A molecular cytogenetic analysis of chromosome behavior in Lilium ...

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Chapter 1counterparts (Finnegan 2002; Liu and Wendel 2002; Pikaard 2001; Rieseberg 2001b; Soltisand Soltis 1999; Song et al. 1995). Since exchange of genetic contents is also critical fortransferring traits across distantly related plant species to obtain combinations of desirablecharacteristics in agriculture and horticulture (Lim et al. 2003), intergenomic chromosomerecombination has been extensively induced and utilized in introgression breeding and cropimprovement of some main crops. Hexaploid wheat (AABBDD, 2n=6x=42) which contains atranslocated chromosome fragment on the long arm of the 1B chromosome from the rye(Secale cereale) 1R chromosome are widely used in wheat breeding, this satellite from 1Rcontains several agronomical important genes including those for seed storage proteins andfor disease resistance. In the oilseed Brassica napus, lines with the N7-N16 reciprocalrecombination harvested a significant higher seed yield compared with that without thereciprocal recombination (Osborn et al. 2003).Methods used for the detection of chromosome rearrangementsDue to the importance of chromosome structure variation in plants, research on chromosomerearrangements has been a topic of interests for many decades, and the methods used to detectthem cover classical cytogenetic methods, molecular marker systems, molecular cytogenetictechniques and sequence-based innovational methods.A wide range of classical cytogenetic methods have been applied for detectingchromosome rearrangements, both in diploid and polyploid species. Many small chromosomerearrangements that are not detected by mitotic observation can be seen in meiotic analysisaccording to the meiosis configuration. For example, an inversion heterozygote can berecognized by its association loop at metaphase I and dicentric & acentric fragments atanaphase I. A translocation heterozygote can also be detected by its multivalent formation atmetaphase I and the aberrant segregation at anaphase I (reductional or equational segregation),which will cause duplication and deletion in the resultant gametes. Since the mid-20 th century,chromosome banding has become one of the main methods to analyze chromosomerearrangements. Because of the different banding karyotypes, some of the introgressedchromosome/segments can be distinguished by their specialized bands (Badaeva et al. 2007),For example, the chromosome 1R from rye demonstrates divergent C bands on the long arm,and as a result, the long arm becomes obviously visible when C banding technique is appliedin the translocation lines. Furthermore, some structural variation can also be identified bycombined banding techniques. A range of chromosome rearrangements, viz. inversion,deletion, fission and fusion, have been detected in many different species/species hybrids,such as Equus africanus somaliensis (Houck et al. 2000) and wheat (Friebe et al. 1996).4
General IntroductionWith the development of modern techniques, molecular markers are widely used for thedetection of genome rearrangements. Compared with the traditional methods, molecularmarkers have solved the problem of poor resolution in detecting chromosome rearrangements,and have been proved to be a precise and effective way of detecting inter- and intra- specificchromosome rearrangements. Some types of structural variation of a chromosome, such asduplication and deletion, which are difficult to recognize with traditional cytogenetic methods,can be detected and reflected by the presence/absence of bands. One of the advantages is thatthe non-homologous translocation within the same genome can also be reflected. Furthermore,extensive inter- and intra- genomic rearrangements have been detected in many model plants,and the rates are much higher compared with conventional methods. In wheat, intergenomictranslocation between non-homologous genomes can be easily detected using molecularmarkers (Mickelson-Young et al. 1995). Meanwhile, translocation between wheat and otherspecies has also been characterized using different marker systems (Bonierbale et al. 1988;Boyko et al. 1999; Zhang et al. 1998). Furthermore, the characterization of chromosomerearrangements with molecular markers has also been used in some other plant species. Forexample, comparative genetics with RFLP mapping has revealed the existence ofchromosome rearrangements between different plant species, viz., the comparison amongwheat, maize, rice and other grass species(Gale and Devos 1998), between eggplant andtomato (Doganlar et al. 2002). As a result, comparative genetic mapping, in which differentmarker systems are used, has been proved to be an efficient way for detecting chromosomerearrangements.However, there are some drawbacks when detecting chromosome rearrangements withmolecular markers, which will mislead the real occurrence of chromosome rearrangements.Firstly, markers can just identify the changes in the progeny, which leave the origin of suchchanges behind, and that is why molecular markers confused recombination from naturalmeiosis process and real chromosome rearrangements. Secondly, changes in the intensity ofbands cannot be well reflected by using DNA profiling method via counting the presence andabsence of bands, when the parental bands share the same molecular weight or genelosses/conversion in duplications. Furthermore, balanced chromosome rearrangements such asreciprocal translocation and inversion, cannot be detected by molecular markers. As reportedby many researchers, reciprocal recombinations in unreduced gametes produced by someinterspecific hybrids could not be detected (Nicolas et al. 2007; Xie et al. 2010). In addition,marker systems require long-term collaborative research and is applicable for a limitednumber of plants (Badaeva et al. 2007).DNA in situ hybridization, including genomic in situ hybridization (GISH) andfluorescence in situ hybridization (FISH), was the predominant way and has received a5
Page 3 and 4: A molecular cytogenetic analysis of
Page 5: Table of ContentsChapter 1General I
Page 8 and 9: Chapter 1LilyLilies belong to genus
Page 12 and 13: Chapter 1renewed interest in detect
Page 14 and 15: Chapter 1recombination, mechanisms
Page 16 and 17: Chapter 1is only an equational segr
Page 18 and 19: Chapter 1quite divergent with vario
Page 21 and 22: Chapter 2An assessment of chromosom
Page 23 and 24: Chromosome rearrangements in Lilium
Page 37 and 38: Chapter 3Elucidation of intergenomi
Page 39 and 40: Intergenomic recombination and chro
Page 49: Intergenomic recombination and chro
Page 52 and 53: Chapter 4AbstractMeiotic abnormalit
Page 54 and 55: Chapter 4There are some criteria to
Page 56 and 57: Chapter 4FISH experiments were perf
Page 58 and 59: Chapter 4was apparently shorter, wi
Page 60 and 61:
Chapter 4bridges is explained as U-
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Chapter 4of the sexual polyploidize
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Chapter 4fragment have the same len
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Chapter 5AbstractSupernumerary (B)
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Chapter 5their origin, the structur
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Chapter 5Fig. 5.1. Discovery of B c
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Chapter 5In order to investigate th
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Chapter 5Centric breakage and fusio
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Chapter 5It has not, however, been
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Chapter 6The results presented in t
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Chapter 6model for molecular cytoge
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Chapter 6Fig. 6.2. The meiosis proc
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Chapter 6over events during FDR mei
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Chapter 6been detected with GISH an
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Chapter 6Another feature caused by
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ReferencesAbe, H.A., Nakano, M.N.,
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ReferencesChen, Q., and Armstrong,
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ReferencesHartlerode, A.J., and Scu
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ReferencesLarson, S.R., Kishii, M.,
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ReferencesMcClintock, B. 1931. Cyto
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ReferencesRai, R., Zheng, H., He, H
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ReferencesStewart, R.N. 1947. The m
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ReferencesZhang, L., Pickering, R.,
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Summarychromosome rearrangements. T
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SamenvattingLelie (Lilium) is in de
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Samenvattingaantal 35 met daarnaast
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摘要百合系百合科百
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Acknowledgements淡看世事去
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Curriculum VitaeSonglin Xie was bor
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Education Statement of the Graduate
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