Scientific foundationsSalicylic acidHormone central to defense against pathogens (fungi, bacteria), complementary to jasmonates (more focused on insects).Origin: Yolia LibraryExact route: /biblioteca?ruta=fundamentos/acido-salicilico FULL TOPICSalicylic acid Name and classification Salicylic Acid. A plant hormone central to defense against pathogens such as fungi and bacteria, present and functional in every living cell of all 4 species in Yolia's catalog without exception, within Yolia's complete home cultivation catalog. What it is It's a defense hormone, complementary to jasmonates, which focus more on insects, responsible for activating the plant's resistance specifically against attacks by pathogenic fungi and bacteria present in the environment, a useful starting point for understanding the rest of the topic. Where and how it was studied Identified within modern plant physiology when studying acquired systemic resistance, a phenomenon where a locally attacked plant ends up with better overall defense throughout the rest of its complete vegetative structure, with broad consensus among different specialized sources. Why it matters for cultivation Part of the systemic acquired resistance mechanism — a plant facing a mild attack in one part ends up with better defense in the rest, even though those other areas have not been directly attacked by the same pathogen, a factor the grower should keep in mind in practice. Chemistry — mechanism It accumulates at the exact infection site and is transported to other parts of the plant, activating preventive defense genes before the pathogen can physically reach those still-healthy areas of plant tissue, a process described precisely in modern plant biochemistry. Mechanism of action Upon detecting a pathogen, the infected cell synthesizes salicylic acid, which acts as a signal carried throughout the plant and activates pathogenesis-related defense proteins in tissue not yet directly affected, a necessary step for the process to complete correctly. Where it occurs in the plant It is produced at the infection site and transported systemically throughout the plant, being especially relevant in leaf and stem, tissues with the greatest direct exposure to fungi and bacteria present in the growing environment, in the usual context of home cultivation managed by Yolia. How it's regulated Its production is regulated according to the intensity and type of threat detected — a mild attack triggers a moderate response, while a more aggressive infection can generate a proportionally greater and more sustained defensive response, dynamically according to the physiological state of the moment. What triggers/affects it The detection of a fungal or bacterial pathogen, through specialized cell receptors, triggers the synthesis of salicylic acid as an immediate defensive response within the tissue directly affected by that pathogen, a factor the grower can observe and influence in practice. Which other processes it interacts with With jasmonates, a complementary hormone focused on defense against insects, and with ethylene, which participates alongside this pathway in the overall coordination of the plant's complete defense response to any threat, both relevant for understanding the full physiological picture. Relevant differences between catalog species The mechanism is identical across the 4 species in the catalog; sensitivity to specific fungal pathogens varies, resin and trichomes being particularly vulnerable to gray mold during dense flowering with sustained high humidity, a detail worth considering when comparing species in the catalog. How it's observed in practice It is not directly observable without specialized laboratory equipment; it is inferred from the lower incidence of fungal or bacterial disease in plants with good overall nutrition and proper environmental management of the active crop, a signal an attentive grower can learn to recognize. What happens if it's severe Without enough salicylic acid signaling, the plant responds more slowly to present pathogens, allowing a localized infection to spread more easily into healthy tissue before its complete defense is activated, a consequence worth preventing with good preventive management. How Yolia uses it It explains why modules like resilient greening or protective phenols are not direct-contact antifungals — they reinforce this internal systemic defense, a mechanism distinct from and complementary to an external barrier applied to the tissue, a direct practical application within Yolia's complete system. Common interpretation errors Thinking that an internal defense module acts like a contact fungicide — in reality it reinforces the plant's own capacity to activate its systemic response, an internal mechanism distinct from a directly applied external barrier, a common misunderstanding worth avoiding in practice. Evidence and limits of current knowledge The mechanism of systemic acquired resistance is well documented in modern plant physiology; the exact details of its interaction with jasmonates in each type of threat remain subject to active research, with reasonable room for future research on the topic. Related topics and modules Jasmonates, a complementary defense hormone — Ethylene, a coordinator of the overall defense response — Abscisic acid (ABA), a related stress hormone — Anthocyanins, a pigment with a protective function within the catalog; consult the full corresponding sheet in the Library. Related topicsAbscisic acid (ABA)Calcium as a cellular signalCarbohydrates and sugarsPlasmodesmataAnthocyaninsEthylene