Location: Crop Genetics Research2012 Annual Report
1a. Objectives (from AD-416):
1. Develop high yielding soybean germplasm with enhanced seed composition and plant protection traits for soybean production system of the mid-south United States; 2. Identify the physiological mechanisms that regulate seed composition qualities of oil, fatty acids, and protein under stress environment; 3. Optimize Early Soybean Production Systems (ESPS) and pest management strategies for the mid-south United States; and 4. Coordinate and participate in the Uniform Soybean Test - Southern States.
1b. Approach (from AD-416):
Use publicly available genetic diversity in soybean germplasm, including fatty acid mutants, phytic acid mutants and Plant Introductions from USDA collections, to develop germplasm with modified fatty acid and phytic acid levels which are adapted to the mid-south; use publicly available genetic diversity and known charcoal rot resistant lines to improve charcoal rot resistance in germplasm with high yield potential for the mid-south; develop high-yielding agronomically superior lines with adaptation to Early Soybean Production System (ESPS) using available genetic diversity from both northern and southern USA lines; determine the effects of nutrient uptake and assimilation on oil, fatty acids, and protein production in seed under drought; measure the effects of drought and heat stress on nutrient uptake and assimilation on oil, fatty acids, and protein production in seed; determine optimum plant density and row spacing for cultivars of different maturities and plant architecture adapted to ESPS for yield or fungicide deposition; relate optimum population to light interception; determine optimum seeding rate for late plantings; evaluate planting date effect on soybean rust infection; determine effect of late season insecticide application on yield; coordinate, analyze data, and publish the annual reports of the Uniform Soybean Tests – Southern States.
3. Progress Report:
The research program of this project focused on the measurement and analysis of seed composition traits as affected by biotic and abiotic environmental conditions and the development of soybean germplasm with improved seed composition. Additionally, this project is responsible for the Southern States Uniform Soybean Tests. Soybean seed composition analysis for protein, oil, fatty acids, lignin, phenolics, isoflavones, and minerals were conducted in the Early Soybean Production System under irrigated and non-irrigated conditions. To determine the effect of genotype, diseases, drought, and heat on seed composition constituents, soybean lines susceptible and resistant to charcoal rot and phomopsis, lines varying in germinability, the slow-wilting trait and sensitive to drought were used. The results showed that both charcoal rot and Phomopsis increased seed protein and oleic acid, but decreased oil and linolenic acid. However, maintaining this pattern of effect depended on maturity group. The results demonstrated that a) seed composition constituents were altered by drought, Phomopsis, and charcoal rot, and the degree of alteration depended on the level of resistance of the genotype to charcoal rot or Phomopsis, and maturity group; b) there were positive correlations between germination and boron, indicating a possible role of boron in seed germination; c) higher levels of calcium (Ca), potassium (K), boron (B), manganese (Mn), and zinc (Zn) in seed of resistant genotypes to phomopsis suggested that these minerals may be associated with Phomopsis infection and drought stress; and d) seed K, Ca, Mn, B, Zn, and Cu may play an important role in Phomopsis resistance. New crosses for improving germination of low phytate lines were successfully made in 2011 with high germination lines. The goal is to improve the germination and seed vigor of the donor line TN09-239. Work advanced to introgress reduced phytate into lines adapted to the mid-south using single crosses, backcrosses and molecular markers. Work continued to evaluate lines for low linolenic acid on single cross and backcross populations. Lines from 2,007 single crosses, 2,008 single crosses and 2,008 backcrosses were grown in yield trials. Plant rows were evaluated as appropriate. Molecular markers were used to select individuals from lines with high yield or important agronomic traits in the preliminary yield trials that will breed true for low linolenic acid or low phytate. These selections will be increased in summer 2012. Additionally, new high oleic acid crosses were made in 2011. Over 330 experimental breeding lines were sent to Paraguay in 2011-12 for field screening for Asian Soybean Rust resistance. Lines from crosses in 2006-2010 were included. Data will be used for generation advancement decisions. For the Uniform Tests, data was collected from Stoneville, MS, all data from other locations was compiled and summarized. Seed for this year’s experiments were distributed to cooperators and planted at the Stoneville location. Overall, activities are proceeding according to plan.
1. Effect of Phomopsis and charcoal rot on seed composition and mechanisms of disease resistance. Phomopsis and charcoal rot are major diseases in the Early Soybean production System. The effects of these diseases on seed composition have not been well investigated. The research identified that levels of seed coat lignin, total phenol, and total isolflavones along with calcium, zinc, boron and copper are associated with increased resistance mechanism in Phomopsis and charcoal rot. This information will help in understanding resistance mechanisms and in developing selection criteria for use by plant breeders.
2. Effect of planting date on seed composition and nitrogen metabolism in the Early Soybean Production System. Information on the effect of planting date and irrigation on soybean seed composition in the Early Soybean Production System (ESPS) is limited and inconclusive. The research demonstrated that early planting date increased nitrogen fixation and assimilation rates. Late planting tends to increase seed oil, oleic acid, sucrose, and raffinose, but decrease protein, linoleic and linolenic acids, and stachyose under irrigated conditions as compared to non-irrigation. Soybean producers may use this information to maintain yield and seed quality, and soybean breeders to select for seed quality traits and mineral translocation efficiency in stress environments.
Bellaloui, N., Gillen, A.M. 2011. Soybean seed protein, oil, fatty acids N and S partitioning as affected by node position and cultivar differences. Journal of Agricultural Science. 1:110-118.