CHROMOSOME 5D INSTABILITY IN CELL-LINES OF TRITICUM-TAUSCHII AND MORPHOLOGICAL VARIATION IN REGENERATED PLANTS

Immature embryos of Triticum tauschii cultured on L2 medium with 30 g . L(-1) maltose gave rise to compact and highly structured callus that readily regenerated shoots when transferred to MS medium supplemented with zeatin and indole-3-acetic acid. Two cell suspensions were initi ated from the callus induced on L2 medium. An analysis of chromosome n umber in these cell suspensions after 3 months of culture showed that 95 and 75% of the cells had a normal complement. After 5 months, in bo th lines the majority of cells had chromosome complements of 2n = 13 a nd many of these aneuploid cells possessed a dicentric chromosome. C-b anding indicated that the dicentric was often formed from chromosomes 2D and 5D. Fifty-six plants regenerated from callus were grown to matu rity. Variation was observed in tiller number, flowering time, and see d-set; in two cases, the variation in early flowering was shown to be heritable. All the regenerants analysed had normal chromosome counts ( 2n = 2x = 14) and meiotic analyses of 35 plants revealed no obvious st ructural rearrangements.