Genotypic Differences in the Effect of P Fertilization on Phytic Acid Content in Rice Grain

Abstract

Phytic acid (PA) prevents the absorption of minerals in the human intestine, and it is regarded as an antinutrient. Low PA rice is beneficial because of its higher Zn bioavailability and it is suggested that the gene expression level of myo-inositol 3-phosphate synthase 1 (INO1) in developing grain is a key factor to explain the genotypic difference in PA accumulation among natural variants of rice. P fertilization is also considered to affect the PA content, but it is not clear how it affects INO1 gene expression and the PA content in different genotypes. Here, we investigated the effect of P fertilization on the PA content in two contrasting rice genotypes, with low and high PA accumulation, respectively. Based on the results of the analysis of the PA content, inorganic P content, INO1 gene expression, and xylem sap inorganic P content, we concluded that the effect of P fertilization on PA accumulation in grain differed with the genotype, and it was regulated by multiple mechanisms.

Phytic Acid and Mineral Biofortification Strategies: From Plant Science to Breeding and Biotechnological Approaches

“…In the second article, Fukushima et al [9] analyzed the response to P fertilization of two previously selected rice genotypes differing for their PA content with the World Rice Core Collection 5 (WRC 5) genotype showing the lowest and WRC 6 showing the highest PA content among different accessions [21]. The authors reported that differences in PA content between the two contrasting cultivars were observed only under standard P fertilization conditions, while, if two different doses of P fertilizer were applied at different developmental stages (at seedling or heading stage) an increase in PA content was observed in both genotypes, highly reducing the differences between the two genotypes.…”

“…PA is also a very important signaling molecule involved in different regulatory processes during plant development and responses to different stimuli [12]. Different contributions to the present Special Issue treat aspects related to PA and lpa mutants [4][5][6][7][8][9][10].…”

“…Seed PA content is affected by the amount of supplied P in various crops [18][19][20]. In this Issue, two articles investigate the effects of P fertilization in genotypes differing in their PA content, particularly in a soybean lpa mutant compared with two normal-phytate cultivars [10] and in two rice cultivars described for their contrasting grain PA content [9].…”

“…A review and a commentary are focused on lpa mutants in transporters [5,6]. Four articles describe the isolation and characterization in different crops of lpa mutants [7][8][9][10], derived from mutagenized populations [7,9,10] or from the genome editing technology approach [8]. An overview of the role of inositol pyrophosphates and useful recommendations for the development of novel lpa mutants is presented by Freed et al [11].…”

Phytic Acid in Brown Rice Can Be Reduced by Increasing Soaking Temperature

“…Therefore, reducing PA content without the need for polishing out the aleurone layer is an efficient way to improve mineral bioavailability in rice. Although, the genetic and environmental factors controlling P content in rice have been investigated, including P fertilizers, there is still not enough information to help understand the dynamics of P contents in brown rice [ 15 , 16 ]. Low phytic acid ( lpa ) mutant rice has been developed to increase mineral bioavailability [ 17 , 18 , 19 ].…”