Molecular cytogenetic genome analysis of a cultivated cotton (Gossypium hirsutum L.) /
Fluorescent in situ hybridization (FISH) was performed on metaphase chromosomes of the cotton AD-genome tetraploid Gossypium hirsutum and diploid species closely related to its ancestors. Four classes of probes were used: a bacterial artificial chromosome (BAC), 5S and 18S-28S rDNA repeats, a Tyl-c...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739793761&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Fluorescent in situ hybridization (FISH) was performed on metaphase chromosomes of the cotton AD-genome tetraploid Gossypium hirsutum and diploid species closely related to its ancestors. Four classes of probes were used: a bacterial artificial chromosome (BAC), 5S and 18S-28S rDNA repeats, a Tyl-copia-like retrotransposon and 20 uncharacterized interspersed repetitive elements. BAC-FISH demonstrated the reliable detection of single/low-copy genomic clones in plants, establishing a powerful tool for physical mapping. Eleven 18S-28S rDNA loci were detected in G. hirsutum; 5 in the A-subgenome and 6 in the D-subgenome. The G. hirsutum subgenomes each had 2 more 18S-28S rDNA loci than putative A- genome and D-genome diploid ancestors of the tetraploid. Dual-color FISH of 5S and 18S-28S rDNA loci allowed size comparisons between rDNA loci on homoeologous chromosomes, revealing significant changes in the sizes of Gossypium 18S-28S rDNA loci. Tyl-copier like retrotransposon clone A108 yielded strong FISH signal on all G hirsutum chromosomes, roughly equal in intensity between the A- and D-subgenomes. Hybridization of Al 08 to G. arboreum gave similar results, whereas no signal was detected on chromosomes of the D-genome diploid G. raimondii, the putative diploid ancestor of the G. hirsutum D-subgenome. FISH of 20 G. hirsutum repetitive elements revealed that 17 of the 20 occurred in both subgenomes of G. hirsutum, while 3 were specific to the A-subgenome. Eight elements, 2 subgenome-specific and 6 non-subgenome specific elements, were selected for FISH to G. arboreum (AZ), G. raimondii (D5) and / or an A2D5 synthetic diploid. All eight selected elements hybridized to the A2 genome of G. arboreum but none hybridized to the D5 genome of G. raimondii. The results described herein indicate that repetitive elements can behave in a highly variable and dynamic nature in polyploid organisms and represent a significant advance in the understanding of polyploid genome evolution, a topic with profound implications for the evolution of plant species. |
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| Item Description: | Vita. "Major Subject: Genetics". |
| Physical Description: | x, 97 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 75-94. |