, Volume 31, Issue 8, pp 1297-1303
Date: 09 Apr 2009

Functional analysis of an Aspergillus ficuum phytase gene in Saccharomyces cerevisiae and its root-specific, secretory expression in transgenic soybean plants

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Abstract

Phytases release inorganic phosphates from phytate in soil. A gene encoding phytase (AfPhyA) was isolated from Aspergillus ficuum and its ability to degrade phytase and release phosphate was demonstrated in Saccharomyces cerevisiae. A promoter from the Arabidopsis Pky10 gene and the carrot extensin signal peptide were used to drive the root-specific and secretory expression of the AfPhyA gene in soybean plants. The phytase activity and inorganic phosphate levels in transgenic soybean root secretions were 4.7 U/mg protein and 439 μM, respectively, compared to 0.8 U/mg protein and 120 μM, respectively, in control soybeans. Our results demonstrated the potential usefulness of the root-specific promoter for the exudation of recombinant phytases and offered a new perspective on the mobilization of phytate in soil to inorganic phosphates for plant uptake.

Guilan Li and Shaohui Yang authors contribute equally to the paper.