Molecular characterization of a genomic interval with highly uneven recombination distribution on maize chromosome 10 L.

Homologous recombination in meiosis provides the evolutionary driving force in eukaryotic organisms by generating genetic variability. Meiotic recombination does not always occur evenly across the chromosome, and therefore genetic and physical distances are not consistently in proportion. We discovered a 278 kb interval on the long arm of chromosome 10 (10 L) through analyzed 13,933 descendants of backcross population. The recombinant events distributed unevenly in the interval. The ratio of genetic to physical distance in the interval fluctuated about 47-fold. With the assistance of molecular markers, the interval was divided into several subintervals for further characterization. In agreement with previous observations, high gene-density regions such as subinterval A and B were also genetic recombination hot subintervals, and repetitive sequence-riched region such as subinterval C was also found to be recombination inert at the detection level of the study. However, we found an unusual subinterval D, in which the 72-kb region contained 6 genes. The gene-density of subinterval D was 5.8 times that of the genome-wide average. The ratio of genetic to physical distance in subinterval D was 0.58 cM/Mb, only about 3/4 of the genome average. We carried out an analysis of sequence polymorphisms and methylation status in subinterval D, and the potential causes of recombination suppression were discussed. This study was another case of a detailed genetic analysis of an unusual recombination region in the maize genome. © Springer Science+Business Media B.V. 2011