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Chapter 3abnormal bivalents, in all other cases variable frequencies of bivalents and univalents wereobserved. Because of chromosome pairing abnormalities, the expected metaphase Iorientation at the equatorial plate of the cell was rare.Anaphase I separationSince anaphase I separation of homoeologous chromosomes occurred regularly only in someof the pollen mother cells, normal metaphase I orientation had occurred in those cases. Inother cases, the chromosomes (half-bivalents) were present haphazardly in the cells (Fig. 3.2a,b, c and d). Nevertheless, it was possible to identify the pairs of half-bivalents with andwithout recombinant segments in the sister and non-sister chromatids. The remarkable featurewas that it was possible to identify the types of crossovers that had occurred between the nonsisterchromatids of the pairs of homoeologous chromosomes during meiosis based ondifferential fluorescence. Based on the number and positions of recombinant segments on thenon-sister chromatids it was possible to classify the types of intergenomic recombinationevents that had occurred. These were classified into five classes: a) two strand single (Fig.3.2a and c), b) two strand double (Fig. 3.2b and c), c) three strand double (Fig. 3.2a and d), d)four strand double (Fig. 3.2a, b and d) and e) multiple cross-overs (Fig. 3.2d). The frequenciesof each of these events were estimated in five genotypes (Table 3.2). From an analysis of atotal of 637 pairs of half-bivalents it was evident that a large majority (65 %) were two strandsingle crossing overs, 5.5 % were two strand double, 3.0 % three strand double, 9.3 % fourstrand double and 17.3 % were multiple crossing over events. Although there was differencesin the frequencies of these events, two conclusions could be made from these observations. 1)Regardless of the type of cross-over event, equational separation had occurred for therecombinant segments. 2) All the five crossover types of half-bivalents were similar to theevents that are expected (Fig. 3.2) following a normal meiosis in the parent. This evidentlyindicated that despite genome differentiation between the genomes of the species of L.longiflorum and Asiatic lilies they retained homoeology that enabled normal crossing-overbetween the homoeologous pairs of chromosomes. In the two genotypes (006001-6 and006001-13) with multivalent and nonhomologous bivalent formation there was no deviation atanaphase I that could be observed with regard to disjunction as compared with othergenotypes without multivalent formation.38
Intergenomic recombination and chromosome translocation in Lilium hybridsTable 3.2. Crossover events in 166 anaphase I pollen mother cells from five progenies of aninterspecific LA hybridGenotypeNr. ofcellsPairs ofrecombinantchromosomesSingleTwo strandDoubleThreestrandsdoubleFourstrandsdoubleMultiplecrossover006001-6 52 194 115 5. 11 15 48006001-9 15 75 41 6 0 9 19006001-13 4 9 8 0 0 1 0006001-16 66 266 180 20 5 23 38006001-88 29 93 70 4 3 11 5TotalFrequency(%)166 637 41465355.5193.0599.311017.3DiscussionIn order to resolve the difference between intergenomic recombination and chromosometranslocation, we have investigated two genotypes with translocations (006001-6 and 006001-13) and 11 genotypes without translocations (Table 3.1). Because of disturbed chromosomepairing between L and A genomes during meiosis in the F1 hybrids, the pairing configurationsreported in L. maximowiczii which had normal chromosome synapsis (Noda 1960) could notbe found in any of the genotypes used in the present study. Nevertheless, non-homologousbivalents and multivalent formation (Figs. 1 and 2) were clear enough evidence for thepresence of translocations in two genotypes. A unique feature of the translocation in L.maximowiczii was that as a result of translocation it had given rise to two pairs ofheteromorphic chromosomes whose modes of distribution during anaphase I stage could beidentified morphologically due to the inequality of the arms. Taking advantage of the easilyidentifiable interchanged chromosomes, Noda (1960) quantified the frequencies of crossingoverin the interstitial segments based on equational segregations at anaphase I. Unlike intraditional staining techniques, however, GISH provides opportunities to identify the modesof chromosome segregation during anaphase I due to differential fluorescence. This facilitates39
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 10 and 11: Chapter 1counterparts (Finnegan 200
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 43: 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 84 and 85: Chapter 6over events during FDR mei
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
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ReferencesRai, R., Zheng, H., He, H
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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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