Ensifer meliloti overexpressing Escherichia coli phytase gene (appA) improves phosphorus (P) acquisition in maize plants.

Die Naturwissenschaften

PubMedID: 27597170

Sharma V, Kumar A, Archana G, Kumar GN. Ensifer meliloti overexpressing Escherichia coli phytase gene (appA) improves phosphorus (P) acquisition in maize plants. Naturwissenschaften. 2016;103(9-10):76.
The Escherichia coli phytase gene appA encoding enzyme AppA was cloned in a broad host range plasmid pBBR1MCS2 (lac promoter), termed pVA1, and transformed into the Ensifer meliloti 1020. Transformation of pVA1 in Ensifer meliloti {E. m (pVA1)} increased its phosphatase and phytase activity by ~9- and ~50-fold, respectively, compared to the transformants containing empty plasmid as control {E. m (pBBR1MCS2)}. The western blot experiments using rabbit anti-AppA antibody showed that AppA is translocated into the periplasm of the host after its expression. Ensifer meliloti harboring AppA protein {E. m (pVA1)} and {E. m (pBBR1MCS2)} could acidify the unbuffered phytate minimal media (pH 8. 0) containing Ca-phytate or Na-phytate as sole organic P (Po) source to below pH 5. 0 and released P. However, both {E. m (pVA1)} and {E. m (pBBR1MCS2)} neither dropped pH of the medium nor released P when the medium was buffered at pH 8. 0 using Tris-Cl, indicating that acidification of medium was important for the enzymatic hydrolysis of phytate. Further experiments proved that maize plants inoculated with {E. m. (pVA1)} showed increase in growth under sterile semi solid agar (SSA) medium containing Na-phytate as sole P source. The present study could be helpful in generating better transgenic bioinoculants harboring phosphate mineralization properties that ultimately promote plant growth.