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Effect of exogenous phosphatase and phytase activities on organic phosphate mobilization in soils with different phosphate adsorption capacities
- Maruyama, Hayato, Yamamura, Takuya, Kaneko, Yohei, Matsui, Hirokazu, Watanabe, Toshihiro, Shinano, Takuro, Osaki, Mitsuru, Wasaki, Jun
- Soil science and plant nutrition 2012 v.58 no.1 pp. 41-51
- Agrobacterium, Andosols, Lupinus albus, Nicotiana tabacum, Regosols, acid phosphatase, adsorption, complementary DNA, dry matter accumulation, genes, genetic transformation, phosphates, phosphorus, phytases, phytic acid, soil treatment, solubility, tobacco, transgenic plants
- This study evaluated the effects of exogenous LASAP2 for acid phosphatase (APase) and LASAP3 for phytase of white lupin (Lupinus albus L.) on phosphorus (P) accumulation from organic P in soils. The potential for LASAP2 -overexpressing tobacco (Nicotiana tabacum L.) to increase organic P in soil was examined in our previous study. However, LASAP2 has low specificity for phytate, the predominant form of unavailable P in the brown lowland soil. For the present study, we isolated the full length of LASAP3 cDNA and introduced it into tobacco plants using Agrobacterium -mediated transformation. Transgenic tobacco plants were grown in two different soils (Andosols and Regosols; high and low P-adsorption capacity, respectively) supplemented with either inorganic phosphate (+Pi) or phytate (Po) as the sole P source, or control conditions that lacked phosphorus (No P). Dry matter production and P content of the transgenic line was higher than that of wild type in all treatments. The ratio of P accumulation increase by exogenous enzymes was found to be dependent on the P treatment and soil type. In all lines, the increase in +Po was less than that in +Pi, but higher than in No P. The P uptake ability of plants in Regosols was higher than in Andosols for all treatments, suggesting that the P utilization efficiency of both Pi and Po is dependent on the solubility. In no soil type or P treatment was a significant difference found between LASAP2 - and LASAP3- overexpressing lines. These results demonstrate that introducing an APase and phytase gene such as LASAP2 and LASAP3 into tobacco by genetic transformation is a promising strategy for improving P mobilization in soil, although the bottleneck for mobilization of phytate-P is not the specificity of the enzyme but its solubility in soils.