Chromosome fragile sites in Arabidopsis harbor matrix attachment regions that may be associated with ancestral chromosome rearrangement events.

Mutations in the BREVIPEDICELLUS (BP) gene of Arabidopsis thaliana condition a pleiotropic phenotype featuring defects in internode elongation, the homeotic conversion of internode to node tissue, and downward pointing flowers and pedicels. We have characterized five mutant alleles of BP, generated by EMS, fast neutrons, x-rays, and aberrant T-DNA insertion events. Curiously, all of these mutagens resulted in large deletions that range from 140 kbp to over 900 kbp just south of the centromere of chromosome 4.