Developing the Perfect Molecular Markers and New Germplasm for Rapid Incorporation of Resistance to Soilborne Pathogens in Soybean (Year 4)

Developing the Perfect Molecular Markers and New Germplasm for Rapid Incorporation of Resistance to Soilborne Pathogens in Soybean a. Proposal Summary (298 words) The goal of this multi-state collaborative project is to identify novel genes that confer resistance to soilborne soybean pathogens and incorporate these genes into elite soybean cultivars with the fewest breeding cycles possible. This project matters to U.S. soybean farmers because soilborne pathogens such as Phytophthora sojae, numerous species of Pythium, Cadophora gregata, and many others are responsible for yield losses amounting to 90 million bushels every year. Naturally occurring resistance genes (R genes) and quantitative disease resistance loci (QDRLs) are the most effective and economical tools to fight these pathogens. Because these resistance traits are scattered in thousands of unadapted soybean germplasms, there is a need to identify such loci through genetic screening and mapping, and migrate them into commercial cultivars. With previous USB support, this team has identified and mapped many R genes and QDRLs conferring resistance to seedling pathogens. More importantly, our research has provided commercial partners with adapted germplasms, enabling the adoption of these genes in soybean fields across the U.S. Here we propose to continue and intensify these efforts, because soilborne pathogens frequently evolve escape mechanisms to overcome existing resistance traits, necessitating relentless search for novel R genes/QDRLs and perfect molecular markers to facilitate the breeding process. Our team has a successful track record with the release of 11 cultivars, 12 licenses, and 61 Material Transfer Agreements; more than a dozen new R genes/QDRLs since 2018; and >200 molecular markers. Renewed support from USB will allow this team to deliver additional high-quality, high-yield soybean varieties/germplasms to soybean farmers. Renewed support will also enable functional characterization of a select set of important and durable R genes/QDRLs with potential broad spectrum efficacy. Finally, we will develop novel genetic and molecular biological tools that accelerate the identification of novel R genes/QDRLs, and hasten the development of cultivars with resistance to multiple soilborne pathogens.