APS Homepage

Poster: Biology & Disease Mgmt: Genetics of Resistance


Development and evaluation of germplasm lines resistant to Sclerotinia stem rot
M. MCCAGHEY (1), M. McCaghey (1), J. Willbur (1), C. Grau (2), S. Chapman (2), B. Diers (3), C. Groves (2), A. Ranjan (2), M. Kabbage (2), D. Smith (1) (1) University of Wisconsin- Madison, U.S.A.; (2) University of Wisconsin- Madison, U.S.A.; (3) Univers

Sclerotinia sclerotiorum, the causal agent for Sclerotinia stem rot (SSR), is a devastating fungal pathogen in soybean and reduced yield by 59 million bushels in 2009. Incomplete resistance in commercial cultivars can be improved through additional breeding efforts and understanding the genetic basis of resistance. SSR-resistant soybean germplasm was developed by crossing two sources of resistance, W04-1002 and AxN-1-55, with lines exhibiting resistance to other pathogens such as Heterodera glycines. After multiple screenings, 31 lines were selected for advanced SSR in field screens in 2014 and were down-selected to 16 lines with a high-level of multi-disease resistance in 2015. Germplasm lines 91-38, 51-23, and SSR51-70 exhibited SSR resistance with minimal lodging. Line 91-38 yielded 2605.5 kg/ha, 51-23 yielded 3156.2 kg/ha, and SSR51-70 yielded 2801.8 kg/ha. The highest yield achieved was 3748.8 kg/ha for 52-82B. While many of these experimental lines have excellent physiological resistance, yield and agronomic performance of these lines are not at the level of an elite commercial cultivar. For example, 91-38 yielded over 1000 kg/ha less than the best line in the trial, however it exhibited one of the lowest disease severity rankings. Germplasm lines such as 91-38, 51-23, SSR51-70, or 52-82B could be improved through further breeding to generate high-yielding commercial soybean cultivars with a high level of physiological resistance to SSR