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faster accumulation of useful mutations at relatively low costs for breeding programs ( Van Harten, 1998 ). Such treatments were first discovered by Muller in 1927. He discovered that irradiating Drosophila melanogaster with X-rays caused a massive

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ornamental plants with new characteristics. If limited natural variation exists, mutation breeding can improve a crop by artificially inducing genetic variation. This breeding technique has been shown to cause phenotypic variations in color, flower shape

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Citrus fruit with sector chimeras were collected in commercial packinghouses and from the field. Chimeric fruit from eight cultivars of sweet oranges [Citrus sinensis (L.) Osbeck], grapefruit (C. paradisi Macf.), tangelo (C. paradisi × C. reticulate Blanco), and tangors (C. reticulate × c. sinensis) were found at a frequency of 0.009% to 0.271%. Tetraploid plants obtained from one type of sector mutant (termed gigas) and albino plants obtained from another type of sector mutant confirmed that some genetic mutations observed in fruit rind can be recovered in nucellar seedlings. The gigas chimeras were identified as a source of citrus tetraploids. Several types of potentially useful sector mutants with altered rind color were observed, and plants were produced from some mutant sectors by developed seed or culture of aborted ovules. HPLC analysis of rind tissues from sectors of one chimeric fruit revealed substantial quantitative and qualitative differences in pigment composition. Propagation of plants from mutant sectors may yield cultivars with improved fruit color, altered maturation date, and reduced disease or mite susceptibility and may eventually lead to breeding of seedless triploid hybrids.

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A teaching module was developed for computer-aided instruction of mutation theory. The Hypercard-driven, Macintosh compatible module illustrates the concepts of: 1) Changes in allele frequency with mutation pressure; 2) Number of alleles maintained in populations, and; 3) The Neutrality Hypothesis. The concepts are integrated in an application by using a game format.

Mutation is the ultimate source of genetic variation. Mutation pressure results in changes in allele frequency. Concept 1 illustrates the theoretical changes in allele frequency under pressure of reversible mutation. Mutation equilibrium is depicted as P=V/u+v; where v=mutation rates of allele A and u of allele a. The Infinite-Alleles Model of mutation is illustrated in Concept 2 and specifies characteristics of new mutations by F=1/4Nu+1, where F=fixation index and N=number in population. Concept 3 demonstrates the hypothesis that polymorphisms result from selectively neutral alleles maintained in a balance between mutation and random genetic drift.

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A teaching module was developed for computer-aided instruction of mutation theory. The Hypercard-driven, Macintosh compatible module illustrates the concepts of: 1) Changes in allele frequency with mutation pressure; 2) Number of alleles maintained in populations, and; 3) The Neutrality Hypothesis. The concepts are integrated in an application by using a game format.

Mutation is the ultimate source of genetic variation. Mutation pressure results in changes in allele frequency. Concept 1 illustrates the theoretical changes in allele frequency under pressure of reversible mutation. Mutation equilibrium is depicted as P=V/u+v; where v=mutation rates of allele A and u of allele a. The Infinite-Alleles Model of mutation is illustrated in Concept 2 and specifies characteristics of new mutations by F=1/4Nu+1, where F=fixation index and N=number in population. Concept 3 demonstrates the hypothesis that polymorphisms result from selectively neutral alleles maintained in a balance between mutation and random genetic drift.

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,000 varieties have been produced globally by conventional hybridization techniques and spontaneous mutation, and annually, several hundred new cultivars are released ( Ghisleni and Martinetti, 1995 ). The breeding of Sainpaulia is nevertheless hampered by the

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( Kuligowska et al. 2016 ; Schum 2003 ). Mutation breeding has proven to be a very effective tool for ornamental plant improvement ( Schum 2003 ). Many of the traits that are economically important in ornamentals, such as novel flower color or patterning and

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primarily occur naturally from spontaneous mutations. The frequency of spontaneous mutation is usually very low and a few variations such as flower color, disease resistance, and plant stature have been intensively used in many breeding programs. Therefore

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during cell division to provide a theoretical basis for the high-quality production and genetic breeding of Korla fragrant pear and its bud mutation. Materials and Methods Plant materials. A field experiment was conducted at the Shayidong

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can reduce maintenance and labor costs of gardeners, landscapers, and nurseries. Mutagenesis is a way to obtain new cultivars for sterility and compactness. Mutation breeding generates random variation, resulting in mutant plants with unique

Open Access