Figure 2.

Molecular characterization of the Y-cs allele. (A) Detection of RFLP. Genomic DNA samples from red revertant (R) and candystripe (C) plants were digested with BamHI and hybridized to the indicated probe fragments. Probe 8A is a genomic DNA fragment of the maize p1 gene containing exons 1 and 2, which encode part of the MYB DNA-binding domain (37). Probes F3, F2, and F1 are restriction fragments of the y-cs clone λCS-16 (B). The approximately 8.0-kb polymorphic band present in candystripe DNA that hybridizes to all the probe fragments is indicated with an asterisk. The 5.0-kb band (arrow) present in red revertant DNA hybridizes to the maize p1-Myb probe 8A and sorghum Y gene intron2 probe F3. Nonpolymorphic bands hybridizing to 8A probe may represent other Myb-homologous genes in sorghum. Molecular sizes are shown in kb. (B) Partial restriction map of the y-cs allele (not to scale). The Y gene exons are represented as black boxes. The Candystripe1 (Cs1) element present in the second intron of the Y gene is indicated by a bold line. Outwardly oriented arrow heads represent 20-bp TIR sequences found at the borders of the Cs1 element. Positions of DNA fragments 8A, 12, F1, F2, F3, and 28E used as hybridization probes are indicated below the y-cs map. Restriction enzyme sites shown are B, BamHI; E, EcoRI; H, HindIII; and X, XhoI. The y-cs map was constructed from overlapping λ clones (Lower). Arrows marked as P-1 and P-2 indicate positions of primer 1 and primer 2, respectively, used for the PCR amplification.