Phytic Acid and Inorganic Phosphate Composition in Soybean Lines with Independent IPK1 Mutations

Abstract

Soybean seeds contain a large amount of P, which is stored as phytic acid (PA). Phytic acid is indigestible by nonruminant livestock and considered an antinutritional factor in soybean meal. Several low PA soybean lines have been discovered, but many of these lines have either minor reductions in PA or inadequate germination and emergence. The reduced PA phenotype of soybean line Gm-lpa-ZC-2 was previously shown to be the result of a mutation in a gene encoding an inositol pentakisphosphate 2-kinase on chromosome 14 (14IPK1). While the 14IPK1 mutation was shown to have no impact on germination and emergence, the reduction in PA was modest (up to 50%). Our objective was to determine the effect on seed P partitioning for a novel mutation of an independent IPK1 gene on chromosome six (06IPK1) on its own and in combination with mutant alleles of the 14IPK1. We developed soybean populations and conducted genotype and phenotype association analyses based on the genotype of the 06IPK1 and 14IPK1 genes and the seed P partitioning profile. The lines with both mutant IPK1 genes had very low PA levels, moderate accumulation of inorganic phosphate (Pi), and accumulation of high amounts of P in lower inositols. The developed lines did not have significant reductions in germination or field emergence. In addition, characterization of the lower inositols produced in the mutant lines suggests that IPK1 is a polyphosphate kinase and provides some insight into the PA biosynthesis pathway in soybean seeds.

GmKIX8‐1 regulates organ size in soybean and is the causative gene for the major seed weight QTL qSw17‐1

“…In soybean, several mutant populations have been created using various mutagenic agents such as chemical, irradiation, or transposon (Campbell & Stupar, 2016). More recently, fast neutron (FN) mutant populations were utilized to identify and characterize several causative genes or genetic loci for important seed composition phenotypes in soybean such as increased production of vitamin E (Stacey et al ., 2016), sucrose (Dobbels et al ., 2017), stearic acid (Gillman et al ., 2014), reduced seed phytic acid (Vincent et al ., 2015) or altered plant morphology (Bolon et al ., 2011; Hwang et al ., 2015). One advantage of FN mutagenesis is the induction of genetic deletions which can be rapidly identified by comparative genome hybridization (CGH).…”

Chromatographic Study of Mineral–phytate and Protein–phytate Interactions in Soymilk

“…Another possibility is that the peak for fraction 53 represents inositol pentaphosphate (IP5) bound to calcium. It has been reported that in soybean phytic acid contributes 93 % of the total inositol phosphate and IP5 contributes only 3 % (Vincent et al, 2015), while in soy flakes, 14 % of the inositol phosphate is in the form of IP5 (Lehrfeld, 1989). Further studies are needed to identify the peak for fraction 53.…”

Soybean (Glycine max) Mutant and Germplasm Resources: Current Status and Future Prospects

“…However, when this novel mutation was combined with the mutated IPK1 isoform encoded on chromosome 14 (Glyma14g07880), a drastic reduction in seed phytic acid accumulation was observed. Unlike other low phytic acid mutants in soybean, the double IPK1 mutant showed no significant reductions in germination or field emergence (Vincent et al., ).…”