[Genomic variation in maize]. Final project report
These studies have sought to learn how different DNA sequences and sequence arrangements contribute to genome plasticity in maize. We describe quantitative variation among maize inbred lines for tandemly arrayed and dispersed repeated DNA sequences and gene families, and qualitative variation for sequences homologous to the Mutator family of transposons. The potential of these sequences to undergo unequal crossing over, non-allelic (ectopic) recombination and transposition makes them a source of genome instability. We have found examples of rapid genomic change involving these sequences in Fl hybrids, tissue culture cells and regenerated plants. We describe the repetitive portion of the maize genome as composed primarily of sequences that vary markedly in copy number among different genetic stocks. The most highly variable is the 185 bp repeat associated with the heterochromatic chromosome knobs. Even in lines without visible knobs, there is a considerable quantity of tandemly arrayed repeats. We also found a high degree of variability for the tandemly arrayed 5S and ribosomal DNA repeats. While such variation might be expected as the result of unequal cross-over, we were surprised to find considerable variation among lower copy number, dispersed repeats as well. One highly repeated sequence that showed a complex tandem and dispersed arrangement stood out as showing no detectable variability among the maize lines. In striking contrast to the variability seen between the inbred stocks, individuals within a stock were indistinguishable with regard to their repeated sequence multiplicities.
- Research Organization:
- Oregon State Univ., Corvallis, OR (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG06-85ER13377
- OSTI ID:
- 10179939
- Report Number(s):
- DOE/ER/13377-6; ON: DE92040970
- Resource Relation:
- Other Information: PBD: [1991]
- Country of Publication:
- United States
- Language:
- English
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