Molecular Characterization of Defense of (Oilseed Rape) to AG2-1 Confirmed by Functional Analysis in .

is a necrotrophic, soilborne fungal pathogen associated with significant establishment losses in (oilseed rape; OSR). The anastomosis group (AG) 2-1 of is the most virulent to OSR, causing damping-off, root and hypocotyl rot, and seedling death. Resistance to AG2-1 in OSR has not been identified, and the regulation of OSR defense to its adapted pathogen, AG2-1, has not been investigated. In this work, we used confocal microscopy to visualize the progress of infection by sclerotia of AG2-1 on varieties with contrasting disease phenotypes. We defined their defense response using gene expression studies and functional analysis with mutants. Our results showed existing variation in susceptibility to AG2-1 and plant growth between OSR varieties, and differential expression of genes of hormonal and defense pathways related to auxin, ethylene, jasmonic acid, abscisic acid, salicylic acid, and reactive oxygen species regulation. Auxin, abscisic acid signaling, and the MYC2 branch of jasmonate signaling contributed to the susceptibility to AG2-1, while induced systemic resistance was enhanced by NAPDH RBOHD, ethylene signaling, and the ERF/PDF branch of jasmonate signaling. These results pave the way for future research, which will lead to the development of crops that are more resistant to AG2-1 of and reduce dependence on chemical control options.