Performing Department
School of Plant and Environmental Sciences
Non Technical Summary
Problem Statement. While soybean is one of the most important sources of plant protein worldwide, with high digestibility and all essential amino acids (AAs), soybean protein contains an imbalanced AA profile. As with many other legumes, soybean provides insufficient sulfur-containing AA, such as methionine (Met, Friedman and Brandon, 2001). To overcome the deficiency of Met, humans consume food with complementary AA patterns (Woolf, et al., 2011). However, monogastric livestock such as poultry and swine producers have synthetically-produced AA added as a supplement into animal diets as these species cannot synthesize these AAs themselves (Warringon et al., 2015). A 10% increase of soybean Met would enhance the commercial soybean meal value by $2.7/T (Clark and Wiseman, 2000). Unfortunately, Met leaching during meal processing and bacterial degradation causes the formation of undesirable volatile sulfides released in the environment (George and De Lumen, 1991). In addition, the cost to add 0.1% DL-Met alone into soybean-based meal to overcome AA deficiency is approximately $100 million annually in poultry and pork production (Imsande, 2001). Thus, agricultural stakeholders, in particular meat producers, indicate the urgent need to develop new soybean varieties with balanced AA for both human and animal consumption. Therefore, soybean varieties with balanced AA profile, in particular increased Met through genetic improvement, will provide high nutritional quality protein and meal, and reduce the existing negative impacts related to AA supplementation.Relevance to Advancing Virginia and the U.S. Soybean, one of the world's major crops, is the top USA commodity export, estimated at $22.3 billion (Moody, 2017), and a top five commodity in Virginia with $200.5 million in annual cash receipts (Patterson, 2015). In addition, being the top soybean producing country for more than one decade, the U.S. produces over one third of the soybean in the world annually, Because soybean provides protein with high quality, it has been used widely in animal feeds for production of several other top 10 Virginia commodities (poultry, beef, dairy, eggs), pork, and aquaculture as well as in human diets. Therefore, stakeholders in soybean seed, meal and soyfood markets will be highly interested in this project that will break the limitation in soybean varieties with imbalanced AA profile, especially deficient Met content. Developing soybean varieties with beneficial AA profile that are adapted to VA and the Mid-Atlantic region will improve animal nutrition, so they will open additional markets for VA seed growers, reduce transportation costs to the VA beef/poultry growers, and increase the economic return to VA farmers.Approach. The proposed study is innovative because we will take advantage of the molecular markers associated with high Met to screen as early as F2 population, and confirm F3 seeds' Met content using near-infrared spectroscopy (NIR). The molecular markers include simple sequence repeat (SSR) and single nucleotide polymorphism (SNP). The NIR instrument will be equipped with calibration equations using samples from the Mid-Atlantic region.Anticipated Outcomes and Impacts. Our long-term goal is to improve the nutritional profile of soybean-based food and meal. Our overall objective for this study is to develop and release soybean varieties with higher Met content adapted to the Mid-Atlantic Region. Successful completion of this project will provide soyfood consumers and livestock farmers with more nutritional soybean varieties to improve human and animal health.
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
Our long-term goal is todevelope soybean varieties with balanced AA adapted to the Mid-Atlantic region.Our specific objectives for this proposed project are to: 1) Develop soybean breeding lines with high Met using marker-assisted selection at early breeding stages; 2) validate the association between Met concentration and published molecular markers to explore effective markers for our genetic populations; and 3) develop a calibration equation for Perten 7250 NIR spectrometer using Met data generated by HPLC to estimate Met concentration.
Project Methods
Objective 1: Develop soybean breeding lines with high Met using marker-assisted selection at early breeding stagesCrossing planTN04-5321 and other potential PIs from the USDA Soybean Germplasm Collection based on published Met concentration are being crossed or will be crossed with elite food-grade and feed-grade soybeans including herbicide tolerant varieties either in greenhouse or in the field. In addition, 5-10 crosses will be made every year. Top advanced breeding lines from those crosses will be chosen as elite parents in the future.Breeding schemeThe breeding populations will be advanced and will be screened using molecular markers and NIR for Met concentration. The breeding scheme will be slightly modified if crosses are made in the field. Briefly, true hybrid seeds will be harvested and advanced either in the field or winter nursery to advance generations. Leaf tissues of F2 individuals will be collected, and molecular markers will be run on DNA from those leaf tissues to determine if the F2 individuals have high Met QTL. Positive F2 plants will be harvested and seeds will be evaluated using NIR to confirm the Met value. Only the samples with 10% higher Met value than elite parents will be planted the following year. The same procedure will be applied to F3 populations. F4 populations will be planted at the Eastern Virginia Agricultural Research and Experiment Center (EVAREC, Warsaw, VA) as this environment is close to commercial production regions. Seeds from single F4 plants will be tested using NIR to identify high Met F4:5 progenies for next year's planting. Progenies will be planted in Warsaw again, and those that pass visual selection and have high Met concentration will be planted in Warsaw and Suffolk, VA (Tidewater AREC) for multi-location yield trials. In the first two years of the proposed project, Satt564 and HPLC will be used to genotype and phenotype progenies, respectively for MAS.Potential difficulties and limitations and alternative plans Because soybean is self-pollinated, there is a high probability that female plants may produce false F1 hybrids. We will design the combinations between female parents with white flower and male parents with purple flower. The true F1 plants will show purple flower because purple color is a dominant trait. In case the cross combinations are between the parents with the same color in order to implement the best traits into one population, we will use diverse genetic markers to identify true F1 hybrids.Objective 2: Validate the association between Met concentration and published molecular markers to explore effective markers for our genetic populationsPopulation developmentNo less than 200 F2 progenies from one population derived from each high Met donor developed in the Obj.1 will be used to validate all published markers associated with Met QTL. DNA of all progenies and parents will be extracted and screened using all the markers, and the seeds of all progenies will be evaluated using NIR spectroscopy.Association AnalysisSingle marker analysis by QTL Cartography 2.5 (Raleigh, NC) will be conducted to explore the association between the genotype of each population screened by each marker and Met concentration of that population. The marker and trait association with p < 0.01 or less will confirm the selection effect of that marker on the populations we develop for MAS.Potential difficulties and limitations and alternative plans It has been very practical and feasible to identify SNP markers through linkage and association mapping for quantitative traits. The pitfall is that many published molecular markers may be explored using the populations with different genetic background from ours. In case we cannot confirm any published markers using our materials, we will use the bi-parental populations to identify QTL and validate the QTL for amino acids.Objective 3. Develop a calibration equation for Perten 7250 NIR spectrometer using Met data by HPLC to estimate Met concentrationSamplesA calibration set of 300 accessions from a germplasm collection of maturity groups IV and V were planted and harvested in Blacksburg, VA and Clayton, NC in 2017. Therefore, 600 samples of 300 exotic soybeans from locations will be ground and evaluated for Met concentration to develop a calibration equation. Another set of 150 elite varieties from USDA Uniform Test from 2018 will be used to validate the models.HPLC and NIR measurementThe protocol to measure Met concentration using HPLC will follow the one established in Varzaru et al. (2013). The Agilent 1260 Infinity series (Agilent Technologies, Santa Clara, CA) will be used. NIR measurement will follow the protocol described in Sato et al. (2002) using Perten 7250 (Hagersten, Sweden).Multivariate modelingRegression models such as partial least square (PLS) and support vector machines (SVM) will be used to develop calibration equations for the estimation of Met concentration as described in Kovalenko et al. (2006). The validation set will be applied to the two models, and calculated parameters including predicted residual error sum of squares, standard error of prediction corrected for bias, difference between NIR-predicted and reference HPLC concentrations, etc. will be computed to characterize their predictive ability.