Distinct kinesin motors drive two types of maize neocentromeres

Abstract

A maize chromosome variant called abnormal chromosome 10 (Ab10) converts knobs on chromosome arms into neocentromeres, causing their preferential segregation to egg cells in a process known as meiotic drive. We previously demonstrated that the gene <i>Kinesin driver</i> (<i>Kindr</i>) on Ab10 encodes a kinesin-14 required to mobilize neocentromeres made up of the major tandem repeat knob180. Here we describe a second kinesin-14 gene, <i>TR-1 kinesin</i> (<i>Trkin</i>), that is required to mobilize neocentromeres made up of the minor tandem repeat TR-1<i>. Trkin</i> lies in a 4-Mb region of Ab10 that is not syntenic with any other region of the maize genome and shows extraordinary sequence divergence from <i>Kindr</i> and other kinesins in plants. Despite its unusual structure, <i>Trkin</i> encodes a functional minus end-directed kinesin that specifically colocalizes with TR-1 in meiosis, forming long drawn out neocentromeres. TRKIN contains a nuclear localization signal and localizes to knobs earlier in prophase than KINDR. The fact that TR-1 repeats often co-occur with knob180 repeats suggests that the current role of the TRKIN/TR-1 system is to facilitate the meiotic drive of the KINDR/knob180 system.