The invention relates to a recombinant DNA molecule coding a polypeptide having phytase activity after being expressed in a prokaryotic or eukaryotic host cell.

Although the thymosin has been successfully expressed in the prokaryotic cell system, its application is restricted because of its deficiency of modification after translation.

Phytoplasmas are cell wall-less prokaryotic pathogens causing many plant diseases with various host plants, widely geographical distribution and adverse impacts on economics and environments.