Organization of the R chromosome region in maize. [Progress report]
The maize R gene is said to show more phenotypic variation than any other locus in higher plants. The locus is organized on a modular basis. Individual units -- termed ``genic elements`` since they function as independent genes -- differ by regulating the presence, intensity and timing of anthocyanin pigmentation in different plant parts. A given allele may comprise only one genic element or, more commonly, an allele comprises a complex of elements, organized as a small gene family. Different numbers and combinations of even a few genic elements gives a large number of possible complexes. Following molecular cloning of R we concentrated effort initially on a genic element that confers strong pigmentation only to the kernel. The functional limits of this gene (R-sc:124) had been defined genetically by extensive mutagenesis with the transposable element Dissociation. Subsequently, a set of contiguous probes were prepared from a genomic clone of R-sc:124. This set of probes distinguishes among various R-genic elements, providing physical evidence on gene complexes whose overall organization had been determined genetically. Some surprises were in store, as detailed below. These same tools made it possible to analyze the effect of position of Ds insertion within R-sc:124 on spotting phenotype, germinal reversion rate and frequency of Ds excision. Furthermore, we are now able to address in much more detail some of the unique phenomena of R action, such as a difference in kernel phenotype when certain alleles are transmitted by ovules relative to sperm. The last category of objectives is discussed in the section entitled ``updated research plan.``
- Research Organization:
- Wisconsin Univ., Madison, WI (United States). Lab. of Genetics
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-86ER13539
- OSTI ID:
- 10134663
- Report Number(s):
- DOE/ER/13539-3; ON: DE92010791
- Resource Relation:
- Other Information: PBD: Mar 1992
- Country of Publication:
- United States
- Language:
- English
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Organization of the R chromosome region in maize: Report of progress
Somatic variegation and germinal mutability reflect the position of transposable element dissociation within the maize R gene