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.
The 5,600 experimental lines in the Nested Association Mapping study were divided into sets and decisions were made on what sets would be grown in each location of the experiment. The lines within each set were randomized and the seeds for the 37,600 plots were distributed to cooperators in eight states for planting. This seed has been used to plant one replication of the entire set of tests at the Urbana, IL location, which includes four sets from each of 40 populations with 40 entries per set for a total of 6,400 plots.