1a. Objectives (from AD-416)
1. Strategically expand the USDA Soybean Germplasm Collection, conserve and distribute available genetic diversity in genus Glycine, and evaluate genetic resources in the collection. 2. Develop experimental lines derived from exotic germplasm with high yield and/or modified seed composition and map the loci associated with these traits. 3. Elucidate genetic mechanisms of resistance to sudden death syndrome, white mold, and soybean rust in diverse soybean germplasm.
1b. Approach (from AD-416)
Identify genes associated with defense to various pathogens such as Fusarium solani, Sclerotinia sclerotiorum, and Phakopsora pachyrhizi by comparing genomic mRNA levels between resistant and susceptible lines. Candidate genes related to defense will be characterized by functional molecular studies and will be located on the physical map to determine if gene is from a region of the genome associated with any known QTLs for resistance to the specific disease. Analyze soybean interactions with Sclerotinia by analyzing effects of oxalic acid on soybean. Examine physiological conditions that might enhance soybean susceptibility to rust disease caused by Phakopsora pachyrhizi. Strategically expand the USDA Soybean Germplasm Collection to better represent the diversity of the genus Glycine. Conserve, evaluate and distribute available genetic diversity in genus Glycine. Develop experimental lines derived from exotic germplasm with high yield, high protein concentration and/or high oil concentration. Map and confirm quantitative trait loci for yield, and protein and oil concentration with the positive allele coming from exotic germplasm.
3. Progress Report
Determined soybean gene expression response to Fusarium virguliforme and verified the results using qRT-PCR. Determined the expression of genes in plants naturally infected. We expanded our original study over 6 time points. This addresses NP301 National Program Action Plan Problem Statement 1B: Assess the Systemic Relationships and Genetic Diversity of Crop Genetic Resources and NP303 National Program Action Plan Problem Statement 3A: Mechanisms of Plant Resistance. Added an additional replicate to our Sclerotinia stem infection study. We conducted additional array studies related to effect of virulence factor oxalic acid. This addresses NP301 National Program Action Plan Problem Statement 1B: Assess the Systemic Relationships and Genetic Diversity of Crop Genetic Resources and NP303 National Program Action Plan Problem Statement 3A: Mechanisms of Plant Resistance. Over 1,400 plots have been planted for seed replacement for the USDA Soybean Germplasm Collection. We received and planted 214 new introductions from northern Vietnam. During the first 6 months of 2008 we have already distributed nearly 16,000 seed samples in response to 391 seed requests. This addresses National Program Action Plan Problem Statement 1A: Efficiently and Effectively Manage Plant and Microbial Genetic Resources. Nearly 3200 four-row yield plots are being grown to identify yield genes from exotic soybean germplasm or to confirm genes already tentatively identified in previous research. The objective is to find yield enhancing genes from exotic germplasm that can improve the yield of U.S. commercial varieties. This addresses National Program Action Plan Problem Statement 2C: Genetic Analyses and Mapping of Important Traits. Over 90 accessions from the USDA Soybean Germplasm Collection are being planted at 7 locations to confirm resistance to soybean rust that has been identified in previous research. This addresses National Program Action Plan Problem Statement 3B: Capitalizing on Untapped Genetic Diversity Nearly 2400 four-row yield plots and 4200 one-row yield plots were planted to identify high yielding experimental lines derived from exotic germplasm. These lines have pedigrees that range from 13 to 100% exotic germplasm. Two hundred thirty advanced experimental lines are being cooperatively tested with soybean breeders in private industry. This addresses National Program Action Plan Problem Statement 3C: Germplasm Enhancement/Release of Improved Genetic Resources and Varieties.