COLD SPRING HARBOR, NEW YORK
Cold Spring Harbor Lab
BERKELEY, CALIFORNIA1
University of California
A new Mu-induced suppressible
mutation
--J. Colasanti, M. Freeling1
and V. Sundaresan
Recently a Mu-induced mutation at
the hcf106 locus has been described which appears to be suppressed
when Mu-activity is lost (Martienssen et al., EMBO J. 8:1633-1639,
1989). This raises the possibility that other Mu-induced mutations
may also be suppressible by Mu inactivation. We have now found that
this appears to be the case with a dwarf mutation isolated in a Mu
stock. This mutant (MF 6316-21) arose in a self of a Mu outcross
ear and was observed to segregate at less than 1 in 4 in this ear. In subsequent
generations of selfing, the mutation disappeared altogether. DNA from the
later generations was analyzed and the Mu1 elements were found to
be methylated, suggesting that Mu activity was lost (Chandler and
Walbot, PNAS 83:1761-1771, 1986; Bennetzen, MGG 208:45-51, 1987). During
the winter of 1988, plants from this line were crossed to active Mu
lines and the progeny were selfed this summer. The seeds from these selfs
were planted. One out of 5 selfs screened so far have been found to segregate
dwarf plants, at ratios of 1 in 4, suggesting that the mutation has been
rescued by crossing to active Mu stocks. Therefore, the suppression
phenomenon described for hcf106 may be representative of a whole
class of Mu-induced mutations.
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