Agronomic Performance of Low Phytic Acid Wheat M. J. Guttieri, K. M. Peterson, and E. J. Souza* ABSTRACT Low phytic acid (LPA) genotypes of wheat (Triticum aestivum L.) improve the nutritional quality of wheat by reducing the concentration of phytic acid (PA) in the aleurone layer, thus reducing the chelation of nutritionally important minerals and improving the bioavailability of phosphorus. Field studies were conducted at Aberdeen and Tetonia, ID, in 2003 and 2004 to evaluate the effects of the LPA genotype on the agronomic performance of wheat. These studies included wild- type (WT) and LPA genotypes in hard red spring, hard white spring, and soft white spring wheat genetic backgrounds. In the hard red spring genetic background, LPA genotypes had delayed development and reduced grain yield (8–25%) in the high yield environment, in part due to reduced kernel size (up to 3 mg kernel 21 ). In the hard white spring genetic background, differences in crop development and grain yield were not observed; however, in the high yield environment LPA genotypes produced smaller kernels (2.0–2.4 mg kernel 21 ). In the soft white spring genetic background, LPA genotypes developed earlier, but the grain yield of LPA genotypes was reduced 20 to 24% in the high yield environment. However, LPA kernels, on average, were heavier and larger in diameter than WT kernels. The absence of con- sistent effects of the LPA genotype across the three genetic back- grounds suggests that deleterious effects of the LPA genotype may be mitigated by plant breeding. P HYTATE IS THE PRIMARY storage form in cereal grains of seedborne P. Most surveys of native variation in cereals for PA have identified only limited variation in the fraction of seed P stored as phytate. Therefore, mutagenesis has been used to develop LPA mutants. We identified LPA mutants of wheat that reduce seed phytate by about 30 to 40% (Guttieri et al., 2004). Low phytic acid mutants of other crops, including barley (Hordeum vulgare L.; Larson et al., 1998), rice (Oryza sativa L.; Larson et al., 2000), soybean [Glycine max (L.) Merr.; Wilcox et al., 2000], and maize (Zea mays L.; Raboy et al., 2000) were identified earlier, with most mutants reducing seed phytate and elevating seed in- organic P concentration. Low phytic acid wheat may improve the nutritional quality of wheat fed to livestock and humans. Animals fed diets with LPA corn and barley have demonstrated greater feed efficiency, improved digestibility, better re- tention of P, Ca, and N, and a significant decrease in P excretion (Mendoza, 2002). Human diets high in PA can lead to Zn deficiency, as phytate is negatively correlated with Zn absorption. Phytic acid does not affect Cu absorption in humans, but slightly inhibits Mn absorp- tion (reviewed by Lo ¨ nnerdal, 2002). Phytic acid forms insoluble complexes with Fe that are nutritionally unavailable at the pH of the small intestine. Diets high in PA and low in Fe can lead to Fe deficiency. However, in human populations with high-Fe diets, the formation of PA–Fe complexes may provide protection against colon cancer by reducing Fe-induced oxidative injury (reviewed by Minihane and Rimbach, 2002). Although the biochemical characteristics of these mutant seed are well described, published reports of the agronomic performance of LPA crops are limited. The germplasm registration notice for KBNT lpa1-1, an LPA rice, noted that the yield of the LPA mutant genotype was about 90% of standard Arkansas rice cultivars (Rutger et al., 2004a). The germplasm registration notice for Goldhull Low Phytic Acid (GLPA) rice in- cluded limited yield trial data (Rutger et al., 2004b). However, the GLPA and KBNT lpa1-1 rice germplasms yielded 95 to 98% of the check cultivar, ‘Kaybonnet’, from which KBNT lpa1-1 was derived. There are no published reports of replicated agronomic trials with LPA barley or maize. Low phytic acid soybean lines with the pha1pha1pha2pha2 genotype had significantly lower seedling emergence than WT lines (Oltmans et al., 2005). Other agronomic traits were not consistently dif- ferent among the three soybean populations studied. The LPA soybeans with the mips allele also had sig- nificantly lower seedling emergence than WT lines with the Mips allele (Meis et al., 2003). The LPAwheat mutant, Js-12 LPA, was described as “agronomically unacceptable” because of its reduced stature, markedly weak straw, and dramatically reduced grain yield (Guttieri et al., 2004). However, mutagenesis often induces undesirable traits that segregate indepen- dently of the target trait. Within our breeding program we have observed that backcross progeny of crosses to transfer the LPA trait from Js-12 LPA to non-LPA cultivars has resulted in LPA germplasm that is pheno- typically similar to the non-LPA parent in all aspects other than P partitioning in the seed. In this study, we report on the assessment of the agronomic effects of the LPA genotype from Js-12-LPA in backcross-derived wheat lines. MATERIALS AND METHODS Generation of Experimental Materials Hard Red Spring Two families of F 2 plants derived from two BC 3 F 1 plants with the pedigree ‘Grandin’*4/Js-12 LPA were grown in the greenhouse. The two BC 3 F 1 plants were designated B and C, with progeny families derived from the two plants named after the two BC 3 F 1 plants. A preliminary evaluation of a high M.J. Guttieri and K.M. Peterson, Univ. of Idaho Research and Extension Center, P.O. Box 870, Aberdeen, ID 83210; E.J. Souza, 105AWilliams Hall, OARDC, 1680 Madison Ave., Wooster, OH 44691. Received 6 Jan. 2006. *Corresponding author (souza.6@osu.edu). Published in Crop Sci. 46:2623–2629 (2006). Crop Breeding & Genetics doi:10.2135/cropsci2006.01.0008 ª Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA Abbreviations: HIP, high inorganic phosphorus; LPA, low phytic acid; PA, phytic acid; PAP, phytic acid phosphorus; WT, wild-type. Reproduced from Crop Science. Published by Crop Science Society of America. All copyrights reserved. 2623 Published online November 21, 2006