Evidence for somatic sectoring early in aleurone development with the bz1-mu1 allele --Virginia Walbot Most excision events from Mu-induced mutants give rise to tiny spots of revertant tissue in the aleurone (1 - 100 cells) or short streaks in leaf tissue (1 - few hundred cells). Indeed, late timing is considered a feature of the Mutator system (D. S. Robertson, Science 213:1515, 1981). All of the Mu-induced mutables in our collection share this property. In 1987, however, a few progeny ears in a family carrying bz1-mu1 had larger spots (250 - 2,000 cells). This allele contains a 1.4 kb Mu1-like element (Taylor et al., Maydica 31:31, 1986). The kernels with large spots (bz1-mu1 or bz1-mu1/bz1) were selected, and selfed or crossed by bz1 tester. Among the 77 progeny ears, 3 had both kernels with large sectors and fully purple kernels, putative germinal revertants. The remaining 74 ears contained many kernels with large sectors (250 - 2,000 cells), and most progeny ears had at least a few half- or quarter-kernel somatic reversion events. More careful analysis of the distribution of types is in progress. Even the preliminary results demonstrate, however, that selection for large spots can result in a stock with a reasonable frequency of early events, including likely germinal revertants. The nature of the original switch in timing is completely unknown. The only clue is that sister lines grown in adjacent field rows did not show this change in phenotype, suggesting that the switch was not caused by environmental conditions.

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

Return to the MNL 64 On-Line Index
Return to the Maize Newsletter Index
Return to the Maize Genome Database Page