Genetic and molecular characterization of a-mrh-Mrh, a new mutable system of Zea mays

Dev Genet. 1989;10(6):507-19. doi: 10.1002/dvg.1020100610.


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.

MeSH terms

  • Alleles*
  • Base Sequence
  • Chromosome Mapping
  • Cloning, Molecular
  • Crosses, Genetic
  • DNA / genetics
  • DNA Transposable Elements
  • Genetic Linkage
  • Molecular Sequence Data
  • Mutation*
  • Phenotype
  • Zea mays / genetics*


  • DNA Transposable Elements
  • DNA