INDUCTION OF CENTROMERIC ACTIVITY IN MAIZE BY SUPPRESSOR OF MEIOTIC DRIVE-1

The Abnormal chromosome 10 (Ab10) in maize causes normally-quiescent b lacks of heterochromatin called knobs to function as meiotic centromer es. Under these circumstances genetic markers associated with knobs ex hibit meiotic drive, i.e., they are preferentially transmitted to prog eny. Here we describe a mutation called suppressor of meiotic drive (s md1) that partially suppresses meiotic drive, and demonstrate that smd 1 causes a quantitative reduction in the mobility of knobs on the meio tic spindle. We conclude that Smd1 encodes a product that is necessary for the activation of ectopic centromeres, and that meiotic drive occ urs as a consequence of the resulting change in chromosome movement. A s a genetic system, Ab10 offers a new and powerful approach for analyz ing centromere/kinetochore function.