be useful to optimize the conservation of the cherry genetic resources present in the area. Moreover, this approach can be applied to optimize the conservation of local genetic resources of other fruit tree species.     

Controlled Atmosphere Storage of Sour Cherry (Prunus cerasus L.)

Sour cherry (Prunus cerasus L.) variety 'English Morello' fruits were stored for up to 20 days at 2°C in air or controlled atmosphere (CA) consisting of 25% CO₂+10% O₂, 15% CO₂+10% O₂, or 5% CO₂+10% O₂. The effects were compared on decay, juice optical density, titratable acidity, pH, soluble solids content and firmness. CA treatment has a great potential for sour cherry storage in maintaining quality and in extending the length of the storage period. The study has indicated that the decay of sour cherry can be greatly reduced by 25% CO₂. High CO₂ concentration gave the best retention of red colour and titratable acidity throughout the storage period. Fruit juice optical density and firmness increased with storage time. Fruits stored in 25% CO₂+10% O₂ had higher soluble solids content compared with fruits stored in air.     

Morphological characterization of sweet and sour cherry cultivars in a germplasm bank at Portugal

Nine sweet cherry and eight sour cherry varieties located in a germplasm bank at Fundão, Portugal, were studied from the viewpoint of characterization. Most of them were autochthonous cultivars that have a high risk of extinction since at the present they are markedly minor varieties. Morphological characteristics were evaluated in different organs: crown and trunk of the trees, leaves, flowers and fruits, over a three consecutive years period. Statistical analyses were carried out in order to detect similarities between cultivars as well as the existence of synonymies. Qualitative characteristics of the fruits were scored in order to carry out the multivariate analysis. A dendrogram of the evaluated characters shows the marked differentiation between sour and sweet cherries and suggests the existing synonymies. Conservation of the autochthonous cultivars in the future is highly recommended.     

Chloroplast Microsatellites to Investigate the Origin of Grapevine

The origin of the grapevine, Vitis vinifera ssp . sativa L., has been investigated with archaeobotanical–archaeological, cultural and historical data indicating a unique domestication centre located in the Caucasian and Middel-East regions about 6–7000 years ago, but, events leading to the domestication of this species are still an open issue. In this work, eight universal chloroplast microsatellites are used to assess genetic relationships among varieties selected as representatives of four distinct geographical groups from Middle-East to Western European regions. Results show that two out of the eight analysed chloroplast loci are polymorphic within the 142 individuals. Allele variants of the cpSSR loci combine in a total of six different haplotypes. The analysis of haplotypes distribution and haplotype diversity (HD) suggest that only three out of the six haplotypes are represented in the Caucasian and Middle-East samples, with 90% of individuals sharing the same haplotype. Moreover, the presence of all six haplotypes in the European accessions, with a high level of haplotype diversity, suggests varietal influx in these areas. Concerning the Western European varieties, especially in Spanish accessions, half of the individuals share haplotype VI which is completely absent in the Caucasian and Middle-East cultivars. This result opens the discussion about the existence of a unique and common domestication centre, located in the Caucasian and Middle-East area, for all the European cultivars. This work suggests the usefulness of chloroplast genome markers to provide information on haplotype distributions that could help to identify further geographical areas for grapevine varietal evolution.     

A review of genetic resources of almonds and stone fruits (<Emphasis Type="Italic">Prunus</Emphasis> spp.) in Iran

Iran is amongst the countries in the world widely known for cultivation of Prunus spp. (or stone fruits). It is both a centre of origin and diversity of the stone fruits. Numerous wild species as well as many cultivars and landraces of these fruit crops are important genetic resources today in Iran and can be used for improvement and breeding of scion and rootstock cultivars which are resistant to many biotic and abiotic stresses through modern genomics and genetic technologies. This paper discusses the distribution, ethno-botany, diversity and utilization of wild and domesticated genetic resources of stone fruits including almond (Prunus dulcis (Miller) D. A. Webb.), peach and nectarine (P. persica Batsch), European and Japanese plum (P. × domestica L., and P. salicina L., respectively), sweet and sour cherry (P. avium L., and P. cerasus L., respectively), and apricot (P. armeniaca L.), all of which are members of the Rosaceae family. The goal of this paper is to highlight the importance of Iran as a main contributor to the diversity of Prunus genetic resources in the world, as well as, present major achievements regarding identification, collection, evaluation, conservation and utilization of this valuable genetic resource in Iran.     

Conservation strategies and management guidelines for wild Prunus genetic resources in Andalusia, Spain

Six species of the genus Prunus occur inAndalusia. Matters regarding their ecology, ethnobotanical aspectsand conservation are discussed, as well as knowledge about thegermplasm of those species with greater economic importance and theirdegree of conservation, namely: P.avium, P.mahaleb and P.insititia. Various conservation measures areproposed for wild germplasm and for the germplasm of local varieties:a) conservation efforts should target the best populations,except in the case of P.avium and P.insititia, where every individual should beaddressed, including both wild and local cultivars; b) theDehesa del Camarate (Sierra Nevada) is proposed as an areafor in situ germplasm conservation; c) theawareness of the importance of Prunus germplasmshould be increased among forest workers, environmental managers andthe public; d) some silvicultural techniques are proposed, suchas mixed Prunus patches, hedge treatment,Z-tree selection at the early stages and the protection ofroot suckers; e) improved, selected P.avium and P.mahaleb germplasm should be used at highlyproductive sites since these two species can be cultivated as highvalue timber trees; f) some Prunus speciescan also provide profitable NTFPs in the region. Details regardingdifferent collection areas are covered. Finally, some topics arerecommended for scientific research. Three tables and a distributionmap of Prunus species in Andalusia areincluded.     

Polymorphisms Among Chloroplast and Mitochondrial Genomes of <Emphasis Type="Italic">Citrullus</Emphasis> Species and Subspecies

Twelve and six DNA clones representing various parts of chloroplast and mitochondrial genomes, respectively, were used to detect polymorphism among five watermelon cultivars and 21 U.S. Plant Introductions (PIs) collected from diverse geographical locations and representing major groups of Citrullus species. Cluster analysis based on 20 chloroplast DNA (cpDNA) and 10 mitochondrial DNA (mtDNA) restriction fragment length polymorphism (RFLP) markers differentiated the accessions into three major phenetic groups: PIs and watermelon cultivars of Citrullus lanatus subsp. vulgaris (Schrad. ex Eckl. et Zeyh.) Fursa (also designated as C. lanatus var. lanatus) (group I), PIs of C. lanatus var. citroides (of C. lanatus subsp. lanatus Schrad. ex Eckl. et Zeyh.)(group II), and C. colocynthis (L.) Schrad. PIs (group III). The chloroplast and mitochondrial genomes of watermelon cultivars are distinct, but closely related to those of the C. lanatus var. lanatus PIs. On the other hand, the chloroplast and mitochondrial genomes of the wild species C. colocynthis are more similar to those of C. lanatus var. citroides. Polymorphic cpDNA and mtDNA markers identified in this study can complement isozyme and nuclear DNA data used in earlier phylogenetic and phenetic classifications of Citrullus PIs. These cpDNA and mtDNA markers are being used in experiments designed to enhance watermelon cultivars by replacing the chloroplast and mitochondrial genome of cultivated watermelon with those of the wild species C. colocynthis.     

Controlled Atmosphere Storage of Sweet Cherries (Prunus avium L.)

Sweet cherry (Prunus avium L.) cultivars 'Emperor Francis', 'Huldra', 'Sam', 'Stella', 'Kristin', and 'Van' were stored in controlled atmosphere (CA) during one, two or three seasons. The cherries were held at a temperature of 0°C, or 2°C for up to three weeks. The fruit quality was evaluated on juice optical density (OD), titratable acidity (TA), pH, soluble solids content (SSC), ethanol, firmness and flavour. In general, CA had little effect on SSC in the three seasons and did not show any effects in reducing pitting. Controlled atmosphere has shown some beneficial effects on flavour, reducing decay, reducing toughening, and maintaining TA in sweet cherries. Generally, flavour score was higher for fruit kept in CA than for fruit stored in air, and the higher the CO₂ the better the taste. 'Van' and 'Sam' showed excellent taste scores after three weeks both from CA and air storage. There was very little ethanol accumulation in the fruits under CA, and it was well below the detrimental level. It is recommended that O₂ levels for sweet cherry storage can be further reduced below 10% and/or CO₂ can be increased above 15%.     

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.     

Analysis of genetic diversity in Piper nigrum L. using RAPD markers

RAPD analysis was conducted in 22 cultivars of P. nigrum(black pepper) from South India and one accession each of P. longum and P. colubrinum. Twenty-four primers generated 372 RAPD markers of which 367 were polymorphic. Jaccard's similarity between pairs of accessions ranged between 0.11 and 0.66 with a mean of 0.38. Among P. nigrum cultivars, the similarity ranged between 0.20 and 0.66 and the mean was 0.42. The existence of wide genetic diversity as revealed in the present study is supported by earlier reports of extensive inter- and intrapopulation morphological variability in pepper cultivars from South India. UPGMA dendrogram and PCO plot revealed P. colubrinum to be most distant of the three species. Genetic proximity among P. nigrum cultivars could be related to their phenotypic similarities or geographical distribution. Greater divergence was observed among landraces than among advanced cultivars. Landraces grown in southern parts of coastal India and those grown in more northern parts were grouped in separate clusters of the dendrogram.     

Storage protein and amino acid contents of Tunisian and Chinese pomegranate (Punica granatum L.) cultivars

In the present study, free amino acids and seed protein contents of pomegranate germplasm from Tunisia and China were conducted using Hitachi L8800 amino acid analyzer, Bradford and Kjeldahl methods. The work offers more consideration to protein pomegranate seeds which can be with great importance regarding the nutritive seed value of this crop. In other hand, the protein and amino acids contents were used to compare the Tunisian and Chinese pomegranate cultivars based on multivariate analyses (principal component and clustering analyses). Results show that the Tunisian and Chinese pomegranate seeds were rich in storage proteins independently of organoleptic taste as sweet, sour sweet or sour. Qualitatively, the storage protein and free amino acids of pomegranate seeds were identical. Besides, the segregation of Chinese and Tunisian pomegranate cultivars into three groups was reveled based on high, low or moderate amino acids contents. Statistically, the differences between organoleptic groups (sweet, sour sweet and sour) were not significant (P?<?0.05). However, the differences between pomegranate cultivars were statistically significant within groups. The separation of cultivars is independent to the organoleptic taste neither the geographical origin.     

Chloroplast DNA Variation in the Most Primitive Cultivated Diploid Potato Species Solanum stenotomum Juz. et Buk. and its Putative Wild Ancestral Species using High-Resolution Markers

Solanum stenotomum Juz. et Buk. (2n = 2x = 24) is considered to be the most primitive diploid cultivated species from which all the other Andean cultivated potatoes were originated (Hawkes 1990). To disclose chloroplast DNA (ctDNA) variability and the maternal origin of S. stenotomum, 36 accessions of S. stenotomum and 86 accessions of putative wild ancestral species were determined for ctDNA types and analyzed by high-resolution markers (seven ctDNA microsatellites and an H3 marker). High-resolution markers discriminated 57 different ctDNAs (haplotypes), which were classified into the W-type ctDNA group and C-, S- and A-type ctDNA group, and within the latter group S- and A-type ctDNAs were distinct from each other among many different haplotypes mostly having C-type ctDNA. This ctDNA relationship supported our previous findings obtained for mostly Andean cultivated species (Sukhotu et al. 2004). Compared with other putative ancestral wild species, S. stenotomum showed somewhat limited ctDNA diversity, having two major haplotypes 1 and 2 also found in different wild species in different places. Therefore, the ctDNA in S. stenotomum was of at least dual origins either by successive domestication from different species or else by introgression after initial S. stenotomum arose.     

Using diversity of the chloroplast genome to examine evolutionary history of wheat species

Chloroplast microsatellites (SSRs) are conserved within wheat species, yet are sufficiently polymorphic between and within species to be useful for evolutionary studies. This study describes the relationships among a very large set of accessions of Triticum urartu Thum. ex Gandil., T. dicoccoides (Körn. ex Asch. et Graebn.) Schweinf., T. dicoccon Schrank, T. durum Desf., T. spelta L., and T. aestivum L. s. str. based on their cpSSR genotypes. By characterising the chloroplast diversity in each wheat species in the evolutionary series, the impact on diversity of major evolutionary events such as domestication and polyploidyisation was assessed. We detected bottlenecks associated with domestication, polyploidisation and selection, yet these constrictions were partially offset by mutations in the chloroplast SSR loci that generated new alleles. The discrete cpSSR alleles and haplotypes observed in T. urartu and Aegilops tauschii, combined with other species specific polymorphisms, provide very strong evidence that concur with current opinion that neither species was the maternal and thus cytoplasmic donor for polyploid wheats. Synthetic hexaploid wheats possessed the same chloroplast haplotypes as their tetraploid progenitors demonstrating how the novel synthetic wheat lines have captured chloroplast diversity from the maternal parents, the chloroplast is maternally inherited and novel alleles are not created by genomic rearrangements triggered by the polyploidisation event.     

RESPONSE OF ‘BURLAT’ SWEET CHERRY TREES TO POSTHARVEST SPRAYS OF NITROGEN,BORON AND ZINC

The aim of the study was to examine effects of postharvest sprays of nitrogen (N), boron (B), and zinc (Zn) on reproductive response of sweet cherry (Prunus avium L.) trees, fruit quality and plant nutrition. The experiment was conducted during 2007–2009 in central Poland on mature ‘Burlat’ sweet cherry trees/F12, grown on a coarse-textured soil with low level of organic matter, and optimal soil reaction. Soil status of phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), Zn and copper (Cu) was optimal, whereas B – low. Sweet cherry trees were sprayed with boric acid-B, ethylenediaminetetraacetic acid (EDTA)-Zn, and urea-N at 30–40 d prior to initiation of leaf fall according to following schema: i) spray of N at a rate of 23 kg ha^?1; ii) spray of B and Zn at a dose of 1.1 kg ha^?1 and 0.5 kg ha^?1, respectively; and iii) spray of N, B and Zn at the same rates as in the above spray combinations. The trees sprayed with water served as the control. The results showed that fall spray treatments had no influence on cold damage of flower buds, plant N status and soluble solids concentration in fruit. Postharvest spray of N and combined spray of N, B and Zn injured leaves in the fall but did not cause defoliation. Sprays of B and Zn with or without N increased status of Zn and B in fall leaves, and B in flowers and midsummer leaves. Those sprays also improved fruit set and yield. In one out of two years of the study, fall sprays of N with or without B and Zn decreased mean fruit weight. The above results indicate that only leaf-applied B in the fall improved reproductive response of sweet cherry trees. It is concluded that under conditions of B shortage in a soil and/or plant tissues, postharvest B sprays can be recommended in sweet cherry orchards to improve reproductive growth of the trees.     

Response of Cherry Rootstocks to Boron and Salinity

ABSTRACT

The objective of the present research was to study the effects of boron (B) and potassium chloride (KCl) induced salinity on growth, nutritional status, and chlorophyll content of the cherry rootstocks CAB 6P (Prunus cerasus L.) and Gisela 5 (Prunus cerasus L. × Prunus canescens L.). Plants produced the longest shoots, more leaves, and the greatest fresh weights of shoots and leaves when treated with 0.025 mM B combined with the lower level of salinity (0.75 dS m^?1). CAB 6P plants retained most of their leaves until the end of the experiment, whereas Gisela 5 plants showed higher leaf shedding. Irrigation of plants with solutions containing 0.2 mM B and electrical conductivities (EC) of 4 dS m^?1 resulted in lower leaf chlorophyll contents (SPAD units) when compared with all other treatments. Nitrogen (N) concentrations of leaves from both rootstocks decreased as the EC of the nutrient solution increased from 0.75 to 4 mM. Potassium (K) concentrations of leaves from both rootstocks increased as salinity levels increased.     

Nuclear DNA content estimations in wild olive ( Olea europaea L. ssp. europaea var. sylvestris Brot.) and Portuguese cultivars of O. europaea using flow cytometry

Olive tree (Olea europaea L.) is an economically important woody fruit crop widely distributed in the Mediterranean regions. In this work the genome size of six Portuguese cultivars of olive (O. europaea ssp. europaea var. europaea) and wild olive (O. europaea spp. europaea var. sylvestris) was estimated for the first time. The nuclear DNA content of O. europaea cultivars ranged between 2.90 ± 0.020 pg/2C and 3.07 ± 0.018 pg/2C and the genome size of wild olive was estimated as 3.19 ± 0.047 pg/2C DNA. These results suggest a low intraspecific variation at least among the studied cultivars and between them and wild olive. This is not in accordance with previous results in some Italian cultivars where high genome size heterogeneity was found. The methodology presented here seems appropriate for genome size estimations within this genus and opens good perspectives for a large screening of estimation of nuclear DNA content among O. europaea cultivars and Olea species that could clarify this issue.     

Biological nitrogen fixation in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) by <Superscript>15</Superscript>N isotope-dilution and identification of associated culturable diazotrophs

The nitrogen-fixing capacity of a range of commercial cultivars of maize (Zea mays L.) was evaluated by the ¹⁵N isotope-dilution method. Biological nitrogen fixation (BNF) expressed as percent nitrogen derived from air (Ndfa) ranged from 12 to 33 regardless of nitrogen fertilization. BNF was not affected by mineral nitrogen fertilization except on cultivar Topacio and PAU-871 cultivars. Subsequently, culturable bacterial diazotrophs were isolated from endophytic tissue of maize: seed, root, stem, and leaf. All isolates were able to grow on N-free semisolid medium. Eleven bacteria isolates showed nitrogen-fixing capacity by the reduction of acetylene to ethylene and confirmed by PCR the presence of nifH gene in their genome. Identification of the 11 isolates was performed by bacteriological methods, 16S rRNA gene sequences, and phylogenetic analysis, which indicated that the bacteria isolated were closely related to Pantoea, Pseudomonas, Rhanella, Herbaspirillum, Azospirillum, Rhizobium (Agrobacterium), and Brevundimonas. This study demonstrated that maize cultivars obtain significant nitrogen from BNF, varying by maize cultivar and nitrogen fertilization level. The endophytic diazotrophic bacteria isolated from root, stem, and leaf tissues of maize cultivars may contribute to BNF in these plants.