A molecular and cytogenetic characterization of asymmetric somatic hybrids of Nicotiana was performed to study the use of somatic hybridization as a tool for gene transfer between plant species. The asymmetric somatic hybrids had been previously formed by protoplast fusion between wild-type Nicotiana tabacum and a plant line of N. plumbaginifolia carrying a stably integrated kanamycin-resistance gene. These plants were examined with respect to their morphology, fertility, organellar and nuclear genomic organization, and inheritance of the selectable marker. To determine the extent of genomic asymmetry in the hybrids, a species-specific repetitive DNA sequence was cloned from N. plumbaginifolia and used as a probe for both dot blot and in situ hybridization studies. Dot-blot hybridization data indicated two groups of hybrid plants: Asymmetric hybrids containing 15-25% N. plumbaginifolia DNA and extremely asymmetric hybrids with 1-4% N. plumbaginifolia DNA. Using in situ hybridization it was possible to visualize individual N. plumbaginifolia chromosomes in the hybrids. The asymmetric hybrids retain 8-12 chromosomes and chromosome fragments from N. plumbaginifolia, whereas the extremely asymmetric hybrids contain only a single N. plumbaginifolia chromosome. In several of the hybrids it was possible to show the presence of intergenomic translocations between the chromosomes of N. tabacum and N. plumbaginifolia. RFLP analysis, using a cloned 5S-gene repeat sequence, provided evidence for chromosomal linkage of the kanamycin-resistance gene and a 5S-gene cluster from N. plumbaginifolia. Absence of this linkage was correlated with intergenomic translocations in two of the hybrids. Analysis of organellar DNAs was performed to detect any extra-nuclear genomic recombination in the hybrids. The results of these analyses were correlated with morphological and / fertility data in an attempt to understand the molecular basis of male sterility and partial female fertility exhibited in the asymmetric hybrids. / Source: Dissertation Abstracts International, Volume: 52-02, Section: B, page: 0663. / Major Professor: George W. Bates. / Thesis (Ph.D.)--The Florida State University, 1990.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78433 |
| Contributors | Piastuch, William Craig., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 134 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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