Hybrids between the tetraploids of Bromus inermis and B. pumpellianus

Abstract

Tetraploid F1 hybrids from Bromus pumpellianus ssp. dicksonii (2n = 4x = 28) × B. inermis (2n = 4x = 28) were highly sterile. Chromosome pairing was regular but a low frequency of unpaired chromosomes and multivalents at metaphase I and a low frequency of bridge and fragment configurations at anaphase were recorded. These results indicate that the chromosomes of the parents differ by one or more interchanges and one or more small inversions. The karyotype of the F1 hybrid suggested some structural difference in the satellite-bearing chromosomes of the two species but no other definite evidence of structural changes.