1992 Volume 58 Issue 4 Pages 514-521
To clarify the mode of action of soybean lecithin (SL), we studied the effect on morphology of Pyricularia oryzae by using the onion epidermal strip method. SL at 500ppm induced an abnormal structure at the surface of the conidium or the germ tube. From observation 24hr after inoculation. SL did not inhibit appressorial formation at 5ppm, but 500ppm or more SL inhibited 86.2% or more appressorial formation. 500ppm SL also induced a morphological abnormality in germ tube with its branching at the tip and consequently inhibited appressorial formation. Besides, SL inhibited 96% appressorial penetration at 5ppm. The inhibition of appressorial penetration is the most characteristic action of SL.