2011 Annual Report
Seeds of 256 experimental lines in maturity groups II to IV derived from exotic germplasm were sent to soybean breeders in 6 commercial companies for testing and use in their variety development programs. The pedigrees of these lines include 63 exotic accessions including three wild soybean accessions and by pedigree, these line range from 12 to 100% exotic germplasm.
In the Northern Uniform Tests, 8 lines that had yields at least 100% of the best commercial varieties. Three lines were in the Preliminary Test II but were 5 to 7 days later than the group II commercial varieties. Two lines were equal to the best commercial variety in Preliminary III Test and similar in maturity. One of those lines is LG06-2284 which has 6 introductions that contribute 50% of the pedigree. The other line is LG07-2309 which has a pedigree that is 12% wild soybean. Three lines in Uniform Test IV were equal or better than the best commercial variety. LG06-5798 and LG06-5920 have the same pedigree which is 50% exotic germplasm. LG06-5798 yielded a statistically significant 7% more than the highest yielding check and is being released. LG07-9814, that was equal to the highest yielding commercial variety, also has a pedigree with 50% exotic pedigree from four introductions. We successively produced over 2500 fertile progeny from G. max (soybean) by G. tomentella crosses. We have transferred resistance to Phytophthora rot and sudden death syndrome (SDS) from G. tomentella to G. max. We have tentatively identified transferred resistance to soybean rust and soybean cyst nematode. In addition to the fertile progeny with the same number of chromosomes as soybean (2n=40), we have identified numerous self-fertile, genetically stable 2n=42 lines that have a pair of chromosomes from G. tomentella.
Our research strategy of conducting gene expression studies to identify defense-associated genes is progressing well. We published on the gene expression response in soybean roots to SDS, and have started to prepare a manuscript on the response in soybean leaves to SDS toxin. From these studies we have identified over 2000 genes that were pathogen and/or toxin responsive and have started to conduct virus-induced gene silencing assays to verify function of the most promising defense-associated genes from the lists. Likewise, we have identified candidate defense-associated genes from our Sclerotinia studies and are developing transgenic plants (in collaboration with AgCanada) of RNAi lines to test the importance of these candidate defense genes. We also have good candidate genes for Rpp1 and rpp5 and are conducting VIGS assays for those genes. We have used the gene expression database that we developed to see how genes are being expressed across many disease and stress experiments, and from that analysis found about 20 genes that were strongly induced in a pathogen-specific manner. These genes will be candidates for future functional characterization.
Krishnan, H.B., Nelson, R.L. 2011. Proteomic analysis of high protein soybean (Glycine max) accessions demonstrates the contribution of novel glycinin subunits. Journal of Agricultural and Food Chemistry. 59:2432-2439.
Libault, M., Farmer, A., Brechenmacher, L., Franck, W.L., Drnevich, J., Langley, R.J., Bilgin, D.D., Radwan, O., Neece, D.J., Clough, S.J., May, G., Stacey, G. 2009. Complete Transcriptome of the Soybean Root Hair Cell, a Single Cell Model, and its Alteration in Response to Bradyrhizobium japonicum Infection. Plant Physiology. 152: 541-552.
Lee, J., Vuong, T.D., Moon, H., Yu, J., Nelson, R.L., Nguyen, H.T., Shannon, J.G. 2011. Genetic diversity and population structure of Korean and Chinese soybean [Glycine max (L.) Merr.] accessions. Crop Science. 51:1080-1088.
Nelson, R.L. 2011. Managing self-pollinated germplasm collections to maximize utilization. Plant Genetic Resources. 9:123-133.
Oliveira, M.F., Nelson, R.L., Geraldi, I.O., Cruz, C.D., Toledo, J.F. 2010. Establishing a soybean germplasm core collection. Field Crops Research. 119:277-289.
Radwan, O., Liu, Y., Clough, S.J. 2011. Transcriptional analysis of soybean roots response to Fusarium virguliforme, the causal agent of sudden death syndrome. Molecular Plant-Microbe Interactions. 24:958-972.