Molecular mechanism of “aroma” glycosylation of to enhance chemical defense～Differences in aroma diglycosyltransferase in cultivated and wild tomato species～

Abstract

Plants have developed sophisticated defense mechanisms to respond to biotic stresses through a process known as plant-plant communication. This involves the transfer of signaling molecules, particularly volatile organic compounds (VOCs), between plants. When a plant is attacked by herbivores, it releases specific VOCs that are detected by neighboring plants. These nearby plants, although not directly attacked, respond by strengthening their own defense systems. Since around 2000, numerous chemical and ecological studies have focused on the role of VOCs in plant defense, revealing that the biosynthesis and emission of these compounds are crucial for plant survival. However, while significant progress has been made in understanding the molecular mechanisms of VOC biosynthesis and emission, the study of how plants receive and respond to VOCs has lagged behind. Research into receptors for volatile phytohormones, such as methyl jasmonate and methyl salicylate, have been shown, but the molecular mechanisms underlying the perception of VOCs remain less understood due to the vast structural diversity of these compounds. Recent discoveries have shed light on this area. For example, when tomato plants are attacked by insects, they release (Z)-3-hexenol known as a green leaf volatile. This compound is absorbed by neighboring tomato plants and is then glycosylated into (Z)-3-hexenyl β-vicianoside (HexVic). HexVic functions as a poison, with lethal and growth-retard effects on herbivorous insects. This finding indicates that glycosylation of VOCs is one of the molecular mechanisms for the perception in plant-plant communication.

This research note shows the chemical and ecological significance of VOC glycosylation in plant-plant communication, highlighting the recently identified glycosyltransferase UGT91R1 responsible for the production of the insecticidal HexVic. This discovery provides key insights into how plants use VOCs not only to communicate but also to protect themselves from potential threats in near future, offering new perspective for understanding plant resilience and adaptability in dynamic environments.