Widespread gene conversion in centromere cores.
Centromeres are the most dynamic regions of the genome, yet they are typified by little or no crossing over, making it difficult to explain the origin of this diversity. To address this question, we developed a novel CENH3 ChIP display method that maps kinetochore footprints over transposon-rich areas of centromere cores. A high level of polymorphism made it possible to map a total of 238 within-centromere markers using maize recombinant inbred lines. Over half of the markers were shown to interact directly with kinetochores (CENH3) by chromatin immunoprecipitation. Although classical crossing over is fully suppressed across CENH3 domains, two gene conversion events (i.e., non-crossover marker exchanges) were identified in a mapping population. A population genetic analysis of 53 diverse inbreds suggests that historical gene conversion is widespread in maize centromeres, occurring at a rate >1x10(-5)/marker/generation. We conclude that gene conversion accelerates centromere evolution by facilitating sequence exchange among chromosomes.
Department of Plant Biology, University of Georgia, Athens, Georgia, United States of America.
Jinghua
J
Shi
Sarah E
SE
Wolf
John M
JM
Burke
Gernot G
GG
Presting
Jeffrey
J
Ross-Ibarra
R Kelly
RK
Dawe
D005075:Biological Evolution; D002503:Centromere / Q000235:genetics / Q000378:metabolism; D032461:Chromosomes, Plant; D005785:Gene Conversion; D005819:Genetic Markers; D005828:Genetics, Population; D017404:In Situ Hybridization, Fluorescence; D018386:Kinetochores / Q000378:metabolism; D015810:Linkage Disequilibrium; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018626:Retroelements / Q000235:genetics; D003313:Zea mays / Q000235:genetics*
D005819:Genetic Markers; D010940:Plant Proteins; D018626:Retroelements