Phytate in seeds of wild plants

Abstract

Phytic acid, the free-acid form of myo-inositolhexakiphosphate, is found widely among eukaryotes. It constitutes the major storage form of phosphate in seeds and fruit in the form of phytate, a mixed cation salt with, e.g., K or Mg. However, the general claim that phytate represents between 60 and 80% of total phosphorus in mature seeds is based almost entirely on work with crop plants. A few reports with wild plants with contrasting findings raised doubts about the generality of the current view. To put this notion to the test, we collected mature dry seeds and dry fruits from 55 species of wild plants from a number of habitats and determined concentrations of both total P and phytate. In the majority of species the contribution of phytate-P to total P was either higher than the “typical” range or considerably lower, with minimum values of just 12%. The proportion of P in phytate was a function of total P: in high-P seeds c. 80% of P was found in phytate, while this proportion decreased gradually with decreasing total P. We conclude that it was indeed premature to generalize the quantitative role of phytate in seeds based on a highly biased data set.