Concerted action of endogenous and heterologous phytase on phytic acid degradation in seed of transgenic wheat (Triticum aestivum L.)

Expression of heterologous phytases in crops offers a great potential for improving phosphate and mineral bioavailability in food and feed. In this context it is of relevance to describe the concerted action of endogenous and hetrologous phytases on the transgenic seed inositol phosphate profile. Here we report metal-dye detection HPLC analysis of inositol phosphate degradation in flour from transgenic wheat materials possessing wheat endogenous 6-phytase [EC 3.1.3.26] and Aspergillus 3-phytase [ EC 3.1.3.8] activities under the control of the maize ubiquitin-1 promoter and the wheat high molecular weight glutenin subunit 1DX5 promoter respectively. During 50 min incubation there is an accumulation of InsP(5) to InsP(2) breakdown products in non-transgenic material. Aspergillus niger phytase specific breakdown products are transiently detected in transgenic material but after 50 min incubation virtually all InsP(5), InsP(4) and InsP(3) isomers are hydrolysed.