Seed Biofortification and Phytic Acid Reduction: A Conflict of Interest for the Plant?

Abstract

Most of the phosphorus in seeds is accumulated in the form of phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate, InsP6). This molecule is a strong chelator of cations important for nutrition, such as iron, zinc, magnesium, and calcium. For this reason, InsP6 is considered an antinutritional factor. In recent years, efforts to biofortify seeds through the generation of low phytic acid (lpa) mutants have been noteworthy. Moreover, genes involved in the biosynthesis and accumulation of this molecule have been isolated and characterized in different species. Beyond its role in phosphorus storage, phytic acid is a very important signaling molecule involved in different regulatory processes during plant development and responses to different stimuli. Consequently, many lpa mutants show different negative pleitotropic effects. The strength of these pleiotropic effects depends on the specific mutated gene, possible functional redundancy, the nature of the mutation, and the spatio-temporal expression of the gene. Breeding programs or transgenic approaches aimed at development of new lpa mutants must take into consideration these different aspects in order to maximize the utility of these mutants.

Transcriptomic Profiling of Soybean in Response to High-Intensity UV-B Irradiation Reveals Stress Defense Signaling

“…Owing to a lack of InsP3 receptors in plants, InsP3 is converted into the more phosphorylated forms of inositol, i.e., tetra, penta, and hexaphosphates (InsP4, InsP5, and InsP6), through further phosphorylation steps involving at least two types of inositol polyphosphate 2-kinase (IPK1) and inositol polyphosphate kinase 2 (IPK2, synonym for inositol 1,3,4-trisphosphate 5/6-kinase) (Munnik and Vermeer, 2010; Zhou et al, 2012; Sparvoli and Cominelli, 2015). Among these enzymes, Buseok exhibited enhanced expression of two IPK2 family genes under 0.5 and 6 h UV-B irradiation compared to Cheongja 3 (Table 2).…”

Identification of phytic acid mutants in oilseed rape (Brassica napus) by large‐scale screening of mutant populations through amplicon sequencing

“…Phytic acid is the major phosphorous storage compound in seeds with levels from 2% to 4% in oilseed rape seeds, 2–5% in the defatted meal, and 5–7% for the protein concentrates (Thompson, ). Many low phytic acid mutants have been identified in barley ( Hordeum vulgare ), rice ( Oryza sativa ), wheat ( Triticum aestivum ), soybean ( Glycine max ), maize ( Zea mays ), peas ( Pisum sativum ), and sesame ( Sesamum indicum ) (Sparvoli & Cominelli, ). No stable mutants have been reported in oilseed rape, but a downregulation of MIPS genes by RNA interference (RNAi) has been described with a reduced phytate content in a patent (Georges et al , ).…”

Bioavailability of iron and zinc as affected by phytic acid content in rice grain

“…Food fortification has been recommended as one of the preferred approaches for preventing and eradicating Fe and Zn deficiency (Mehansho, ). The bioavailability of minerals in rice can also be enhanced by selecting varieties with inherently high mineral content and cultivating them under good agricultural practices or screening of lines having low PA with high mineral content (Sparvoli & Cominelli, ). IPK1 (Inositol 1,3,4,5,6‐pentakisphosphate 2‐kinase) is the key enzyme believed to catalyze the final step in PA biosynthesis.…”