has also been documented ( Wenefrida and Spencer, 1993 ). Genetic diversity has been documented in D. rosae using molecular marker analyses. Lee et al. (2000) examined 10 isolates using restriction fragment length polymorphism (RFLP) analysis of
Vance M. Whitaker, Stan C. Hokanson, and James Bradeen
Wenting Wang, Chao Feng, Zehuang Zhang, Liju Yan, Maomao Ding, Changjie Xu, and Kunsong Chen
parentage analysis, hybrid identification, cultivar discrimination, and genetic diversity studies in various fruits ( Heidi and Andrew, 2007 ). However, despite the availability of SSR markers from previous studies, the number of high-quality and highly
F.J. Keiper and R. McConchie
Umbrella fern [Sticherus flabellatus (R. Br.) St John] is a successful Australian native foliage product. Currently, all umbrella fern sold on the market is bush-harvested. To meet the growing demand for this product on local and international markets, a commercially viable method for its production must be developed, with effective management of the germplasm resource in terms of conservation and exploitation. To manage this resource, breeders require a detailed knowledge of the amount and distribution of genetic variability within the species. Traditionally, plant breeders focus on a combination of agronomic and morphological traits (phenotype) to measure genetic diversity. In umbrella fern there are a limited number of morphological traits, and these are influenced by environmental factors and therefore do not reflect true genetic diversity. To overcome these problems, molecular techniques such as PCR-based DNA markers are used to complement traditional strategies for genotype assessment. DNA markers have the advantages of being independent of environmental effects, as well as being fast, cost-effective, reproducible, and largely accessible to the nonmolecular geneticist. Amplified fragment length polymorphisms (AFLPs) fulfil many of the desirable features of molecular markers, as well as requiring little knowledge of the genome to be investigated. AFLPs have been used widely in the analysis of breeding systems, ecogeographical variation, and genetic variation within and between natural populations. To date there are no published accounts of DNA molecular marker research on umbrella fern. A DNA extraction protocol has been developed for this species, and AFLP markers have been used to analyse genetic diversity within and between natural populations sampled in the Sydney Basin. A large number of polymorphic loci were revealed using 11 primer combinations. The genetic variation detected was partitioned between rather than within populations, suggesting that the mating system in Sticherus is primarily inbreeding. Data will be presented illustrating AFLPs as useful molecular markers for assessing genetic diversity within and between populations of umbrella fern and providing insight on the breeding system used by the species.
Fenny Dane and Yuqing Fu
Chestnut blight, caused by the Asian fungus Cryphonectria parasitica, has severely affected chinkapin populations (Castanea pumila), especially those limited to the Ozark mountains (var. ozarkensis). Genetic diversity within and between geographic populations of the Allegheny (var. pumila) and Ozark chinkapin populations was evaluated for development of appropriate conservation strategies. Nuts or dormant buds collected from populations along the range of the species were analyzed using allozymes. A unique allele was detected in populations along the gulf of Mexico. Significant differences in genetic diversity were observed among Allegheny populations, but not among Ozark populations. High levels of genetic identity were detected among widely distributed populations from Florida to Virginia (Allegheny chinkapin populations) and Arkansas (Ozark chinkapin populations).
Amnon Levi, Alvin M. Simmons, Laura Massey, John Coffey, W. Patrick Wechter, Robert L. Jarret, Yaakov Tadmor, Padma Nimmakayala, and Umesh K. Reddy
watermelon cultivars ( Si et al., 2009 ; Wang et al., 2014 ). A previous study using randomly amplified polymorphic DNA markers ( Levi et al., 2001a , 2001b ) indicated that high levels of genetic diversity exist among CC PIs. In a later study, we developed
Hongwen Huang, Fenny Dane, and J.D. Norton
The genetic diversity within and between geographic populations of the American chestnut tree was evaluated with allozyme and RAPD markers. Winter dormant or mature shoot buds from American chestnut trees collected in Alabama, Georgia, North Carolina, Virginia, Pennsylvania, Ohio, Michigan, and Connecticut were used for isozyme assays. Genetic diversity statistics calculated for 20 isozyme loci indicated that the highest level of heterozygosity was detected in the Alabama and Connecticut populations, the lowest level in the Great Smoky Mountain populations. RAPD analyses were conducted on American chestnut plant material. The best results were obtained with seed tissue. Seed from New York, Virginia, and Pennsylvania populations and buds from Alabama and Georgia populations were evaluated for RAPD markers scattered throughout the chestnut genome.
Lack of variation among black raspberry cultivars is thought to be a limiting factor in fruit production and in breeding improved cultivars. An assessment of the available diversity in black raspberry is needed to effectively develop improved cultivars. Such an assessment was done to estimate the genetic similarities for RAPD markers in 16 black raspberry genotypes and to determine the genetic diversity among these genotypes based on these markers. In addition, the ability to distinguish between the black raspberry genotypes, two red raspberry cultivars (Rubus idaeus L.), and a blackberry cultivar (Rubus hybrid) was determined. A similarity matrix from 379 RAPD markers was calculated, and a phylogenetic tree was constructed using the PHYLIP suite of phylogeny software, which revealed the relationship among the genotypes. An average of 81% similarity was calculated among 16 black raspberry genotypes with a maximum similarity of 98% and a minimum of 70%. The average similarity between black raspberry and red raspberry was 41% and was 26% between black raspberry and blackberry. Combined marker profiles from six RAPD primers could be used to distinguish between the 16 black raspberry genotypes. Red raspberry and blackberry could be distinguished from black raspberry by 27 and 29 of 30 RAPD primers tested, respectively. Genetic diversity was most prominent in genotypes from the extremes of the black raspberry indigenous range. Diversifying the germplasm pool for black raspberry cultivar improvement can be achieved through utilizing genotypes from the extremes of the black raspberry range and through interspecific hybridization.
Fachun Guan, Shiping Wang, Rongqin Li, Mu Peng, and Fanjuan Meng
rigorous conditions and inaccessibility of the Tibetan Plateau, few studies regarding the genetic diversity in plant populations have been conducted ( Guo et al., 2006 ). Prunus mira Koehne ( Prunus mira Koehne Kov et. Kpst) has been recognized as an
Eric Stafne, Jon Lindstrom, and John Clark
Passiflora is an important ornamental genus, mainly within tropical zones. However, two cold-hardy, North American Passiflora species exist. Previous work has been done to incorporate these species into breeding programs with some success. The intent of this study was to evaluate the extent of genetic diversity among five different Passiflora genotypes, including the two native North American species, P. incarnata L. and P. lutea L. Results indicate low genetic similarity among all genotypes with none at 50% or greater. P. incarnata and the ornamental cultivar `Lady Margaret' displayed the highest relationship at 49%. P. incarnata averaged 35.5% similarity with the other genotypes and P. lutea was 29.5%. Average overall similarity among all genotypes was 31.1%. These and other results show that the Passiflora genus has a high degree of genetic variation and breeding efforts could expand interest within North America.
Adam Dale, Patrick P. Moore, Ronald J. McNicol, Thomas M. Sjulin, and Leonid A. Burmistrov
Abbreviations: CR, coefficient of relationship; GC, genetic contributions. We thank C. Fear and V.H. Knight for contributions of unpublished pedigrees. The cost of publishing this paper was defrayed in part by the payment of page charges. Under