Centromere inactivation in a dicentric rice chromosome during sexual reproduction

T0135 is a variant selected from the progeny of a rice line telotrisomic for the short arm of chromosome 11 (2n+11S·). Fluorescent in situ hybridization (FISH) results indicated that T0135 contained two telocentric chromosomes, which have two centromere-specific molecular markers (5S rDNA) for chromosome 11; thus T0135 is a newly-described rice chromosome variant with two dicentric chromosomes, named 22+11L·+11L·+11S·11S·+11S·11S· (22 represents the 22 chromosomes excluding chromosome 11 in the rice genome, “·” represents the centromere). To investigate the genetic stability of the rice dicentric chromosomes during sexual reproduction, we observed the chromosome types in the progeny. Ninety-four percent of the progeny had the same chromosome type as the parental line. This result indicates that the dicentric chromosomes are mostly stable during mitosis and meiosis. Immunofluorescence analysis for centromere specific histone H3 (CENH3) revealed that only one centromere is active and the other centromere is inactivated in the rice dicentric chromosomes.