Abstract
Reactive oxygen species (ROS) play a central role in plant immune responses. The most important virulence factors of Stagonospora nodorum are multiple fungal necrotrophic effectors (NEs) (SnTox) that affect the redox status and cause necrosis and/or chlorosis in wheat lines possessing dominant susceptibility genes (Snn). However, the effect of NEs on ROS generation in the early stages of infection has not been studied. In this study, our aim was to research the effect of S. nodorum effectors SnToxA, SnTox1, and SnTox3 on development of disease symptoms, the generation of hydrogen peroxide, and the enzyme activity of the redox metabolism in the early stage of infection in various wheat genotypes infected with isolates of S. nodorum (Sn4VD, SnB, and Sn9MN) carrying a set of various NE genes. Our results indicate that all three NEs of SnToxA, SnTox1, and SnTox3 play an important role in the inhibition of ROS in the initial stage of infection. Tsn1–SnToxA and Snn3–SnTox3 inhibited ROS production in wheat by affecting NADPH oxidases, peroxidases, superoxide dismutase, and catalase. Snn1–SnTox1 inhibited the production of ROS in wheat by mainly affecting peroxidase. NEs suppress ROS production only in the presence of the susceptibility genes Tsn1, Snn1, Snn3.