Supernumerary B chromosomes of Aegilops speltoides undergo precise elimination in roots early in embryo development

B chromosomes are supernumerary chromosomes exhibiting dramatic differences between different organs in same species. Here, the authors show programmed B chromosome elimination in goatgrass starts at the onset of embryo differentiation by nondisjunction of chromatids, anaphase lagging, and ends with the degradation of micronucleated DNA.