Identification of Linalool Disaccharide Glycoside (Linalyl β-Vicianoside) in Soybean Leaves and Its Implication for Herbivore Resistance.

Linalool is anticipated to have significant ecological roles. In this study, linalyl 6-O-α-arabinopyranosyl-β-D-glucopyranoside (linalyl β-vicianoside: LinVic) was synthesized, and a linalool diglycoside purified from soybean leaves was identified as LinVic by using liquid chromatography-mass spectrometry. High levels of LinVic were detected in leaves and sepals during soybean plant growth. The LinVic content did not significantly increase following methyl jasmonate treatment of the leaves, indicating that its synthesis is independent of the jasmonic acid signaling pathway. In addition to LinVic, soybean also contains 1-octen-3-yl primeveroside. We treated soybean leaves with vaporized linalool and 1-octen-3-ol to determine whether the glycosylation system discriminates between these two volatile alcohols. Linalool treatment resulted in the accumulation of LinVic, while 1-octen-3-ol treatment caused little change in the amount of 1-octen-3-yl primeveroside, suggesting discrimination between these compounds. Linalool-treated soybean leaves exhibited increased resistance against common cutworms, indicating that LinVic may contribute to herbivore resistance.