Low-phytic-acid Grains

Abstract

As one approach to the improvement of the nutritional quality of crops for both foods and feeds, low-phytic-acid (lpa) mutants of maize and other cereals have been isolated. An important advantage of lpa mutants is that the bioavailability of a range of minerals may be improved, although phytic acid can also function as an antioxidant. Livestock producers are primarily concerned with excretion of feed phytic acid phosphorus by livestock and fish. This contributes to water pollution and is a major environmental issue in developed countries. In these mutants, phytic acid phosphorus is reduced by 55% to 66%, which is matched by an equal increase in inorganic phosphorus. Greater reductions in phytic acid, as high as 95% to 99%, may be desirable and are possible. The first two studies of an lpa maize in human nutrition found increased fractional absorption of iron and zinc in the lpa maize as compared with the control maize. Yields of the best lpa lines, first developed in the mid-1990s, now range between 5% and 15% below those of the highest-yielding commercial varieties. Because of benefits for animal nutrition, lpa crops could become highly profitable for use as animal feeds. All lpa lines to date have been developed using classical genetic methods; these classically obtained mutants affect the expression of a given gene throughout the tissues and organs of a plant. BY using a biotechnology approach, it may be possible to achieve optimal levels of phytic acid reduction and target the desired effect to the seed, thereby reducing any undesirable agronomic effects of whole-plant mutants.