Development of Glycine max Germplasm Highly Resistant to Sclerotinia sclerotiorum

Sclerotinia stem rot (SSR) of soybean caused by Sclerotinia sclerotiorum is a devastating disease of soybean, especially in the Upper Midwest region of the United States. To mitigate yield losses due to this disease, many control methods are available for producers including cultural control practices, chemical control, and cultivars with quantitative resistance. However, due to few commercial cultivars with high levels of resistance, producers are often limited in their seed selection. The aim of this study was to develop novel conventional soybean cultivars with high levels of resistance to SSR, favorable agronomic traits, and levels of resistance to additional economically important diseases. Initial crosses were conducted in 2016 with two different sources of SSR resistance. Across multiple generations of screening for resistance to SSR, three highly resistant soybean lines were identified as the elite lines. These elite lines demonstrated to be highly resistant across multiple years in both greenhouse and field trials including high levels of resistance to multiple diverse S. sclerotiorum isolates. The three selected elite lines also resulted in moderately high yields and favorable agronomic traits such as low lodging and moderate branching indicating their viability for being released for production. In addition to SSR resistance, these three elite lines also demonstrated resistance to other economically important soybean diseases such as frogeye leaf spot, anthracnose, Cercospora leaf blight, and brown stem rot. Overall, this work has led to three SSR resistant soybean lines which could be useful for future breeding efforts or commercial soybean production.