Objective 1. Germplasm Evaluation
In the first part of the project, experimental lines developed by soybean breeders throughout the north central U.S. will be field tested. This research will be organized similar to past years with breeders entering their experimental lines into the test and also growing field locations. We also will attempt to include a couple of varieties from each of the major seed companies assuming the appropriate MTAs can be made with these companies. Field tests also will be grown of experimental lines developed through the backcrossing of SDS resistance QTL. This research will focus on confirming SDS resistance QTL on soybean linkage groups (LGs) D2 and L that were previously mapped from the SDS resistance source Ripley. Additionally, a new method for testing SDS resistance in soybean will be evaluated during year one. This is potentially a powerful method for screening for toxin resistance and if it works well, additional funding will be requested during years two and three to expand these efforts.

Objective 2. Develop New Sources of SDS Resistance
In the first part of this research, SDS resistance QTL that were previously mapped will be retested in new populations and backgrounds to confirm their effects. In the second part of this research, populations already phenotyped for SDS resistance will be genotyped with markers to identify SDS resistance QTL. In addition, during the second and third year of the project, we will explore the possibility of mapping SDS resistance QTL from genotypes in the soybean germplasm collection. Many genotypes in the collection have been evaluated for SDS resistance and these will all be tested with 50,000 SNP markers as part of a United Soybean Board funded project. The marker and resistance data will be analyzed together using a method called association analysis that could potentially allow us to uncover SDS resistance genes in the collection.

Objective 3. Develop Tools for Marker-Assisted Selection for SDS Resistance
The research will first focus on SDS resistance QTL on LGs D2 and L that were originally mapped from Ripley. These QTL have been confirmed and already backcrossed into five genetic backgrounds and genetic populations have been established with recombinations near these QTL. These recombinant populations will be tested for SDS resistance in the greenhouse and/or field, and the genetic region where the QTL are mapped will be analyzed to identify single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers near these QTL.

Objective 4. Identify Factors that Affect Development of SDS
In this objective we will use several approaches, including metagenomics, to identify rhizosphere organisms and soil abiotic factors that interact with F. virguliforme to cause SDS. In addition, we will use characterized and modified F. virguliforme strains to study the root infection and colonization processes of F. virguliforme in the presence and absence of other microorganisms, focusing on SCN, the brown stem rot pathogen, and other organisms identified with the metagenomics approach. .

Objective 5. Improving the resolution of field evaluations for resistance to SDS
Field trials have provided good environments for identifying resistant and susceptible varieties. Established protocols utilize early planting (April to mid-May), irrigation, artificial inoculation (when available), and appropriate check varieties. Even though proper deployment of these factors often results in successful trials, consistency of disease pressure is sometimes lacking. This project will seek to reduce the limitations in field trials by improving on current screening methodology.

Objective 6. Contribution to Regional Outreach Coordination to Optimize SDS
The main goal is coordination of regional communication and outreach by centralizing SDS information and to address the needs of stakeholders including soybean producers, public investigators, and private industry. These plans include organizing events to bring together public and private stakeholders to evaluate the status of SDS management and plan future activities; organization and centralization of research data and outreach information; development of new educational and outreach information; and fostering communications with agribusinesses to enable both the public and private efforts to benefit soybean producers by protecting yield from loss due to sudden death syndrome.