1a. Objectives (from AD-416):
Our objective is to identify and utilize exotic germplasm to improve U.S. soybean productivity. We will deliver 1) high yielding lines derived from exotic germplasm that are available to all U.S. soybean breeders developing new cultivars, 2) quantitative trait loci (QTL) affecting yield with the positive allele derived from exotic germplasm and the DNA markers associated with these loci, and 3) lines derived from exotic germplasm that will improve the yield and seed quality in the Early Planting Production System of the mid-south.
1b. Approach (from AD-416):
High-yielding experimental lines will be developed from exotic germplasm to expand the genetic base and accelerate the rate of yield improvement of soybean production in the U.S. This breeding project will use over 150 soybean introductions and many experimental lines derived from these introductions in past USB projects. These introductions include modern Asian varieties that are unrelated to U.S. cultivars, diverse primitive varieties that predate scientific plant breeding, and wild soybean. The number of exotic lines that we are using exceeds the total number of all the ancestral lines, regardless of the size of their contribution, of all of the current varieties grown in the U.S. Our projects are located in all major soybean-growing regions of the U.S. so that new genes for increasing yield from exotic germplasm will be accessible to soybean breeders and eventually soybean farmers in every soybean-producing state. We will also be testing exotic germplasm and lines derived from exotic germplasm in the Early Planting Production System of the mid-south to select for high yield and improved germination rates in the harvested seeds. Concurrently with developing high yielding experimental lines, we are developing sets of lines (mapping populations) that will allow us to begin the process of identifying specific genes (quantitative trait loci, QTL) from exotic germplasm that can increase yield of commercial varieties and then to confirm those QTL in independent populations.
3. Progress Report:
In 2013, Georgia released two soybean lines, G08PR-394 and G09PR-80. G08PR-394 is derived from 5601T x R01-3637F. R01-3637F is a maturity group V line that has 25% of its pedigree derived from exotic germplasm. It yielded 2%, 4%, and 20% greater than the seed yield of check genotypes Young, N6202 and N6201, respectively. G09PR-80 is a maturity group V line derived from an F5 plant selection from the cross of 5601T x PI 157440. It yielded 95%, 93%, 87% and 84% of the seed yield of the check genotypes Dillon, Hutcheson, JTN-5503 and its elite parent 5601T, respectively. Two soybean lines, G08-5385RR and G08-5408RR, derived from P97M50 x LG00-3372 were yield tested for two years during 2011-2012 in USB DIV MG7. LG00-3372 is a maturity group III lines with 100% of its pedigree derived from exotic germplasm.They yielded 101% and 100% of check mean in comparable maturity groups. Georgia also has 13 diverse lines entered into USB diversity trial in 2013. 150 recombinant inbred lines (RILs) were developed from the cross of 5601T x PI 471931. 5601T is an elite MG V variety released by University of Tennessee and PI 471931 is a MG V line originally collected in Nepal. In the 1998 and 1999 Soybean Asian Germplasm Evaluation (SAGE) Test, PI 471931 yielded 94% of Manokin, the MG V U.S. check variety. Based on the maturity dates, the population was divided into 3 sets, with 50 RILs in each. In the summer of 2012, the population including the parents was yield tested at three locations, De Witt and Stuttgart, AR; and Mount Olives, NC. Of 150 RILs, 6 lines numerically yielded 0.1 to 2.4 bu/a better than elite parent with maturity similar as the elite parent. Based on data from 1536 SNP markers on an F5-derived population of ‘5601T’ x PI 157440, we have developed a computer program written in R language to conduct a parent-offspring test to quality control the individuals which are genotyped with a fixed set of SNP markers and will be used for further genetic studies and breeding efforts. The program uses monomorphic SNP marker genotypes between parents as an input file to calculate similarity between each offspring and their parents. Based on the similarity of parents and offspring, the users could determine the threshold level for the individuals to be included in further study or data analysis. The R code can be used in any crops which are genotyped with a fixed set of SNP markers and will be submitted for publication.