THE EFFECT OF SUPEROXIDE ANION ON GERMINATION AND INFECTIVITY OF WHEAT-STEM RUST (PUCCINIA-GRAMINIS PERS F SP TRITICI-ERIKS AND HENN) UREDOSPORES

The effect of superoxide anion on uredospores of wheat stem rust was s tudied in the riboflavin/methionine photochemical system. Both spore g ermination and elongation of germ tube could be almost perfectly inhib ited by superoxide treatment. When superoxide dismutase (SOD) enzyme w as added to the system, the germination percentage and the germ tube l ength were similar to the control, non-treated ones. Changes in infect ivity and in virulence spectrum of spores after treatment was also inv estigated on near isogenic wheat lines with or without single resistan ce genes to stem rust. As a result of superoxide treatment the number of pustules decreased, but the reaction type on isogenic lines with va rious resistance genes did not change. on the contrary, when leaves we re treated 5-6 days after infection with superoxide, the original comp atible infection type changed to hypersensitive necrosis. The phosphol ipid content was lower, while lipid peroxidation was 8 times higher in treated then in control spores.