Improvement of organic phosphate acquisition in transgenic tobacco plants by overexpression of a soybean phytase gene Sphy1

Abstract

Due to the huge amount in the soil, phytate is an important potential source for providing the plants with available phosphorus (Pi) by the involved catalytic reaction of phytase. In this study, a construct fusing the open reading frame (ORF) of Sphy1 into corresponding positions in the fragment of binary expression vector pBI121 was created and used to transform tobacco. Molecular identification by PCR and RT-PCR indicated the target gene Sphy1 in the transgenic tobacco plants was transcribed under the regulation of an upstream promoter. Compared with the control plants, the phytase activities in all the transgenic plants were increased, with the increased range consistent with the expression levels in the transgenic plants. Under the growth conditions with phytate as the sole phosphorus source, the transgenic line 1 plants displayed a high expression level of Sphy1 and shows notable improved growth performance, such as higher fresh weight and dry weight, as well as higher total P content and more accumulative P amount per plant than CK. This clearly indicated that overexpression of Sphy1 could improve the phosphorus acquisition by the extruded Sphy1 phytase in the rhizosphere, where this enzyme could catalyze the degradation of the phytate and release the available Pi for plants. The Sphy1 gene seemed to have a potential value in the creation of new crop cultivars with high phosphorus use efficiency.

Key words： Sphy1 gene; overexpression; phosphorus utilization; transgenic tobacco

Acknowledgements

This work was supported by the Natural Science Foundation of Hebei Province, China (No. C2006000434), the Ph.D. Programs Foundation of Ministry of Education of China (No. 20060086001)and the National Basic Research Program of China (973) in the early stage (No.2007CB116209).

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