Molecular Marker Assisted Development and Stability Analysis of Low Phytate, High Inorganic Phosphorus Soybean [Glycine max (L.) Merrill]

Phytate [myo-inositol 1,2,3,4,5,6-hexakisphosphate] is a mixed cation salt of phytic acid which binds to other minerals, in many field crops including soybean [Glycine max (L.) Merr.]. Livestock with monogastric digestive systems lack the ability to break bonds between phytate and these minerals, causing phytate phosphorus (P) to be excreted in the waste and contributing to possible P and other mineral deficiencies. Discovery of single sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers associated with low phytate QTL (cqPha-001 and cqPha-002) have aided in development of low phytate soybean lines. The objectives of this study were to 1) utilize SSRs and SNPs to identify the heterozygous and recessive allelic forms of low phytate loci during trait introgression into a high yielding commercial cultivar; 2) evaluate differences in genotypic values for agronomic and seed quality traits, and seed inorganic phosphorous (Pi) concentration between the recurrent parent 5601T and BC₄, BC₃, and BC₂ derived progeny lines; and 3) evaluate those traits and environmental stability of inorganic P in the recurrent parent 5601T and the BC₄ derived line TN09-239 across ten southern U.S. environments. Successful trait introgression was confirmed in the BC₄ line TN09-239 via SNP assay. In comparison to the recurrent parent 5601T (222.9 ng µL^-1) the BC₄ derived line TN09-239 (1675.9 ng µL^-1) contained significantly higher Pi (P-1 for 5601T and 3151 kg ha^-1 for TN09-239) (P0.05), while TN09-239 had a slope significantly different from zero as well as from one (P