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
We made available for distribution to all public soybean breeders 58 heterogeneous inbred populations, in maturity groups II, III and IV, derived from exotic germplasm and selected for high yield. These lines were derived from 24 exotic parents. Seeds were sent to 8 public soybean breeders. In the 2010 Uniform Preliminary IIB Test - Northern Region, LG08-3838 ranked third of 29 entries for yield. It has a pedigree that includes two introductions not previously used in U.S. soybean breeding that have been in the USDA Soybean Germplasm Collection for over 50 years. In the 2010 Uniform Preliminary IIIB Test - Northern Region, LG07-2309 and LG06-2284 ranked second and fourth of 26 entries for yield. LG06-2284 has 50% of its pedigree derived from 6 exotic parents and LG07-2309 has 12% of its pedigree from wild soybean. In the 2010 Uniform IV Test - Northern Region, LG07-5798 ranked first of 13 entries yielding statistically more than the highest yielding cultivar in the test. LG07-5798 has 50% of its pedigree derived from 2 Chinese introductions A population of 153 lines from the cross of LG98-1605 x LD00-3309 was planted in yield tests at 6 locations to identify yield QTL. LG98-1605 has a pedigree that is 100% exotic germplasm including PI 28331, PI 253665D, PI 361064, and PI 384469A.This is the second year of testing for this population. In 2010 in cooperative tests with private industry, we identified 57 of 255 lines tested that numerically exceeded the yield of the check variety in the test. The pedigrees of these highest yielding lines ranged from 25 to 87% exotic germplasm and included 3 wild soybean accessions. Activities of this project are monitored through quarterly reports, an annual planning meeting, and periodic phone calls and e-mails.