Plant & Animal Genome VI Conference Plant & Animal Genome VI Conference
P6
Waksman Institute, Rutgers, The State University of New Jersey, P.O. Box 759, Piscataway NJ 08855
Zeins are the major storage proteins present in maize endosperm. The most
abundant class, a-zeins, includes 19- and 22-kDa proteins encoded by a multigene
family. In the inbred line BSSS53, all 22-kDa zein genes and pseudogenes are
clustered on the short arm of chromosome 4. The postranscriptional regulator
dzr1, responsible for the overexpression of a methionine-rich d-zein in BSSS53,
maps at the cluster. To characterize the organization of the cluster region, we
have previously constructed a physical map and shown that the 3.4-cM 22-kDa
alpha-zein cluster region spans only 250 kb, and includes two subclusters of
zein genes, separated by a large (70kb) intervening spacer. We have taken
advantage of the synteny between maize and sorghum to identify gene-like
sequences within its large segments of repetitive DNA as well as to bridge the
physical distance and orient the subclusters. Sequencing of the entire region is
in progress. Thus far, a 78.1 kb sequence that includes 10 zein-related
sequences show three other additional predicted genes and extensive evidence of
transposition. Our progress in the comparative analysis of the cluster between
maize and sorghum will be reported. The use of shotgun approaches to the
sequencing of clustered multigene families in plants will be discussed.