Genetic and molecular characterization of a-mrh-Mrh, a new mutable system of Zea mays.
A new allele of the maize A1 gene, a gene required for anthocyanin pigment biosynthesis, was identified in a genetic stock exhibiting a high frequency of chromosome breakage at the second microspore mitosis. This allele, a-mrh, is unstable in both somatic and germinal tissue when an independent locus, Mrh, is present in the genome. a-mrh was molecularly cloned, and a 246 bp DNA insertion with characteristics of a transposable element was identified within the fourth exon of the gene. Southern blot analysis of germinal derivatives of a-mrh suggests that the DNA insert rMrh is excised from the locus when a wild-type phenotype is restored. Genetic crosses with components of other two-element mutable systems of maize failed to induce mutability. We therefore conclude that rMrh is a member of a new, two-element transposon system of maize. The genetic and molecular characteristics of the elements involved are discussed with respect to stress-activated transposition, response of an element to developmental signals, and a possible new role of plant transposons in gene evolution.
Shepherd
N S
NS
Central Research and Development Department, E.I. du Pont de Nemours Company, Wilmington, Delaware 19880-0328.
Rhoades
M M
MM
Dempsey
E
E
D000483:Alleles; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D004247:DNA / Q000235:genetics; D004251:DNA Transposable Elements; D008040:Genetic Linkage; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D003313:Zea mays / Q000235:genetics*
D004251:DNA Transposable Elements; D004247:DNA