ARS | Publication request: MOLECULAR CLONING AND CHARACTERIZATION OF A GIBBERELLIN-INDUCIBLE ALPHA- GLUCOSIDASE GENE FROM BARLEY

Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 29, 1995
Publication Date: N/A

Interpretive Summary: The degradation of stored starch in cereal seeds is crucial for germination and for industrial applications. Alpha-glucosidase is one of the enzymes involved in starch degradation. It's synthesis is controlled by a hormone signal from the embryo. The problem is to be able to control the activity of this enzyme in order to optimize starch degradation. To understand its regulation, we first needed to clone the gene that produces it and determine its DNA sequence (genetic structure). We did this, and then we determined how the gene is regulated to induce alpha-glucosidase synthesis. These results help us understand how starch is degraded in cereal seeds and may lead to a method for enhancing this process in industrial applications.

Technical Abstract: A cDNA clone, pAGL.2752, encoding an alpha-glucosidase has been isolated from a library constructed from mRNA of GA-treated barley aleurones. The clone is 2752 bp in length and has an open reading frame capable of coding for a polypeptide of 877 amino acids. The deduced amino acid sequence reveals a 680 amino acid region that has high homology with human lysosomal alpha-glucosidase and other glycosol hydrolases. In isolated aleurones, alpha-glucosidase mRNA levels increase strongly after the application of GA, similar to the pattern exhibited by low-pI alpha-amylase mRNA. High levels of alpha-glucosidase mRNA are also observed in the aleurone and scutellum after germination, while low levels are found in developing seeds. The genome contains a single copy of the alpha-glucosidase gene and two additional sequences that may be related genes or pseudogenes.