A Kinesin-14 Motor Activates Neocentromeres to Promote Meiotic Drive in Maize.

Maize abnormal chromosome 10 (Ab10) encodes a classic example of true meiotic drive that converts heterochromatic regions called knobs into motile neocentromeres that are preferentially transmitted to egg cells. Here, we identify a cluster of eight genes on Ab10, called the Kinesin driver (Kindr) complex, that are required for both neocentromere motility and preferential transmission. Two meiotic drive mutants that lack neocentromere activity proved to be kindr epimutants with increased DNA methylation across the entire gene cluster.

The maize Ab10 meiotic drive system maps to supernumerary sequences in a large complex haplotype.

The meiotic drive system on maize abnormal chromosome 10 (Ab10) is contained within a terminal domain of chromatin that extends the long arm of Ab10 to approximately 1.3 times the size of normal chromosome 10L. Ab10 type I (Ab10-I) does not recombine with normal chromosome 10 (N10) over an approximately 32-cM terminal region of the long arm.

Plant neocentromeres: fast, focused, and driven.

Plant neocentromeres are large heterochromatic domains that associate with microtubules and move rapidly poleward during meiotic cell division. In maize, neocentromeres are part of a process that leads to the preferential recovery (meiotic drive) of knobs in progeny. These 'classical' plant neocentromeres differ from animal neocentromeres by their morphology, inability to mediate sister chromatid cohesion, and their rates of movement on the spindle.

Four loci on abnormal chromosome 10 contribute to meiotic drive in maize.

We provide a genetic analysis of the meiotic drive system on maize abnormal chromosome 10 (Ab10) that causes preferential segregation of specific chromosomal regions to the reproductive megaspore. The data indicate that at least four chromosomal regions contribute to meiotic drive, each providing distinct functions that can be differentiated from each other genetically and/or phenotypically. Previous reports established that meiotic drive requires neocentromere activity at specific tandem repeat arrays (knobs) and that two regions on Ab10 are involved in trans-activating neocentromeres.

The meiotic drive system on maize abnormal chromosome 10 contains few essential genes.

In maize, a distal portion of abnormal chromosome 10 (Ab10) causes the meiotic drive of itself as well as many unlinked heterochromatic regions known as knobs. The Ab10 drive system, which encodes trans- as well as cis-acting components, occupies a large region of chromosome 10L equivalent to approximately 3% of the genome. Here we describe five new structural mutations of Ab10 (five deletions and a duplication) that arose from a screen for meiotic drive mutants.

Independently regulated neocentromere activity of two classes of tandem repeat arrays.

Tandem repeat arrays often are found in interstitial (i.e., normally gene-rich) regions on chromosomes.