Identification and Characterization of a Low Phytic Acid Wheat

Abstract

Phytic acid (myo-inositol-1,2,3,4,5,6-hexakisphosphate, or Ins P6) is the most abundant storage form of P in seeds, yet indigestible by humans and nonruminant livestock. A wheat (Triticum aestivum L.) mutant is described herein with greatly reduced seed phytic acid P but little change in seed total P, similar to lpa1-type mutants described in other grain species. One nonlethal mutant from 562 ethyl-methanesulfonate (EMS) mutagenized M2 lines was identified with a high inorganic phosphate (HIP) phenotype and designated Js-12-LPA. Js-12-LPA homozygotes produced seed in which phytic acid P represented 48.2% of seed total P, in contrast to 74.7% of seed total P in nonmutant or wild-type control, Js-12-WT. The inorganic portion of seed P was increased from 9.1% in Js-12-WT to 50.1% in Js-12-LPA, with little effect on total seed P. Weight distributions among milling fractions were similar for the Js-12-LPA and Js-12-WT genotypes. The low phytic acid trait altered the distribution of total P within the kernel, increasing the P content of the central endosperm and decreasing the P content of the bran. The low phytic acid trait decreased the phytic acid concentration in the bran by 43% and increased the inorganic P concentration in the bran nearly four-fold. Inheritance data of F2 and F4:6 families was inconsistent with a single-gene mutation and suggests the involvement of two or more genes. This low phytic acid wheat mutant is a genetic resource for studying the biology of seed phytic acid metabolism and wheat quality improvement.