Project Number: 3602-21220-012-00
Project Type: Appropriated

Start Date: Apr 23, 2012
End Date: Apr 22, 2017

Objective:
This project plan describes the hypothesis-based research to be conducted for two root rot diseases of soybean, PRR and SDS. The aim of this project is to mitigate the impact of these diseases on yield by improving our understanding of pathogen biology, disease development, and host-pathogen interactions. To this end, we propose: Objective 1: Evaluate the outcrossing and diversity of Phytophthora sojae populations and host plant interactions. In this objective, this research group will look into the role of outcrossing in diversifying populations of P. sojae, which may be contributing to the rapid adaptation of this pathogen to deployed R-genes (resistance genes). The research group will also screen for race-specific and partial resistance, which minimizes colonization as well as symptom development, to P. sojae in germplasm with resistance to other root-infecting pathogens. Objective 2: Evaluate the population dynamics of Fusarium virguliforme, sudden death syndrome disease cycle, and host plant interactions. For this objective, the research group will study the effect of the isolate of F. virguliforme on SDS foliar and/or root rot resistance to determine if known quantitative trait loci (QTL) are isolate-specific. In addition, the research group will also examine the early stages of the disease cycle to determine the cause, timing, and mechanism of initial infection by F. virguliforme. Objective 3: Organize, manage, and conduct the Northern Uniform Soybean Tests. The goal of this non-hypothesis based component of the project is to provide public breeders with information needed to determine if a breeding line is to be released as a new variety. Although the aim of Objective 3 differs from that of Objectives 1 and 2, the Uniform Soybean Tests (USTs) serve a key role in advancing soybean production in the U.S.

Approach:
Established cultural techniques and markers linked to known avir genes will be used to evaluate the role of outcrossing in diversifying populations of Phytophthora sojae. Soybean germplasm will be evaluated for race-specific (hypocotyl test) and partial (percent root rot-layer test and colonization-qPCR) resistance to P. sojae. QTLs for resistance to SDS will be evaluated for isolate specificity using multiple RIL and NIL populations and isolates of Fusarium virguliforme that are genetically (DNA fingerprinting) and geographically diverse. Soybean hairy roots and a GFP-expressing isolate of F. virguliforme will be used to study the infection process and to assess morphological differences between SDS-resistant and susceptible varieties. Publically developed lines will be evaluated for agronomic qualities and disease resistance in multiple field environments to determine their release as a variety.