Multi-Location Field Testing of New Environmentally Friendly, High Yielding, Low Phytate Soybean Lines Developed Via Molecular Breeding.

Soymeal is the primary food source for poultry, swine, and fish, however it contains phytic acid or phytate (myo-inositol 1,2,3,4,5,6 hexakisphosphate). Phytate chelates key nutrients making them less available in the diet. Phyate accumulates in animal waste and causes nonpoint phosphorous (P) pollution leading to eutrophication. Two confirmed QTL exist for seed phytate cqPha-001(Gm03) and cqPha-002 (Gm19). Our program developed high yielding maturity group V soybean cultivar 5601T, whose soymeal is excellent for poultry nutrition. The goal of this study was to produce a high yielding, low phytate (LP) backcross (BC) derived progeny of 5601T. However, the genetic linkage between the stem termination locus (Dt1) and the low phytate pha-002 locus prevented progress until we were able to use SNP technology to assist in breaking the genetic linkage.

In 2012, a field trial using a randomized complete block was grown at two locations to evaluate the agronomic performance of 10 BC₅ LP lines in comparison to recurrent and donor parents 5601T and TN09-239 and high yield check cultivar Osage. In 2013, the study was grown at three locations with the addition of two BC₅ LP lines. The yields from four BC₅ LP lines were excellent:  56CX-1273 (4107 kg ha^-1), 56CX-1274 (4137 kg ha^-1), 56CX-1277, (4112 kg ha^-1) and 56CX-1282 (4160 kg ha^-1), and were not significantly different (p>0.05) than that of recurrent parent 5601T (4227 kg ha^-1) or Osage (4089 kg ha^-1). SNP analysis revealed that these four BC₅ LP lines were determinate (dt1 dt1) having broken the linkage between Dt1 and pha-002 on Gm19. These results indicated that LP trait introgression is possible with high yield.