THE EFFECT OF ABNORMAL CHROMOSOME 10 ON TRANSPOSITION OF MODULATOR FROM THE R LOCUS IN MAIZE

Elizabeth Williams ¹ and R. Alexander Brink ¹

¹ Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706

Transposition of the non-specific repressor element, Modulator, from the R locus on chromosome 10 in maize, is enhanced by coupling with the K10 segment at a distance of at least 35 map units from R. There is no detectable interaction in the repulsion phase. The K10 effect appears to be relatively greater in the earlier somatic cell generations during ear development. The transposition rate also is affected by the direction of crosses, being somewhat higher on the ears of F₁ plants which received the compound mutable R allele from the pollen parent. The significance of the behavior of Modulator and other instability phenomena of higher plants is discussed in relation to chromosome organization.