Maize stocks modified to enhance the recovery of Ac-induced mutations

The Activator (Ac) transposable element of maize has had limited use in transposon tagging. Two reasons for this are that Ac is transpositionally most active when it occurs as a single genomic copy and Ac tends to transpose locally on a chromosome. These two features are exploited in the development of a set of stocks where, in each a different region of the maize genome is made more vulnerable to insertion by Ac. Each stock possesses either a pericentric inversion or a reciprocal translocation involving a rearrangement of the short arm of chromosome 1 (1S). In each case the rearranged 1S chromosome has been converted by genetic recombination so that it possesses an Ac-bearing allele of the pericarp color (p1) locus. Also incorporated into the stocks are color factors that give spotted aleurone when Ac is present. By noting pericarp color and aleurone spotting pattern, one can increase the efficiency of mutation screens more than 10-fold by selecting only kernels that possess a transposed Ac. Thirty-nine stocks have been converted and are now available for use in transposon tagging.