Developing the Perfect Molecular Markers and New Germplasm for Rapid Incorporation of Resistance to Soil Borne Pathogens in Soybean - Year 5

This project aligns tightly with the USB Strategic Plan because it tackles a class of serious and persistent pathogens that inflict yield losses of 90 million bushels annually. These pathogens include Phytophthora sojae, Pythium species, Cadophora gregata, and many others. Naturally occurring resistance genes (R genes) and quantitative disease resistance loci (QDRLs) are the most effective and economical tools to fight them. Because these resistance traits are scattered in thousands of unadapted soybean germplasm, we need to identify these loci through genetic screening and mapping, and introgress them into commercial cultivars. With previous USB support, we identified and mapped numerous R genes and QDRLs conferring resistance to these pathogens. More importantly, our research provided commercial partners with adapted germplasm, enabling the adoption of these genes into soybean cultivars grown across the U.S. Here we propose to continue and intensify these efforts, because soilborne pathogens frequently evolve to escape plant defense mechanisms, overcoming existing resistance traits. Such resistance escape necessitates relentless searches for novel R genes/QDRLs, and corresponding perfect molecular markers to accelerate their adoptions. Our team has a successful track record. We have released 11 cultivars, 12 licenses, 61 Material Transfer Agreements, over a dozen new R genes/QDRLs, and >200 molecular markers since 2018. Renewed support from USB will allow us to deliver additional high-quality, high-yield soybean varieties to soybean farmers and enable functional characterization of a select set of important and durable R genes/QDRLs with broad spectrum efficacy. Finally, we will develop novel genetic and molecular tools that accelerate the identification of novel R genes/QDRLs, and hasten the development of cultivars with resistance to multiple soilborne pathogens.