Location: Soybean and Nitrogen Fixation Research2012 Annual Report
1a. Objectives (from AD-416):
1) To map of the QTLs conditioning the levels of sulfur-containing amino acids in this population and release improved germplasm with elevated sulfur-containing amino acids (>36 g/kg), and 2) To develop Public MG VII soybean line(s) with at least 44% protein, low phytate and elevated sulfur amino acids for use by other soybean breeders.
1b. Approach (from AD-416):
For Objective 1: We have created a RIL mapping population from the cross of G03-3366 x TN04-5321. Year 1: The 284 RIL mapping population of G03-3666 x TN04-5321 will provide lines with higher levels of sulfur-containing amino acids than in previous experiments. These lines will be grown in 5 environments across their range of adaption and seed will be analyzed for protein content and amino acid profile. Year 2: These data will allow the identification of the QTL alleles necessary to significantly improve the level of sulfur-containing amino acids in improved soybean germplasm and varieties containing high protein and low phytate content. NIR determinations will be used to provide amino acid profiles and protein levels on these 284 RILs from five locations. Year 3: Once the major QTLs are found, we will develop melting curve SNP assays for their use in high throughput marker assisted selection. For Objective 2: We have developed a breeding line, G03-3666, with 32 g/kg of cysteine + methionine. Year 1: We will select lines with G03-3666 alleles at the four sulfur-containing amino acids QTLs. In addition we have crossed G00-3213 with the BC5 line Haskell containing the Lg-I high protein allele from Danbaekkong and the Lg-N and Lg-L low phyate alleles from CX1834-1-2. We will pyramid the high protein allele from Danbaekkong, the low phytate QTL alleles from CX1834-1-2, and the high sulfur-containing alleles from G03-3666 into G00-3213. This will be achieved by the development of two parallel backcross populations, one backcross population to incorporate the Lg-I high protein allele from Danbaekkong and Lg-N and Lg-L low phytate alleles from CX1834-1-2 into G00-3213 and the other backcross population to incorporate the elevated sulfur-containing amino acid alleles from G03-3666 at the Lg-C2, Lg-O, and Lg-L QTLs into G00-3213. We will make the 1st and 2nd backcrosses. Year 2: Make the 3rd and 4th backcrosses. Year 3: Make the 5th backcrosses. Once the backcross 5 has been achieved for these two populations, we will cross the two backcross 5 populations to pyramid high protein, low phytate, and elevated sulfur-containing amino acids into the conventional G00-3213.
3. Progress Report:
This project is related to Objective 2 of the in-house project: To discover novel genes/alleles in soybean for seed composition, determine their inheritance, determine genomic location, transfer to adapted germplasm, and release. Data were analyzed from the Athens and Plains locations for the backcross-derived lines of Benning RR with the high protein and low phytate quantitative trait loci (QTL). The data were then combined across locations and analyzed. Two of the backcross 5 Benning RR lines containing the Lg-I high protein QTL (3.2 g/kg higher in protein than Benning RR) and the Lg-N and Lg-L QTL for low phyate (35% of the phytate as Benning RR) averaged 36.0 and 3.67 bu/a in yield compared to an average of 38.0 bu/a for Benning-RR. The yields were low in both the Athens and Plains locations due to the extreme heat during the summer of 2011. Also, crosses combining high sulfur amino acid QTL Lg-B2, Lg-C2, and Lg-G I –were made and F1 seed was planted in the 2012 winter greenhouse.