Beyond Aroma: Analytical Challenges, Metabolism and Biological Significance of Volatile Sulfur Compounds in Tomato...

Volatile sulfur compounds (VSCs) are a subgroup of plant volatile organic compounds (VOCs) that are chemically reactive and sensory-active. In tomato (Solanum lycopersicum), sulfur-containing volatiles such as methanethiol, dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, volatile thiols, and heterocyclic sulfur compounds are of particular relevance due to their extremely low odor thresholds and strong influence on aroma perception. Beyond their sensory importance, VSCs have been shown to be involved in plant defense mechanisms, stress responses, redox homeostasis, and multitrophic interactions with microorganisms, herbivores, and neighboring plants. The formation of these structures is governed by complex interactions between sulfur assimilation pathways, lipid peroxidation processes, environmental factors, and both enzymatic and non-enzymatic reactions. The accurate characterization of VSCs remains challenging due to the following factors: their high reactivity; their low abundance; their chemical instability; and their susceptibility to oxidation. Despite the significant enhancement in detection of VSC capabilities brought about by modern analytical approaches, such as gas chromatography coupled with sulfur-selective detection and high-resolution mass spectrometry, significant methodological limitations remain. This review summarizes the current state of knowledge on the analytical challenges of VSCs in tomato plants, their biosynthesis and biological functions, mainly in the context of plant defense.