Lipoxygenase-derived aldehydes inhibit fungi pathogenic on soybean.

Several unsaturated aldehydes are produced from polyunsaturated fatty acids via the lipoxygenase pathway when soybean (Glycine max) plants are wounded mechanically or by pathogens. The effects of four of these aldehydes were examined on the growth of isolated fungal cultures ofColletotrichum truncatum, Rhizoctonia solani, andSclerotium rolfsii. (E)-2-Hexenal, (E)-2-nonenal, and (Z)-3-nonenal inhibited the growth ofR. solani andS. rolfsii at 35 μmol added per liter or greater when applied as volatiles, although higher levels were required for inhibition ofC. truncatum. (E)-4-Hydroxy-2-nonenal was the most inhibitory compound when applied directly in the growth medium, but it had the least effect as a volatile.