Abstract
The I-R element at the R locus destabilizes kernel pigmentation giving the variegated pattern known as stippled ( R-st). In trans linkage phase with R-st the element was shown to act as a modifier of stippled, intensifying seed spotting in parallel with effects of the dominant linked modifier M-st. Presence of I-R in the genome was, therefore, shown to be detectable as a modifier of R-st. When this test was used, new modifiers resembling M-st were often detected following mutations of R-st to the stable allele R-sc. Such mutations evidently occurred by transposition of I-R away from the R locus to a site where it was identifiable as a modifier. M-st may be such a transposed I-R. Analysis of mutations to R-sc during the second (sperm-forming) mitosis in pollen grains showed that some of the transposed I-R elements were linked with R, whereas others assorted independently. Their strengths varied from barely discernible to a level equal to M-st. Overreplication frequently accompanied transposition at the sperm-forming mitosis, leading to transposed I-R elements in both the mutant and nonmutant sperm.
Full Text
The Full Text of this article is available as a PDF (741.7 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Brink R A, Nilan R A. The Relation between Light Variegated and Medium Variegated Pericarp in Maize. Genetics. 1952 Sep;37(5):519–544. doi: 10.1093/genetics/37.5.519. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Greenblatt I M, Brink R A. Twin Mutations in Medium Variegated Pericarp Maize. Genetics. 1962 Apr;47(4):489–501. doi: 10.1093/genetics/47.4.489. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McCLINTOCK B. Chromosome organization and genic expression. Cold Spring Harb Symp Quant Biol. 1951;16:13–47. doi: 10.1101/sqb.1951.016.01.004. [DOI] [PubMed] [Google Scholar]
- McWhirter K S, Brink R A. Continuous Variation in Level of Paramutation at the R Locus in Maize. Genetics. 1962 Aug;47(8):1053–1074. doi: 10.1093/genetics/47.8.1053. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peterson P A. The Pale Green Mutable System in Maize. Genetics. 1960 Jan;45(1):115–133. doi: 10.1093/genetics/45.1.115. [DOI] [PMC free article] [PubMed] [Google Scholar]