Partial Resistance to White Mold in a Transgenic Soybean Line

Abstract

Oxalic acid is an important pathogenic factor for the fungus Sclerotinia sclerotiorum (Lib.) de Bary. An oxalate degrading enzyme, oxalate oxidase (OxO), in transgenic soybean [Glycine max (L.) Merr.] has reduced pathogen growth in indoor seedling studies. The objective of this study was to characterize the response of this OxO transgenic soybean line to white mold under field conditions and also to characterize the agronomic performance of this transgenic line under noninfected conditions. The transgenic line 80(30)-1contains the wheat germin gene gf-2.8 that codes for OxO. This line was compared with 80(30)-9, a sib line which does not contain the gene, as well as resistant and susceptible cultivars. Field tests were conducted at three sites infested with white mold in Ontario and Quebec across 3 yr. The Sainte-Foy site provided the highest infection potential and the transgenic line had a disease severity index (DSI) of 7 compared with 80(30)-9 with a DSI of 46, across 3 yr. Across 2 yr, resistant commercial cultivars had an average DSI of 2 and susceptible cultivars a DSI of 46. Stem inoculations were performed in the field at Elora and the transgenic line was significantly less infected compared with 80(30)-9. In noninfested trials, no significant differences were found between the transgenic, the negative sib, and the parental lines for seed yield, maturity, seed weight, or seed protein and oil content. The transgene provided white mold resistance equivalent to the best commercial cultivars in a white mold susceptible background.