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The author acknowledges the assistance of Richard Craig and Gregory Anderson in the development of techniques for determining ploidy in plants. The cost of publishing this paper was defrayed in part by the payment of page charges. Under

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( Hättenschwiler and Körner, 2003 ). In attempts to address shot-hole symptoms and the weedy tendencies in this species, we created chromosome doubled forms of the cultivar Schipkaensis. Although many studies have compared morphological variability in ploidy series

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is dynamic, as we gradually learn more about their reproductive biology, ploidy, phenotypic stability, and long-term consequences. For nearly 2 decades, we have conducted a series of experiments that have evaluated more than 25 heavenly bamboo

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cells is measured. The theory behind this method of screening for changes in ploidy levels is simple. The cell volume of a plant is directly proportional to the amount of DNA present in the cell, so that doubling the amount of DNA, which occurs when

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Traditional genetic manipulation methods have proven ineffective or irrelevant for many citrus breeding objectives. Alternative approaches to Citrus genetic improvement are now available as a result of technological developments in genetics and tissue culture. For example, mapping DNA marker polymorphisms should lead to identifying markers closely linked to important loci, thereby facilitating early selection and minimizing costs associated with plant size and juvenility. Genetic transformation methods allow trait-specific modification of commercial cultivars. By selecting beneficial variants from sectored fruit chimeras and the recovering plants via somatic embryogenesis, the problems of nucellar embryony and the hybrid nature of commercial cultivar groups can be avoided. Induced mutagenesis from mature vegetative buds may overcome these problems, as well as juvenility. Ploidy level manipulation in vitro can increase the number and diversity of tetraploid breeding parents, leading to the development of seedless Citrus triploids and mitigating sterility, incompatibility, and nucellar embryony.

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Anther culture has been one of the most successful techniques for generating haploid plants over a wide range of species. It is a reasonably simple procedure that can be accomplished successfully without sophisticated laboratory facilities; yet, the plants generated through anther culture can be used to demonstrate the application of many modern methods that have direct applicability to plant breeding. Anthers of diploid potato clones that have been selected for competence in anther culture can be cultured in a simple medium to yield androgenic embryos after 5 weeks. Plant regeneration requires an additional 3 to 4 weeks. Regenerated plants should be large enough 2 weeks after transfer to basal medium for ploidy determination by any of three methods depending on available facilities: chromosome counts in root tips; chloroplast counts in stomatal guard cells; or flow cytometry of nuclei released from in vitro plantlets. DNA can be extracted from anther-derived plantlets using a rapid extraction procedure to demonstrate segregation of PCR (polymerase chain reaction)-based markers such as RAPD (randomly amplified polymorphic DNA), RAMPs (randomly amplified microsatellite polymorphisms), or microsatellites. Microsatellite markers that were heterozygous in the anther donor can be used to verify haploidy in anther-derived plants. If an anther culture laboratory is scheduled early in a semester, such molecular analysis can be planned for late in the same semester.

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. Additional information on each cultivar (bloom season, winter foliage, ploidy, originator, and year of registration) was obtained from the database of the American Hemerocallis Society (2015) . For statistical analysis, median rust ratings were grouped into

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rooting of wild-type (22 x ) ‘Schipkaensis’ cherrylaurel with a chromosome-doubled form (44 x ). They found that rooting percentage, average root length, and total root length per rooted cutting were not significantly different between ploidy types

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guard cell length as predictors of ploidy in diverse rose cultivars, species, and breeding lines Floricul. Ornamental Biotechnol. 3 53 70 Zuzek, K. Richards, M. McNamara, S. Pellett, H. 1995 Performance of shrub and old garden roses at the Minnesota

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Parkland or Morden series (led by Lynn Collicutt and Henry Marshall, Morden Research Station, Morden, MB, Canada) ( American Rose Society, 2007 ; Svejda, 2008 , 2014 ). Table 1. The commercial class, flower color, year of introduction, origin, ploidy, and

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