The ability of centromeres to alternate between active and inactive states indicates significant epigenetic aspects controlling centromere assembly and function. In maize (Zea mays), misdivision of the B chromosome centromere on a translocation with the short arm of chromosome 9 (TB-9Sb) can produce many variants with varying centromere sizes and centromeric DNA sequences. In such derivatives of TB-9Sb, we found a de novo centromere on chromosome derivative 3-3, which has no canonical centromeric repeat sequences. This centromere is derived from a 288-kb region on the short arm of chromosome 9, and is 19 megabases (Mb) removed from the translocation breakpoint of chromosome 9 in TB-9Sb. The functional B centromere in progenitor telo2-2 is deleted from derivative 3-3, but some B-repeat sequences remain. The de novo centromere of derivative 3-3 becomes inactive in three further derivatives with new centromeres being formed elsewhere on each chromosome. Our results suggest that de novo centromere initiation is quite common and can persist on chromosomal fragments without a canonical centromere. However, we hypothesize that when de novo centromeres are initiated in opposition to a larger normal centromere, they are cleared from the chromosome by inactivation, thus maintaining karyotype integrity.centromere misdivision | epigenetics | de novo centromere | centromere inactivation T he centromere is an important chromosomal region responsible for correct chromosome segregation during cell division. Centromeres are found in the primary constriction region on the chromosome, upon which the kinetochore complex assembles to produce a platform for spindle binding (1). Centromere function is conserved among different species, and several epigenetic markers of active centromeres have been found, including a histone H3 variant referred to as CENH3 in plants (2, 3) or CENP-A in animals (4-6) and phosphorylation of histone H2A at Thr133 in plants (7). Correct loading of CENH3 to the centromere region is a key component of kinetochore assembly (8). Centromeric DNA sequences have experienced rapid evolution (9, 10), and arrangements of DNA sequence in centromere regions differ in species and even in different chromosomes of an individual organism (11). Myriad repeat sequences exist in the centromeres of higher plants. In maize (Zea mays), there are two major types of centromere specific DNA sequences: the simple satellite repeat sequence CentC (12) and centromeric retrotransposon of maize (CRM) (3). Many epigenetic features have been identified in centromeric regions, including DNA methylation levels, histone variants, histone modifications, and RNA components (11). Both epigenetic elements and DNA sequences take part in centromere formation and maintenance, but it is still unknown how genetic and epigenetic factors work together in this process.The centromere is one of the most complex regions on the chromosome, and complete DNA sequencing through the centromeric region is difficult to obtain due to their highly repetitive nature...