Behaviour and transmission of supernumerary chromosomes in diploid Dactylis glomerata

The somatic stability and the mode of transmission of B chromosomes were studied in diploid Orchard Grass: Dactylis glomerata L. ssp. judaica Steb. et Zoh. Somatic mosaics (different numbers of B's in different tillers) were detected in 4 out of 17 plants. Examination of the first and the second divisions of the male gametophyte revealed non-disjunction and preferential migration of the B's to the generative nucleus. Progeny from eight different cross-combinations were examined. The results obtained corroborate the direct evidence on accumulation of B's in the pollen grains, but the transmission patterns observed are too complex to be explained by this mechanism only.