Jasmonates, Salicylates, and Defense Signaling
Explain jasmonate and salicylate signaling, defense crosstalk, growth costs, and why elicitor claims require organism-, tissue-, dose-, and outcome-specific evidence.
Explain jasmonate and salicylate signaling, defense crosstalk, growth costs, and why elicitor claims require organism-, tissue-, dose-, and outcome-specific evidence.
Core science
Jasmonates rise after wounding and many herbivore or pathogen interactions and regulate defense genes, specialized metabolism, growth, and reproduction. Salicylic acid participates in local resistance, systemic signaling, stomatal and redox responses, and defense against many biotrophic pathogens. The common JA-versus-necrotroph and SA-versus-biotroph rule is a useful starting model, not a complete classifier.
Defense pathways interact with ethylene, ABA, auxin, light, sugars, circadian timing, and pathogen effectors. JA and SA can antagonize or cooperate depending on dose, order, tissue, and attacker. Defense activation consumes carbon, nitrogen, reducing power, and time; increased expression of one pathway is not proof of improved whole-crop resistance or yield.
Cannabis experiments show salicylic acid and other signals can alter promoter activity and cannabinoid-pathway expression. That is mechanistic evidence, not a universal instruction to spray elicitors. Transcript change, metabolite concentration, total metabolite yield, disease suppression, phytotoxicity, residue, and worker safety are separate endpoints.
Why this matters in cultivation
- Use sanitation, exclusion, scouting, identification, environment control, and lawful IPM as the foundation. Elicitors do not replace diagnosis or registered controls.
- When testing a signaling treatment, include untreated and carrier controls, defined disease or quality endpoints, tissue sampling, residue review, and total yield—not only one concentration result.
Measure and record
Trigger
Wound, pest, pathogen, mechanical treatment, compound, dose, formulation, and timing.
Biological identity
Pest/pathogen species or strain, confirmation method, disease stage, and inoculum pressure.
Defense response
Gene/metabolite method, tissue, sampling time, symptom score, and phytotoxicity.
Production response
Growth, leaf area, flower mass, cannabinoid/terpene concentration and total yield.
Compliance
Product label, legal status, PPE, preharvest interval, residue test, and waste handling.
Common misconceptions
Misconception: Defense activation is free
Correction: Resources diverted to defense can reduce growth or reproduction.
Misconception: JA and SA always oppose each other
Correction: Their interaction depends on tissue, attacker, timing, concentration, and other signals.
Misconception: More cannabinoid-pathway expression guarantees more finished product
Correction: Transcript, concentration, total yield, maturity, and degradation are different endpoints.
Evidence limits and uncertainty
Cannabis signaling studies remain limited in genotypes and production contexts. Exogenous elicitor research cannot substitute for pesticide registration, residue limits, or controlled disease-efficacy trials.
Check your reasoning
- For "Jasmonates, Salicylates, and Defense Signaling", explain the mechanism behind this objective: Explain jasmonate and salicylate signaling, defense crosstalk, growth costs, and why elicitor claims require organism-, tissue-, dose-, and outcome-specific evidence. Which observation or measurement would best test whether that mechanism is operating in the real crop?
- A learner claims, "Defense activation is free" Use the lesson’s science and evidence limits to explain why that claim is unreliable, then name one observation or measurement that could separate the competing explanations.
- Applied case — Use sanitation, exclusion, scouting, identification, environment control, and lawful IPM as the foundation. Elicitors do not replace diagnosis or registered controls. Build a verification plan using the lesson’s record set (Trigger, Biological identity, Defense response). What would you compare before and after the action, and what result would make you revise the original interpretation?
Require lesson-specific evidence, not memorized universal targets. Open the rationales after you have written or discussed your own answer.
Answer rationale 1: Mechanism / workflow rationale
- A strong answer should connect the response to the lesson objective: Explain jasmonate and salicylate signaling, defense crosstalk, growth costs, and why elicitor claims require organism-, tissue-, dose-, and outcome-specific evidence.
- Jasmonates rise after wounding and many herbivore or pathogen interactions and regulate defense genes, specialized metabolism, growth, and reproduction. Salicylic acid participates in local resistance, systemic signaling, stomatal and redox responses, and defense against many biotrophic pathogens. The common JA-versus-necrotroph and SA-versus-biotroph rule is a useful starting model, not a complete classifier.
- Defense pathways interact with ethylene, ABA, auxin, light, sugars, circadian timing, and pathogen effectors. JA and SA can antagonize or cooperate depending on dose, order, tissue, and attacker. Defense activation consumes carbon, nitrogen, reducing power, and time; increased expression of one pathway is not proof of improved whole-crop resistance or yield.
- The most useful verification evidence includes Trigger: Wound, pest, pathogen, mechanical treatment, compound, dose, formulation, and timing.
- Keep this limit explicit: Cannabis signaling studies remain limited in genotypes and production contexts. Exogenous elicitor research cannot substitute for pesticide registration, residue limits, or controlled disease-efficacy trials.
Answer rationale 2: Misconception rationale
- The shortcut is unreliable because the lesson explicitly teaches a more conditional explanation.
- Representative misconception: Defense activation is free: Resources diverted to defense can reduce growth or reproduction.
- Jasmonates rise after wounding and many herbivore or pathogen interactions and regulate defense genes, specialized metabolism, growth, and reproduction. Salicylic acid participates in local resistance, systemic signaling, stomatal and redox responses, and defense against many biotrophic pathogens. The common JA-versus-necrotroph and SA-versus-biotroph rule is a useful starting model, not a complete classifier.
- A useful discriminator is Biological identity: Pest/pathogen species or strain, confirmation method, disease stage, and inoculum pressure.
- Do not overextend the conclusion beyond this limit: Cannabis signaling studies remain limited in genotypes and production contexts. Exogenous elicitor research cannot substitute for pesticide registration, residue limits, or controlled disease-efficacy trials.
Answer rationale 3: Applied verification rationale
- In practice: Use sanitation, exclusion, scouting, identification, environment control, and lawful IPM as the foundation. Elicitors do not replace diagnosis or registered controls.
- Record before action: Trigger: Wound, pest, pathogen, mechanical treatment, compound, dose, formulation, and timing.
- Also record: Biological identity: Pest/pathogen species or strain, confirmation method, disease stage, and inoculum pressure.
- After the action, repeat the same measurement or observation so the comparison is valid.
- Revise the interpretation if the result conflicts with the lesson limit or the expected response: Cannabis signaling studies remain limited in genotypes and production contexts. Exogenous elicitor research cannot substitute for pesticide registration, residue limits, or controlled disease-efficacy trials.
Related lessons
Sources and evidence
- Taiz L, Moller IM, Murphy A, and Zeiger E. Plant Physiology and Development. 7th ed. Oxford University Press, 2022.
- Sands LB et al. Hormonal Control of Promoter Activities of Cannabis sativa Prenyltransferase 1 and 4 and Salicylic Acid-Mediated Regulation of Cannabinoid Biosynthesis. Scientific Reports. 2023;13:8620.
- THC – Teaching Healthy Cultivation. Cannabis Plant Science Source Packet v1. May 2026. Project source packet.
- THC – Teaching Healthy Cultivation. Cultivation SOP Source Materials Packet v1. May 2026. Project source packet.
Downloads
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