Maize genomic DNA Southern blot analysis. Genomic DNA digested with BamHI (B), EcoRI (E), or HindIII (H) was separated, blotted, and hybridized at high stringency with the [32P]-labeled maize cDNAs encoding P1, P2a, P2b, and P3, respectively. (A) rpp1, (B) rpp2a-1, (C) rpp2b, (D) rpp3. Migration of DNA standards (in kilobases) are indicated.