1-Octen-3-ol is formed from its primeveroside after mechanical wounding of soybean leaves

Hydrolysis of 1-octen-3-yl β-primeveroside implemented by a system with high structure-specificity is accountable for the rapid formation of 1-octen-3-ol from soybean leaves after mechanical wounding. 1-Octen-3-ol is a volatile compound ubiquitous in fungi; however, a subset of plant species also has the ability to form 1-octen-3-ol. Owing to its volatile nature, it has been anticipated that 1-octen-3-ol is associated with the effort of the emitter to control the behavior of the surrounding organisms; however, its ecological significance and the enzymes involved in its biosynthesis have not been fully elucidated, particularly in plants. We previously found that soybean (Glycine max) seeds contain 1-octen-3-yl β-primeveroside (pri). To elucidate the physiological significance and the biosynthesis of 1-octen-3-ol in plants, changes in the amount of 1-octen-3-yl pri during development of soybean plants was examined. A high 1-octen-3-yl pri level was found in young developing green organs, such as young leaves and sepals. Treatment of soybean leaves with methyl jasmonates resulted in a significant increase in the amount of 1-octen-3-yl pri; suggesting its involvement in defense responses. Although 1-octen-3-ol was below the detection limit in intact soybean leaves, mechanical damage to the leaves caused rapid hydrolysis of almost all 1-octen-3-yl pri to liberate volatile 1-octen-3-ol. Under the same conditions, the other glycosides, including isoflavone glycoside and linalool diglycoside, were hardly hydrolyzed. Therefore, the enzyme system to liberate aglycone from glycosides in soybean leaves should have strict substrate specificity. 1-Octen-3-yl pri might function as a storage form of volatile 1-octen-3-ol for immediate response against stresses accompanying tissue wounding.