Molecular Marker Assisted Backcross Development and Evaluation of an Environmentally Friendly, Commercially Acceptable Low Seed Phytate Soybean
Boehm, J. D.  2014.  M.S. Thesis, University of Tennessee. August 2014.

Soybean [Glycine max (L). Merrill] is the world’s top oilseed crop. High protein soymeal is a primary soybean use and staple food of livestock and fish. The storage form of phosphorus (P) in the seed is phytic acid, or phytate [myo-inositol 1,2,3,4,5,6 hexakisphosphate] which binds and chelates key nutritional cations forming stable salts that are non-digestible. Livestock waste laden with phytate P is an environmental concern, and a source of nonpoint P pollution causing eutrophication and surface water quality deterioration. The primary objective of this research was the development of a commercially acceptable low phytate (LP) soybean line which would enhance nutritional qualities of soymeal and sustainably lessen P pollution. The LP soybean lines evaluated in this study were twelve BC5 [5th generation backcross] derived lines from their recurrent parent ‘5601T’, a high yielding University of Tennessee developed cultivar. The presence of the two LP loci in all twelve BC5 derived lines was confirmed using perfect SNP [single nucleotide polymorphism] molecular markers near the confirmed QTL [quantitative trait loci] cqPha-001 and cqPha-002. In 2012, a field trial using a randomized complete block design with two replications was grown at two locations in two row plots to evaluate the agronomic performance of 10 BC5 LP lines in comparison to their parents 5601T, TN09-239, and high yield check cultivars; the study was repeated in 2013, evaluating 12 BC5 LP lines in four row plots in two locations and in two row plots in a third location with three replications per location. Data analyzed using SAS version 9.3 revealed that the yields of four BC5 LP lines, 56CX-1273 (4107 kg ha-1 [kilograms per hectare]), 56CX-1274 (4137 kg ha-1 ), 56CX-1277 (4112 kg ha-1) and 56CX-1282 (4160 kg ha-1), were not significantly different (p>0.05) than that of 5601T (4227 kg ha-1) and also were numerically better than the yield of current USDA Maturity Group V check ‘Osage’ (4089 kg ha-1). These results indicate that LP trait introgression to those four BC5 LP lines did not have detrimental effects on yield and one of the lines may be considered for a cultivar or germplasm release.