A COMPARISON OF CHROMOSOME INSTABILITY IN CELL-SUSPENSIONS OF DIPLOID, TETRAPLOID AND HEXAPLOID WHEATS

Chromosome instability was monitored through time in cell suspensions of the diploids Triticum tauschii (the D genome donor) and T monococcum (the A genome donor), the tetraploids, T. durum and T dicoccum (both AABB) and in the cultivars Copain and Sicco of hexaploid (AABBDD) breadwheat (T aestivum). Differences in stability were observed between the different ploidy levels and between species within the ploidy levels. The diploids were most stable, particularly T tauschii, and the hexaploids were least stable. Instability was greatest in all the lines during the first months of culture. In all but one line, very few structural aberrations were observed, even after many months in culture. Morphogenetic capacity was lost in all lines, even though some retained high proportions of euploid cells. The relevance of these results is discussed in relation to the regeneration of breadwheat from protoplasts.