The biochemical origin of pentenol emissions from wounded leaves

• Published in: Phytochemistry (Oxford) Vol. 62; no. 2; pp. 159 - 163
• Main Authors: Fisher, A.J, Grimes, H.D, Fall, R
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 2003; Elsevier
• Subjects: alpha-Linolenic Acid - analogs & derivatives; alpha-Linolenic Acid - metabolism; Biological and medical sciences; Freezing; Fundamental and applied biological sciences. Psychology; Gas chromatography; Gene Expression Regulation, Plant; Genes, Plant; Glycine max; Glycine max - enzymology; Glycine max - metabolism; Leguminosae; Lipoxygenase; Lipoxygenase - metabolism; Metabolism; Metabolism. Physicochemical requirements; Oxygen; Pentanols - metabolism; Pentanones - metabolism; Pentenol; Pentenone; Plant Leaves - metabolism; Plant physiology and development; Reduction gas detector; Soybean; Substrate Specificity; Volatile organic compound; PVPP; VLX; ADH; DTT; SHAM; Volatile organic compound; Soybean; VOC; Glycine max; Reduction gas detector; RGD; 13-OTA; Gas chromatography; Leguminosae; LOX; PG; Pentenone; Pentenol; Lipoxygenase; GC; 13( S)-HPOT; Gas emission; Enzyme; Isozyme; Plant leaf; Ketone; Freeze thaw cycle; Linolenic acid; Enzymatic activity; Gene; Dicotyledones; Angiospermae; Spermatophyta; Oxidoreductases; Recombinant protein; Secondary alcohol
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/S0031-9422(02)00521-6

Experiments are presented demonstrating that 1-penten-3-ol and 1-penten-3-one, C5 volatile wound compounds, are products of lipoxygenase-dependent reactions in soybean leaves. Large releases of 1-penten-3-ol (pentenol) and 1-penten-3-one (pentenone) were recently observed from a variety of leaves subjected to freeze–thaw damage in the presence of oxygen. In order to understand the biochemical origins of these volatiles, soybean leaf extracts were used to determine if the formation of pentenol and pentenone can be explained by known O 2-dependent lipoxygenase (LOX) reactions. Enzymatic formation of these C5 volatiles was found to be dependent on α-linolenic acid or the 13( S)-hydroperoxide of α-linolenic acid [13( S)-HPOT] and blocked by LOX inhibitors. Five soybean leaf LOX isozyme genes (VLXA, VLXB, VLXC, VLXD, and VLXE) were then expressed in Escherichia coli and used in in vitro incubations with 13( S)-HPOT to test for volatile formation. Each of the LOX isozymes catalyzed the formation of low levels of pentenol, but not pentenone. It therefore seems likely that the C5,13-cleavage activity of LOX is the direct source of abundant pentenol and the indirect source of pentenone observed upon leaf wounding.