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Bouchaib Khadari, Amal Zine El Aabidine, Cinderella Grout, Inès Ben Sadok, Agnès Doligez, Nathalie Moutier, Sylvain Santoni and Evelyne Costes

published to date: ‘Leccino’ × ‘Dolce Agogia’ by De La Rosa et al. (2003) and ‘Frantoio’ × ‘Kalamata’ by Wu et al. (2004) . These maps are mostly based on randomly amplified polymorphism DNA and AFLP markers including only five and six codominant SSR

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Umesh R. Rosyara, Audrey M. Sebolt, Cameron Peace and Amy F. Iezzoni

‘Bing’ as a grandparent ( Table 3 ). Table 1. Sweet cherry cultivars, selections, and wild accessions, their parents if known, coefficient of relatedness (ρ) to ‘Bing’ using single nucleotide polymorphism markers (n = 519), and S -locus genotype. z

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Ruby Valdez-Ojeda, José Luis Hernández-Stefanoni, Margarita Aguilar-Espinosa, Renata Rivera-Madrid, Rodomiro Ortiz and Carlos F. Quiros

ensure band pattern reproducibility. The PCR products were run in a sequencer (IR2 4200; LI-COR, Lincoln, NE). Table 1. Sequence-related amplified polymorphism primers used to develop the polymorphic markers used in the study. Analysis

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Shuiming Zhang, Zhongshan Gao, Changjie Xu, Kunsong Chen, Guoyun Wang, Jintu Zheng and Ting Lu

Chinese bayberry accessions, 98 of them cultivars or lines, were analyzed by amplified fragment length polymorphism (AFLP), a reliable molecular marker with wide applications such as in parentage analysis, hybrid identification, cultivar discrimination

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Robert D. Marquard

Six phosphoglucomutase phenotypes were observed in pecan [Carya illinoensis (Wangenh.) K. Koch] progeny after controlled pollinations. At least one locus (Pgm-1) is present that controls polymorphism of phosphoglucomutase (PGM) isozymes in pecan. The inheritance appears simple with three observed alleles. However, progeny produced from two crosses resulted in significant deviation from the expected segregation ratios. Out of 65 named cultivars, 61 were of a single phenotype, and two of six possible phenotypes were not observed. Only one region of PGM activity was consistently expressed by gel electrophoresis from pecan tissue.

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Sriyani Rajapakse, Mark Hubbard, Albert Abbott, John Kelly and Robert Ballard

Restricted Fragment Length Polymorphisms (RFLPs) were investigated in closely and distantly related rose cultivars as means of identifying those cultivars for the purpose of patent protection. A random genomic DNA library was constructed using the cultivar `Confection' and the Escherichia Coli strain JM83 plasmid vector pUC8. Clones with interspersed repeat sequences were then identified by hybridizing restriction digested cloned DNA fragments with nick translated genomic DNA of the rose cultivar `Confection'. Hybridization positive clones were screened for polymorphism by Southern hybridization on restriction digested genomic DNA of various rose cultivars. About 75% of the interspersed repeat copy probes screened revealed polymorphisms. We have identified probes that give fingerprint patterns for rose cultivars. From this information, a dichotomous key which differentiates the rose cultivars examined was prepared. Current research involves screening more probes and rose cultivars for polymorphisms, and examining single copy probes for potential use in RFLP genetic linkage map construction in roses.

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Limeng Xie, Patricia Klein, Kevin Crosby and John Jifon

, including restriction fragment length polymorphism (RFLP), simple sequence repeat (SSR), and SNP markers have been developed and applied in construction of high-density linkage maps of tomato. This has allowed extensive QTL mapping for many horticulturally

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Jinggui Fang, Chih Cheng Chao, Richard J. Henny and Jianjun Chen

Plant tissue culture can induce a variety of genetic and epigenetic changes in regenerated plantlets, a phenomenon known as somaclonal variation. Such variation has been widely used in the ornamental foliage plant industry as a source for selection of new cultivars. In ornamental aroids alone, at least 63 somaclonal-derived cultivars have been released. In addition to morphological differences, many somaclonal aroid cultivars can be distinguished by amplified fragment length polymorphism (AFLP) analysis. However, a few cultivars have no detectable polymorphisms with their parents or close relatives by AFLP fingerprints. It is postulated that DNA methylation may be involved in the morphological changes of these cultivars. In this study, methylation-sensitive amplification polymorphism (MSAP) technique was used to study DNA methylation in selected somaclonal cultivars of Alocasia, Aglaonema, Anthurium, Dieffenbachia, Philodendron, and Syngonium. Results showed that polymorphisms were detected in the somaclonal cultivars, suggesting that DNA methylation polymorphisms may associate with tissue culture-induced mutation in ornamental aroids. This is the first study of methylation variation in somaclonal variants of ornamental foliage plants. The results clearly demonstrate that the MSAP technique is highly efficient in detecting DNA methylation events in somaclonal-derived cultivars.

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Vyacheslav Gurevich, Uri Lavi and Yuval Cohen

Date palm (Phoenix dactylifera L.) is a major tree crop in arid regions of the Middle East and North Africa, having an important impact on the economy of many countries in these regions. Date palms are traditionally propagated through offshoots. The development of propagation methods through tissue culture resulted in massive expansion of date palm plantations. While most trees generated from tissue culture are normal and true-to-type, several typical abnormal phenotypes are detected. The present study applies amplification fragment length polymorphism (AFLP) analysis to characterize the genetic variation of two elite date cultivars, `Barhee' and `Medjool', as well as male clones, propagated from offshoots and through tissue culture. The two cultivars have very distinct AFLP band patterns. Most offshoots, as well as the tissue culture-propagated plants, have very similar band patterns, demonstrating a low level of genetic variation. However, a significant level of genetic variation was detected among `Medjool' plants generated from tissue culture. Several phenotypically abnormal trees were characterized by unique and different AFLP band patterns. The male clones are characterized by a high level of polymorphic bands. Genetic variation was also detected between various tissues of variegated `Medjool' trees propagated from tissue culture. The significance of these results, regarding the mechanism of the phenomenon and its relevance to agricultural practice, is discussed.

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Channapatna S. Prakash, Guohao He and Robert L. Jarret

Highly polymorphic DNA markers were identified in sweetpotato (Ipomoea batatas) using PCR amplification and arbitrary primers. More than 100 accessions representing US cultivars and their progenitors, and germplasm lines from around the world were analyzed. Sweetpotato germplasm exhibited high genetic variability and individual-specific profiles were obtained for all accessions. US cultivars formed a tight cluster in the principal coordinate analysis suggesting a narrow genetic base. The genetic relationship data of US cultivars and their progenitors based on DNA polymorphisms was in agreement with their known pedigree. The putative paternal parents of certain cultivars selected through open pollination were identified based on shared polymorphisms. The PCR-based markers are valuable in the characterization of sweetpotato germplasm and in ensuring a broad genetic base for future cultivars.