Plants sense
Plants sense, biochemically interpret, and respond through their immune systems
Yes, you read that right.
Modern plant physiology has begun to discuss the immune system in plants as well.
Today, we know that a plant subjected to biotic or abiotic stress does not simply activate a “chemical reaction,” but initiates a true, complex metabolic reprogramming—that is, an entire biochemical pathway involving phytohormones, secondary metabolites, the microbiome, and highly integrated biochemical networks (Amin, 2026).
Therefore, molecules such as flavonoids, terpenes, glucosinolates, phytoalexins, phenolic compounds, and signaling molecules such as salicylic acid and jasmonates do not act in isolation.
These molecules form a DYNAMIC NETWORK, capable of modulating the plant’s response depending on the type of stress, the physiological state, the tissue involved, and even the time of day (Erb & Kliebenstein, 2020; Amin, 2026).
This scientific approach is very close to the agroecological vision: plant health does not depend solely on pathogen suppression, but on the agroecosystem’s ability to maintain its balance, thanks to its level of biodiversity and adaptive capacity.
From this perspective, Nature-Based Solutions (NBS) take on an extremely interesting role.
Plant extracts, hydrolates, macerates, fermented products, metabolites, and bioactive substances at low or highly diluted concentrations can be interpreted as tools capable of interacting with the regulatory systems of agroecosystems without altering their biological balance and supporting the ecological capacity of the entire agricultural environment.
Natural substances that could be used in this direction include:
– extracts rich in flavonoids and polyphenols;
– hydrolates and essential oils at very low doses;
– algae and phycocolloids;
– amino acids and natural protein hydrolysates;
– organic acids and humic substances;
– beneficial microorganisms and their metabolites;
– compost tea and microbiological fermentations;
– plant extracts obtained on farm from wild plants;
– natural elicitors such as chitin, chitosan, laminarin, and plant derivatives;
– aromatic and terpenic substances distributed in microdoses;
– highly diluted preparations used as metabolic and physiological stimulants.
The most recent scientific literature clearly highlights that the effectiveness of many natural molecules depends not only on the quantity distributed, but also on their function as “metabolic signals,” capable of directing defense responses, modifying secondary metabolism, and influencing interactions with the microbiome (Lacchini & Goossens, 2020; Wu et al., 2023).
Furthermore, the biological function of a metabolite depends on its concentration and the location where it is accumulated, transported, or released within the plant and rhizosphere (Amin, 2026).
This concept is central to agroecology: increasing doses is not always necessary;
It is often more important to understand how to correctly activate specific biological cascades.
It is important to identify immune priming and take into account the epigenetic memory of stress.
Indeed, after a mild and targeted stimulus, the plant can prepare to respond more rapidly, in a more coordinated, and less costly manner to a subsequent biotic attack.
This “pre-alert” state involves chromatin modifications, DNA methylation, histone modifications, transcriptional regulation, and hormonal networks (SA/JA/ET), without necessarily requiring a massive and continuous defense response (MartÃnez-Medina et al., 2016; Hilker et al., 2019; Parker et al., 2022; Harris et al., 2023).
From this perspective, microdoses, root applications, targeted foliar treatments, natural elicitors, and highly diluted preparations can be interpreted, with the necessary experimental caution, as tools for physiological modulation: they do not “force” the plant, but can help activate or predispose metabolic, immune, and epigenetic networks already present in the plant system.
The paradigm shift, therefore, is to move from a defense “imposed from the outside” to a resilience built from within the living system, where the dose is not just the quantity of substance distributed, but also biological information, timing, application route, and the ability to interact with the plant’s physiological memory.
Perhaps the future of plant protection will not be based on the strength of molecules, but on the ability to understand and interact with the deep physiology of plants and agroecosystems.
Francesco Di Lorenzo
Agronomist