Genes and mRNAs coding for zein polypeptides in Zea mays

Area of Science:

• Molecular Biology
• Plant Science
• Genetics

Background:

• Zeins are the major storage proteins in maize endosperm.
• Understanding zein gene expression is crucial for maize seed development and nutritional quality.

Purpose of the Study:

• To purify and characterize zein messenger RNAs (mRNAs) from maize endosperm.
• To determine the complexity and abundance of zein genes in the maize genome.

Main Methods:

• Purification of zein mRNAs using oligo(dT)-cellulose chromatography and sucrose gradient centrifugation.
• Analysis of mRNA size classes via denaturing polyacrylamide gel electrophoresis.
• Synthesis of complementary DNA (cDNA) and hybridization kinetics with mRNA and maize DNA.

Main Results:

• Two distinct zein mRNA size classes (Mr 3.5 x 10(5) and 4.10 x 10(5)) were identified.
• Zein mRNA preparations contained approximately 15 non-cross-hybridizing sequences.
• Estimated zein gene copy number at ~120 per haploid maize genome.
• No significant amplification or deletion of zein genes observed in mutant endosperm.

Conclusions:

• Zein mRNA populations are complex, containing multiple distinct sequences.
• The maize genome contains a moderate number of zein gene copies, consistent with their role as storage proteins.
• Zein gene copy number appears stable in tissues specialized for zein synthesis.