BEHAVIOR OF PARENTAL GENOMES IN THE HYBRID HORDEUM-VULGARE X H-BULBOSUM

In situ hybridization of labeled total genomic DNA with unlabeled blocking DNA enabled the parental origin of all chromosomes to be established in root tips of the mature sexual hybrid plant Hordeum vulgare x H. bulbosum. The parental genomes tended to remain spatially separated throughout the cell cycle, with the chromosomes of H. vulgare origin lying in a more central domain than those of H. bulbosum origin. During anaphase and telophase, chromosomes of H. bulbosum origin tended to lag. Although the chromatids usually separated, they did not have the V shape characteristic of anaphase chromatids. Aneuploid nuclei, missing H. bulbosum origin chromosomes, arose when the lagging chromatids were not incorporated into the daughter nuclei, although most cells remained diploid, Some interphase cells contained micronuclei, all of which were of H. bulbosum origin, Information about chromosome disposition and movement is important to enable the understanding of chromosome stability.