Functional analysis of regulatory elements in a plant embryo-specific gene

Area of Science:

• Plant Molecular Biology
• Genetics
• Biotechnology

Background:

• The alpha' subunit of beta-conglycinin is a soybean seed storage protein.
• Expression of embryo-specific genes in heterologous systems is crucial for understanding gene regulation.

Purpose of the Study:

• To identify regulatory elements controlling the expression of the soybean embryo-specific gene Gmg17.1 in transgenic petunia.
• To determine the role of specific DNA sequences in achieving high-level gene expression.

Main Methods:

• Construction and analysis of a series of 5' deletion mutants of the Gmg17.1 gene.
• Introduction of deletion mutants into petunia cells using Ti-plasmid-derived vectors.
• Regeneration of transgenic petunia plants and examination of Gmg17.1 gene expression in immature embryos.

Main Results:

• A deletion mutant with 159 nucleotides upstream (Gmg17.1 delta-159) showed low expression in immature embryos.
• A mutant with 257 nucleotides upstream (Gmg17.1 delta-257) exhibited a significant, at least 20-fold, increase in expression.
• An additional 8 kb of upstream sequence, including a potential enhancer-like motif, did not further enhance expression levels.
• The region between -159 and -257 nucleotides contains four repeats of a (G+C)-rich sequence, suggesting their importance.

Conclusions:

• The (G+C)-rich repeats located between 159 and 257 nucleotides upstream of the transcription start site are critical for high-level expression of the soybean Gmg17.1 gene in transgenic petunia.
• These repeats likely function as key regulatory elements for seed storage protein gene expression.