Plant centromeres

The centromeres of maize, Arabidopsis, and rice are compared. Plant centromeres are quite diverse on the DNA sequence level but possess similar structural features across taxa, namely megabase-sized arrays of small repeats interspersed with a specific retrotransposon family. On the contrary, the protein components of the kinetochore that functions in chromosome movement and forms over the site of the centromere is highly conserved. Plant centromeres exhibit epigenetic properties of specification as evidenced by the frequent finding of inactive centromeres that contain a full spectrum of DNA elements but are inherited over generations without forming a kinetochore. Plant centromeres have been demonstrated to be divisible by the process of misdivision, but the smaller centromeres produced show impaired function when their size falls below a threshold of a few hundred kilobases.