Current insights into plant volatile organic compound biosynthesis.

Plant-derived volatile organic compounds (VOCs) are essential for various ecological interactions, including plant communication, pollinator attraction, and defense against herbivores. Some VOCs are active ingredients with significant economic and medicinal value. For example, monoterpenoids such as linalool, geraniol, menthol, camphor, borneol, citral, and thymol are well-known for their flavor and aroma. Most monoterpenoids have a strong scent and physiological activity; some compounds, like thymoquinone, have excellent anti-cancer activities, making them important for pharmaceuticals and also beneficial in food and cosmetics. VOCs encompass a diverse range of chemical classes, such as terpenoids, benzenoids/phenylpropanoids, amino acid derivatives, and fatty acid-derived compounds. With the development of genomic, transcriptomic, and metabolomic techniques, significant progress has been made in the discovery of genes for the biosynthesis of VOCs. Herein, recent advances in the biosynthesis of plant-derived VOCs, focusing on two main classes: benzenoids/phenylpropanoids and monoterpenes, are discussed. It highlights the identification of a peroxisomal enzyme, benzaldehyde synthase, in petunia that elucidates the biosynthetic pathway of benzaldehyde, and a bifunctional enzyme, geranyl/farnesyl diphosphate synthase (RcG/FPPS1), in roses (Rosa chinensis "Old Blush") that contributes to the production of cytosolic geranyl diphosphate. Current understanding about canonical and non-canonical pathways for monoterpene formation and some approaches that are useful for gene discovery have been discussed. Open questions and future perspectives in this field have also been presented.