c2-m1 - the frequency of revertant and colorless derivatives

The c2-m1 allele, an Spm allele (McClintock, Carnegie Yearbook 62:486, 1963), is an autonomous-acting allele that has a pattern of mutability that can be classified as medium-early.

In a search for revertants (Rev) among two families of plants that were homozygous c2-m1/c2-m1 and were test crossed by a marked tester, the following was found:
 
Rev (%) Spotted Clls (%) Other Total
1 65(6.2) 980 1 (0.9) 2 1048
2 40(4.2) 902 2 ( .2) 5  949

In previous studies with En-controlled alleles, as a-m(papu) (Peterson, TAG 40:367, 1970), it is the colorless non-spotting types that appear in high frequency. This high frequency of Rev relative to the low frequency of colorless types may possibly be indicative of its exon vs. intron placement of the element within the c2 locus.

Peter A. Peterson

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

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