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Effects of Four Independent Low-Phytate Mutations in Barley (Hordeum vulgare L.) on Seed Phosphorus Characteristics and Malting Quality

¹National Small Grains Germplasm Research Facility, Agricultural Research Service, United States Department of Agriculture, 1691 S. 2700 W., Aberdeen, ID 83210. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. E-mail: pbregit@uidaho.edu

Conversion of the seed phosphorus storage compound phytic acid, which is poorly digested by nonruminants, to available forms of phosphorus will have nutritional and environmental benefits. Low-phytate (LP) barley (Hordeum vulgare L.) cultivars are in development and their commercialization will be facilitated by understanding their phosphorus profiles and malting quality. To study these issues, LP and normal types derived from mutagenized populations of barley cultivar Harrington (sets of sib lines homozygous for the wild-type [WT] allele, or for one of four low-phytic acid mutations, lpa1-1, lpa2-1, lpa3-1, or M955), were developed through backcrosses to Harrington. Grain was produced in irrigated and rain-fed environments. WT phosphorus profiles were similar to those of Harrington, suggesting that the major variable was the presence or absence of mutant alleles. All mutations conferred increased inorganic phosphorus. Total P was reduced for lpa1-1. Phosphorus profiles were relatively stable across environments, which will facilitate the inclusion of LP barley in animal rations. Utilization of LP cultivars for malting may be difficult, as the LP trait was associated with substantial reductions in diastatic power. All mutations, except for lpa2-1, affected wort β-glucan levels, which could not be attributed to altered grain β-glucan levels.