Fig. 1. Photomicrographs and drawings of C-banded preparations of a normal 6R chromosome from triticale T-701 and four deletion mutants in a wheat background. (a) disomic substitution line of normal chromosome 6R(6D) showing 2n = 42 chromosomes, (b) monosomic addition line of deletion chromosome 6RL22 showing 2n = 43 chromosomes, (c) disomic substitution line of deletion chromosome 6RL21 (6D) showing 2n = 42 chromosomes, (d) and (d') normal 6R chromosome showing prominent short arm telomere and interstitial C-bands on the long arm, (e) and (e') telocentric 6RL chromosome, (f) and (f') telocentric 6RS chromosome, (g) and (g') deletion chromosome 6RL22, (h) and (h') deletion chromosome 6RL21, (i) and (i') deletion chromosome 6RL1807, (j) and (j') deletion chromosome 6RL1801 and (k) metaphase I spread with monosomic addition line of deletion chromosome 6RL1807 showing 21 wheat bivalents and the deletion chromosome as a univalent. Note that Fig. (a) to (c) show whole cell spreads with intact mitotic wheat chromosomes indicating that the 6R deletion mutants did not arise from chromosome breakage during slide preparation. In Fig. (a) to (c) and (k), arrowheads denote 6R chromatin and in Fig. (d') to (j'), the small arrows indicate the approximate positions of the centromeres. Bars represent 10 µm with Fig. (d) to (j) being of the same magnification.