Location and differential expression of a Zein gene in maize

Abstract Zein, the storage protein accumulated in maize endosperm is composed of several polypeptides coded by a family of multigenic structural genes clustered on at least three different chromosomal segments. Single genes affecting the accumulation rate of some or all zein components are known. A structural gene controlling the zein band 22/2 was found to be closely linked to a ‘general’ regulatory gene O 7 located on chromosome 10. Quantitative analysis of the gene product (zein band 22/2) in endosperm carrying 0,1,2,3, doses of the Zp 22/2 allele revealed the usual linear dosage effect. A deviation from this was found in the progeny of a cross between a line containing Zp 22/2 and a line marked with Rnj ; no zein band 22/2 was observed when only one dose of Zp 22/2 was present. This result suggests that in addition to ‘general’ regulatory genes, band specific regulatory factors also exist in the zein genetic system.