Molecular Marker Assisted Backcross Development and Evaluation Of An Environmentally Friendly, Commercially Acceptable Low Seed Phytate Soybean.

Soybean [Glycine max (L). Merrill] is the world’s top oilseed crop. High protein soymeal is a primary use of the crop for livestock feed. The storage form of phosphorus in the seed is phytic acid, or phytate (myo-inositol 1,2,3,4,5,6 hexakisphosphate) which binds and chelates many 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 pollution causing accelerated eutrophication. The objective of this research is the development of a high yielding, low phytate soybean line which would enable enhanced feed nutritional qualities of soymeal and sustainably lessen P water pollution from animal agricultural waste runoff. 

The low phytate soybean lines being evaluated in this experiment are ten BC5 derived lines of their recurrent parent ‘5601T’, a high yielding cultivar developed at the University of Tennessee. The line TN09-239 was the low phytate, donor parent. The presence of the two low phytate loci in all ten BC5 derived lines was confirmed using SNP molecular markers near the confirmed QTL cqPHA-001 and cqPHA-002.

In 2012, a randomized complete block design (RCBD) with two replications grown at two locations in two row plots was used to evaluate the agronomic performance of the ten BC5 low phytate lines in comparison to their parents 5601T, TN09-239, and high yield check cultivars. Data were analyzed using SAS version 9.3 (SAS Institute, Cary, NC) and revealed that two BC5F3:5 lines, 56CX-1273 and 56CX-1283, yielded 4,501 and 4487 kg ha^-1 which was not significantly different (p> 0.05) than that of 5601T (4,650 kg ha^-1).

New SNP data based on gene sequence of the stem termination locus (Dt1) showed that 56CX-1273 and 56CX-1283 were homozygous recessive (dt1dt1), expressing the desired MG V determinate growth habit. An important goal is the targeted release of a new MG V high yielding, low phytate cultivar or germplasm line.