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SUMMARY
Progenies of a B- carrying individual plant found in a particular strain of Aegilops speltoides, were used in an attempt to trace the way whereby B's can be transmitted through EMCs. For comparison, progenies of non-B carrying plants from the same strain and offspring from other strains, without B- chromosomes, were included in the project.
According to the results of meiotic observations at PMCs, only the progenies of the B carrier contained supernumerary chromosomes, which probably derived from the female parent, since male parents (grown under common experimental conditions) had been recognised as non-B carriers.
In contrast to the maternal plant, which constanly contained a B bivalent, the present material showed considerable inter- and intraplant variation with respect to the number ot B chromosomes. The most frequent cytological configuration was that of PMCs containing 17 chromosomes (7 bivalents plus 3 supernumeraries) and representing the majority of plants and cells. Thus B- chromosomes behave in a way leading to an increase rather than a decrease of their number, which took place through pre- or postmeiotic mechanisms. However, the observed variability, in association with lacking of B's in root-tips, lead to the conclusion that supernumeraries in Ae. speltoides are unstable.
