Figure 4.

Molecular mechanisms of the drive of knob domains in maize. (a) Kinesin-14 motor proteins, Kindr and Trkin, bind to knob180 and TR-1 repeats, respectively, in meiosis I and II. (b) Kindr and Trkin travel faster on microtubules, pulling the knob towards the upper and lower megaspores. This increases the likelihood that the knob domain will be incorporated into the lower megaspore which will become the egg. (c) When chromosomes pair, they recombine and remain attached by chiasmata. If recombination occurs between the heterozygous locus of interest and the telomere, both sister chromatids on the same side of the bivalent have the same allele, resulting in homomorphic dyads. If recombination occurs between the centromere and a heterozygous locus of interest, strands are exchanged such that each side of the bivalent now has one of each allele for that locus. This creates heteromorphic dyads.