Plant Growth Promotion by Phytases and Phytase-Producing Microbes due to Amelioration in Phosphorus Availability

Abstract

Phosphorus is a major and critical component of cell and its constituents. It is also an important macronutrient for plant growth and development. Phytic acid, a major form of organic phosphorus in soil, is not readily available to plants either due to the formation of complex with cations or adsorption to various soil components. Phosphate solubilizing microorganisms are ubiquitous in soils and play an important role in making P available from insoluble sources. Phytate hydrolyzing microorganisms are present in cultivated soils as well as in wetland, grassland and forest soils. Several fungi and bacteria hydrolyze the organic insoluble forms of phosphorus by secreting phytases and phosphatases, and thus promote the growth of plants. Insoluble phytates are a major problem in soil, as these are not readily hydrolyzed by all phytases. A large number of transgenic plants have been developed that are able to grow on phytate as sole source of phosphorus. Phytate-phosphorus utilization could be improved by enhancing phytase/phosphatase activity in the rhizosphere. Furthermore, genetic engineering approach could be employed for enabling plants to utilize accumulated forms of organic phosphorus in soils.