Mutations in homeotic genes disturb the spatial and timing patterns of development often leading to the appearance of tissues in abnormal locations. In plants, homeotic genes are known to be involved in floral development. Many floral homeotic genes code for proteins with a highly conserved domain designated the MADS box, which acts as a sequence-specific DNA binding protein. Three floral development mutants were isolated from a M2 fast neutron irradiated barley population. The phenotypes are multiovary, i.e. stamens replaced with carpels (mo7a), stamens replaced with carpels and lodicules converted to sepal-like structures (mo6b), and only one of the three stamens converted to a carpel in only some of the florets (mo8). These phenotypes resemble the Arabidopsis mutants APETALA3(AP3) and PISTILATA(PI). The mo6b and mo7a mutants were mapped to the centromeric region of chromosome 1(7H) (mo6b) and to the telomeric region of chromosome 3(3H) (mo7a). A barley genomic clone was identified with an Arabidopsis PI probe and a low copy subclone, JS192.1, was found to be strongly linked to the mo6b trait. A cDNA clone was identified with sequence identity to the genomic coding region and with high homology to the AP3 gene family. This cDNA hybridized to two barley genomic bands that mapped to mo6b and mo7a locations. The JS192.1 and the cDNA probes identified five BACs from a 1.5X Morex library