Title : Visible and invisible: The multi-faceted benefits of plants to humanity
Abstract:
Plants are of enormous importance to humans, having developed alongside each other during co-evolution over millions of years. In fact, the majority of the Earth's organic matter originates from plants, which capture the sun’s energy via photosynthesis. Plants provide the vital oxygen we breathe and as it is estimated that the vast diversity of plant organisms produces up to one million bioactive molecules. Primarily, plants form the basis of the human diet. They synthesize macronutrients— carbohydrates, proteins, and lipids—and, particularly, for meat, plants are indirectly also the foundation via food chains. Humans rely on plants for substances they cannot produce themselves but need as micronutrients for survival, including vitamins as well as essential amino and fatty acids. Many secondary plant compounds are volatile organic bioactives that often serve as signaling molecules and defense mechanisms for plants. By interactions between various biological systems, they simultaneously can have diverse, positive effects for human health as the following example illustrates. Citral, a volatile monoterpene consisting of two isomers, is found, among other sources, in the peel of citrus fruits. When ingested, citral influences physiological signaling pathways in humans and displays antioxidant effects. The compound additionally possesses direct antimicrobial properties, can disrupt bacterial membranes, and inhibits fungal growth. It binds with high affinity to viral particles like SARS-CoV-2, thus hindering their entry into cells. In plants, citral acts as a defense and signaling molecule. Depending on its concentration and ecological context, citral can either attract pollinators, such as bees, to play a role in fruit and seed formation, or repel herbivores. These effects are highly concentration-dependent, demonstrating that biological activity often depends on physiologically relevant concentration ranges and not solely on the presence of a substance. Combining modern molecular methods with traditional botanical knowledge mechanistically explains these effects, allowing us to decipher the intricate, often invisible dependence of human life on plant biochemistry.
