Extraordinary Tertiary Constrictions of Tripsacum dactyloides Chromosomes: Implications for Karyotype Evolution of Polyploids Driven by Segmental Chromosome Losses

摘要

Tripsacum dactyloides (2n = 2x = 36) is an ancient tetraploid species. Here we report that T. dactyloides chromosomes contain an extraordinary tertiary constriction, which causes a radical and distant separation of a terminal segment from the chromosome. The relationships between extraordinary tertiary constriction and segmental chromosome loss as well as karyotype evolution of polyploid species are discussed.