Fig. 2: The subtelomeric region of the long arm of the rye B chromosome controls the drive.

a The repeat composition of the terminal region of the long B chromosome arm of the drive-positive B variants B^s, B^k, B^k−2 and the drive-negative B variants B^s−8, B^k−1, B^k−3 were analyzed by FISH using the rye genome-specific repeat Revolver (magenta), and the B-specific repeats D1100 (green), E3900 (sky blue), Sc9c130 (violet), and Sc26c38 (orange) were used as probes to determine the drive control region. Corresponding complete mitotic cells after FISH are shown in Supplementary Figs. 1–3. The experiment was independently repeated twice with similar results. White arrowheads indicate the signal gap in the D1100-positive region. Chromosomes are counterstained with DAPI (blue). Bar = 10 μm. b Schemata of the different rye B chromosome variants showing based on (a), the distribution of the B-specific repeats D1100 (green), E3900 (sky blue), Sc9c130 (violet), and Sc26c38 (orange). Light gray and diagonal stripes depict rye and wheat chromatin, respectively. The continuous long black lines represent the ends of B^k−8, B^s, and B^k. The blue dotted lines indicate the ends of B^k−1, B^k−3, and B^k−2. On the right, the chromosomal position of the drive control region is shown as a read region of a drive-positive B chromosome.