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Lydia E. Wahba, Nor Hazlina, A. Fadelah, and Wickneswari Ratnam

morphological character states provides additional support to the groupings recovered in molecular phylogenetic trees ( Figueroa et al., 2008 ; Salazar, 2009 ; Salazar et al., 2009 ). The objectives of this study were to 1) determine genetic relatedness among

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

), Hemerocallis L. ( Tomkins et al., 2001 ), and Rosa L. ( Vosman et al., 2004 ). The objective of this study was to determine the genetic relatedness of currently cultivated ornamental Ficus species and cultivars using AFLP markers. Materials and Methods

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Ashish K. Pathak, Sudhir P. Singh, and Rakesh Tuli

studies. The AFLP fingerprinting and genetic relatedness presented in the study are useful for unequivocal identification of lychee cultivars, selecting appropriate accessions for cultivar improvement, germplasm management, and deciding suitable

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

The feasibility of using RFLP to distinguish genetically related Hybrid Tea rose cultivars for DNA `fingerprinting' was examined with a group of cultivars related to `Peace'. The following cultivars used in this study, `Chicago Peace', `Flaming Peace', `Climbing Peace' and `Lucky Piece', were derived from bud mutations (sports) of `Peace'. We also investigated two additional cultivars, `Perfume Delight' and `Garden Party', in which one of the parents for each was `Peace'. Genomic rose DNA probes, cloned in pUC8 plasmid of Escherichia coli, were hybridized with genomic DNA of these cultivars digested with different restriction enzymes. Although polymorphisms were observed among these related cultivars, only a few probe/enzyme combinations screened produced RFLPs due to the high degree of genetic relatedness of these cultivars. We have identified probes that can distinguish all of these related rose cultivars. This study demonstrates that RFLP markers can be used effectively in DNA `fingerprinting' of genetically related rose cultivars, eventhough the level of detectable polymorphism is quite low.

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Jianjun Chen, Richard J. Henny, David J. Norman, Pachanoor S. Devanand, and Chih-Cheng T. Chao

Dieffenbachia Schott is an important ornamental foliage plant genus. A total of 30 species has been recognized, but most cultivars come from or are related to a single species, D. maculata (Lodd.) G. Don. At least 11 of the cultivars are sports or somaclonal variants. As a result, the potential lack of genetic diversity in cultivated Dieffenbachia has become a concern. However, no research has been conducted to determine the genetic relatedness of the cultivars. This study analyzed the genetic similarity of 42 Dieffenbachia cultivars using amplified fragment length polymorphism (AFLP) markers. Six primer sets, selected from an initial screening of 48, generated a total of 453 scorable AFLP fragments of which 323 (71%) are polymorphic. All cultivars were clearly differentiated by their AFLP fingerprints. A dendrogram was constructed using the unweighted pair-group method of arithmetic averages, and principal coordinated analysis was carried out to show multiple dimensions of the distribution of the cultivars. The 42 cultivars were divided into three clusters; clusters I and II comprise 18 and 23 cultivars, respectively. Jaccard's similarity coefficients for cultivars in the clusters I and II varied from 0.44 to 0.95 and 0.41 to 0.87, respectively. These results indicate that broadening the genetic variability in the Dieffenbachia gene pool is needed, but the genetic similarity of many cultivars is not as close as previously thought. Additionally, Jaccard's similarity coefficients between most sports or somaclonal variants and their parents were 0.73 or lower, suggesting that accumulation of somatic mutations through tissue culture may play a role in the increased variation between some sports or variants and their parents.

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Patrick J. Conner and Bruce W. Wood

Genetic variation among pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars was studied using randomly amplified polymorphic DNA (RAPD) markers. Using a combination of primers, a unique fingerprint is presented for each of the pecan genotypes studied. The genetic relatedness between 43 cultivars was estimated using 100 RAPD markers. Genetic distances, based on the similarity coefficient of Nei & Li, varied from 0.91 to 0.46, with an average value of 0.66 among all cultivars. The phenetic dendrogram developed from cluster analysis showed relatively weak grouping association. However, cultivars with known pedigrees usually grouped with at least one of the parents and genetic similarity estimates appear to agree with known genetic relationships.

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Patrick J. Conner and Bruce W. Wood

Genetic variation among pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars was studied using randomly amplified polymorphic DNA (RAPD) markers. Using a combination of primers, a unique fingerprint was produced for each of the pecan genotypes studied. The genetic relatedness between 44 cultivars was estimated using more than 100 RAPD markers. Genetic distances based on the simple matching coefficient varied from 0.91 to 0.59. The phenetic dendogram developed from cluster analysis showed relatively weak grouping association. However, cultivars with known pedigrees usually grouped with at least one of the parents and genetic similarity estimates appear to agree with known genetic relationships. Using RAPD information in determining genetic relationships among pecan cultivars with unknown or questionable pedigrees and the integration of that knowledge into the breeding program is discussed.

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Rajeev Arora, Michael Wisniewski, and Ralph Scorza

Deciduous fruit trees undergo endo-dormancy during fall at which time they also attain maximum cold hardiness (CH). Because these two processes occur simultaneously it is difficult to study them independently. We have been able to overcome this limitation with the use of genetically related (sibling) deciduous and evergreen peach trees. Using this system we conducted a time course study to characterize the seasonal fluctuations in CH and proteins in bark and xylem tissues. Cold hardiness (LT50) was assessed using electrolyte leakage method. Polypeptides were separated using SDS-PAGE. The data indicated that 1) CH of bark increased from -5°C (in August) to -49°C (in January) and from -3°C to -22°C for deciduous and evergreen trees, respectively. In January, under favorable conditions, evergreen trees were actively growing. 2) CH of xylem successively increased from -11°C to -36°C in deciduous trees and from -7°C to -16°C (in November) in evergreen trees and then plateaued. 3) LT50 of xylem in both genotypes closely approximated the mid-point of low temperature exotherms determined by differential thermal analysis. 4) As CH increased several qualitative and quantitative differences in polypeptides were noted between two genotypes. These changes during cold acclimation will be compared with those during de-acclimation.

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Josh A. Honig, Vincenzo Averello, Stacy A. Bonos, and William A. Meyer

conditions ( Giancola et al., 2002 ; Ibanez et al., 2009 ; Kwon et al., 2005 ; Lombard et al., 2000 ; Roldan-Ruiz et al., 2001 ). Finally, common morphological or performance characteristics may not necessarily equate to genetic relatedness. As a result

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Hongwen Huang, Desmond R. Layne, and Thomas L. Kubisiak

Thirty-four extant pawpaw [Asimina triloba (L.) Dunal] cultivars and advanced selections representing a large portion of the gene pool of cultivated pawpaws were investigated using 71 randomly amplified polymorphic DNA (RAPD) markers to establish genetic identities and evaluate genetic relatedness. All 34 cultivated pawpaws were uniquely identified by as few as 14 loci of eight primers. Genetic diversity of the existing gene pool of cultivated pawpaws, as estimated by Nei's gene diversity (He), was similar to that of wild pawpaw populations. The genetic relatedness among the cultivated pawpaws examined by UPGMA cluster analysis separated 34 cultivars and selections into two distinct clusters, a cluster of PPF (The PawPaw Foundation) selections and a cluster including a majority of the extant cultivars selected from the wild and their derived selections. The results are in general agreement with the known selection history and pedigree information available. The consensus fingerprint profile using the genetically defined RAPD markers is a useful and reliable method for establishing the genetic identities of the pawpaw cultivars and advanced selections. This also proved to be an improved discriminating tool over isozyme markers for the assessment of genetic diversity and relatedness. RAPD profiling of data presented in this study provides a useful reference for germplasm curators engaged in making decisions of sampling strategies, germplasm management and for breeders deciding which parents to select for future breeding efforts.