The diversity of phytic acid content and grain processing play decisive role on minerals bioavailability in rice

Abstract

Rice is a staple food and important source of micronutrients for more than three billion people globally. However, the bioavailability of iron (Fe) and zinc (Zn) is affected by phytic acid (PA). In this work, we analyzed 67 genotypes for Fe, Zn and PA contents. Contrasting PA genotypes were selected in each category of high protein, scented, pigmented and general rice for bioavailability analysis. Our results explain that though Fe content in genotype PB 140 was high, the bioavailability was low which might be due to its higher PA content (21.03 g/kg). The Fe and PA are majorly located in outer bran layer of endosperm, therefore, its bioavailability was affected by PA. However, Zn bioavailability was not much affected by PA as it is distributed homogenously in the rice grain. Moreover, PA biosynthetic genes (IPK1, MIPS1) and grain specific phosphorus transporter gene (SPDT) expressed higher in the middle stage of grain filling which was correlated with higher PA accumulation. Our study provides an insight into the improvement of mechanism of Fe and Zn bioavailability in rice grain which help breeders involved in biofortification programme to develop high minerals bioavailable genotypes by targeting PA related genes.