Tryptamine (TAM) and serotonin (SER) are two compounds derived from tryptophan that belong to a widespread class of bioactive molecules known as indolamines or indole alkaloids. In plants, TAM and SER are primarily recognized as intermediates in the biosynthesis of melatonin, a well-studied molecule involved in crucial biological processes such as responses to biotic and abiotic stress, reactive oxygen species (ROS) scavenging, embryo development, and plant morphogenesis (Negri et al., 2021).

Although TAM and SER have been detected at high concentrations (μg/g of fresh weight) in the edible fruits and seeds of numerous plant species, their biological functions in reproductive organs remain unclear, and their metabolic pathways still need to be fully elucidated.

The biosynthesis of TAM and SER in plants typically involves consecutive decarboxylation and hydroxylation reactions of tryptophan, catalyzed by the enzymes tryptophan decarboxylase (TDC) and tryptamine 5-hydroxylase (T5H), respectively.