Organization of the R chromosome region in maize: Report of progress
The maize R gene exhibits various features of regulated gene expression. Alleles collected from diverse geographic sources govern the presence and distribution of anthocyanin pigmentation, plant part by plant part. Some alleles confer stable patterns of pigmentation, while others confer unstable somatic phenotypes with frequent germinal mutations. A remarkable change in expression occurs when certain alleles are combined as heterozygotes. Efficient analysis of such phenomena requires a basic understanding of allelic organization. R is organized on a modular basis, with polymorphism both for number and kind of unit. An allele may carry one such unit, or two or more associated with duplicated chromosome segments. When multiple, each unit mutates independently, with its variants constituting a single complementation group. Because such units behave as separate genes, they have been referred to as ''genic elements''. Alleles organized as gene complexes often have been utilized in the discovery and initial description of phenomena of R regulation. When this is so, subsequent analysis proceeds in two stages. The complex is first fractionated by recombination into simpler derivatives that manifest the phenomenon. Such derivatives, preferably carrying a single element, are then candidates for detailed analysis. For the present study, insertional mutagenesis using transposable sequences proved the most effective means of producing R variants for fine structure study. It was also necessary to describe the pattern of recombination that prevailed in this region when insertions were present. With the advent of molecular cloning of maize genes by transposon tagging, a more direct means of investigating R structure was envisioned. 12 refs.
- Research Organization:
- Wisconsin Univ., Madison (USA). Lab. of Genetics
- DOE Contract Number:
- FG02-86ER13539
- OSTI ID:
- 6709393
- Report Number(s):
- DOE/ER/13539-1; ON: DE87007966
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Organization of the R chromosome region in maize. [Progress report]
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