[Expression characteristics of MtPAP1 and its exotic expression in Arabidopsis affecting organic phosphorus absorption of plants]

The MtPAP1 encodes 465 amino acids (Fig.1). The transcript of MtPAP1 was detected mainly in leaf under high-phosphate conditions (Fig.2). While under low-phosphate condition, the transcript level was low in leaves and very high in roots, with the strongest hybridization signal detected in roots (Fig.2). Chimeric MtPAP1 binary vector was constructed and the transcript levels of MtPAP1 in roots of transgenic T(3) Arabidopsis lines were analyzed (Fig.3). Under the condition in which phytate was the sole source of phosphorus, transgenic Arabidopsis plants over-expressing MtPAP1 showed acid phosphatase activities in root apoplast increasing markedly than that of the control plant (Fig.4). The results of analysis of organic phosphorus degradation in liquid culture by HPLC indicated that the APase secreted by the transgenic plants could quickly degrade the phytate (Fig.5). Significant increase in biomass production, Pi and total phosphorus content of plants achieved in the transgenic lines when phytate, an organic phosphorus compound, was supplied as the sole source of phosphorus (Fig.6,7).