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

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Chapter 6over events during FDR meiosis in the present study, only half of them can be detected bymolecular markers (Fig. 6.3), which significantly underestimates the real occurrence ofcrossover. For SDR originating allopolyploids, underestimation will also occur in case ofrecombination in a three strand double crossing over (Fig. 6.3). In conclusion, progenyanalysis of genetic mapping in polyploids resulted from unreduced gametes will considerablyunderestimate the real crossing over events during meiosis.Similarly, underestimation of crossing over events also takes place in autopolyploidgenetic mapping. Currently, most polyploidy mapping is based on disomic inheritance (1:1and 3:1 segregation) and maps were based on the scoring of allele number and/or dosageusing dominant markers (Luo et al. 2001; Zhang et al. 2006), while trisomic inheritance(trivalent formation during meiosis), tetrasomic inheritance (quadrivalent formation duringmeiosis), as well as intermediate inheritance were ignored. However, multivalent formation,like trivalents and quadrivalents, is quite a normal phenomenon in polyploids, especially inautopolyploids (Kamiri et al. 2011; Stift et al. 2008). At anaphase I, segregants including twoor more chromosomes resemble random segregation in FDR-like meiosis in the secondmeiotic division, and crossing over between non-sister chromatids in the same segregant alsoform reciprocal and non-reciprocal products. Recombinant sites can be detected in the former,on the contrary, the latter cannot be detected, which will lead to the underestimation ofcrossing over and errors in locating the exact positions of markers in the linkage groups (Fig.6.3). Since reciprocal recombination is impossible to be detected with molecular markers,polyploidy with the formation of multivalent should be avoided when generating a mappingpopulation. Hence, analytic breeding is proposed and genetic mapping can be done at diploidlevel and the ploidy level can be raised by mitotic or meiotic polyploidization.78
General DiscussionFig. 6.3. A comparison of detecting efficiency of crossing over events in the unreduced gametesresulted from a FDR or SDR meiosis. Numbers stand for recombination sites detected by molecularmarkers. In some cases, GISH is more accurate when detecting reciprocal products (in brackets)Meiotic abnormalities in lily hybridsDifferent types of meiotic irregularities has been found during meiosis of interspecific hybridsof lily. Homoeologous chromosome pairing as well as univalents is one of the main featuresat metaphase I during meiosis of lily hybrids. Bivalent numbers ranging from 0 to 12 as wellas univalents are present. These bivalents predominantly involve homoeologous chromosomepairing, while the univalents are chromosomes with failed association (Chapter 3; Barba-Gonzalez et al. 2005a; Lim et al. 2001a; Zhou et al. 2008a). Except homoeologous bivalentsand univalents, abnormal pairing is also observed in some of the genotypes of lily hybrids(Chapter 3). Multivalents and non-homologous bivalents have been found in two of LAhybrids, and it has been proven that a reciprocal translocation exists in the paternal parent‘Connecticut King’ (Chapter 3). Another abnormality is the chromosome disjoining atanaphase stage in the first division. Bivalents divided into two half-bivalents normally,whereas two chromatids of a univalent segregated and moved to different poles (Chapter 3;Lim et al. 2001a; Zhou et al. 2008a). Chromosome breakage also contributes to theirregularity of meiosis. At both metaphase and anaphase I stages, broken chromosomes have79
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A molecular cytogenetic analysis of
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Table of ContentsChapter 1General I
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Chapter 1LilyLilies belong to genus
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Chapter 1counterparts (Finnegan 200
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Chapter 1renewed interest in detect
Page 14 and 15:
Chapter 1recombination, mechanisms
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Chapter 1is only an equational segr
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Chapter 1quite divergent with vario
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Chapter 2An assessment of chromosom
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Chromosome rearrangements in Lilium
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Page 33 and 34: Chromosome rearrangements in Lilium
Page 35 and 36: 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-
Page 62 and 63: Chapter 4of the sexual polyploidize
Page 64 and 65: Chapter 4fragment have the same len
Page 66 and 67: Chapter 5AbstractSupernumerary (B)
Page 68 and 69: Chapter 5their origin, the structur
Page 70 and 71: Chapter 5Fig. 5.1. Discovery of B c
Page 72 and 73: Chapter 5In order to investigate th
Page 74 and 75: Chapter 5Centric breakage and fusio
Page 76 and 77: Chapter 5It has not, however, been
Page 78 and 79: Chapter 6The results presented in t
Page 80 and 81: Chapter 6model for molecular cytoge
Page 82 and 83: Chapter 6Fig. 6.2. The meiosis proc
Page 86 and 87: Chapter 6been detected with GISH an
Page 88 and 89: Chapter 6Another feature caused by
Page 91 and 92: ReferencesAbe, H.A., Nakano, M.N.,
Page 93 and 94: ReferencesChen, Q., and Armstrong,
Page 95 and 96: ReferencesHartlerode, A.J., and Scu
Page 97 and 98: ReferencesLarson, S.R., Kishii, M.,
Page 99 and 100: ReferencesMcClintock, B. 1931. Cyto
Page 101 and 102: ReferencesRai, R., Zheng, H., He, H
Page 103 and 104: ReferencesStewart, R.N. 1947. The m
Page 105: ReferencesZhang, L., Pickering, R.,
Page 108 and 109: Summarychromosome rearrangements. T
Page 111 and 112: SamenvattingLelie (Lilium) is in de
Page 113 and 114: Samenvattingaantal 35 met daarnaast
Page 115 and 116: 摘要百合系百合科百
Page 117 and 118: Acknowledgements淡看世事去
Page 119: Curriculum VitaeSonglin Xie was bor
Page 123: Education Statement of the Graduate
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