B chromosomes (Bs) are dispensable chromosomes found in the genomes of animals, plants and fungi. Typically, their transmission to the progeny is not governed by Mendelian inheritance. They are maintained in the population by accumulation mechanisms (e.g. non-disjunction). In plants, the incidence of Bs is generally stable in all parts of one plant. In some species, however, the disappearance (elimination) of B chromosomes from the roots or aerial parts was demonstrated. Representatives of the genus Sorghum are an extreme example in which the presence of Bs has been proved only in the germline. Despite this interesting phenomenon, knowledge of Bs in this genus is very limited. Modern methods and advanced approaches allow us to clarify the onset of the elimination process and how it proceeds within the developing embryo and so later in a growing plant. It is known that elimination is a strictly directed, tissuespecific process and transcriptomic analysis of B-positive nuclei may reveal a candidate genes involved in its regulation.