ARS | Publication request: Identification of the Molecular Basis of the Seed Low Phytic Acid Phenotype in Soybean Line CX1834

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2009
Publication Date: N/A

Technical Abstract: Plant seeds accumulate phosphorus in the form of myo-inositol-1,2,3,4,5,6 hexakisphosphate, commonly referred to as phytic acid. Phytic acid is complexed with cationic mineral species in the form of phytate, which is not well digested or absorbed by monogastric species such as humans, poultry and swine. As a result, soybean has an effective deficiency of phosphorus and other minerals, despite high levels of these components in the seed. Excreted phytate can also contribute to phosphorus contamination of groundwater and eutrophication of freshwater lakes and streams. In maize, a recessive mutation in a conserved region with the low phytic acid 1 (lpa1) gene is responsible for the low phytic acid phenotype. We have identified recessive mutations in two soybean homologues of the maize lpa1 gene in CX1834, a soybean line with a low phytic acid phenotype derived from EMS mutagenesis of a breeding line with normal phytate levels. In three populations analyzed, we identified complete association between homozygosity for mutant alleles of the two lpa1 homologues and the low phytic acid phenotype. Molecular marker assays were designed that can be used to directly select for the mutant alleles that control the phenotype. The identification of the molecular basis for the low phytic acid phenotype will dramatically ease the introgression of the low phytic acid trait into elite soybean cultivars. The ultimate goal of such introgression is soybean-derived food and feed which require less nutrient supplementation, are more nutritious, and are more environmentally friendly.