Crop Performance and Nutritional Quality of "Low Phytic Acid" and "High Phytase" Genotypes.

Phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate) represents one to several percent of a seed’s dry weight. In the intestinal tract dietary phytic acid binds tightly to nutritionally important minerals, which subsequently are mostly excreted. This phenomenon can contribute to mineral deficiency in humans, most notably iron and zinc deficiency, particularly in populations that rely on grains and legumes as staple foods. However, dietary phytic acid may also have health beneficial roles as an anticarcinogen and antioxidant.  One approach to evaluating and possibly dealing with seed-derived dietary phytic acid's positive or negative roles is the development of low phytic acid (lpa) or “high-phytase” crop genotypes. Both animal and human nutrition studies have shown that the use of lpa types in foods can enhance iron, zinc and calcium absorption and utilization. Thus the production and consumption of lpa crops could in theory mitigate mineral deficiency problems in the developing world. Agronomic studies conducted to date indicate that while many lpa genotypes impact germination, emergence, abiotic stress tolerance and ultimately yield, some perform quite well. Breeding strategies such as recurrent selection for enhanced performance, stress tolerance or yield within an lpa population or genotype may contribute to the development of high-yielding lpa cultivars or hybrids. Genetic engineering approaches such as targeted blocks in phytic acid synthesis or overexpression of the enzyme phytase in seeds are also being pursued.