Mineral Distributions in Milling Fractions of Low Phytic Acid Wheat

Abstract

Low phytic acid (LPA) wheat (Triticum aestivum L.) is one approach to improving nutritional quality of wheat by reducing the major storage form of P and increasing the level of inorganic P (P i ), which is more readily absorbed by humans and other monogastric animals. A LPA mutant of wheat, designated Js-12-LPA was isolated following mutagenesis. LPA and wild-type (WT) sib selections of hard red spring wheat families with the pedigree 'Grandin'*4/Js-12-LPA were grown in replicated field trials in 2003 and 2004. Grain was milled on an experimental mill, and the distribution of P, phytic acid P (PAP), and P i was measured in milling fractions. Mineral concentrations also were determined. LPA selections had elevated concentrations of P i and Mg in flour fractions. The concentration of P i in LPA flour was three times the concentration in WT flour, and Mg concentration in LPA flour was 25% greater than in WT flour. Therefore, P and Mg in LPA wheat appear to be redistributed within the kernel. The increase in P i is similar to that observed for other LPA mutants and should improve the mineral nutrition of monogastric animals fed whole grain LPA wheat. As most wheat is milled for flour and bran, the detailed distribution of minerals in the LPA wheat should assist geneticists and nutritionists in assessing the value of this mutation.

Quantitative Analysis of Phytate Globoids Isolated from Wheat Bran and Characterization of Their Sequential Dephosphorylation by Wheat Phytase

“…The concentrations of Fe, Mg, and P were all 7-fold higher in the purified globoids as compared with wheat bran. This copurification of Fe and Mg with phytate-P allows us to suggest an association between these compounds and confirms a connection between phytic acid and Mg, verifying what has been documented in low-phytate wheat [Js-12-LPA (11)] and rice [lpa1-1 (24)]. Other minerals such as Ca, Zn, and K increased 5-fold in concentration from wheat bran to purified globoids ( Table 1).…”

“…In wheat, the greatest concentrations of minerals have been found in the bran (8,9). Direct positive associations between grain phytic acid and Zn have been reported (10), and it has been shown that redistribution within the kernel of phosphate and Mg, from the aleurone layer to the flour, takes place in the wheat mutant Js-12-LPA (11).…”

Assessment of the contents of phytic acid and divalent cations in low phytic acid (lpa) mutants of rice and soybean

“…Results obtained for maize (Lin et al, 2005), barley (Liu et al, 2007a) and wheat (Guttieri et al, 2006) indicated that lpa mutations do not result in systematic increases or decreases of the mineral contents in these crops.…”

Moving micronutrients from the soil to the seeds: Genes and physiological processes from a biofortification perspective

“…The high concentration of the phosphorus storage molecule phytate in cereal grains [178] is also problematic, as phytate can also bind Fe and Zn, and decrease absorption of these nutrients in the animal gut. Increasing wheat grain Zn levels by agronomic practices did not result in increased phytate [160], and lines of cereals with mutations that result in low phytate concentration did not consistently have altered levels of Fe or Zn in rice, maize, wheat, barley, or soybean seeds [179][180][181][182][183]. These results suggest that phytate can be decreased in future variety development while Fe and Zn concentrations remain at current levels or higher.…”