COLD SPRING HARBOR, NEW YORK
Cold Spring Harbor Laboratory
Mu1-associated hm1alleles
--Guri Johal and Steven P. Briggs
A collection of hm1 mutants from
a Mutator background (Briggs, Curr. Topics Plant Biochem. Physiol. 6:59-67,
1987) was assayed for co-segregation of the mutant alleles with Mu1
homologous sequences. The mutant alleles were characterized by hybridization
with the Pioneer RFLP probes PIO200644 and PIO200044, which are 5 cM proximal
and distal, respectively, to hm1. Both probes could distinguish
the alleles in our material, restricting our error in classification to
double crossovers (estimated to occur in less than 1% of the progeny).
For Mu1 hybridizations, the DNA was cut with either SstI,
BamHI, or HindIII, none of which cut Mu1. Southern
blots were probed with the AvaI-BstNI fragment of Mu1,
isolated from pAB-5 (pAB-5 was obtained from Loverine Taylor). Analysis
was simplified by outcrossing progeny in which the Mutator system was inactive,
to reduce the number of Mu1-homologous fragments. Two mutants were
identified in which a unique Mu1-homologous fragment co-segregated
with the mutant hm1 allele. No recombination between the co-segregating
Mu1-homologous fragments and the hm1-flanking RFLP probes
has been observed in studies of 74 progeny for the hm1-6561 allele
and 91 for the hm1-10621 allele. Our tentative conclusion is that
these co-segregating fragments are Mu1 insertions in the Hm1
gene.
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