Genetic Regulation of Phytic Acid Biosynthesis in Rice: Pathways and Breeding Approaches for Low-Phytate Varieties

Phytic acid (PA), or myo -inositol 1,2,3,4,5,6-hexakisphosphate, is the main storage form of phosphorus (P) in seeds, accounting for 65% to 85% of their total phosphorus content. The negative charge of phytic acid attracts metal cations, forming insoluble salts called phytates. These phytates, contain six negatively charged ions, can bind divalent cations such as Fe 2+ , Zn 2+ , Mg 2+ , and Ca 2+ , preventing their absorption in monogastric animals. To overcome P deficiency in non-ruminants, phytase is usually given as a supplement, which then results in excess P excretion, leading to environmental problems, such as eutrophication. Improved fertilizer management, food processing techniques, and the development of low-PA crops through plant breeding are all envisioned as effective ways to improve P-utilization and lessen the environmental impact while minimizing the effect of PA. A better understanding of the molecular and physiological basis of PA biosynthesis, the distribution of grain PA, the effects of genetic and environmental factors on PA accumulation, and possible ways to increase micronutrient bioavailability by lowering the effects of PA is essential for developing low-PA crops.