Smells like spring spirit

Editorial https://doi.org/10.1038/s41477-026-02302-y Smells like spring spirit Check for updates The return of spring is an excellent occasion to celebrate the secondary metabolites that are the basis for the wonderfully diverse aromas and tastes of plants, which are used for our culinary pleasure. T here are many ways to connect to the natural world and appreciate the plants around us. When spring arrives, a simple stroll on local trails is a pleasure for the eyes, but the connection goes beyond beautiful sights of colourful flowers and fresh young leaves. It also involves a raw, direct interaction with our senses of smell and taste. Around the Mediterranean shores, between white limestone cliffs and deep blue sea, perfectly adapted to the dry and sunny environment, rosemary and thyme grow everywhere. They produce a woody, lemony and long-lasting smell when a leaf is crushed between two fingers, and a feeling of happiness and mild nostalgia for those who were raised in these regions. Both herbs are usually sprinkled on barbecued meat to enhance flavour. On the same shores, the yellow flower-heads of fennel produce a distinctive aroma of anise, reminiscent of liquorice sweets, anise cakes and, for the adults among us, various alcoholic drinks, from the ‘green fairy’ absinthe to ouzo, raki and pastis. Nearby in Provence, France, lavender fields start to bloom and the fragrant perfume of these small purple flowers lingers in the warm air. Bunches of dried flowers are traditionally placed in wardrobes to keep insects out and give clothes a fresh, aromatic smell. In central Europe, wild garlic quickly and densely covers entire patches of forest undergrowth, the pungent smell permeating the atmosphere. The leaves and flowers, once harvested and washed, make a wonderful pesto, or a spicy addition to a salad. Beyond the basic satisfaction of satiety, the pleasure of food is a multisensorial experience. Sight: we enjoy the deep ruby-red colour of a fine wine, or a colourful salad with ingredients such as carrots, red cabbage, coriander and pepper. Hearing: the noise of exploding maize popcorn or searing courgette in olive oil makes us salivate in anticipation. Touch: the simple act of tearing by hand the tip of a crispy, warm nature plants baguette or grabbing a fresh fruit from a tree is a prelude to the enjoyment that will soon arrive. All of these preliminary hedonic experiences come from plants, but the best is yet to come. Direct perception of the molecules that create flavour is due to the combined action of smell and taste. Whereas lipids, proteins and carbohydrates provide us with much-needed energy, plant secondary metabolites are responsible for flavour. They can be partially volatile and travel to our nasal cavity to bind receptors, which then transmit aromas by sending electrical signals to the brain. Similarly, when food reaches our mouth, chemoreceptors in our taste buds perceive molecules and transmit the feeling to the cerebral cortex. It is commonly said that there are five basic tastes (sweet, salty, sour, bitter and umami), although other sensations can be perceived through alternative mechanisms, for example, astringency by tannins that bind to and precipitate salivary proteins, or temperature perception such as the coolness of spearmint’s menthol versus the spiciness of pepper’s capsaicin. The simple act of eating can trigger complex feelings and powerful emotions. Food influences our brain, and plant molecules play a big part in that. Biochemists focusing on secondary metabolism can talk extensively about these molecules and their biosynthesis in plants, through complex pathways requiring dozens of specialized enzymes and the exchanging of precursors between cell compartments. Ecologists and phytopathologists look for these molecules’ primary functions, as plants are not concerned with pleasing us with fragrant food but evolved specific molecules for their own fitness benefit. The functions of caffeine, nicotine, morphine, cocaine, quinine, camphor, digoxin, tetrahydrocannabinol, taxol and so on are mostly for chemical defence against herbivory, but they have found some alternative use for human therapeutics or entertainment. It is the same for molecules that influence taste or smell: we enjoy consuming them, but their primary functions might be diverse, from defence to interaction with the microbiome or neighbouring plants. Historians might write about how the search for a certain type of flavouring plant, the spices, which were once more valuable than gold, influenced the ancient world and changed the course of history. Finally, metabolic engineers find ways to modify these molecules to give them new functions or higher stability; to transfer biosynthetic pathways into fast-growing microorganisms for industrial-level production, or even into other plants to produce biofortified food; or, why not, to increase the repertoire of flavours, a canonical example being the introduction of capsaicin to engineer spicy tomatoes. Among the tens of thousands of known flavour molecules that titillate our senses, we can cite a few interesting ones. When garlic tissues are damaged by insects in soil or by a small metal press in the kitchen, the odourless cytosolic amino acid alliin, which is derived from cysteine and contains sulfur, becomes a substrate for the vacuolar enzyme alliinase, producing allicin. This volatile compound is a strong antioxidant and is mostly responsible for the intense aroma used in culinary recipes around the world. Allicin in small doses can enhance bland ingredients such as fish, grains, or vegetables. Garlic, and its close cousin onion, contains many more molecules beneficial for human health, such as antioxidant polyphenols. On a slightly different note, ripe fleshy fruits such as banana, pear, or apple produce a floral, creamy and generally pleasant aroma that we associate with high sugar content. This odour often comes from a complex mixture of different types of volatile compound, dominated by esters such as amyl acetate or butyrate and including specific phenolic, aldehyde, or terpenoid modifiers. It is possible to artificially recreate specific fruit aromas by precisely mixing these chemicals, for example, for perfumes and confectionary. There are many reasons to love plants, for example, their alterity, complexity, the different evolutionary paths they took to survive on this planet and their colourful diversity. A more selfish reason is because they maintain animal life by providing us with energy and oxygen. Another consideration, quite fundamental in many cultures around the world, is that plants give us endless pleasure of the senses, from smelling their fragrances to enjoying their taste. We tend to forget it, but plants bring essential joy and pleasure to everyone. Think about this during your next meal. Published online: 23 April 2026 Volume 12 | April 2026 | 669 | 669  (...truncated)