Physical map of the 346-kb region derived from BAC clones. Two BAC clones, BAC 204 and BAC 171 (see Fig. 1) were used to construct a physical map of the 22-kD α zein cluster region (346-kb contig). Bars above and below the overlapping BAC clones represent the other BAC clones and the cosmid clones that have been sequenced in this study. A leftward arrow on the bottom of the figure points to cosmid clone IV.1E1, containing the fl2 allele that is located 19.6 cm closer to the centromere. However, we do not know the orientation of the Fl2 gene or the zein cluster relative to each other or to the centromere. The physical map is divided into three parts, with themiddle portion highlighted by a heavy bar. This 168-kb region is enlarged below to illustrate the tandem array of the 22 clustered 22-kD α zein genes. Gene copies are designated only by the numbers following the (azs22;) prefix. The two other parts of the sequence represent the 94-kb upstream and the 84-kb downstream regions. The upstream region contains the php200725 region sequenced from two overlapping cosmids, V.9D7 and III.3C12, and has been marked by a bar above the sequence. The position of subclusters B and A have been marked by bars as well. Note that sequences in gap1 and gap2 have been derived from BAC clone 204.