A γ-hordein gene

Area of Science:

• Plant Molecular Biology
• Genetics
• Biochemistry

Background:

• γ-hordein polypeptides are major endosperm storage proteins in barley.
• Understanding hordein gene structure and regulation is crucial for improving grain quality.

Purpose of the Study:

• To present the nucleotide and amino acid sequence of a barley γ-hordein gene.
• To analyze the gene's regulatory elements and mRNA expression patterns.
• To compare the γ-hordein gene with related storage protein genes in other cereals.

Main Methods:

• Nucleotide sequencing
• Amino acid sequence deduction
• Sequence homology analysis
• Northern blot analysis of mRNA

Main Results:

• The 1614 bp gene encodes a 305 amino acid γ-hordein polypeptide with distinct N-terminal and C-terminal domains.
• Homology was observed with γ-gliadin (wheat) and γ-secalin (rye) polypeptides.
• The 5' non-coding region contains regulatory elements (TATA box, AGGA, -300 element) typical of prolamin genes.
• Two mRNA size classes (1350 and 1450 nt) are expressed in wild-type endosperm.
• The mutant hor 2ca shows normal γ-hordein mRNA levels, while lys 3a has significantly reduced levels.

Conclusions:

• The characterized γ-hordein gene provides insights into cereal endosperm storage protein evolution.
• Regulatory elements identified suggest conserved mechanisms for prolamin gene expression.
• Differential mRNA abundance in mutants highlights the complex genetic control of hordein synthesis.