Is It Possible To Develop a Low Phytic Acid Soybean With Improved Emergence?.

Soybean [Glycine max (L.) Merr] seeds contain a large amount of phosphorus, which is stored as phytic acid (PA).  PA is indigestible by nonruminent livestock and considered an anti-nutritional factor because PA chelates divalent cations and prevents the uptake of essential nutrients.  Interest in reducing PA has increased greatly over the years and several low PA soybean lines have been discovered; however, many of these lines have inadequate germination and emergence.  A gamma irradiated soybean line, ZC-2, with 50% reduction in PA was found to have excellent germination and emergence.  The low PA phenotype was a result of a mutation in a gene orthologous to inositol pentakisphosphate 2-kinase (IPK1; Glyma14g07880), which is responsible for phosphorylating inositol pentakisphosphate into PA.  Our objective was to reduce PA levels by more than 50% with conventional breeding methods.  Our own fast neutron irradiated line, FN38, has a large deletion of an independent gene homologous to IPK1 (Glyma06g03310).  Initial characterization of PA and inorganic phosphorus (Pi) levels for the deletion were inconclusive but continuing.  In order to determine if we could reduce PA, FN38 was bred with ZC-2 to develop a population of soybean lines for phenotype and genotype association analysis.  We developed and utilized molecular marker assays to select for the two IPK1 mutations.  We intend to perform high-performance liquid chromatography (HPLC) to measure PA levels and a colorimetric assay to measure Pi levels in the selected soybean lines.  Results will be presented during the poster presentation.