Root herbivore performance suppressed when feeding on a jasmonate‐induced pasture grass

1. Plants defend themselves from insect herbivore attack using a range of physical and chemical defences which are in many cases regulated by phytohormones such as jasmonates. While much more is known about how jasmonates regulate defence against above‐ground herbivores (e.g. herbivores of leaves), there is increasing interest in how they influence below‐ground defences. 2. For the Poaceae, most below‐ground studies focus on highly domesticated cereals. Here it is demonstrated how exogenous application of methyl jasmonate (MeJA) to the leaf blades of a non‐domesticated pasture grass (Microlaena stipoides) caused a more than two‐fold decrease in relative growth rate (RGR) of a root‐feeding chafer (Dermolepida albohirtum). MeJA treatment did not affect root consumption rates, but substantially reduced the efficiency of conversion of ingested food to body mass. 3. Non‐targeted metabolomics identified significant changes in the metabolome of MeJA‐induced plants, with three compounds (a galactolipid, a trihydroxy fatty acid and a lysophospholipid) found to be correlated with herbivore RGR, although their roles in herbivore defence remain uncertain. 4. This study suggests that an important Australian pasture grass can become better defended against root herbivores via enhanced jasmonate activity.     

Jasmonic acid signalling and herbivore resistance traits constrain regrowth after herbivore attack in Nicotiana attenuata

Because traits conferring resistance on herbivores can reduce fitness-associated traits, trade-offs may occur between tolerance and resistance responses. We examined these trade-offs in genotypes of Nicotiana attenuata that were transformed to silence trypsin proteinase inhibitor (TPI) production (AS-Natpi), an antiherbivore defense associated with (14%) reductions in seed production, and the jasmonate signal cascade that elicits these defenses (AS-Nalox3), by measuring stalk and axillary branch growth and seed production after two defoliation regimes and Manduca sexta larval attack to bottom or middle and top stalk leaves. Larval attack and defoliation at middle and top leaves depressed seed production and increased axillary branching more than at bottom leaves. AS-Nalox3 and AS-Natpi plants produced significantly longer (two- to fourfold) branches than did wild-type (WT) plants, results that are consistent with resource-based trade-offs between resistance and regrowth. Methyl jasmonate (MeJA) treatment of AS-Nalox3 plants restored WT branch growth, suggesting that jasmonic acid (JA) signalling suppresses regrowth and contributes to apical dominance. These results are consistent with the existence of JA- and resource-mediated trade-offs between regrowth and herbivore resistance traits.     

Jasmonic acid does not mediate root growth responses to wounding in Arabidopsis thaliana

Jasmonic acid (JA) is a crucial plant defence signalling substance that has recently been shown to mediate herbivory-induced root growth reduction in the ecological model species Nicotiana attenuata . To clarify whether JA-induced reduction of root growth might be a general response increasing plant fitness under biotic stress, a suite of experiments was performed with the model plant Arabidopsis thaliana . JA bursts were elicited in leaves of A. thaliana in different ways. Root growth reduction was neither induced by foliar application of herbivore oral secretions nor by direct application of methyl jasmonate to leaves. Root growth reduction was observed when leaves were infected with the pathogen Pseudomonas syringae pv. tomato, which persistently induces the JA signalling pathway. Yet, high resolution growth analyses of this effect in wild type and JA biosynthesis knock-out mutants showed that it was elicited by the bacterial toxin coronatine that suggests ethylene- but not JA-induced root growth reduction in A. thaliana . Overall, the results demonstrate that the reaction of root growth to herbivore-induced JA signalling differs among species, which is discussed in the context of different ecological defence strategies among species.     

Jasmonate modulates endocytosis and plasma membrane accumulation of the Arabidopsis PIN2 protein

The subcellular distribution of the PIN-FORMED (PIN) family of auxin transporters plays a critical role in auxin gradient-mediated developmental processes, including lateral root formation and gravitropic growth. Here, we report two distinct aspects of CORONATINE INSENSITIVE 1 (COI1)- and AUXIN RESISTANT 1 (AXR1)-dependent methyl jasmonate (MeJA) effects on PIN2 subcellular distribution: at lower concentration (5 μM), MeJA inhibits PIN2 endocytosis, whereas, at higher concentration (50 μM), MeJA reduces PIN2 accumulation in the plasma membrane. We show that mutations of ASA1 (ANTHRANILATE SYNTHASE a1) and the TIR1/AFBs (TRANSPORT INHIBITOR RESPONSE 1/AUXIN-SIGNALING F-BOX PROTEINs) auxin receptor genes impair the inhibitory effect of 5 μM MeJA on PIN2 endocytosis, suggesting that a lower concentration of jasmonate inhibits PIN2 endocytosis through interaction with the auxin pathway. In contrast, mutations of ASA1 and the TIR1/AFBs auxin receptor genes enhance, rather than impair, the reduction effect of 50 μM MeJA on the plasma membrane accumulation of PIN2, suggesting that this action of jasmonate is independent of the auxin pathway. In addition to the MeJA effects on PIN2 endocytosis and plasma membrane residence, we also show that MeJA alters lateral auxin redistribution on gravi-stimulation, and therefore impairs the root gravitropic response. Our results highlight the importance of jasmonate-auxin interaction in the coordination of plant growth and the adaptation response.     

Improvement of drought tolerance of soybean plants by using methyl jasmonate

Methyl jasmonate (MeJA) is a naturally occurring plant growth regulator and play vital roles in plant defense and many developmental processes such as root growth and seed germination. This study was undertaken to study the possible role of using methyl jasmonate to alleviate the adverse effect of water stress on soybean genotypes (Giza 22 and 35). The results showed that water stress reduced shoot length, fresh and dry weights of shoot and root, photosynthetic pigments, relative water content and oil content in the shoots of all soybean genotypes. On the other hand, there was a considerable increase in cell wall fractionation, saturated and unsaturated fatty acids, flavonoids, phenolic acid and sugar fraction content in the shoots of the soybean genotypes in response to the water stress. Foliar spray with methyl jasmonate increased all the above parameters as compared to stressed plants. The results investigate the important role of MeJA in alleviation of water stress in soybean plants and suggest that MeJA could be used for improving plant growth under water stress as a potential growth regulator. The soybean genotypes Giza 22 was found to be more resistant to water stress than Giza 35.     

Root growth of Nicotiana attenuata is decreased immediately after simulated leaf herbivore attack

Image-based non-destructive methods were used to quantify root growth reactions happening within hours following simulated leaf herbivore attack.¹ The induction of wound reactions in leaves of seedlings of Nicotiana attenuata led to transiently decreased root growth rates: Upon application of the oral secretions and regurgitants of the specialist herbivore Manduca sexta, a transient decrease in root growth was observed that was more pronounced than if a mere mechanical wounding was imposed. Root growth reduction was more severe than leaf growth reduction and the timing of the transient growth reduction coincided with endogenous bursts of jasmonate (JA) and ethylene emissions reported in literature. The reaction of root growth was superimposed by a strong diel variation of root growth, which was caused by the fluctuating temperature to which the plants were exposed. Apart from the observed root growth reaction, other defense-related traits such as increased nicotine concentration, trichome length and density were activated within 72 h after wounding. Further experiments indicated that the response was elicited by fatty acid-amino acid conjugates that are contained in the oral secretions and that JA signalling is crucial for root-shoot communication here.Key words: image analysis, plant-insect interactions, Manduca sextaPlants constantly need to acclimate to a suite of fluctuating biotic and abiotic factors. Within the framework of their genetically determined response options, they react towards stress situations by maximizing protection against stress while minimizing deviations from optimal growth and development. Feeding of the larvae of the specialist lepidopteran herbivore Manduca sexta on N. attenuata has become a model case scenario for studying biotic stress.² It has been shown in great detail there, that a diverse set of plant hormones like JA, methyl jasmonate and ethylene are rapidly induced immediately following wounding or herbivore attack.^3,4,5 Acclimation occurs both on the biochemical and morphological level, e.g., by increasing defence compounds,⁶ by synthesizing defence related proteins, by emitting volatiles to attract predators and parasites of herbivores⁷ and by altering plant morphology via increased formation of trichomes, thorns or scleromorphy.^8,9 Many studies demonstrated resource based trade-offs between growth and defence on a large time scale (e.g. refs. ¹⁰ and ¹¹). Yet, it is unclear how fast a trade-off-linked reorganization of plant metabolism, diverting resources away from growth or development towards defence, can occur.Recently, development of growth imaging methods has allowed to study short-term growth responses of above-and belowground sink organs towards fluctuations of environmental factors, such as alterations of light climate¹² or responses towards gravitropic stimuli.^13–15 Clear responses are often seen best in young seedlings as they grow fast and as they can be cultivated in agar-filled, translucent Petri dishes allowing live imaging. Hence, it was the aim of our study to monitor defence reactions in the N. attenuata seedling system while at the same time assessing the dynamics of root growth reaction following such an attack.Herbivory-induced wound reactions were simulated by applying different substances on the mechanically wounded primary leaf of the seedling plant 16 d after germination.¹ Investigated substances were: (i) oral secretions and regurgitants of M. sexta larvae (OS), (ii) methyl jasmonate, (iii) fatty acid-amino acid conjugates, (iv) control solutions for the different test substances (water, buffer, lanolin). All wounding treatments were performed at the same time of the day to make sure that the reaction was not masked by fluctuating responses of the plant to temperature changes (plants were grown in a 14 h/10 h light/ dark regime with temperatures of 26°C and 22°C at day and night, respectively).Root growth was affected strongly by temperature (Fig. 1A) and increased linearly with temperature in the analyzed range. Root growth decreased markedly, if OS was added to the wounds. OS-treated and wounded control plants differed in growth reduction from about 2 h after wounding onwards. To uncouple this reduction from temperature-induced growth reductions, the experiment was repeated under continuous light and temperature, leading to a comparable result (Fig. 1B). When OS was added to wounds, nicotine concentration and trichome length and density increased within 72 h after the wounding reaction. Root growth reaction was comparable between OS-treatment and treatments, in which methyl jasmonate or fatty-acid amino acid conjugates were supplied to the wounds. The strongest difference concerning the distribution of relative elemental growth rate along the root growth zone between control and OS treatment was observed about 1 mm behind the root tip in the beginning of the central elongation zone. Leaf growth was monitored in an additional set of experiments. There, a transient decrease of growth was seen as well, but it was not as pronounced as for root growth.Open in a separate windowFigure 1Root growth in Nicotiana attenuata, grown on agar-filled Petri dishes. (A) Velocity of the root tip (V_Tip) versus temperature of the agar medium. (B) Velocity of the root tip of control plants and of plants with leaves that were wounded at t=0 and treated with oral secretions and regurgitants (OS) of Manduca sexta. Plants were grown in continuous light at T = 26°C (n = 3, mean values and SE).The kinetics of the root growth depression point on a superposition of two physiological effects: During the first hour after wounding, root growth decreases similarly in control and OS-treated plants, indicating a mere hydraulic response due to the loss of water and turgor pressure.¹² Thereafter, a specific response towards OS is observed, which coincides with the time frame of about 2–3 h that was reported for the systemic increase of JA transported from shoot to root. Baldwin et al¹⁶ reported that JA pools in roots are increased systemically (3.5-fold) within 180 minutes following mechanical wounding. Hence, JA might mediate the reduction in root growth and induce the defense machinery, which diverts resources from growth to defense.     

Methyl jasmonate induces ATP biosynthesis deficiency and accumulation of proteins related to secondary metabolism in Catharanthus roseus (L.) G. hairy roots

Jasmonates are specific signal molecules in plants that are involved in a diverse set of physiological and developmental processes. However, methyl jasmonate (MeJA) has been shown to have a negative effect on root growth and, so far, the biochemical mechanism for this is unknown. Using Catharanthus roseus hairy roots, we were able to observe the effect of MeJA on growth inhibition, cell disorganization and cell death of the root cap. Hairy roots treated with MeJA induced the perturbation of mitochondrial membrane integrity and a diminution in ATP biosynthesis. Furthermore, several proteins were identified that were involved in energy and secondary metabolism; the changes in accumulation of these proteins were observed with 100 μM MeJA. In conclusion, our results suggest that a switch of the metabolic fate of hairy roots in response to MeJA could cause an increase in the accumulation of secondary metabolites. This is likely to have important consequences in the production of specific alkaloids important for the pharmaceutical industry.     

Two Methyl Jasmonate-Insensitive Mutants Show Altered Expression of AtVsp in Response to Methyl Jasmonate and Wounding

Jasmonates are plant signal molecules that are derived from lipids through the action of lipoxygenase. Jasmonates regulate gene expression during plant development and in response to water deficit, wounding, and pathogen elicitors. The signal transduction chain that mediates jasmonate action was investigated by isolating and studying two methyl jasmonate (MeJA)-insensitive mutants of Arabidopsis thaliana. The recessive mutants, jin1 and jin4, are nonallelic and neither corresponds to coi1, a previously identified MeJA-insensitive mutant. Both mutants showed reduced sensitivity to MeJA-mediated root growth inhibition as well as reduced MeJA induction of AtVsp in leaves. Expression of AtVsp in flowers was not altered in the mutants. Furthermore, MeJA modulation of the jasmonate-responsive lipoxygenase and phenylalanine ammonia lyase genes was not altered in the mutants. jin4 plants exhibited increased sensitivity to abscisic acid in seed germination assays, whereas jin1 plants showed wild-type sensitivity. Neither mutant showed altered sensitivity to ethylene in hypocotyl growth inhibition assays. jin1 and jin4 identify genes that modulate the response of AtVsp to MeJA in leaves of A. thaliana.     

Methyl jasmonate and cis-jasmone do not dispose of the herbivore-induced jasmonate burst in Nicotiana attenuata

The oxylipin pathway mediates wound- and herbivore-induced defense reactions in Nicotiana attenuata as evidenced by a transient jasmonic acid (JA)-burst that precedes these defense responses. The fate of this induced JA-burst remains unknown. Two derivatives of JA, its methylester, methyl jasmonate (MeJA) and cis -jasmone ( cis J), are thought to be a means of disposing of JA through volatilization at the plant surface. In N. attenuata, the headspace quantities of these compounds did not change over 3 days, although levels of MeJA and cis J increased 100- and 70-fold, respectively, in surface extracts of attacked leaves after feeding of Manduca sexta larvae or application of larval regurgitant to mechanical wounds. Inhibition of the wound-induced increase in JA with indole-3-acetic acid (IAA) revealed an association between the JA accumulation and subsequent increases in MeJA and cis J. Induced systemic increases of MeJA were not of local origin and therefore do not contribute to the inactivation of the JA-burst in the wounded leaf. The total amount of MeJA and cis J produced could only account for 9% of the JA-burst elicited by herbivore attack and therefore their production do not represent major disposal pathways of JA in N. attenuata .     

内源茉莉酸甲酯的积累改变了大豆叶片与根的发育

茉莉酸甲酯是一种调节植物形态发生、诱导防御相关基因的植物信号转导分子。为了解内源茉莉酸甲酯在植物发育中的作用,将编码茉莉酸甲基转移酶的NTR1基因与CaMV 35S启动子连接并导入大豆植株。PCR及Northern杂交结果表明,NTR1基因稳定整合在大豆基因组并得到过量表达。与野生型植株相比,转基因大豆叶片与根的形态发生了显著的变化。大部分转基因大豆叶片变得细长,初生根生长受到抑制而侧根的生长却受到促进。定量分析结果表明,转基因大豆植株叶片中茉莉酸甲酯的含量比对照高出 2～2.5 倍。这些结果表明,内源茉莉酸甲酯的积累参与了大豆形态发生的调控。     

Differential Secretion and Accumulation of Terpene Indole Alkaloids in Hairy Roots of <Emphasis Type="Italic">Catharanthus roseus</Emphasis> Treated with Methyl Jasmonate

The induction of several secondary metabolites in plants is one of the most commonly observed effects after the external addition of methyl jasmonate (MeJA). After the elicitation of Catharanthus roseus hairy roots with different concentrations of MeJA, changes in the accumulation of alkaloids such as ajmalicine, serpentine, ajmaline and catharanthine were observed. In addition to the increased accumulation of alkaloids in the tissues, the root exudation of phytochemicals increased compared to that of the non-treated control hairy roots. Moreover, MeJA induced differential secretion of several C. roseus hairy root metabolites.     

Methyl jasmonate does not induce changes in Eucalyptus grandis leaves that alter the effect of constitutive defences on larvae of a specialist herbivore

The up-regulation of secondary metabolic pathways following herbivore attack and the subsequent reduction in herbivore performance have been identified in numerous woody plant species. Eucalypts constitutively express many secondary metabolites in the leaves, including terpenes and formylated phloroglucinol compounds (FPCs). We used clonal ramets from six clones of Eucalyptus grandis and two clones of E. grandis x camaldulensis to determine if methyl jasmonate (MeJA) treatment could induce changes in the foliar concentrations of either of these groups of compounds. We also used bioassays to determine if any changes in the performance of larvae of Paropsis atomaria, a chrysomelid leaf beetle, could be detected in treated ramets versus the untreated controls, thus indicating whether MeJA induced the up-regulation of defences other than terpenes or FPCs. We found no significant effects of MeJA treatment on either the foliar concentrations of terpenes and FPCs or on herbivore performance. We did, however, detect dramatic differences in larval performance between Eucalyptus clones, thereby demonstrating large variations in the levels of constitutive defence. Larval feeding on clones resistant to P. atomaria resulted in high first instar mortality and disruption of normal gregarious feeding behaviour in surviving larvae. Histological examination of larvae feeding on a resistant clone revealed damage to the midgut consistent with the action of a toxin. These findings concur with mounting evidence that most evergreen perennial plants lack foliar-induced defences and suggest that constitutively expressed secondary metabolites other than those commonly examined in studies of interactions between insect herbivores and Eucalyptus may be important in plant defence.     

Expression of Flowering Repressor Gene CsSVP,Carbohydrates, and Antioxidants Affected by Plant Growth Regulators in Saffron

Improving flower yield through lengthening flowering duration is a primary breeding objective in saffron (Crocus sativus L.). Asexual reproduction in saffron limits biodiversity and conventional breeding. Hence, eliciting flowering-related gene expression by plant growth regulators is one way to achieve this aim. The phytohormones methyl jasmonate (MeJA) and 6-benzyl amino purine (BAP) signals are received by the MADs-box gene family. In this study, to elucidate the role of phytohormones on flower development, plant were treated with BAP (0 and 5 mg L^?1), and methyl jasmonate (MeJA) (0, 20, and 100 mM) at three developmental stages of the saffron life cycle. Then, the expression of the SHORT VEGETATIVE PHASE (CsSVP) gene as a MADS-box gene family was assessed in the saffron corm. The activities of antioxidant enzymes, soluble sugar, starch content, and soluble protein content were also measured in corm, leaf, and root tissues. The application of MeJA and BAP treatments resulted in down-regulation of CsSVP expression in the corm during dormancy. At the dormancy stage, catalase, peroxidase activity decreased, and ascorbate peroxidase activity increased following MeJA treatment. In contrast, an increment in catalase and peroxidase activity and reduction of ascorbate peroxidase activity were observed after treatment with MeJA during the flowering stage. This change in enzyme activity is most likely due to flowering, which demands the re-allocation of resources. As flowering is a process heavily influenced by the environment, plants treated with MeJA, which may mimic environmental stress, showed changes in antioxidant enzyme activity. Overall, these results suggested that MeJA and BAP treatments play a significant role in the vegetative-to-reproductive phase change in saffron.

     

Beta and habitat diversity in marine systems: a new approach to measurement, scaling and interpretation

Specialist herbivores are known to alter their host's wound-induced responses but the beneficiaries of these alterations are unknown. Nicotiana attenuata plants release a burst of ethylene specifically in response to feeding by Manduca sexta larvae, which is known to suppress wound- and methyl jasmonate (MeJA)-inducible nicotine accumulation. The ethylene burst may be a mechanism by which M. sexta larvae feed "stealthily" on their host plants or, alternatively, it may allow the plant to optimize its defense response against this specialist herbivore by reducing costs of induction. We examined the impact of the ethylene burst on defense-related fitness costs that are readily observed when plants are treated with MeJA and grown in competition with untreated plants. We elicited nicotine induction (with MeJA), the ethylene burst (with the ethylene releasing compound, ethephon) and inhibited the plant's ability to perceive ethylene (with applications of an antagonist of ethylene receptors, 1-methylcyclopropene, 1-MCP). By simultaneously applying MeJA and ethephon we mimicked the plant's hormonal response to larval attack. We hypothesized that if the ethylene burst benefited the plant, the fitness costs of MeJA induction should be reduced by ethephon and restored if the plants were additionally treated with 1-MCP. In a second experiment, we applied larval oral secretion (OS) to elicit endogenous hormone production and predicted that the 1-MCP treatment should reduce the fitness of OS-treated plants. Our measures of plant fitness, namely the rate of stalk elongation and lifetime capsule production, supported these predictions. We conclude that the ethylene burst elicited by this specialist herbivore can reduce MeJA-induced fitness costs and increase the competitive strength of OS-treated plants. Suppressed nicotine production is likely to contribute to, but is not sufficient to explain, the observed fitness outcomes. The intensity of intra-specific competition and herbivore attack will likely determine the adaptive value of the M. sexta-elicited ethylene response.     

茉莉酸甲酯:一种重要的植物信号转导分子

作为一种信号转导分子,茉莉酸甲酯在植物生长发育、代谢调节、抗病、耐逆、防御相关基因的诱导表达等方面均起着重要的作用。由于茉莉酸甲酯所具有的上述多效性,其作用与机制受到人们的广泛关注。本文简要介绍了植物中茉莉酸甲酯信号转导作用的相关研究进展。     

MdARF8: An Auxin Response Factor Involved in Jasmonate Signaling Pathway in Malus domestica

Auxin response factor (ARF) is a key component of auxin signal. The study of MdARF8 gene in apple shows that it is involved in the process of jasmonate regulating plant growth and development. Methyl jasmonate (MeJA) treatment inhibited the growth process of apple calli, and ARF8 played a negative regulatory role in this pathway. The results of ectopic expression in Arabidopsis showed that MdARF8 could reduce the sensitivity of Arabidopsis to MeJA and alleviate the phenotype of promoting leaf senescence and inhibiting taproot elongation. Further results showed that the dysplastic phenotype of transgenic Arabidopsis root hair could be partially recovered by MeJA treatment. This study provided valuable clues for functional characterization of ARF8 and signal crosstalk between jasmonate and auxin in apple.

     

2种植物生长调节剂诱导烟草抗链格孢菌研究

以链格孢菌Alternaria alternata和烟草Nicotiana tabacum品种云烟87为试材,研究不同浓度茉莉酸甲酯(MeJA)和水杨酸(SA)处理下,链格孢菌菌丝生长情况以及成熟期烟叶防御酶活性与多酚含量变化,探讨植物生长调节剂对烟草抗链格孢菌的影响。结果表明,1 mmol·L^–1 MeJA对链格孢菌的抑制效果最好,抑菌率高达59%以上,其次是3.5 mmol·L^–1SA;MeJA和SA对链格孢菌的抑制效果随药剂浓度升高而增强;0.1 mmol·L^–1 MeJA和2.5 mmol·L^–1 SA能诱导烟草叶片SOD、POD、CAT等防御酶活性,并能降低H₂O₂活性氧含量,尤其以MeJA诱导效果较好。2种植物生长调节剂处理并接种链格孢菌能诱导提高烟叶多酚代谢相关酶PPO及PAL活性,但对烟草多酚类物质影响较小;成熟烟叶中含量较高的前3种多酚物质是绿原酸、芸香苷、隐绿原酸。     

Multiannual effects of induced plant defenses: Are defended plants good or bad neighbors?

Defenses induced by herbivore feeding or phytohormones such as methyl jasmonate (MeJA) can affect growth, reproduction, and herbivory, not only on the affected individual but also in its neighboring plants. Here, we report multiannual defense, growth, and reproductive responses of MeJA‐treated bilberry (Vaccinium myrtillus) and neighboring ramets. In a boreal forest in western Norway, we treated bilberry ramets with MeJA and water (control) and measured responses over three consecutive years. We observed the treatment effects on variables associated with herbivory, growth, and reproduction in the MeJA‐treated and untreated ramet and neighboring ramets distanced from 10 to 500 cm. MeJA‐treated ramets had fewer grazed leaves and browsed shoots compared to control, with higher effects in 2014 and 2015, respectively. In 2013, growth of control ramets was greater than MeJA‐treated ramets. However, MeJA‐treated ramets had more flowers and berries than control ramets 2 years after the treatment. The level of insect and mammalian herbivory was also lower in untreated neighboring ramets distanced 10–150 cm and, consistent with responses of MeJA‐treated ramets, the stronger effect was also one and 2 years delayed, respectively. The same neighboring ramets had fewer flowers and berries than untreated ramets, indicating a trade‐off between defense and reproduction. Although plant–plant effects were observed across all years, the strength varied by the distance between the MeJA‐treated ramets and its untreated neighbors. We document that induced defense in bilberry reduces both insect and mammalian herbivory, as well as growth, over multiple seasons. The defense responses occurred in a delayed manner with strongest effects one and 2 years after the induction. Additionally, our results indicate defense signaling between MeJA‐treated ramets and untreated neighbors. In summary, this study shows that induced defenses are important ecological strategies not only for the induced individual plant but also for neighboring plants across multiple years in boreal forests.