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. Comparative RFLP mapping demonstrates that multiple independent rearrangements are responsible for the current organization of Ab10-I, including a set of nested inversions and at least one long supernumerary segment at the end of the chromosome. Four major meiotic drive functions, i.e., the recombination effect, smd3, 180-bp neocentromere activity, and the distal tip function, all map to the distal supernumerary segment. TR-1-mediated neocentromere activity (the fifth known drive function) is nonessential in the type II variant of Ab10 and maps to a central region that may include a second supernumerary insertion. Both neocentromere activity and the recombination effect behave as dominant gain-of-function mutations, consistent with the view that meiotic drive involves new or alien gene products. These and other data suggest that the Ab10 meiotic drive system was initially acquired from a related species and that a complex haplotype evolved around it.
Mroczek
Rebecca J
RJ
Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA.
Melo
Juliana R
JR
Luce
Amy C
AC
Hiatt
Evelyn N
EN
Dawe
R Kelly
RK
D001483:Base Sequence; D002503:Centromere / Q000378:metabolism; D002869:Chromosome Aberrations; D002874:Chromosome Mapping / Q000379:methods; D032461:Chromosomes, Plant; D003433:Crosses, Genetic; D020440:Gene Duplication; D015321:Gene Rearrangement / Q000502:physiology*; D017343:Genes, Plant; D006239:Haplotypes; D008540:Meiosis / Q000235:genetics; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D003313:Zea mays / Q000235:genetics*