Germ Line and Somatic Mutator Activity: Are they Functionally Related?

  • Donald S. Robertson
  • David W. Morris
  • Philip S. Stinard
  • Bradley A. Roth
Part of the Basic Life Sciences book series (BLSC, volume 47)


Results of experiments to test for a relationship, if any, between somatic Mutator (Mu) activity (somatic mutability) and germline Mu activity are described. Somatic Mu activity was measured by the intensity of the mutable pattern in unstable al-Mum aleurone mutants. Germinal activity was determined by the frequency with which a Mu plant transmitted new mutants to its outcross progeny plants. None of the experiments demonstrated tight linkage between these two Mu-regulated phenomena. Not all plants with intense somatic mutability patterns exhibited germline activity. Nor did all plants that had little or no somatic mutability lack germinal activity. In one inbred lineage, which had retained an intense somatic mutability pattern for four generations, there was a sudden shift to low somatic mutability in the progeny of the fifth generation. Some representatives of this lineage, taken from different generations but all with intense mutability, had germinal activity, but others did not. The same was true for the low-intensity lines observed in the progeny of the fifth generation. The lines with a low-intensity somatic mutability pattern had Mu elements that were modified at their HpaII sites. This modification was found in “low” somatic mutability lines with and “low” somatic mutability lines without germinal Mu activity.

At present, there is insufficient evidence to establish how germline activity and somatic mutability in Mutator stocks are regulated and if they are regulated via a common mechanism. There is evidence that DNA modification is involved in both phenomena, but more information on the state of modification of the element inserted at the mutant aleurone locus in different situations with respect to levels of somatic mutability and germinal activity is needed before the role of modification in these two aspects of the Mutator system can be fully understood. What role, if any, putative regulators of somatic activity have in germinal activity is yet to be determined.


Somatic Mutability Mutable Seed Stable Derivative Mutability Score Medium Mutability 
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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Donald S. Robertson
    • 1
  • David W. Morris
    • 2
  • Philip S. Stinard
    • 1
  • Bradley A. Roth
    • 3
  1. 1.Department of GeneticsIowa State UniversityAmesUSA
  2. 2.Department of Biological SciencesGeorge Washington UniversityUSA
  3. 3.Plant Gene Expression Center U.S. Department of AgricultureAgricultural Research ServiceAlbanyUSA

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