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 released three high-yielding MG IV to VI germplasm lines with diverse pedigrees (50% PI) that were registered in the 2011 Journal of Plant Registration [2011 JPR 5(2): 220-226]. All three lines (R99-1613F, R01-3474F, R01-2731F) were derived from 50% PI crosses. R99-1613F (MG IV from NKRA 452 x PI 290126B), R01-3474F (MG V from Caviness × PI 594208), and R01-2731F (MG VI from Caviness × PI 592947) had yields equivalent to 97 to 101% of the corresponding checks with similar maturity. These lines have been used as crossing parents in several other breeding programs. In 2011, an advanced PI-derived line, R06-1270 (Lonoke x PI 88310), was evaluated in the USDA Uniform Preliminary Test (56 entries) at nine locations. R06-1270 averaged 46.1 Bu/Ac, 95.2% of the average yield of three checks (AG 5606, 5002T, and Osage), and ranked 35th in the test. This line will be re-tested in the 2012 USB southern diversity yield trials. We also tested 2 MG IV lines (R99-1613F and R09-5373), 9 MG V lines (R01-3474F, R06-1234, R08-3112, R06-1270, R09-1510, R08-3151, R09-1148, R09-1363, and R09-1455), and a MG VI line (R01-2731F) in the USB southern diversity yield trials at 4 to 5 additional locations in other southern states in 2011. All these lines were derived from 50% PI or 25% PI crosses. For the MG IV test, the yields of R99-1613F and R09-5373 were 98% and 94% of the check average, respectively. The 9 MG V lines ranged from 88% to 104% of the check average in the test with three lines (R01-3474F, R06-1234, and R08-3112) better than the check average (101% to 104%). The yield of the MG VI line (R01-2731F) was 96% of the check average. Some of the higher yielding lines will be re-evaluated in the 2012 USB southern diversity yield trials. In Arkansas, we evaluated 27 advanced PI-derived lines from 50% PI or 25% PI crosses in replicated yield trials at 4 locations (Rohwer, Stuttgart, Pine Tree, and Kibler). Yields of our advanced PI-derived lines ranged from 62% to 101% of best check in the test. Overall, 9 of the 50% PI-derived lines and 2 of the 25% PI-derived lines (R08-3119, R09-1363, R08-3112, R06-1234, R05-4519, R01-3474F, R06-1270, R09-5373, R09-1371, R09-1418 and R09-1368) yielded between 90% and 104% of the average of the commercial check cultivars (‘AG4907’, ‘AG5605’, and ‘AG5905’). The best line in the test, R08-3119 (PI 612750 x R01-4787), numerically better than the best check, will be entered in the 2012 USDA Uniform Preliminary Test. Two QTL mapping populations were grown this season in Fayetteville, AR. The first population had 207 F3:4 lines from ‘Caviness’ x R01-3474F (Caviness x PI 594208) and the second one, had 250 F3:4 lines from Caviness x R01-2731F (Caviness x PI 592947). Single plants were pulled from each line for development of recombinant inbred lines. In addition, a total of 28 and 9 progeny rows were selected from each population, respectively, and they will evaluated in a preliminary yield test in 2012.