Biosynthesis of plant‐derived flavor compounds

TLDR

Plants synthesize diverse low‑molecular‑weight volatiles—alcohols, aldehydes, ketones, esters, ethers, and nitrogen/sulfur compounds—that are commercially valuable as flavorants, drugs, pesticides, and industrial feedstocks, yet natural abundance is low, leading to synthetic replacements. The looming shortage of crude oil, a primary source of artificial flavors, has spurred research into the biosynthetic pathways of plant‑derived volatiles and their engineering. Engineering flavor modification relies on identifying genes encoding key enzymes that direct or divert the biosynthetic routes of these volatiles. Recent molecular and biochemical studies have uncovered numerous genes responsible for volatile biosynthesis, marking major progress in the field.

Abstract

Summary Plants have the capacity to synthesize, accumulate and emit volatiles that may act as aroma and flavor molecules due to interactions with human receptors. These low‐molecular‐weight substances derived from the fatty acid, amino acid and carbohydrate pools constitute a heterogenous group of molecules with saturated and unsaturated, straight‐chain, branched‐chain and cyclic structures bearing various functional groups (e.g. alcohols, aldehydes, ketones, esters and ethers) and also nitrogen and sulfur. They are commercially important for the food, pharmaceutical, agricultural and chemical industries as flavorants, drugs, pesticides and industrial feedstocks. Due to the low abundance of the volatiles in their plant sources, many of the natural products had been replaced by their synthetic analogues by the end of the last century. However, the foreseeable shortage of the crude oil that is the source for many of the artifical flavors and fragrances has prompted recent interest in understanding the formation of these compounds and engineering their biosynthesis. Although many of the volatile constituents of flavors and aromas have been identified, many of the enzymes and genes involved in their biosynthesis are still not known. However, modification of flavor by genetic engineering is dependent on the knowledge and availability of genes that encode enzymes of key reactions that influence or divert the biosynthetic pathways of plant‐derived volatiles. Major progress has resulted from the use of molecular and biochemical techniques, and a large number of genes encoding enzymes of volatile biosynthesis have recently been reported.