Overexpression of HvPAPhy_a Gene Increases Phytase Activity in Mature Barley Straw and Grains

Phytases hydrolyze phytic acid, the most important phosphorous storage compound in plant seeds. In its degradation of phytic acid, phytases ensure the bioavailability of phosphate. A research team led by Inger Bæksted Holme of Aarhus University in Denmark recently studied the phytase purple acid phosphatase (HvPAPhy_a), expressed during barley (Hordeum vulgare) seed development, determine increasing phytase activity in grains and other parts of barley, as well as a potential side product from barley cultivation.

The team overexpressed the gene in barley and phytase was found to be expressed constitutively in barley. Phytase activity was detected in mature grains, green leaves as well as in the dry mature vegetative plant parts. The T₂-generation of HvPAPhy_a transformed barley showed phytase activity increased by up to 19-fold. Furthermore, phytase activities were increased significantly in green leaves and mature dry straw.

The HvPAPhy_a-transformed barley plants with high phytase activities possess several potential uses, including the use of mature grains as feed to increase the release of bio-available phosphate. Another potential use would be that the high phytase stubble could be plowed into the soil to release the phosphate bound in phytate form for plant growth.

For more details on this study, read the article in Plant Biotechnology Journal.