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Background: Plants allocate resources to growth, defense, and stress resistance, and resource availability can affect the balance between these allocations. Allocation patterns are well-known to differ among species, but what controls possible intra-specific trade-offs and if variation in growth vs. defense potentially evolves in adaptation to resource availability. Methods: We measured growth and defense in a provenance trial of rubber trees (Hevea brasiliensis) with clones originating from the Amazon basin. To test hypotheses on the allocation to growth vs. defense, we relate biomass growth and latex production to wood and leaf traits, to climate and soil variables from the location of origin, and to the genetic relatedness of the Hevea clones. Results: Contrary to expectations, there was no trade-off between growth and defense, but latex yield and biomass growth were positively correlated, and both increased with tree size. The absence of a trade-off may be attributed to the high resource availability in a plantation, allowing trees to allocate resources to both growth and defense. Growth was weakly correlated with leaf traits, such as leaf mass per area, intrinsic water use efficiency, and leaf nitrogen content, but the relative investment in growth vs. defense was not associated with specific traits or environmental variables. Wood and leaf traits showed clinal correlations to the rainfall and soil variables of the places of origin. These traits exhibited strong phylogenetic signals, highlighting the role of genetic factors in trait variation and adaptation. The study provides insights into the interplay between resource allocation, environmental adaptations, and genetic factors in trees. However, the underlying drivers for the high variation of latex production in one of the commercially most important tree species remains unexplained. [ABSTRACT FROM AUTHOR]

In nature, plants are constantly colonized by a massive diversity of microbes engaged in mutualistic, pathogenic or commensal relationships with the host. Molecular patterns present in these microbes activate pattern-triggered immunity (PTI), which detects microbes in the apoplast or at the tissue surface. Whether and how PTI distinguishes among soil-borne pathogens, opportunistic pathogens, and commensal microbes within the soil microbiota remains unclear. PTI is a multimodal series of molecular events initiated by pattern perception, such as Ca2+ influx, reactive oxygen burst, and extensive transcriptional and metabolic reprogramming. These short-term responses may manifest within minutes to hours, while the long-term consequences of chronic PTI activation persist for days to weeks. Chronic activation of PTI is detrimental to plant growth, so plants need to coordinate growth and defense depending on the surrounding biotic and abiotic environments. Recent studies have demonstrated that root-associated commensal microbes can activate or suppress immune responses to variable extents, clearly pointing to the role of PTI in root–microbiota interactions. However, the molecular mechanisms by which root commensals interfere with root immunity and root immunity modulates microbial behavior remain largely elusive. Here, with a focus on the difference between short-term and long-term PTI responses, we summarize what is known about microbial interference with host PTI, especially in the context of root microbiota. We emphasize some missing pieces that remain to be characterized to promote the ultimate understanding of the role of plant immunity in root–microbiota interactions. [ABSTRACT FROM AUTHOR]

Background Plants allocate resources to growth, defense, and stress resistance, and resource availability can affect the balance between these allocations. Allocation patterns are well-known to differ among species, but what controls possible intra-specific trade-offs and if variation in growth vs. defense potentially evolves in adaptation to resource availability. Methods We measured growth and defense in a provenance trial of rubber trees (Hevea brasiliensis) with clones originating from the Amazon basin. To test hypotheses on the allocation to growth vs. defense, we relate biomass growth and latex production to wood and leaf traits, to climate and soil variables from the location of origin, and to the genetic relatedness of the Hevea clones. Results Contrary to expectations, there was no trade-off between growth and defense, but latex yield and biomass growth were positively correlated, and both increased with tree size. The absence of a trade-off may be attributed to the high resource availability in a plantation, allowing trees to allocate resources to both growth and defense. Growth was weakly correlated with leaf traits, such as leaf mass per area, intrinsic water use efficiency, and leaf nitrogen content, but the relative investment in growth vs. defense was not associated with specific traits or environmental variables. Wood and leaf traits showed clinal correlations to the rainfall and soil variables of the places of origin. These traits exhibited strong phylogenetic signals, highlighting the role of genetic factors in trait variation and adaptation. The study provides insights into the interplay between resource allocation, environmental adaptations, and genetic factors in trees. However, the underlying drivers for the high variation of latex production in one of the commercially most important tree species remains unexplained.

Plant cell walls are dynamic structures that play crucial roles in growth, development, and stress responses. Despite our growing understanding of cell wall biology, the connections between cell wall integrity (CWI) and cell cycle progression in plants remain poorly understood. This review aims to explore the intricate relationship between CWI and cell cycle progression in plants, drawing insights from studies in yeast and mammals. We provide an overview of the plant cell cycle, highlight the role of endoreplication in cell wall composition, and discuss recent findings on the molecular mechanisms linking CWI perception to cell wall biosynthesis and gene expression regulation. Furthermore, we address future perspectives and unanswered questions in the field, such as the identification of specific CWI sensing mechanisms and the role of CWI maintenance in the growth-defense trade-off. Elucidating these connections could have significant implications for crop improvement and sustainable agriculture. Key message: In this review, we provide a comprehensive exploration of the intricate relationship between plant CWI and cell cycle progression. By drawing parallels from studies in yeast and mammals, we offer new insights into this critical facet of plant cell biology. We underscore the role of endoreplication in cell wall composition and the molecular mechanisms linking CWI perception to cell wall biosynthesis and gene expression regulation. The review also identifies key research avenues that remain to be explored, such as specific CWI sensing mechanisms and the role of CWI maintenance in the growth-defense trade-off. Elucidating these links holds significant potential for crop improvement and sustainable agriculture, thus rendering our work of broad interest to researchers in plant biology, agricultural science, and sustainable farming practices. [ABSTRACT FROM AUTHOR]

Summary: Jasmonate (JA) re‐programs metabolism to confer resistance to diverse environmental threats. Jasmonate stimulates the degradation of JASMONATE ZIM‐DOMAIN (JAZ) proteins that repress the activity of MYC transcription factors. In Arabidopsis thaliana, MYC and JAZ are encoded by 4 and 13 genes, respectively. The extent to which expansion of the MYC and JAZ families has contributed to functional diversification of JA responses is not well understood.Here, we investigated the role of MYC and JAZ paralogs in controlling the production of defense compounds derived from aromatic amino acids (AAAs).Analysis of loss‐of‐function and dominant myc mutations identified MYC3 and MYC4 as the major regulators of JA‐induced tryptophan metabolism. We developed a JAZ family‐based, forward genetics approach to screen randomized jaz polymutants for allelic combinations that enhance tryptophan biosynthetic capacity. We found that mutants defective in all members (JAZ1/2/5/6) of JAZ group I over‐accumulate AAA‐derived defense compounds, constitutively express marker genes for the JA–ethylene branch of immunity and are more resistant to necrotrophic pathogens but not insect herbivores.In defining JAZ and MYC paralogs that regulate the production of amino‐acid‐derived defense compounds, our results provide insight into the specificity of JA signaling in immunity. [ABSTRACT FROM AUTHOR]

Foliar fungal pathogens can substantially reduce plant biomass. This effect can be modulated by environment conditions, such as soil nitrogen availability and air temperature. The ongoing global changes are altering these variables and thus interact with pathogens to influence plant biomass, but experimental test of their interactions is scarce.We conducted a 4‐year field experiment in a Tibetan alpine meadow to examine the interactive effects of nitrogen addition, warming and foliar pathogens (via fungicide application) on plant biomass. We also measured plant functional traits, species richness and abundance to test the possible mechanisms underlying these interactions.Our results showed that foliar fungal pathogens reduced plant community biomass under nitrogen addition, which in turn weakened the positive nitrogen effect on community biomass. Mechanistically, nitrogen addition shifted the plant communities towards fast‐growing traits; this happened predominantly because of changes in within‐species trait values, including an increase in specific leaf area and height. These trait changes resulted in greater suppression of plant biomass by pathogens, likely because of the trade‐offs associated with the allocation of resources to plant growth and defense. Moreover, the reduction in species richness amplified the pathogen effect under nitrogen addition due to the increased density and susceptibility of the most dominant species (i.e. Kobresia capillifolia). Furthermore, warming did not interact with pathogens and nitrogen addition to influence plant community biomass, but their three‐way interaction modified the biomass of K. capillifolia. Specifically, warming enhanced the positive effect of nitrogen addition on the biomass of K. capillifolia in the fungicide, low infection plots, while it weakened the nitrogen effect in the no fungicide, high infection plots.Synthesis. Our results demonstrate how pathogens interact with nitrogen addition and warming to influence the biomass of dominant species and the whole plant community. Our study highlights the importance of considering foliar fungal pathogens when assessing ecosystem responses to multiple global change factors. [ABSTRACT FROM AUTHOR]

One grand challenge for studying plant biotic and abiotic stress responses is to optimize plant growth and plasticity under variable environmental constraints, which in the long run benefits agricultural production. However, efforts in promoting plant immunity are often accompanied by compromised morphological "syndromes" such as growth retardation, sterility, and reduced yield. Such a trade-off is dictated by complex signaling driven by secondary messengers and phytohormones. Salicylic acid (SA) is a well-known phytohormone essential for basal immunity and systemic acquired resistance. Interestingly, recent updates suggest that external environmental cues, nutrient status, developmental stages, primary metabolism, and breeding strategies attribute an additional layer of control over SA-dependent signaling, and, hence, plant performance against pathogens. In this review, these external and internal factors are summarized, focusing on their specific roles on SA biosynthesis and downstream signaling leading to immunity. A few considerations and future opportunities are highlighted to improve plant fitness with minimal growth compensation. [ABSTRACT FROM AUTHOR]

Mangrove species are undergoing environmental changes from nutrient-poor to enrichment due to the large nutrient input. The potential difference in adaptive strategies between the slow- and fast-growing species may lead to great changes in species interaction and ecosystem stability. This study aims to test whether the slow-growing species Aegiceras corniculatum (L.) Blanco and Kandelia obovata Sheue, Liu & Yong sp. nov. are distinctly different from a fast-growing species Laguncularia racemosa (L.) Gaertn. f. in response to soil nutrient enrichment. With the increase of soil nutrients, L. racemosa shifted from a more conservative to a more acquisitive strategy. The potential causes included the increases in specific leaf area, nutrient resorption efficiency, and photosynthetic capacity as indicated by the increase of leaf δ13C and unchanged leaf succulence, as well as the relocation of photosynthetic products as indicated by the shift toward fast-growing at the cost of constructive and defense compounds. In contrast, A. corniculatum and K. obovata maintained conservative strategies at any soil nutrient levels with only a slight increase in growth. These findings implied that L. racemosa will be more competitive over the slow-growing species in nutrient-rich soils through altering adaptive strategies. [ABSTRACT FROM AUTHOR]

Premise: The expected concomitant increase in multiple stressors such as herbivory and drought may threaten peatland ecosystems. How Sphagnum, the ecological engineers of peatlands, responds to combined stressors remains largely unexplored. Here we aimed to clarify resource allocations in Sphagnum during concomitant herbivory and drought., Methods: S. magellanicum and S. fuscum were exposed to drought and herbivory together or separately in laboratory experiments and analyzed for growth (biomass production and net photosynthetic rate), defense (phenolics in leachates and phenolics in extraction) and nonstructural carbohydrates (soluble sugar and starch) in relation to untreated controls., Results: Herbivory and drought had significant interactive effects on Sphagnum growth and defense. In both species, drought without herbivory reduced the phenolics in leachate, but with herbivory increased phenolics, indicating a synergistic effect between herbivory and drought on Sphagnum defense. Both stressors significantly decreased biomass production, with the combined stress having a more negative effect. Interestingly, a growth-defense trade-off was found in the drought treatment of both Sphagnum species, but disappeared in the wet treatment. Conversely, a trade-off between soluble sugars and phenolics was found in the wet but not in the drought treatment, suggesting that soluble sugars may play a role in inducing the defense and hence mask the growth-defense trade-off in peat mosses., Conclusions: Our results emphasize that predicting the impact of combined stressors on peat moss traits is complex and challenging. Future models should account for the effects of multiple environmental stressors to guide peatland conservation under climate warming., (© 2024 Botanical Society of America.)

Wounding is a general stress in plants that results from various pest and pathogenic infections in addition to environment-induced mechanical damages. Plants have sophisticated molecular mechanisms to recognize and respond to wounding, with those of monocots being distinct from dicots. Here, we show the involvement of two distinct categories of temporally separated, endogenously derived peptides, namely, plant elicitor peptides (PEPs) and phytosulfokine (PSK), mediating wound responses in rice. These peptides trigger a dynamic signal relay in which a receptor kinase involved in PSK perception named OsPSKR plays a major role. Perturbation of OsPSKR expression in rice leads to compromised development and constitutive autoimmune phenotypes. OsPSKR regulates the transitioning of defense to growth signals upon wounding. OsPSKR displays mutual antagonism with the OsPEPR1 receptor involved in PEP perception. Collectively, our work indicates the presence of a stepwise peptide-mediated signal relay that regulates the transition from defense to growth upon wounding in monocots. [Display omitted] • Wounding in rice triggers a signal relay between the small peptides OsPep3 and PSK • OsPSKR receptor perceives PSK and plays a key role in rice growth and development • OsPSKR dictates gene expression and promotes transition of wound responses • OsPSKR counters OsPEPR1-mediated signaling leading to balanced growth and defense Harshith et al. show that rice wound responses involve small-peptide-mediated signal relay between defense signaling PEPs and growth signaling by a PSK peptide hormone. OsPSKR receptor perceives PSK and maintains balance between growth and defense signaling during homeostasis and promotes growth post-wounding. [ABSTRACT FROM AUTHOR]

Lipid-derived jasmonates (JAs) play a crucial role in a variety of plant development and defense mechanisms. In recent years, significant progress has been made toward understanding the JA signaling pathway. In this review, we discuss JA biosynthesis, as well as its core signaling pathway, termination mechanisms, and the evolutionary origin of JA signaling. JA regulates not only plant regeneration, reproductive growth, and vegetative growth but also the responses of plants to stresses, including pathogen as well as virus infection, herbivore attack, and abiotic stresses. We also focus on the JA signaling pathway, considering its crosstalk with the gibberellin (GA), auxin, and phytochrome signaling pathways for mediation of the trade-offs between growth and defense. In summary, JA signals regulate multiple outputs of plant defense and growth and act to balance growth and defense in order to adapt to complex environments. [ABSTRACT FROM AUTHOR]

Plants are unsurpassed biochemists that synthesize a plethora of molecules in response to an ever-changing environment. The majority of these molecules, considered as specialized metabolites, effectively protect the plant against pathogens and herbivores. However, this defense most probably comes at a great expense, leading to reduction of growth (known as the 'growth–defense trade-off'). Plants employ several strategies to reduce the high metabolic costs associated with chemical defense. Production of specialized metabolites is tightly regulated by a network of transcription factors facilitating its fine-tuning in time and space. Multifunctionality of specialized metabolites—their effective recycling system by re-using carbon, nitrogen, and sulfur, thus re-introducing them back to the primary metabolite pool—allows further cost reduction. Spatial separation of biosynthetic enzymes and their substrates, and sequestration of potentially toxic substances and conversion to less toxic metabolite forms are the plant's solutions to avoid the detrimental effects of metabolites they produce as well as to reduce production costs. Constant fitness pressure from herbivores, pathogens, and abiotic stressors leads to honing of specialized metabolite biosynthesis reactions to be timely, efficient, and metabolically cost-effective. In this review, we assess the costs of production of specialized metabolites for chemical defense and the different plant mechanisms to reduce the cost of such metabolic activity in terms of self-toxicity and growth. [ABSTRACT FROM AUTHOR]

One grand challenge for studying plant biotic and abiotic stress responses is to optimize plant growth and plasticity under variable environmental constraints, which in the long run benefits agricultural production. However, efforts in promoting plant immunity are often accompanied by compromised morphological “syndromes” such as growth retardation, sterility, and reduced yield. Such a trade-off is dictated by complex signaling driven by secondary messengers and phytohormones. Salicylic acid (SA) is a well-known phytohormone essential for basal immunity and systemic acquired resistance. Interestingly, recent updates suggest that external environmental cues, nutrient status, developmental stages, primary metabolism, and breeding strategies attribute an additional layer of control over SA-dependent signaling, and, hence, plant performance against pathogens. In this review, these external and internal factors are summarized, focusing on their specific roles on SA biosynthesis and downstream signaling leading to immunity. A few considerations and future opportunities are highlighted to improve plant fitness with minimal growth compensation.

Premise: Current knowledge about defense strategies in plants under herbivore pressure is predominantly based on vascular plants. Bryophytes are rarely consumed by herbivores since they have ample secondary metabolites. However, it is unknown whether bryophytes have induced defenses against herbivory and whether there is a trade‐off between growth and defense in bryophytes. Methods: In an experiment with two peatland bryophytes, Sphagnum magellanicum Brid. and S. fuscum (Schimp.) H. Klinggr., two kinds of herbivory, clipping with scissors and grazing by mealworms (Tenebrio molitor L.) were simulated. At the end of the experiment, we measured growth traits, carbon‐based defense compounds (total phenolics and cellulose) and storage compounds (total nonstructural carbohydrates) of these two Sphagnum species. Results: Grazing but not clipping increased total phenolics and C:N ratio and reduced biomass production and height increment. A negative relationship between biomass production and total phenolics was found in S. magellanicum but not in S. fuscum, indicating a growth–defense trade‐off that is species‐specific. Grazing reduced the sugar starch content of S. magellanicum and the sugar of S. fuscum. Either clipping or grazing had no effect on chlorophyll fluorescence (including actual and maximum photochemical efficiency of photosystem II) except that a significant effect of clipping on actual photochemical efficiency in S. fuscum was observed. Conclusions: Our results suggest that Sphagnum can have induced defense against herbivory and that this defense can come at a cost of growth. These findings advance our knowledge about induced defense in bryophytes, the earliest land plants. [ABSTRACT FROM AUTHOR]

• Key message: Non-selective thinning of a hybrid aspen coppice stands via corridor or cross-corridor cutting impacts residual trees differently depending on their competitive status. Suppressed residual trees' metabolic profile indicates increased stress level, especially after cross-corridor thinning. • Context: Early thinning with regular corridor harvests is proposed for the management of post-harvest re-sprouted hybrid aspen (Populus tremula L. × P. tremuloides Michx.) coppice stands. The selection of remaining trees is not size-based and their physiological acclimation to the post-thinning conditions is unknown. • Aims: To analyse differences in secondary metabolite profile between thinning treatments and trees competitive status. • Methods: We used an HPLC-qTOF mass spectrometer to analyse the leaf extracts of dominant and suppressed trees from stands with different thinning intensities: un-thinned control with basal area of 15.4 ± 1.52 m2 ha−1, corridor thinning with basal area of 8.5 ± 0.46 m2 ha−1 and cross-corridor thinning with basal area of 3.9 ± 0.34 m2 ha−1. • Results: Competitive status and thinning treatment both had significant effects on the contents of compounds. Higher exposure to irradiance increased the contents of flavonoids and hydroxycinnamates. Corridor thinning treatments doubled the foliar contents of secondary metabolites and lowered macronutrient contents in competitively suppressed residual trees. Dominant residual trees were not affected in this respect. • Conclusion: Forest management practice and competitive status can significantly modify the metabolite profile in tree leaves. After corridor thinning of a young aspen coppice stand, the small-sized residual trees may initially respond with increased allocation to leaf chemical defence rather than to productivity. [ABSTRACT FROM AUTHOR]

Several oligosaccharide fragments derived from plant cell walls activate plant immunity and behave as typical damage-associated molecular patterns (DAMPs). Some of them also behave as negative regulators of growth and development, and due to their antithetic effect on immunity and growth, their concentrations, activity, time of formation, and localization is critical for the so-called “growth-defense trade-off.” Moreover, like in animals, over accumulation of DAMPs in plants provokes deleterious physiological effects and may cause hyper-immunity if the cellular mechanisms controlling their homeostasis fail. Recently, a mechanism has been discovered that controls the activity of two well-known plant DAMPs, oligogalacturonides (OGs), released upon hydrolysis of homogalacturonan (HG), and cellodextrins (CDs), products of cellulose breakdown. The potential homeostatic mechanism involves specific oxidases belonging to the family of berberine bridge enzyme-like (BBE-like) proteins. Oxidation of OGs and CDs not only inactivates their DAMP activity, but also makes them a significantly less desirable food source for microbial pathogens. The evidence that oxidation and inactivation of OGs and CDs may be a general strategy of plants for controlling the homeostasis of DAMPs is discussed. The possibility exists of discovering additional oxidative and/or inactivating enzymes targeting other DAMP molecules both in the plant and in animal kingdoms.

Lipid-derived jasmonates (JAs) play a crucial role in a variety of plant development and defense mechanisms. In recent years, significant progress has been made toward understanding the JA signaling pathway. In this review, we discuss JA biosynthesis, as well as its core signaling pathway, termination mechanisms, and the evolutionary origin of JA signaling. JA regulates not only plant regeneration, reproductive growth, and vegetative growth but also the responses of plants to stresses, including pathogen as well as virus infection, herbivore attack, and abiotic stresses. We also focus on the JA signaling pathway, considering its crosstalk with the gibberellin (GA), auxin, and phytochrome signaling pathways for mediation of the trade-offs between growth and defense. In summary, JA signals regulate multiple outputs of plant defense and growth and act to balance growth and defense in order to adapt to complex environments.

Plants detect and respond to the proximity of competitors using light signals perceived by photoreceptor proteins. A low ratio of red to far-red radiation (R:FR ratio) is a key signal of competition that is sensed by the photoreceptor phytochrome B (phyB). Low R:FR ratios increase the synthesis of growth-related hormones, including auxin and gibberellins, promoting stem elongation and other shade-avoidance responses. Other photoreceptors that help plants to optimize their developmental configuration and resource allocation patterns in the canopy include blue light photoreceptors, such as cryptochromes and phototropins, and UV receptors, such as UVR8. All photoreceptors act by directly or indirectly controlling the activity of two major regulatory nodes for growth and development: the COP1/SPA ubiquitin E3 ligase complex and the PIF transcription factors. phyB is also an important modulator of hormonal pathways that regulate plant defense against herbivores and pathogens, including the jasmonic acid signaling pathway. In this Perspective, we discuss recent advances on the studies of the mechanisms that link photoreceptors with growth and defense. Understanding these mechanisms is important to provide a functional platform for breeding programs aimed at improving plant productivity, stress tolerance, and crop health in species of agronomic interest, and to manipulate the light environments in protected agriculture. Plants can detect and respond to nearby competitors though light signals that they perceive with photoreceptor proteins. We review the signaling networks that allow plants to modify the strength of their shade-avoidance responses and modulate their defense systems against herbivores and pathogens. [ABSTRACT FROM AUTHOR]

Several oligosaccharide fragments derived from plant cell walls activate plant immunity and behave as typical damage-associated molecular patterns (DAMPs). Some of them also behave as negative regulators of growth and development, and due to their antithetic effect on immunity and growth, their concentrations, activity, time of formation, and localization is critical for the so-called "growth-defense trade-off." Moreover, like in animals, over accumulation of DAMPs in plants provokes deleterious physiological effects and may cause hyper-immunity if the cellular mechanisms controlling their homeostasis fail. Recently, a mechanism has been discovered that controls the activity of two well-known plant DAMPs, oligogalacturonides (OGs), released upon hydrolysis of homogalacturonan (HG), and cellodextrins (CDs), products of cellulose breakdown. The potential homeostatic mechanism involves specific oxidases belonging to the family of berberine bridge enzyme-like (BBE-like) proteins. Oxidation of OGs and CDs not only inactivates their DAMP activity, but also makes them a significantly less desirable food source for microbial pathogens. The evidence that oxidation and inactivation of OGs and CDs may be a general strategy of plants for controlling the homeostasis of DAMPs is discussed. The possibility exists of discovering additional oxidative and/or inactivating enzymes targeting other DAMP molecules both in the plant and in animal kingdoms. [ABSTRACT FROM AUTHOR]

Aboveground fungal pathogens can substantially reduce biomass production in grasslands. However, we lack a mechanistic understanding of the drivers of fungal pathogen infection and impact. Using a grassland global change and biodiversity experiment we show that the trade‐off between plant growth and defense is the main determinant of infection incidence. In contrast, nitrogen addition only indirectly increased incidence via shifting plant communities towards faster growing species. Plant diversity did not decrease incidence, likely because spillover of generalist pathogens or dominance of susceptible plants counteracted negative diversity effects. A fungicide treatment increased plant biomass production and high levels of infection incidence were associated with reduced biomass. However, pathogen impact was context dependent and infection incidence reduced biomass more strongly in diverse communities. Our results show that a growth‐defense trade‐off is the key driver of pathogen incidence, but pathogen impact is determined by several mechanisms and may depend on pathogen community composition. [ABSTRACT FROM AUTHOR]

Plants have developed an array of mechanisms to protect themselves against pathogen invasion. The deployment of defense mechanisms is imperative for plant survival, but can come at the expense of plant growth, leading to the 'growth-defense trade-off' phenomenon. Following pathogen exposure, plants can develop resistance to further attack. This is known as induced resistance, or priming. Here, we investigated the growth-defense trade-off, examining how defense priming via systemic acquired resistance (SAR), or induced systemic resistance (ISR), affects tomato development and growth. We found that defense priming can promote, rather than inhibit, plant development, and that defense priming and growth trade-offs can be uncoupled. Cytokinin response was activated during induced resistance, and found to be required for the observed growth and disease resistance resulting from ISR activation. ISR was found to have a stronger effect than SAR on plant development. Our results suggest that growth promotion and induced resistance can be co-dependent, and that, in certain cases, defense priming can drive developmental processes and promote plant yield., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

The growth–defense trade-off in plant biology has gained enormous traction in the last two decades, highlighting the importance of understanding how plants deal with two of the greatest challenges for their survival and reproduction. It has been well established that in response to competition signals perceived by informational photoreceptors, shade-intolerant plants typically activate the shade-avoidance syndrome (SAS). In turn, in response to signals of biotic attack, plants activate a suite of defense responses, many of which are directed to minimize the loss of plant tissue to the attacking agent (broadly defined, the defense syndrome, DS). We argue that components of the SAS, including increased elongation, apical dominance, reduced leaf mass per area (LMA), and allocation to roots, are in direct conflict with configurational changes that plants require to maximize defense. We hypothesize that these configurational trade-offs provide a functional explanation for the suppression of components of the DS in response to competition cues. Based on this premise, we discuss recent advances in the understanding of the mechanisms by which informational photoreceptors, by interacting with jasmonic acid (JA) signaling, help the plant to make intelligent allocation and developmental decisions that optimize its configuration in complex biotic contexts. [ABSTRACT FROM AUTHOR]

Insect herbivores possess a diverse and abundant gut microbiota that may influence plant growth in nature. The application of plant beneficial bacteria to improve agricultural production and soil quality has long been of interest. Thus, these insect-associated microbiota have the potential to be developed into effective bio-fertilizers. The bacterium, Enterobacter ludwigii, was isolated from the regurgitant of field-collected tomato fruitworm, Helicoverpa zea. The bacterium can be secreted by the insect onto tomato seeds during fruit feeding and is also commonly found in the soil. We applied E. ludwigii to germinated tomato seeds and measured tomato plant growth and productivity under controlled greenhouse conditions. Since there are often trade-offs between plant growth and plant defenses, we examined whether the E. ludwigii-mediated faster growth corresponds with weaker anti-herbivore defenses. When E. ludwigii was applied to germinated tomato seeds, the plants exhibited faster root, shoot and hypocotyl growth, and produced more fruits and seeds than untreated control plants. The plants treated with bacteria exhibited the same activity levels of two key enzymes involved in anti-herbivore defenses, polyphenol oxidase and peroxidase, and induced the same levels of mortality and growth inhibition in H. zea larvae as untreated plants. Thus, our results demonstrate that the application of E. ludwigii to seeds can promote tomato plant growth and yield without compromising anti-herbivore defenses. [ABSTRACT FROM AUTHOR]

Plant immune responses mediated by the hormone jasmonoyl-Lisoleucine (JA-Ile) are metabolically costly and often linked to reduced growth. Although it is known that JA-Ile activates defense responses by triggering the degradation of JASMONATE ZIM DOMAIN (JAZ) transcriptional repressor proteins, expansion of the JAZ gene family in vascular plants has hampered efforts to understand how this hormone impacts growth and other physiological tasks over the course of ontogeny. Here, we combined mutations within the 13-member Arabidopsis JAZ gene family to investigate the effects of chronic JAZ deficiency on growth, defense, and reproductive output. A higher-order mutant (jaz decuple, jazD) defective in 10 JAZ genes (JAZ1-7, -9, -10, and -13) exhibited robust resistance to insect herbivores and fungal pathogens, which was accompanied by slow vegetative growth and poor reproductive performance. Metabolic phenotypes of jazD discerned from global transcript and protein profiling were indicative of elevated carbon partitioning to amino acid-, protein-, and endoplasmic reticulum body-based defenses controlled by the JA-Ile and ethylene branches of immunity. Resource allocation to a strong defense sink in jazD leaves was associated with increased respiration and hallmarks of carbon starvation but no overt changes in photosynthetic rate. Depletion of the remaining JAZ repressors in jazD further exaggerated growth stunting, nearly abolished seed production and, under extreme conditions, caused spreading necrotic lesions and tissue death. Our results demonstrate that JAZ proteins promote growth and reproductive success at least in part by preventing catastrophic metabolic effects of an unrestrained immune response. [ABSTRACT FROM AUTHOR]

Trade-offs between plant growth and defense depend on environmental resource availability. Plants are predicted to prioritize growth when environmental resources are abundant and defense when environmental resources are scarce. Nevertheless, such predictions lack a whole-plant perspective—they do not account for potential differences in plant allocation above- and belowground. Such accounting is important because leaves and roots, though both critical to plant survival and fitness, differ in their resource-uptake roles and, often, in their vulnerability to herbivores. Here we aimed to determine how water availability affects plant allocation to multiple metabolic components of growth and defense in both leaves and roots. To do this, we conducted a meta-analysis of data from experimental studies in the literature. We assessed plant metabolic responses to experimentally reduced water availability, including changes in growth, nutrients, physical defenses, primary metabolites, hormones, and other secondary metabolites. Both above- and belowground, reduced water availability reduced plant biomass but increased the concentrations of primary metabolites and hormones. Importantly, however, reduced water had opposite effects in different organs on the concentrations of other secondary metabolites: reduced water increased carbon-based secondary metabolites in leaves but reduced them in roots. In addition, plants suffering from co-occurring drought and herbivory stresses exhibited dampened metabolic responses, suggesting a metabolic cost of multiple stresses. Our study highlights the needs for additional empirical studies of whole-plant metabolic responses under multiple stresses and for refinement of existing plant growth-defense theory in the context of whole plants.

Trade-offs between plant growth and defense depend on environmental resource availability. Plants are predicted to prioritize growth when environmental resources are abundant and defense when environmental resources are scarce. Nevertheless, such predictions lack a whole-plant perspective—they do not account for potential differences in plant allocation above- and belowground. Such accounting is important because leaves and roots, though both critical to plant survival and fitness, differ in their resource-uptake roles and, often, in their vulnerability to herbivores. Here we aimed to determine how water availability affects plant allocation to multiple metabolic components of growth and defense in both leaves and roots. To do this, we conducted a meta-analysis of data from experimental studies in the literature. We assessed plant metabolic responses to experimentally reduced water availability, including changes in growth, nutrients, physical defenses, primary metabolites, hormones, and other secondary metabolites. Both above- and belowground, reduced water availability reduced plant biomass but increased the concentrations of primary metabolites and hormones. Importantly, however, reduced water had opposite effects in different organs on the concentrations of other secondary metabolites: reduced water increased carbon-based secondary metabolites in leaves but reduced them in roots. In addition, plants suffering from co-occurring drought and herbivory stresses exhibited dampened metabolic responses, suggesting a metabolic cost of multiple stresses. Our study highlights the needs for additional empirical studies of whole-plant metabolic responses under multiple stresses and for refinement of existing plant growth-defense theory in the context of whole plants. [ABSTRACT FROM AUTHOR]

Below ground, microbe-associated molecular patterns ( MAMPs) of root-associated microbiota can trigger costly defenses at the expense of plant growth. However, beneficial rhizobacteria, such as Pseudomonas simiae WCS417, promote plant growth and induce systemic resistance without being warded off by local root immune responses. To investigate early root responses that facilitate WCS417 to exert its plant-beneficial functions, we performed time series RNA-Seq of Arabidopsis roots in response to live WCS417 and compared it with MAMPs flg22417 (from WCS417), flg22Pa (from pathogenic Pseudomonas aeruginosa) and fungal chitin. The MAMP transcriptional responses differed in timing, but displayed a large overlap in gene identity. MAMP-upregulated genes are enriched for genes with functions in immunity, while downregulated genes are enriched for genes related to growth and development. Although 74% of the transcriptional changes inflicted by live WCS417 overlapped with the flg22417 profile, WCS417 actively suppressed more than half of the MAMP-triggered transcriptional responses, possibly to allow the establishment of a mutually beneficial interaction with the host root. Interestingly, the sector of the flg22417-repressed transcriptional network that is not affected by WCS417 has a strong auxin signature. Using auxin response mutant tir1afb2afb3, we demonstrate a dual role for auxin signaling in finely balancing growth-promoting and defense-eliciting activities of beneficial microbes in plant roots. [ABSTRACT FROM AUTHOR]

Key message: Two artificially debarked Afrotemperate tree species showed different trade-offs between wound closure and compartmentalisation of decay in the stem. One species had a relaxed trade-off but inefficient defence, and the other showed more efficient defence but a substantial trade-off. Abstract: Bark stripping for medicinal use is a common cause of damage in several indigenous tree species in natural forests of South Africa. Ocotea bullata and Curtisia dentata are in high demand for their bark for medicinal purposes. The study aimed at revealing intra-specific and inter-specific differences of tree growth rates wound closure and decay containment responses ten years after experimental bark harvesting. The results obtained on computer tomography scans of twenty trees showed that C. dentata had significantly higher decay percentages compared to O. bullata, indicating that O. bullata was able to more efficiently contain decay than C. dentata. While decay in O. bullata was confined at the wounded tissues, decay in the C. dentata extended below and above the wounded area. Intra-specifically, O. bullata showed strong positive correlations between tree growth rates and wound closure rates, and wound closure rates with relative volume of decayed wood, indicating that individuals with higher rates of growth and wound closure suffered higher percentages of decay. Results confirmed an intra-specific trade-off between growth rate and defense investment, with fast growing trees showing high percentage decay (poor compartmentalization of decay). Inter-specifically, however, growth versus defense trade-off did not present itself. For C. dentata, no correlations were found between rates of wound closure and percentage decay. The findings and conclusions derived from this study reveal complex, species-specific responses to damage. This study highlights the need to gain an in-depth understanding of underlying morphological, phylogenic, physiological characteristics of species to further explain the observed species differences. [ABSTRACT FROM AUTHOR]

Summary Temperature is a key seasonal signal that shapes plant growth. Elevated ambient temperature accelerates growth and developmental transitions [ 1 ] while compromising plant defenses, leading to increased susceptibility [ 2, 3 ]. Suppression of immunity at elevated temperature is at the interface of trade-off between growth and defense [ 2, 4 ]. Climate change and the increase in average growth-season temperatures threaten biodiversity and food security [ 5, 6 ]. Despite its significance, the molecular mechanisms that link thermosensory growth and defense responses are not known. Here we show that PHYTOCHROME INTERACTING FACTOR 4 (PIF4)-mediated thermosensory growth and architecture adaptations are directly linked to suppression of immunity at elevated temperature. PIF4 positively regulates growth and development and negatively regulates immunity. We also show that natural variation of PIF4-mediated temperature response underlies variation in the balance between growth and defense among Arabidopsis natural strains. Importantly, we find that modulation of PIF4 function alters temperature sensitivity of defense. Perturbation of PIF4-mediated growth has resulted in temperature-resilient disease resistance. This study reveals a molecular link between thermosensory growth and immunity in plants. Elucidation of the molecular mechanisms that define environmental signal integration is key to the development of novel strategies for breeding temperature-resilient disease resistance in crops. [ABSTRACT FROM AUTHOR]

Trade-offs between plant growth and defense are central to theoretical frameworks used to study the ecology and evolution of plant defense against herbivores. However, these frameworks, as well as the experiments designed to test them, rarely include belowground herbivores. We experimentally challenged seedlings of the tropical shrub Solanum lycocarpum (Solanaceae) with either aboveground foliar herbivores ( Spodoptera caterpillars) or belowground root herbivores (the nematode Meloidogyne incognita) and measured the resulting changes in plant growth rates, biomass allocation, and the concentration of defensive terpenoids in roots and leaves. We found that plants that suffered aboveground herbivory responded with aboveground growth but belowground defense. Similarly, belowground herbivory resulted in root growth but elevated defenses of leaves. These results underscore the importance of belowground plant-herbivore interactions, and suggest that, in contrast to theoretical predictions, plants can simultaneously invest in both growth and defense. Finally, they emphasize the need for a 'whole-plant' perspective in theoretical and empirical evaluations of plant-herbivore interactions. [ABSTRACT FROM AUTHOR]

Plants have evolved elaborate surveillance systems that allow them to perceive the attack by pests and pathogens and activate the appropriate defenses. Mechanical stimulation, such as mechanical wounding, represents one of the most reliable cues for the perception of potential herbivore aggressors. Here we demonstrate that mechanical wounding disturbs the growth versus defense balance in tomato, a physiological condition where growth reduction arises as a pleiotropic consequence of the activation of defense responses (or vice-versa). We observed that multiple lesions on tomato leaves impairs the formation of several growth-related traits, including shoot elongation, leaf expansion and time for flowering, while concomitantly activating the production of defense responses such as trichome formation and the upregulation of defense-related genes. We also provide genetic evidence that this wound-induced growth repression is possibly a consequence of tomato plants sensing the injuries via jasmonates (JAs), a class of plant hormones known to be master regulators of the plant growth versus defense balance. Besides providing a mechanistic explanation on how the growth and defense balance is shifted when plants are subjected to a specific type of mechanical stimulus, our results may offer a practical explanation for why tomato productivity is so negatively impacted by herbivore attack. • Growth versus defense antagonism is affected by mechanical wounding in tomato. • Mechanical wounding hinders tomato growth and flowering. • Growth responses to lesions are dependent on the jasmonate signaling pathway. • Mechanical wounding induces the formation of defense traits in tomato. [ABSTRACT FROM AUTHOR]

Herbivores are important drivers of plant species coexistence and community assembly. However, detailed mechanistic information on how herbivores affect dominance hierarchies between plant species is scarce. Here, we used data of a multi-site herbivore exclusion experiment in grasslands to assess changes in the cover of 28 plant species in response to aboveground pesticide application. Moreover, we assessed species-specific values of plant defense of these 28 species measured as the performance of a generalist caterpillar, and the preference of the caterpillar and a slug species in no-choice and choice feeding experiments, respectively. We show that more preferred species in the feeding experiments were those that increased in cover after herbivore exclusion in the field, whereas less preferred ones decreased. Herbivore performance and several measured leaf traits were not related to the change in plant cover in the field in response to herbivore removal. Additionally, the generalist slug and the generalist caterpillar preferred and disliked the same plant species, indicating that they perceive the balance between defense and nutritional value similarly. We conclude that the growth-defense trade-off in grassland species acts via the preference of herbivores and that among-species variation in plant growth and preference to herbivores drives plant community composition. [ABSTRACT FROM AUTHOR]

Interactions between herbivore pressure and resource availability may result in growth-defense trade-offs in plants (resource availability hypothesis), which promote the potential for ecological diversification and have recently been proposed as a new mechanism of plant invasion (resource-enemy release hypothesis). In the present study, we tested this idea by comparing patterns of maximum growth rate and antiherbivore defense capacity against Agasicles hygrophila (a specialist phytophagous insect on Alternanthera philoxeroides) among six morphs of A. philoxeroides from both native (Argentina) and introduced (US and China) ranges. The results revealed that herbivore resistance consistently exhibited a significant trade-off against the growth rate of A. philoxeroides. Compared with native morphs in Argentina, introduced morphs generally exhibited a higher growth rate and lower defense. The results demonstrate that the combination of flea beetle pressure and resource availability facilitates geographical divergence of A. philoxeroides, and that release from natural specialists and increased resource availability may interact to contribute to its successful invasion. [ABSTRACT FROM AUTHOR]

The evolution of increased competitive ability (EICA) hypothesis proposes that invasive species evolve decreased defense and increased competitive ability following natural enemy release. Previous studies have found evidence both for and against EICA. The resource-enemy release hypothesis (R-ERH) suggests that fast-growing species may experience stronger enemy release than slow-growing species. On the basis of R-ERH, the prediction of EICA will be held true for slow-growing genotypes, i.e., the slow-growing genotypes from the introduced range will be less resistant to herbivory and grow faster than those from the home range; while the EICA will not be held for fast-growing genotypes, i.e., there will be no significant differences in growth and defense traits between the introduced and native fast-growing genotypes. We tested these predictions preliminarily using five populations of the invasive plant Alternanthera philoxeroides. This species has two varieties in its home range, which showed a distinct growth-defense strategy: the northern A. p. var. acutifolia (Apa) had higher growth rate but lower resistance, while the southern A. p. var. obtusifolia (Apo) had lower growth rate but higher resistance level. Our results suggest that the EICA hypothesis is consistent with the slow-growing Apo, but not with the fast-growing Apa. We suggest that evolutionary changes in growth or resistance following enemy release are influenced by variation in growth rate within an invasive alien plant. These findings have important implications for the EICA hypothesis, and may partially explain why previous studies have found evidence both for and against EICA. [ABSTRACT FROM AUTHOR]

Abstract: Most models to account for variation in defensive chemical production in plants assume that defensive chemical production is a quantitative trait determined by the additive effects of many genes, and that defensive chemical production is genetically negatively correlated with fitness. The inheritance of quantities of geranylflavanones and seed production, an estimate of female fitness, was studied in reciprocal crosses between several chemically distinct populations of Mimulus aurantiacus to test those assumptions. Genetic analyses using reciprocal crosses were used to test for maternal or paternal genetic effects. The quantities of individual geranylflavanones of the hybrids generally were inherited with dominance or over-dominance. Reciprocal genetic effects were rarely found. Within populations, leaf resin production in M. aurantiacus was independent of seed production. Results are consistent with previous reports suggesting that any evolutionary change in geranylflavanone production within populations may be constrained by low levels of genetic variation in geranylflavanone production. [Copyright &y& Elsevier]

Plants encounter a broad range of natural enemies and defend themselves in diverse ways. The cost of defense can be reduced if a plant secondary metabolite confers resistance to multiple herbivores. However, there are few examples of positively correlated defenses in plants against herbivores of different types. We present evidence that a genetically variable chemical trait that acts as a strong antifeedant to mammalian herbivores of Eucalyptus also deters insect herbivores, suggesting a possible mechanism for cross-resistance. We provide field confirmation that sideroxylonal, an important antifeedant for mammalian herbivores, also determines patterns of damage by Christmas beetles, a specialist insect herbivore of Eucalyptus. In a genetic progeny trial of Eucalyptus tricarpa, we found significant heritabilities of sideroxylonal concentration (0.60), overall insect damage (0.34), and growth traits (0.30–0.53). Population of origin also had a strong effect on each trait. Negative phenotypic correlations were observed between sideroxylonal and damage, and between damage and growth. No relationship was observed between sideroxylonal concentration and any growth trait. Our results suggest that potential for evolution by natural selection of sideroxylonal concentrations is not strongly constrained by growth costs and that both growth and defense traits can be successfully incorporated into breeding programs for plantation trees. [ABSTRACT FROM AUTHOR]

Tropical forests include a diversity of habitats, which has led to specialization in plants. Near Iquitos, in the Peruvian Amazon, nutrient-rich clay forests surround nutrient-poor white-sand forests, each harboring a unique composition of habitat specialist trees. We tested the hypothesis that the combination of impoverished soils and herbivory creates strong natural selection for plant defenses in white-sand forest, while rapid growth is favored in clay forests. Recently, we reported evidence from a reciprocal-transplant experiment that manipulated the presence of herbivores and involved 20 species from six genera, including phylogenetically independent pairs of closely related white-sand and clay specialists. When protected from herbivores, clay specialists exhibited faster growth rates than white-sand specialists in both habitats. But, when unprotected, white-sand specialists outperformed clay specialists in white-sand habitat, and clay specialists outperformed white-sand specialists in clay habitat. Here we test further the hypothesis that the growth-defense trade-off contributes to habitat specialization by comparing patterns of growth, herbivory, and defensive traits in these same six genera of white-sand and clay specialists. While the probability of herbivore attack did not differ between the two habitats, an artificial defoliation experiment showed that the impact of herbivory on plant mortality was significantly greater in white-sand forests. We quantified the amount of terpenes, phenolics, leaf toughness, and available foliar protein for the plants in the experiment. Different genera invested in different defensive strategies, and we found strong evidence for phylogenetic constraint in defense type. Overall, however, we found significantly higher total defense investment for white-sand specialists, relative to their clay specialist congeners. Furthermore, herbivore resistance consistently exhibited a significant trade-off against growth rate in each of the six phylogenetically independent species-pairs. These results confirm theoretical predictions that a trade-off exists between growth rate and defense investment, causing white-sand and clay specialists to evolve divergent strategies. We propose that the growth-defense trade-off is universal and provides an important mechanism by which herbivores govern plant distribution patterns across resource gradients. [ABSTRACT FROM AUTHOR]

• P. indica influences the growth and immunity of passion fruit plants throughout the plant life. • However/In comparison, P.indica promotes the growth of passion fruit seedlings in the late growth period. • SA accumulation and SA-related defensive responses are higher in colonized plants. • More flavonoids or flavonoid contents were determined in colonized passion fruit peels compared to the control peels. • Metabolite profile analysis shows that P. indica can improve the fruit quality. Passion fruit (Passiflora edulis) has an important economic value as exotic ingredient in juice blends. We inoculated the passion fruit cultivar Passiflora edulis Sims f. edulis 's roots with the beneficial root-colonizing fungus Piriformospora indica under greenhouse conditions. The experiments were performed at three different locations and times (between 2017 and 2019). After transient initial growth retardation associated with a mild salicylic-acid (SA)-dependent defense activation and reduced sucrose metabolism, plant performance and growth are promoted during later stages. The elevated SA level in the aerial parts stimulates the plant immune system and promotes pathogen resistance in the adult plants and the fruit peels. P. indica stimulates the fruit size and fruit quality, and the higher amounts of defense-related secondary metabolites in the peels restrict growth of herbivorous insect larvae fed with peel extracts. We conclude that application of P. indica to passion fruits stimulates the plants' immune system and improves the fruits' quality. [ABSTRACT FROM AUTHOR]

The indole-3-pyruvic acid pathway is the main route for auxin biosynthesis in higher plants. Tryptophan aminotransferases (TAA1/TAR) and members of the YUCCA family of flavin-containing monooxygenases catalyze the conversion of l-tryptophan via indole-3-pyruvic acid to indole-3-acetic acid (IAA). It has been described that jasmonic acid (JA) locally produced in response to mechanical wounding triggers the de novo formation of IAA through the induction of two YUCCA genes, YUC8 and YUC9. Here, we report the direct involvement of a small number of basic helix-loop-helix transcription factors of the MYC family in this process. We show that the JA-mediated regulation of the expression of the YUC8 and YUC9 genes depends on the abundance of MYC2, MYC3, and MYC4. In support of this observation, seedlings of myc knockout mutants displayed a strongly reduced response to JA-mediated IAA formation. Furthermore, transactivation assays provided experimental evidence for the binding of MYC transcription factors to a particular tandem G-box motif abundant in the promoter regions of YUC8 and YUC9, but not in the promoters of the other YUCCA isogenes. Moreover, we demonstrate that plants that constitutively overexpress YUC8 and YUC9 show less damage after spider mite infestation, thereby underlining the role of auxin in plant responses to biotic stress signals. [ABSTRACT FROM AUTHOR]

• Maritime pine populations differed in their potential to produce resin. • Populations from harsher environments produced more resin. • Resin flow was positively related with tree growth at the phenotypic level, but. • Resin flow and growth were negatively correlated at the population level. • Resin flow increased with preceding high temperatures and water deficit. Pine trees produce large amounts of oleoresin to defend against biotic threats. Resin is highly costly to produce and investment in its production must be accurately optimized in relation to allocation to other life functions such growth. As a result of these costs, resin production is highly variable both genetically (among and within species) and plastically (across temporal and spatial environmental heterogeneity). The relative contribution of these sources of variation is, however, far from being completely understood. Besides being a main defensive mechanism, pine resin is also a valuable non-timber forest product that is regaining attention as a renewable resource for different industrial sectors. Improving our knowledge on the main drivers of resin production is vital to fine-tune resin-tapping management, especially in regions with little tradition in resin-tapping such are the Atlantic areas of the Iberian Peninsula. Here, we assessed resin flow and growth in a network of seven Maritime pine (Pinus pinaster) provenance tests established in North West Spain to explore the within species variation in resin flow, the plasticity of resin flow across sites and across the season and the (phenotypic and genotypic) relationships between resin flow and tree growth. Resin flow was assessed in three contrasting Maritime pine populations at three times within the season using a micro-tapping procedure that predicts well the resin yield potential for exploitation purposes. Results supported the theoretical predictions as resin flow significantly varied among populations, with populations from more favorable environmental conditions producing less resin than those from harsher conditions. Resin flow was positively correlated with tree size at the phenotypic level. However, the genetically-based relationship between growth potential and resin flow was markedly negative. Fast growing populations produced less resin than slow growing origins. Resin flow was also highly plastic across sites and across seasons, with resin flow consistently increasing towards the end of the growing season. Temperature and water deficit immediately before sampling emerged as main drivers of the observed variation in resin flow across sites and seasons. Results are valuable to understand the extremely large variation in defensive investment on resin-based defenses in conifer species, to model the potential of Atlantic Maritime pine forest for resin tapping, and to fine-tune the resin-tapping management of these forests. [ABSTRACT FROM AUTHOR]

Plant immune responses mediated by the hormone jasmonoyl-l-isoleucine (JA-Ile) are metabolically costly and often linked to reduced growth. Although it is known that JA-Ile activates defense responses by triggering the degradation of JASMONATE ZIM DOMAIN (JAZ) transcriptional repressor proteins, expansion of the JAZ gene family in vascular plants has hampered efforts to understand how this hormone impacts growth and other physiological tasks over the course of ontogeny. Here, we combined mutations within the 13-member Arabidopsis JAZ gene family to investigate the effects of chronic JAZ deficiency on growth, defense, and reproductive output. A higher-order mutant ( jaz decuple, jazD ) defective in 10 JAZ genes ( JAZ1 - 7 , -9 , -10 , and -13 ) exhibited robust resistance to insect herbivores and fungal pathogens, which was accompanied by slow vegetative growth and poor reproductive performance. Metabolic phenotypes of jazD discerned from global transcript and protein profiling were indicative of elevated carbon partitioning to amino acid-, protein-, and endoplasmic reticulum body-based defenses controlled by the JA-Ile and ethylene branches of immunity. Resource allocation to a strong defense sink in jazD leaves was associated with increased respiration and hallmarks of carbon starvation but no overt changes in photosynthetic rate. Depletion of the remaining JAZ repressors in jazD further exaggerated growth stunting, nearly abolished seed production and, under extreme conditions, caused spreading necrotic lesions and tissue death. Our results demonstrate that JAZ proteins promote growth and reproductive success at least in part by preventing catastrophic metabolic effects of an unrestrained immune response., Competing Interests: The authors declare no conflict of interest., (Copyright © 2018 the Author(s). Published by PNAS.)

Ribulose-1,5-bisphosphate carboxylase/ oxygenase (RuBisCO) is the most abundant protein on the planet and in addition to its central role in photosynthesis it is thought to function as a nitrogen (N)-storage protein and a potential source of N for defense biosynthesis in plants. In a recent study in the wild tobacco Nicotiana attenuata, we showed that the decrease in absolute N invested in soluble proteins and RuBisCO elicited by simulated herbivory was much larger than the N-requirements of nicotine and phenolamide biosynthesis; (15)N flux studies revealed that N for defensive phenolamide synthesis originates from recently assimilated N rather than from RuBisCO turnover. Here we show that a transgenic line of N. attenuata silenced in the expression of RuBisCO (asRUB) invests similar or even larger amounts of N into phenolamide biosynthesis compared with wild type plants, consistent with our previous conclusion that recently assimilated N is channeled into phenolamide synthesis after elicitation. We suggest that the decrease in leaf proteins after simulated herbivory is a tolerance mechanism, rather than a consequence of N-demand for defense biosynthesis.