The Differential Expression of Wound-Inducible Lipoxygenase Genes in Soybean Leaves

Two soybean [Glycine max (L.) Merr.] lipoxygenase cDNA clones were isolated that represent lipoxygenase genes (designated LOX7 and LOX8) that display increased expression in leaves following wounding. LOX7 and LOX8 were found to be differentially expressed in soybean leaves after wounding. Increased transcript levels of both genes were detected in wounded leaves within 8 h after wounding, but only the expression of LOX7 displayed a systemic wound response. Additionally, the elevated expression of LOX7 in wounded leaves was transient. Twenty-four hours postwounding, LOX7 transcripts were no longer detectable in leaves. In contrast, LOX8 transcript levels were elevated in wounded leaves from 8 to 72 h after wounding. In addition, treatment of soybean plants with methyl jasmonate resulted in higher levels of both LOX7 and LOX8 transcripts in leaves. High levels of expression of both genes were also detected in young leaves, flowers, and immature seed pods, and increases in LOX7 and LOX8 transcripts were observed in leaves following the removal of reproductive sink tissues. The expression of LOX7 and LOX8 in unwounded soybean tissues and increased expression following wounding suggest that the lipoxygenases encoded by these genes may participate in general physiological processes that are enhanced following physical damage.