The zein genes of maize encode the seed storage proteins. Previous analyses have shown that zeins consist of three distinct protein types designated alpha, beta, and gamma. The alpha zeins account for approximately 70% of the total storage protein and are encoded by a multigene family. The beta and gamma zeins, which account for approximately 10% and 20% of the zein fraction, respectively, are each encoded by only one or two genes. Zein genes are actively expressed during development of normal endosperms, but their expression is quantitatively and qualitatively inhibited in several mutant genotypes. Our preliminary studies indicate that there are differences in the relative expression of genes among zein gene families that correlate with differences in the amount of cytoplasmic mRNA. To define the mechanisms regulating the expression of zein genes during endosperm formation, we propose to characterize the DNA sequences controlling their transcription and developmental regulation. Hybridization of 32P-labeled nuclear RNA to well characterized genomic clones will establish sites of transcription, timing of transcription, and whether transcription or post-transcriptional processing play a major role in the regulation of the zein gene expression. This analysis will also determine the extent to which these reactions are affected by the mutant genotypes. To define DNA sequences regulating transcription, gene flanking sequences will be ligated to a chloramphenicol acetyltransferase (CAT) gene and transferred to plant protoplasts by electroporation. Sequences required for transcription will be monitored by assaying CAT activity in protoplast extracts. We will also analyze transcriptional regulatory sequences following transformation of zein genes into tobacco and petunia plants with a Ti-plasmid vector. In this case we will monitor mRNA and protein synthesis in seeds from regenerated plants to delineate DNA sequences controlling developmental expression. Through labeling of endosperm proteins and differential screening of cDNA libraries we will attempt to identify gene products whose expression is modified in mutants that reduce the level of zein gene expression.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM036970-01
Application #
3291731
Study Section
Molecular Biology Study Section (MBY)
Project Start
1986-07-01
Project End
1991-06-30
Budget Start
1986-07-01
Budget End
1987-06-30
Support Year
1
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Purdue University
Department
Type
Earth Sciences/Resources
DUNS #
072051394
City
West Lafayette
State
IN
Country
United States
Zip Code
47907
Gillikin, J W; Zhang, F; Coleman, C E et al. (1997) A defective signal peptide tethers the floury-2 zein to the endoplasmic reticulum membrane. Plant Physiol 114:345-52
Dannenhoffer, J M; Bostwick, D E; Or, E et al. (1995) opaque-15, a maize mutation with properties of a defective opaque-2 modifier. Proc Natl Acad Sci U S A 92:1931-5
Habben, J E; Larkins, B A (1995) Genetic modification of seed proteins. Curr Opin Biotechnol 6:171-4
Coleman, C E; Lopes, M A; Gillikin, J W et al. (1995) A defective signal peptide in the maize high-lysine mutant floury 2. Proc Natl Acad Sci U S A 92:6828-31
Lopes, M A; Takasaki, K; Bostwick, D E et al. (1995) Identification of two opaque2 modifier loci in quality protein maize. Mol Gen Genet 247:603-13
Lopes, M A; Coleman, C E; Kodrzycki, R et al. (1994) Synthesis of an unusual alpha-zein protein is correlated with the phenotypic effects of the floury2 mutation in maize. Mol Gen Genet 245:537-47
Lopes, M A; Larkins, B A (1993) Endosperm origin, development, and function. Plant Cell 5:1383-99
Or, E; Boyer, S K; Larkins, B A (1993) opaque2 modifiers act post-transcriptionally and in a polar manner on gamma-zein gene expression in maize endosperm. Plant Cell 5:1599-609
Larkins, B A; Lending, C R; Wallace, J C (1993) Modification of maize-seed-protein quality. Am J Clin Nutr 58:264S-269S
Geetha, K B; Lending, C R; Lopes, M A et al. (1991) opaque-2 modifiers increase gamma-zein synthesis and alter its spatial distribution in maize endosperm. Plant Cell 3:1207-19

Showing the most recent 10 out of 14 publications