University of Oregon
All eight insertions alter pigment synthesis in all kernel and plant tissues pigmented by B-Peru, suggesting that each insertion has disrupted a region of the gene required for expression in all tissues.
Two insertion alleles have been cloned using B sequences. b-Perum5 contains an Spm-related element. Restriction mapping of the clone and genetic experiments suggest that it is an Spm-w element. Southern analysis of the b-Perum220 allele suggested that there had been a complex rearrangement at the B-Peru locus, including a duplication of B-Peru sequences. The cloning of a portion of the b-Perum220 allele revealed that a Mu1.7 element had inserted upstream of the B-Peru coding region.
Genetic analysis of one other unstable allele, b-Perum216, is consistent with the presence of a dSpm element in the B-Peru gene. None of the four unstable alleles contained Ac activity. Genetic and molecular analysis of the remaining five insertion alleles is underway.
These results demonstrate that both
Mutator and Spm elements were active in our stocks. Crosses examining
the progenitors of these stocks showed that Spm activity (identified
by crosses to wx-m8, a dSpm) was present in the original
Mutator stocks obtained from D. Robertson. No Spm activity was detected
in our B-Peru and b r-g stocks. These results, combined
with the low spontaneous mutation frequency observed in the progenitor
B-Peru stock (less than 5 X 10-6) (MNL 62:56), suggest that the
source of the Spm activity was the Mutator stocks. Thus, when using
Mutator in transposon tagging experiments, we recommend monitoring the
mutagenesis stocks and isolated mutants for the activity of other transposable
to the MNL 64 On-Line Index
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