RFLP mapping of the centromere of chromosomes 1, 6 and 9 by B-A translocations in maize

The centromere of chromosomes 1, 6 and 9 are physically mapped by the hypoploids of the six most proximal B-A translocations. The hypoploids are deficient for a paternal chromosome arm and, as a result, lose the paternal signal of those RFLP markers located on the missing chromosome arm. Of those markers missing from the hypoploids, the two most proximal ones on each arm of a chromosome define the physical location of the centromere. Analysis of 10 RFLP markers on chromosome 1, 8 on chromosome 6 and 12 on chromosome 9, maps the first centromere to the umc67-umc177a region, the sixth centromere to the bnl6.29-bnl7.28 region, and the ninth centromere to the bnl5.10-umc20 region, an interval of about 3.3, 3 and 0.5 map units, respectively. Other interesting observations are that the A-B chromosome of five of the six B-A translocations is associated with anomalous signals not originated from the paternal parent, suggesting probable presence of chromosome rearrangement(s).