Isolation and characterization of a novel phytase gene () from soybean ( (L.) Merr.)

Abstract

A novel phytase gene Sphy1 was isolated based on screening a cDNA library which was constructed from germinated soybean (Glycine max (L.) Merr. cv. Kefeng 6) cotyledon. The full-length cDNA of Sphy1 was 1644 bp predicated to encode 547 amino acids including an N terminal signal peptide of 27 amino acids. Phylogenetic analysis indicated that Sphy1 had high similarities with the phytase genes from Medicago truncatula and rice, and acid phosphatase genes from M. truncatula and Arabidopsis. Prokaryotic expression of Sphy1 in Escherichia coli BL21 (DE3) showed that the induced protein had high phytase activities. The transcripts of Sphy1 could be detected in various tissues, such as cotyledons, leaves, stems and roots of seedlings. The phytase activities in the above tissues were in accordance with their corresponding Sphy1 transcripts. The transcripts of Sphy1 in cotyledons showed an increasing trend from 5 to 30 days after germination, suggesting that Sphy1 had involved the hydrolyses of the organic phosphorus compounds in seeds from the stages of early seed germination to young seedlings in soybean. Therefore, it was speculated that Sphy1 played an important role during the seed germination and the growth of the seedlings by releasing inorganic phosphorus (P_i) from phosphorus reserve in seeds.

Keywords

soybean (Glycine max (L.) Merr.), phytase gene, Sphy1, gene expression, phytase activity