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 of Colletotrichum truncatum, Rhizoctonia solani, and Sclerotium rolfsii. (E)-2-Hexenal, (E)-2-nonenal, and (Z)-3-nonenal inhibited the growth of R. solani and S. rolfsii at 35 mu mol added per liter or greater when applied as volatiles, although higher levels were required for inhibition of C. 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.