CHROMOSOMAL LOCATION OF ZEIN GENES IN ZEA-MAYS

Zein, the storage protein accumulated in maize endosperm, is composed of several polypeptides which can be separated by isoelectric-focusing (IEF) analysis. Much IEF zein variability is found when analysing different inbred lines—the number of bands varies from 8 to 15 and can occupy about 27 positions—and FI endosperms show an additive parental pattern. Chromosomal location of factors controlling the phenotypic expression of eight IEF bands was studied by means of translocations between A and B chromosomes and trisomic stocks, which allowed a large part of the genome to be explored. Three bands were shown to be controlled by factors localised on the analysed chromosome segments: one close to the R locus on chromosome 10, one on the short arm of chromosome 4 and one on a segment composed of portions from the short arm of chromosome 9 and the long arm of chromosome 4. The band controlled by the factor on chromosome 10 occupies the same IEF position as one which was found to be controlled by a factor on chromosome 7 near the opaque-2 locus. However, on the basis of SDS electrophoresis, these two polypeptides were found to have different molecular weights. The results obtained are discussed in relation to the molecular origin of zein heterogeneity. © 1979 The Genetical Society of Great Britain.