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United States Department of Agriculture

Agricultural Research Service

Title: Mu Element-Generated Gene Conversions in Maize Attenuate the Dominant Knotted Phenotype

Authors
item Mathern, Julie - USDA/UCB PGEC
item Hake, Sarah

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 7, 1997
Publication Date: October 7, 1997
Citation: Mathern, J., Hake, S.C. 1997. Mu element-generated gene conversions in maize attenuate the dominant knotted phenotype. Genetics 147(1):305-14.

Interpretive Summary: The knotted1 gene was first defined by dominant mutations that affect leaf morphology. Mutator (Mu) insertions near the junction of the two repeats suppress the leaf phenotype to different degrees depending on the position of the insertion. The Mu insertions also cause other derivative effects. We propose that gene conversion, stimulated by the double-strand break of the Mu excision, gave rise to these derivatives.

Technical Abstract: The knotted1 gene was first defined by dominant mutations that affect leaf morphology. The original allele, Kn1-O, results from a 17-kb tandem duplication. Mutator (Mu) insertions near the junction of the two repeats suppress the leaf phenotype to different degrees depending on the position of the insertion. The Mu insertions also increase the frequency of recombination at Kn1-O to create derivative alleles in which the Mu element and one copy of the repeat are lost. These derivatives are normal in appearance. Here we describe two derivatives that retained the tandem duplication but gained insertions of 1.7 and 3 kb in length in place of the Mu element. In each case, the inserted DNA is a sequence that normally flanks the distal repeat unit. Thus, each derivative consists of a tandem duplication in which the repeat unit has been extended at its distal end by the length of the new insertion. The 1.7-kb insertion dampens the phenotype, as did the original Mu insertion, whereas the 3-kb insertion completely suppresses the knotted phenotype. We propose that gene conversion, stimulated by the double-strand break of the Mu excision, gave rise to these derivatives.

Last Modified: 10/22/2014
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