**5. Phytic acid**

Phytic acid is an essential constituent in staple foods like legume and cereals, which has been of much concern [57]. In addition to its beneficial effect on human health, it has some anticancer and antioxidant functions and prevents coronary disease, and it is well known that phytic acid acts as strong chelating agent of mineral nutrients such as Ca, Zn, and Fe [65]. It has been seen that due to the presence of complex of phytic acid, in the form of phytate, there is a significant reduction found in bioavailability of nutrient elements [66]. It seems reasonable to control phytic acid contents in edible parts of crops to a level in which the medical and health functions of the food may be maintained and bioavailability of minerals is not much altered [67].

Liu et al. [68] assayed 72 cultivars for protein content and phytic acid and reported a wide range for phytic acid ranging from 0.685 to 1.03%, with an average of 0.873%. Interestingly, grain phytic acid and protein content were not correlated, which suggests the possibility of breeding rice for phytic acid and high protein content. Furthermore, they also reported a significant effect of varieties, locations, and their interactions on phytic acid content, with the location having the most considerable impact which suggests the necessity of multi-environment trials for the accurate evaluation of rice germplasm for phytic acid content.

Although sufficient genetic variation for phytic acid has been reported in various studies [68, 69], unfortunately, only one study has been conducted to map the QTLs for phytic acid in rice [18]. Stangoulis et al. [18] identified two QTLs explaining 15.4–24.3% of PVE for grain phytates from an IR64 × Azucena double haploid population. One common QTL for phytate and total P concentrations on chromosome 5 with the (high concentration) allele contributed from Azucena was identified. Furthermore, it was reported that Fe, Zn, and Mn contents in grains have different genetic regulation because the QTLs of phytate were not located on the same chromosomal regions as those found for Fe, Zn, and Mn [18]. So, there is a great possibility to find segregants having a low level of phytic acid and high level of Fe, Zn, and Mn content. Use of molecular marker in the breeding and selection to reduce grain phytic acid and improving the nutritional value of cereal grains.
