Date of Award:

5-1-1998

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

Richard Wang

Committee

Richard Wang

Committee

Bradley Kropp

Committee

Noelle Cockett

Abstract

DNA markers for Aegilops caudata C-genome chromosomes will be useful in linkage studies of disease resistance and alien gene introgression, e.g., these markers can be tools in gene mapping and plant breeding. However, the individual chromosomes have not been characterized at the molecular level in Ae. Caudata. The objective of this study was to identify and characterize DNA markers for Ae. caudata chromosomes using the randomly amplified polymorphic DNA (RAPD) technique. DNA samples from Ae. caudata, Triticum aestivum (bread wheat), amphiploid of T. aestivum X Ae. caudata, and six disomic addition lines of T. aestivum carrying a pair of Ae. caudata chromosomes were used as templates for RAPD. Twenty-four out of 590 arbitrary decamer primers tested produced polymorphic bands, which were classified into four types of chromosome-specific RAPD markers based on their presence in the six disomic addition lines. Two, three, two, three, three, four, and two different markers were specific for the chromosomes A, B, C, D, E, F, and G of the C genome, respectively. One primer produced a C-genome specific RAPD marker. Four primers produced one marker each for two chromosomes of the C genome. All these markers were identified, isolated, cloned, and sequenced in this experiment. The sequences of these markers were compared with sequences in the GenBank database but no identity was found. At least two of the sequences have short repeats. The specificity of each marker was further confirmed with Southern hybridization by using the cloned marker as a hybridization probe. In situ hybridization was also attempted to localize markers to the chromosomes, but hybridization signals were too weak to be detected. The results from this study are very preliminary. However, it is conceivalbe that the markers, in conjunction with RFLP and isozyme analyses, can be used to detect linkage with disease resistance. The RAPD markers most closely linked to disease genes will be very useful in marker-assisted selection of disease resistant progeny.

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