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Cotton aphids (Aphis gossypii Glover) cause harm by feeding on phloem sap and spreading plant viruses to lily. Understanding the mechanisms by which aphids infest lily plants is crucial for effective aphid management and control. In this study, we investigated the activity of antioxidants, integrated nontargeted metabolomes and transcriptomes of lilies infested by cotton aphids to explore the changes in lily leaves. Overall, the results indicated that the catalase (CAT) activity in the leaves of the lily plants was greater than that in the leaves of the control plants. A comprehensive identification of 604 substances was conducted in the leaves. Furthermore, the differentially abundant metabolite analysis revealed the enrichment of phenylalanine metabolism and α-linolenic acid metabolism. Moreover, 3574 differentially expressed genes (DEGs), whose expression tended to increase, were linked to glutathione metabolism and phenylpropanoid biosynthesis. In addition, the integrated analysis revealed that the defensive response of lily leaves to aphids is manifested through antioxidant reactions, phenylpropane and flavonoid biosynthesis, and α-linolenic acid metabolism. Finally, the key metabolites were CAT, glutathione, coumaric acid, and jasmonic acid, along with the key genes chalcone synthase (CHS), phenylalanine ammonia-lyase (PAL), and 12-oxo-phytodienoic acid reductase (OPR). Accordingly, the findings of this research elucidate the molecular and metabolic reactions of A. gossypii in lily plants, offering valuable insights for developing aphid resistance strategies in lily farming. [ABSTRACT FROM AUTHOR]

The transmission of resistance traits to herbivores across subsequent generations is an important strategy employed by plants to enhance their fitness in environments with high herbivore pressure. However, our understanding of the impact of maternal herbivory on direct and indirect induced chemical defenses of progeny, as well as the associated costs, is currently limited to herbivory by leaf-chewing insects. In this study, we investigated the transgenerational effects of a sap-feeding insect, the green peach aphid Myzus persicae, on direct and indirect chemical defenses of bell pepper plants (Capsicum annuum), and whether the effects entail costs to plant growth. Aphid herbivory on parental plants led to a reduced number of seeds per fruit, which exhibited lower germination rates and produced smaller seedlings compared to those from non-infested parental plants. In contrast, the progeny of aphid-infested plants were less preferred as hosts by aphids and less suitable than the progeny of non-infested plants. This enhanced resistance in the progeny of aphid-infested plants coincided with elevated levels of both constitutive and herbivore-induced total phenolic compounds, compared to the progeny of non-infested plants. Furthermore, the progeny of aphid-infested plants emitted herbivore-induced plant volatiles (HIPVs) that were more attractive to the aphid parasitoid Aphidius platensis than those emitted by the progeny of non-infested plants. Our results indicate that herbivory by sap-feeding insect induces transgenerational resistance on progeny bell pepper plants, albeit at the expense of vegetative growth. [ABSTRACT FROM AUTHOR]

Plants have evolved inducible defenses that allow them to minimize costs associated with the production of constitutive defenses when herbivores are not present. However, as a consequence, some plants might experience a period of vulnerability between damage and the onset of defense and/or between the cessation of damage and relaxation of defense. Few studies have examined the time course in the inducible protective mutualism between ants and extrafloral nectary (EFN)‐bearing plants. None has compared the inducibility of EFNs on vegetative versus reproductive parts or in response to different levels of herbivore damage. Here, we disentangle the inducibility process by evaluating extrafloral nectar production and ant attendance over time, the time course of inducibility on different plant parts, and the time course of inducibility in response to different levels of foliar damage in a Brazilian tree, Qualea multiflora (Vochysiaceae). Using simulated herbivory on leaves and flowers, we found that (a) the production of extrafloral nectar from foliar and floral EFNs, as well as ant attendance, exhibited a lag between the moment of damage and the peak of response, followed by a response peak (usually 24 h after damage) at which the defense remains at its maximum level, then declines to prestimulus levels; (b) the time course of inducibility and the peak activity did not differ between EFNs located in vegetative versus reproductive parts, except for sugar concentration, which was higher in EFNs on vegetative parts; and (c) the time course of inducibility of foliar EFNs depended on damage level. Although considered a cost‐saving strategy, inducible defenses can be disadvantageous since they can leave plants vulnerable to attack for extended periods. Our results illuminate the dynamics of the induced response and the underlying mechanisms that might mediate it, ultimately providing new insights into defense strategies employed by plants. [ABSTRACT FROM AUTHOR]

Cortical reactivation and regain of interareal functional connections have been linked to the recovery of hand grasping behavior after loss of sensory inputs in primates. We investigated contributions of neurons in two hierarchically organized somatosensory areas, 3b and S2, by characterizing local field potential (LFP) and multiunit spiking activity in five states (rest, stimulus-on, sustained, stimulus-off, and induced) and interareal communication after grasping behavior of dorsal column lesioned male squirrel monkeys had mostly recovered. Compared with normal cortex, fMRI, LFP, and spiking response magnitudes to step indentations were significantly weaker. The sustained component of the spiking recovered much better than the stimulus-off response. Correlation between overall spiking and γ LFP remained strong within each recovered areas 3b and S2. The interareal correlations of γ LFP were severely disrupted, except in the resting and stimulus-on periods. Interareal correlation of spiking was disrupted in the stimulus-off period only. In summary, submodality of low threshold mechanoreceptive neurons recovered differentially in input-deprived area 3b and S2 when impaired global hand grasping behavior returned. Slow-adapting-like neurons recovered, whereas rapid-adapting-like neurons did not. Interareal communications were also severely compromised. We propose that slow-adapting-like neurons and afferents in recovered area 3b and S2 mediate recovery of impaired grasping behavior after dorsal column tract lesion. [ABSTRACT FROM AUTHOR]

Many plants are extremely plastic in their vegetative and life-history traits, allowing them to deal with a variety of environmental conditions during their lifetime. However, in our understanding of plant reproduction, plasticity in mating system is not broadly considered. Even though mating system shifts are well studied on an evolutionary timescale, we show that many traits affecting plant mating system also show plasticity within an ecological timeframe. This plasticity in reproduction can be found in prepollination, in interactions with pollinators, and in various postpollination processes. We bring together molecular and ecological work on plant reproduction and guide future research on mating systems to embrace trait plasticity and context dependency of mating strategies., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

When plants receive volatiles from a damaged plant, the receivers become more resistant to herbivory. This phenomenon has been reported in many plant species and called plant-plant communication. Lab experiments have suggested that several compounds may be functioning as airborne signals. The objective of this study is to identify potential airborne signals used in communication between sagebrush (Artemisia tridentata) individuals in the field. We collected volatiles of one branch from each of 99 sagebrush individual plants. Eighteen different volatiles were detected by GC-MS analysis. Among these, 4 compounds; 1.8-cineol, β-caryophyllene, α-pinene and borneol, were investigated as signals of communication under natural conditions. The branches which received either 1,8-cineol or β-caryophyllene tended to get less damage than controls. These results suggested that 1,8-cineol and β-caryophyllene should be considered further as possible candidates for generalized airborne signals in sagebrush.

Key message: Corymbia citriodora subsp. variegata altered the expression of secondary metabolites in response to Paropsis atomaria larval feeding and mechanical wounding but did not alter leaf toughness and leaf trichomes. Plants have evolved strategies against herbivore pressure, relying on constitutive or induced traits that create physical and chemical barriers, which may influence herbivore performance. We evaluated the physical and chemical responses of Corymbia citriodora subsp. variegata, an important hardwood plantation taxon, to feedings by Paropsis atomaria larvae, a pest that causes severe defoliation in young trees. This was undertaken to obtain insights into plant–herbivore interactions, aiming to identify parameters that may improve plant fitness and/or protection that may benefit pest management in forestry plantations. Seedlings of C. citriodora subsp. variegata were submitted to the following treatments: no damage, mechanical wounding, and P. atomaria larval feeding damage. Foliar samples were collected during and after treatment at day 15 and 22, respectively, from damaged and undamaged leaves to detect: local, systemic, or delayed induced responses. Leaf samples were analysed to determine whether there were induced physical (leaf toughness, trichome density) or chemical (secondary metabolite profiles) responses to damage. No physical response in any of the treatments was evident in C. citriodora subsp. variegata foliage at day 15 or 22. Systemic chemical responses were observed for the larval feeding and mechanical treatments, with, a delayed response evident in the larval feeding treatment only. The proportion of long chain hydrocarbons were reduced in these treatments relative to the control, whereas the proportion of monounsaturated hydrocarbons and monoterpenes increased. When analysed across treatments, larval mortality was negatively correlated with long chain hydrocarbons and positively correlated with monounsaturated hydrocarbons. These findings suggest that CCV systemic chemical responses induced by both larval feeding and mechanical damage but only larval feeding induced delayed response, suggesting that CCV responses to herbivory may be associated with plant defence strategies. [ABSTRACT FROM AUTHOR]

Constitutive and inducible terpene production is involved in conifer resistance against insects and fungal infestations. To gain knowledge about local defence responses of Norway spruce bark against pathogens and to find potential chemical markers for resistance breeding, we inoculated the stem of 8‐year‐old Norway spruce (Picea abies) clonal trees with both Endoconidiophora polonica (Ep, a common fungal pathogen associated with the spruce bark beetle Ips typographus) and Heterobasidion parviporum (Hp, a severe pathogen causing root and stem rot disease). Three weeks after inoculation, the fungal‐inoculated and intact bark from each tree was sampled. The terpenes in tree bark were extracted with hexane and characterized by gas chromatography–mass spectrometry (GC‐MS). The two fungi induced varied terpene responses in the four spruce clones used. Three of the clones showed a 2.3‐fold to 5.7‐fold stronger terpene response to Hp relative to Ep inoculation, while one clone responded similarly to inoculation with the two fungal pathogens. The amount of the diterpenes thunbergol and geranyllinalool varied between the clones. The level of thunbergol was higher in both intact and fungal‐inoculated bark from the less susceptible clones compared with the more susceptible clones. Geranyllinalool was present in higher amounts in the susceptible clones and is thus a possible marker for susceptibility. Our observations show that Norway spruce employs a similar chemical mechanism against the two fungal pathogens. Based on the present and earlier published data, we suggest that certain Norway spruce genotypes have a strong defence reaction against these two pathogens. The diterpenes thunbergol and geranyllinalool might be useful markers of susceptibility in tree‐breeding programmes and should be the focus of further detailed investigations. [ABSTRACT FROM AUTHOR]

Corymbia citriodora subsp. variegata (CCV) is an economically and ecologically important timber species, native to eastern Australia. It is highly susceptible to Quambalaria pitereka, a coevolved endemic pathogen, and Austropuccinia psidii, an exotic invasive pathogen. Genes associated with resistance to Q. pitereka are specific and uncorrelated with the genes associated with resistance to A. psidii, suggesting different resistance mechanisms to each pathogen, possibly associated with leaf phenotypic traits. This study examined leaf chemical and anatomical differences in CCV between uninoculated plants and those inoculated with Q. pitereka and A. psidii. The results demonstrate that the pathogens induce different responses in CCV. Plants inoculated with A. psidii exhibited chemical and anatomical changes that were not observed in uninoculated controls and Q. pitereka-inoculated plants, such as deposition of polyphenols and tannins in upper/lower epidermis, variation in the proportion of monoterpenes, steroids, monounsaturated hydrocarbons and long chain hydrocarbons and higher leaf toughness. In contrast, CCV response to Q. pitereka altered the distribution of polyphenols and tannins in the leaves and possible accumulation of these compounds and lignin in necrotic areas. These findings provide a better understanding of factors underlying CCV responses to coevolved and exotic pathogens and add insights into plant-pathogen interactions. [ABSTRACT FROM AUTHOR]

Background and Aims The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloë spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission? Methods We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloë. We measured plant fitness (survival, growth, reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission. Key Results Poa autumnalis hosted two Epichloë taxa, an undescribed vertically transmitted Epichloë sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivory increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission. Conclusions Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations. [ABSTRACT FROM AUTHOR]

Parasites are increasingly recognized as integral members of ecological communities, but their ecological effects remain less clear. Here, I propose that, to uncover the unique role of parasites, we must understand their indirect effects, which differ in important ways from those caused by predators. Similar to predators, parasites can cause density-mediated indirect effects (DMIEs) through their consumptive effects, and trait-mediated indirect effects (TMIEs) through their nonconsumptive effects; however, because they can consume a host without killing it, parasites can also trigger TMIEs through their consumptive effects. I consider the relative importance of each parasite-induced indirect interaction type and demonstrate their population-, community-, and ecosystem-level consequences. This paper contributes to recent efforts to unite predator–prey and parasite–host theory under a general consumer–resource framework. Similar to predators, parasites can trigger DMIEs through their consumptive effects, and TMIEs through their nonconsumptive effects. Unlike predators, parasites can also trigger TMIEs through their consumptive effects. Parasite-induced indirect effects can reverberate at the population, community, and ecosystem levels. If the receiver of one indirect effect initiates another indirect effect, an indirect interaction web can result. By altering host traits, parasites create diverse phenotypes within host populations, thereby expanding ecological niches available to species that interact with their hosts. Thus, parasites might facilitate coexistence and contribute to the maintenance of biodiversity. Applying predator–prey theory to parasite–host dynamics can yield novel insights. [ABSTRACT FROM AUTHOR]

We propose an analysis method that extracts trial-reproducible (i.e., recurring) event-related spatiotemporal EEG patterns by optimizing a spatial filter as well as trial timings of task-related components in the time domain simultaneously in a unified manner. Event-related responses are broadly categorized into evoked and induced responses, but those are analyzed commonly in the time and the time-frequency domain, respectively. To facilitate a comparison of evoked and induced responses, a unified method for analyzing both evoked and induced responses is desired. Here we propose a method of cross-correlation task-related component analysis (xTRCA) as an extension of our previous method. xTRCA constructs a linear spatial filter and then optimizes trial timings of single trials based on trial reproducibility as an objective function. The spatial filter enhances event-related responses, and the temporal optimization compensates trial-by-trial latencies that are inherent to ERPs. We first applied xTRCA to synthetic data of induced responses whose phases varied from trial to trial, and found that xTRCA could realign the induced responses by compensating the phase differences. We then demonstrated with mismatch negativity data that xTRCA enhanced the event-related-potential waveform observed at a single channel. Finally, a classification accuracy was improved when trial timings were optimized by xTRCA, suggesting a practical application of the method for a brain computer interface. We conclude that xTRCA provides a unified framework to analyze and enhance event-related evoked and induced responses in the time domain by objectively maximizing trial reproducibility. • A unified analysis method both for evoked and induced EEG responses is proposed. • Both spatial filter and trial timings are optimized for maximal trial reproducibility. • Spatial filtering extracts a trial-reproducible component by weighted averaging. • Trial timings are optimized to increase temporal overlaps of event-related responses. • The proposed method sharpens and enhances event-related responses. [ABSTRACT FROM AUTHOR]

Plant long-term response against chewing insects could become stronger than initial reactions and even turn into systemic. The objectives of the present study were 1) to evaluate whether the long-running attack to the stem by corn borers can improve the stem antibiotic properties; 2) to check whether hydroxycinnamic acids could be involved in this antibiotic response; 3) and to check whether elicitation by Sesamia nonagrioides Lef. (Lepidoptera: Noctuidae) regurgitant could activate long-term plant responses. In this sense, we observed that long-term feeding by S. nonagrioides larvae induced genotype-dependent changes in stem antibiosis and phenolic profiles, but the hydroxycinnamate content does not have a significant role in the systemic defense induced by the attack. In addition, response to long-term feeding by larvae could not be fully mimicked by elicitation using S. nonagrioides regurgitant alone. For the first time, it has been demonstrated that 'long-term' attack to the stem by corn borers can increase the stem antibiotic properties, and this has to be considered attending to breeding strategies. [ABSTRACT FROM AUTHOR]

1. Ants are recognized as induced biotic defence in mutualistic relationships with myrmecophytic plants. Pseudomyrmex concolor is an aggressive Amazonian ant that works as an anti‐herbivory agent for its host plant Tachigali myrmecophila. However, it is not known how this ant maintains the plant on low levels of herbivory. 2. Tachigali myrmecophila provides no food for P. concolor making this model appropriate to test the hypothesis that ants associated with myrmecophytes act as induced biotic defence by herbivory. Based on Optimal Defence Theory, we tested whether the response to herbivory and the ant daily activity rhythm is more frequent in most valuable parts of the plant, such as young leaves. 3. Ants were observed in young and mature leaves exposed to herbivory by experimental manipulation. Results suggest that ants act as induced biotic defence in T. myrmecophila: number of ants was significantly higher in manipulated leaflets, as well as the daily activity rhythm was increased in young leaves. The time to detect herbivory in young and mature leaves did not differ. However, leaf extracts signs were identified more quickly by the ants. 4. Induced ant responses in the ant–myrmecophytic plants system can be considered constitutive defence because ants are present throughout the development of their host plant from seedling to adulthood, responding aggressively to any intruder. In the Pseudomyrmex–Tachigali system, the presence of ants on the plants is, per se, a constitutive defence. However, the patrolling activity is an induced response, being the result of several plant‐related cues (chemical and physical) associated with herbivory activity. Pseudomyrmex concolor is an aggressive Amazonian ant that works as an anti‐herbivory agent for its host plant Tachigali myrmecophila. However, it is not known how this ant maintains the plant at low levels of herbivory.Based on Optimal Defence Theory, we tested whether the response to herbivory and the ant daily activity rhythm is more frequent in most valuable parts of the plant, such as young leaves.In the Pseudomyrmex–Tachigali system, the presence of ants on the plants is, per se, a constitutive defence, yet the patrolling activity is an induced response, being the result of several plant‐related cues (chemical and physical) associated with herbivore activity. [ABSTRACT FROM AUTHOR]

Plants produce a plethora of variable metabolites that could be involved in constitutive and induced defense against herbivorous insects. Recently, metabolomics have showed to be a complementary approach in chemical ecology to screen dozens of plant metabolites, and identify those related with plant resistance or susceptibility to herbivorous insects. We compared GC–MS metabolic profiles of cambial tissue from Persea americana cv. Hass trees infested and non-infested by the avocado branch borer (ABB), Copturus aguacatae , and between undamaged and ABB damaged branches from the same tree. Using several multivariate techniques we discriminated between several overlaid dimensions of branches phytochemical variation (intraclonal, seasonal and induced response). Specifically, we found a set of sixteen highly correlated terpenoids, showing increasing proportions in borer trees as response to ABB larvae. In addition, low proportions of isoobtusilactone A and α-humulene were found in non-bored trees. The implications of dimensions of avocado phytochemical variation, and diversity as defensive traits in the interaction with Copturus aguacatae are discussed. [ABSTRACT FROM AUTHOR]

In plant–arthropod associations, the first herbivores to colonise a plant may directly or indirectly affect community assembly on that particular plant. Whether the order of arrival of different arthropod species further modulates community assembly and affects plant fitness remains unclear. Using wild Brassica oleracea plants in the field, we manipulated the order of arrival of early‐season herbivores that belong to different feeding guilds, namely the aphid Brevicoryne brassicae and caterpillars of Plutella xylostella. We investigated the effect of herbivore identity and order of arrival on community assembly on two B. oleracea plant populations during two growth seasons. For this perennial plant, we evaluated whether foliar herbivory also affected herbivore communities on the flowers and if these interactions affected plant seed production. Aphid infestation caused an increase in parasitoid abundance, but caterpillars modulated these effects, depending on the order of herbivore infestation and plant population. In the second growth season, when plants flowered, the order of infestation of leaves with aphids and caterpillars more strongly affected abundance of herbivores feeding on the flowers than those feeding on leaves. Infestation with caterpillars followed by aphids caused an increase in flower‐feeding herbivores compared to the reversed order of infestation in one plant population, whereas the opposite effects were observed for the other plant population. The impact on plant seed set in the first reproductive year was limited. Our work shows that the identity and arrival order of early season herbivores may have long‐term consequences for community composition on individual plants and that these patterns may vary among plant populations. We discuss how these community processes may affect plant fitness and speculate on the implications for evolution of plant defences. [ABSTRACT FROM AUTHOR]

Abstract: Intraspecific variation in plant defense phenotype is common and has wide‐ranging ecological consequences. Yet prevailing theories of plant defense allocation, which primarily account for interspecific differences in defense phenotype, often fail to predict intraspecific patterns. Furthermore, although individual variation in defense phenotype is often attributed to ecological interactions, few general mechanisms have been proposed to explain the ubiquity of variable defense phenotype within species. Here, we show experimentally that associational refuges and induced resistance interact to create predictable intraspecific variation in defense phenotype in African savanna plants. Physically defended species from four families (Acanthaceae, Asparagaceae, Cactaceae, and Solanaceae) growing in close association with spinescent Acacia trees had 39–78% fewer spines and thorns than did isolated conspecifics. For a subset of these species, we used a series of manipulative experiments to show that this variability is maintained primarily by a reduction in induced responses among individuals that seldom experience mammalian herbivory, whether due to association with Acacia trees or to experimental herbivore exclusion. Unassociated plants incurred 4‐ to 16‐fold more browsing damage than did associated individuals and increased spine density by 16–38% within one month following simulated browsing. In contrast, experimental clipping induced no net change in spine density among plants growing beneath Acacia canopies or inside long‐term herbivore exclosures. Associated and unassociated individuals produced similar numbers of flowers and seeds, but seedling recruitment and survival were vastly greater in refuge habitats, suggesting a net fitness benefit of association. We conclude that plant‐plant associations consistently decrease defense investment in this system by reducing both the frequency of herbivory and the intensity of induced responses, and that inducible responses enable plants to capitalize on such associations in heterogeneous environments. Given the prevalence of associational and induced defenses in plant communities worldwide, our results suggest a potentially general mechanism by which biotic interactions might predictably shape intraspecific variation in plant defense phenotype. [ABSTRACT FROM AUTHOR]

1. Herbivores sometimes suppress plant defences. This study tested whether the presence of pea aphids ( Acyrthosiphon pisum Harris) on broad bean ( Vicia faba) led to decreased secretion of extrafloral nectar (EFN) which functions as an indirect plant defence against herbivores. 2. To determine effects of aphid infestation on EFN secretion, a comparison was done between EFN secretion in uninfested plants and that in plants infested by A. pisum and another aphid species ( Aphis craccivora Koch). 3. When broad bean plants were infested by A. pisum, they secreted significantly smaller amounts of EFN than did uninfested plants and A. craccivora-infested plants. There was no significant difference in EFN secretion between uninfested plants and A. craccivora-infested plants. The number of extrafloral nectaries did not differ among the three treatments. 4. These results suggest that A. pisum reduced EFN production in broad bean plants. [ABSTRACT FROM AUTHOR]

Evolutionary biologists have long sought to understand the ecological processes that generate plant reproductive diversity. Recent evidence indicates that constitutive antiherbivore defences can alter natural selection on reproductive traits, but it is unclear whether induced defences will have the same effect and whether reduced foliar damage in defended plants is the cause of this pattern. In a factorial field experiment using common milkweed, Asclepias syriaca L., we induced plant defences using jasmonic acid ( JA) and imposed foliar damage using scissors. We found that JA-induced plants experienced selection for more inflorescences that were smaller in size (fewer flowers), whereas control plants only experienced a trend towards selection for larger inflorescences (more flowers); all effects were independent of foliar damage. Our results demonstrate that induced defences can alter both the strength and direction of selection on reproductive traits, and suggest that antiherbivore defences may promote the evolution of plant reproductive diversity. [ABSTRACT FROM AUTHOR]

Reactions of plants to insect pests include the activation of a local and systemic defence response. This response is based on transcriptional changes that are mainly controlled and coordinated by phytohormones. The above- and belowground part of plants can be challenged by different insects and therefore, the defence response to one attacker can influence other insects. The study of plant-mediated interaction between pests that are physically or temporally separated yielded a variety of outcomes, with positive, negative, and neutral effects described in the literature. In this study, we examined possible plant-mediated interactions between above- and belowground insect pests with different feeding guilds in tomato, Solanum lycopersicum L. ( Solanaceae). Root feeding by Agriotes lineatus (L.) ( Coleoptera: Elateridae) larvae caused a decrease in the development rate, fertility, and weight in Myzus persicae ( Sulzer) ( Hemiptera: Aphididae). To gain insights into the plant systemic signalling mechanisms, we also performed a time-course expression analysis of defence-related phytohormone marker genes. The result indicated a dynamic systemic response in leaves following root herbivory, which comprises the activation of genes dependent on different molecular pathways involved in plant stress response. Our work demonstrated that root herbivory increased aphid resistance in tomato and that a combination of signals enables the communication between below- and aboveground pests with different feeding guilds. [ABSTRACT FROM AUTHOR]

Background: Plants can respond to insect attack via defense mechanisms that reduce insect performance. In this study, we examined the effects of several treatments applied to two maize genotypes (one resistant, one susceptible) on the subsequent growth and survival of Sesamia nonagrioides Lef. (Mediterranean corn borer, MCB) larvae. The treatments were infestation with MCB larvae, application of MCB regurgitant upon wounding, wounding alone, or exposure to methyl jasmonate, and they were applied at the V6-V8 stage of maize development. We also monitored changes in the concentrations of compounds known to be involved in constitutive resistance, such as cell wall-bound hydroxycinnamates and benzoxazinoids. Results: In both maize genotypes, the leaves of plants pre-infested with MCB larvae were less suitable for larval development than those from untreated plants. Application of MCB regurgitant upon wounding, and wounding itself, resulted in leaf tissues becoming less suitable for larval growth than those of pre-infested plants, suggesting that there could be herbivore-associated effector molecules that suppress some wounding responses. A single application of MCB regurgitant did not seem to mimic feeding by MCB larvae, although the results suggested that regurgitant deposited during feeding may have enhanced ferulates and diferulates synthesis in infested vs. control plants. Jasmonic acid may play a role in mediating the maize response to MCB attack, but it did not trigger hydroxycinnamate accumulation in the leaves to a level comparable to that induced by larval leaf feeding. The EP39 maize genotype showed an increase in leaf cell wall strength by increasing hemicellulose cross-linking in response to MCB attack, while induced defenses in the EP42 plants appeared to reflect a broader array of resistance mechanisms. Conclusions: The results indicated that leaf feeding by MCB larvae can increase leaf antibiosis against MCB in two maize genotypes with contrasting levels of resistance against this borer. Also, the larval regurgitant played a positive role in eliciting a defense response. We determined the effects of the plant response on larval growth, and detected defense compounds related to borer resistance. [ABSTRACT FROM AUTHOR]

Efficacy of Pseudomonas putida (CKPp9) was tested under in vitro and in vivo conditions for their ability to plant growth promoting characteristics in tomato seedlings against Clavibacter michiganensis subsp. michiganensis ( Cmm Go2) infection. A significant difference was observed between bacterized tomato seedlings with P. putida (CKPp9) and the other treatments ( P < 0.01). Also, Cmm Go2 was detected significant difference the least plant growth parameters for tomato seedlings (P < 0.01). To correlate the induction of phenolic compounds by the CKPp9 with disease resistance, qualitative and quantitative modifications of phenolic compounds in tomato seedlings were observed in different treatments. High performance liquid chromatographic (HPLC) analysis of the leaves of the CKPp9-treated, Cmm Go2-treated, and non-treated (control) plants showed the presence of chlorogenic acid, caffeic acid, catechin and rutin with varied amounts in the CKPp9 treated as well as Cmm Go2-treated and non-treated (control) plants. Maximum accumulation of catechin was observed in plants treated with the CKPp9 strain + Cmm Go2 strain which was almost 10 times higher than the CKPp9-treated plants and also significantly high when compared to other treatments. A direct relationship between the level of catechin and seedling survivability was observed. P. putida -mediated induction of phenolic compounds as a biochemical barrier in tomato seedlings against C. michiganensis subsp. michiganensis infection is envisaged. [ABSTRACT FROM AUTHOR]

Background: Rice (Oryza sativa L.), which is a staple food for more than half of the world's population, is frequently attacked by herbivorous insects, including the rice stem borer, Chilo suppressalis. C. suppressalis substantially reduces rice yields in temperate regions of Asia, but little is known about how rice plants defend themselves against this herbivore at molecular and biochemical level. Results: In the current study, we combined next-generation RNA sequencing and metabolomics techniques to investigate the changes in gene expression and in metabolic processes in rice plants that had been continuously fed by C. suppressalis larvae for different durations (0, 24, 48, 72, and 96 h). Furthermore, the data were validated using quantitative real-time PCR. There were 4,729 genes and 151 metabolites differently regulated when rice plants were damaged by C. suppressalis larvae. Further analyses showed that defense-related phytohormones, transcript factors, shikimate-mediated and terpenoid-related secondary metabolism were activated, whereas the growth-related counterparts were suppressed by C. suppressalis feeding. The activated defense was fueled by catabolism of energy storage compounds such as monosaccharides, which meanwhile resulted in the increased levels of metabolites that were involved in rice plant defense response. Comparable analyses showed a correspondence between transcript patterns and metabolite profiles. Conclusion: The current findings greatly enhance our understanding of the mechanisms of induced defense response in rice plants against C. suppressalis infestation at molecular and biochemical levels, and will provide clues for development of insect-resistant rice varieties. [ABSTRACT FROM AUTHOR]

Spatially separated aboveground (AG) and belowground (BG) herbivores are closely linked through shared host plants, and both patterns of AG-BG interactions and plant responses may vary among plant genotypes. We subjected invasive (USA) and native (China) genotypes of tallow tree ( Triadica sebifera) to herbivory by the AG specialist leaf-rolling weevil Heterapoderopsis bicallosicollis and/or the root-feeding larvae of flea beetle Bikasha collaris. We measured leaf damage and leaves rolled by weevils, quantified beetle survival, and analyzed flavonoid and tannin concentrations in leaves and roots. AG and BG herbivores formed negative feedbacks on both native and invasive genotypes. Leaf damage by weevils and the number of beetle larvae emerging as adults were higher on invasive genotypes. Beetles reduced weevil damage and weevils reduced beetle larval emergence more strongly for invasive genotypes. Invasive genotypes had lower leaf and root tannins than native genotypes. BG beetles decreased leaf tannins of native genotypes but increased root tannins of invasive genotypes. AG herbivory increased root flavonoids of invasive genotypes while BG herbivory decreased leaf flavonoids. Invasive genotypes had lower AG and BG herbivore resistance, and negative AG-BG herbivore feedbacks were much stronger for invasive genotypes. Lower tannin concentrations explained overall better AG and BG herbivore performances on invasive genotypes. However, changes in tannins and flavonoids affected AG and BG herbivores differently. These results suggest that divergent selection on chemical production in invasive plants may be critical in regulating herbivore performances and novel AG and BG herbivore communities in new environments. [ABSTRACT FROM AUTHOR]

This study examines the nature of intraspecific interactions among Nilaparvata lugens ( Stål) ( Hemiptera: Delphacidae) planthoppers feeding on resistant and susceptible rice varieties. Planthopper nymphs produced less honeydew and gained less weight when feeding on rice variety IR62 (resistant) compared to susceptible rice varieties. A series of bioassays was conducted that varied N. lugens nymph densities on IR62 and IR22 (susceptible). Increasing nymph density facilitated feeding by conspecifics; however, intraspecific competition increased mortality of nymphs on IR62 (but rarely on IR22). Furthermore, nymph weights declined with increasing conspecific density on IR22, and the effects were weak on IR62. More female nymphs than males survived on IR62 but this was not affected by density. Nitrogenous fertilizer increased competition among N. lugens on young plants of IR22, but not on IR62. Results indicate that nymphs have a low efficiency in accessing resources when feeding on IR62, even where the plants have received fertilizer. Female-biased survival and biomass compensation for mortality may promote population recovery after development on the resistant plant and accelerate adaptation to the resistant variety. [ABSTRACT FROM AUTHOR]

Coevolution is among the most important evolutionary processes that generate biological diversity. Plant-pollinator interactions play a prominent role in the evolution of reproductive traits in flowering plants. Likewise, plant-herbivore interactions select for myriad defenses that protect plants from damage. These mutualistic and antagonistic interactions, respectively, have traditionally been considered in isolation from one another. Here, we consider whether reproductive traits and antiherbivore defenses are interdependent as a result of pollinator- and herbivore-mediated selection. The evolution of floral traits, self-fertilization, and separate sexes frequently affects the expression and evolution of plant defenses. In turn, the evolution of defense can affect allocation to reproductive traits, and herbivores often impose strong selection directly on floral traits. Theory and empirical evidence suggest that herbivores can influence the evolution of selfing from outcrossing and potentially the evolution of separate sexes from combined sexes. We identify several areas in which future research is needed to increase our understanding of the evolutionary interplay between reproduction and defense in plants. [ABSTRACT FROM AUTHOR]

Plant-insect interactions typically take place in complex settings of interactions among multiple trophic levels as well as multiple species in each trophic level. The complex interaction network may strongly impact on extrapolations of resistance traits to have a defensive function. For example, the induced response plants express to their current attacker often enhances resistance to that attacker, but may make a plant more susceptible to attack by another herbivore. Hence, the defensive function or plant fitness benefit of the response to a single attacker may be misinterpreted from pairwise interactions. Moreover, plant physiological responses to a first stress by herbivory may hamper the response to a second stress and lead to conclusions of maladaptation in plant defence responses. In light of the entire community of attackers and beneficial organisms the plant interacts with, the susceptibility to some attackers may be a consequence of adaptations that reduce fitness costs of herbivory when considering the full sweep of species that affect plant fitness. A similar argumentation may apply for indirect resistance in which predators or parasitoids dampen the effect of herbivores on plants. Plant volatiles that attract third trophic level organisms such as parasitoids may at the same time attract enemies of the parasitoids in the fourth trophic level, hyperparasitoids, which again dampen the effect of parasitoids on herbivores. In addition, the effectiveness of predators and parasitoids may be dependent on habitat complexity. Here, I plea for studies on the full plant-associated community to understand the fitness outcome of an (induced) plant trait and hence coin it induced direct or indirect plant defence. [ABSTRACT FROM AUTHOR]

Within individual plants, cervid herbivory may cause positive or negative plant-mediated effects on insect herbivores, depending on where it occurs. Using a combination of field observations and artificial bark-stripping experiments in Hokkaido, Japan, we examined the plant-mediated effects of bark stripping by sika deer ( Cervus nippon yesoensis) on insect herbivory in two spatially distinct parts of willow ( Salix udensis) trees: resprouting leaves below bark-stripping wounds and canopy leaves above. Natural and artificial bark stripping stimulated resprouting from trunks below wounds. Resprouting leaves on bark-stripped trees had lower total phenolics, condensed tannin, and C/N ratios than did canopy leaves on control trees. Herbivory rates were higher in resprouting leaves on bark-stripped trees than in canopy leaves on controls. Conversely, above-wound canopy leaves on bark-stripped trees had higher total phenolics than did those on controls, while herbivory rates were lower in the canopy leaves of bark-stripped trees than in those on controls. These results demonstrate that plant-mediated effects of bark stripping diverge between plant tissues below and above wounds in individual willow trees. We submit that focusing on multiple plant parts can elucidate plant-mediated effects at the whole-plant scale. [ABSTRACT FROM AUTHOR]

The response of the brain to a sensory stimulus may present itself in the electroencephalogram (EEG) as evoked and/or induced activity. While the evoked response is given by peaks and troughs in the signal, time-locked and phase-locked to the stimuli, the induced response is time- but not phase-locked, and can be considered as an increase or a decrease in the power of EEG in a specific frequency band at a specific time range with regard to the stimulus onset. The induced response does not have the same phase following successive stimuli. It is believed that cognition and perception of a stimulus present themselves primarily as the induced response in the EEG. In this paper, the induced response of the brain to auditory speech stimuli is investigated and different approaches to detect induced activity are compared. It is shown that there is an increase in theta and delta power in response to words compared to the baseline, starting around 500 ms after their onset. During this time, there is also an increase in pairwise coherence between the posterior electrodes. In response to tone bursts, a change in pairwise coherence was observed in the beta band starting around 200 ms. To the best of our knowledge, this is the first time such responses have been described using simple protocols without complex stimulus manipulations being involved. Responses in the EEG to speech rather than the more conventional tone-bursts or clicks suggests that it may be feasible to use the EEG as an objective means to demonstrate brain activation to salient real world stimuli. This would be of particular benefit in investigating access to speech in patients who are unable or unwilling to reliably respond to conventional subjective experimental protocols, such as infants. [ABSTRACT FROM AUTHOR]

Cortical reactivation and regain of interareal functional connections have been linked to the recovery of hand grasping behavior after loss of sensory inputs in primates. We investigated contributions of neurons in two hierarchically organized somatosensory areas, 3b and S2, by characterizing local field potential (LFP) and multiunit spiking activity in five states (rest, stimulus-on, sustained, stimulus-off, and induced) and interareal communication after grasping behavior of dorsal column lesioned male squirrel monkeys had mostly recovered. Compared with normal cortex, fMRI, LFP, and spiking response magnitudes to step indentations were significantly weaker. The sustained component of the spiking recovered much better than the stimulus-off response. Correlation between overall spiking and γ LFP remained strong within each recovered areas 3b and S2. The interareal correlations of γ LFP were severely disrupted, except in the resting and stimulus-on periods. Interareal correlation of spiking was disrupted in the stimulus-off period only. In summary, submodality of low threshold mechanoreceptive neurons recovered differentially in input-deprived area 3b and S2 when impaired global hand grasping behavior returned. Slow-adapting-like neurons recovered, whereas rapid-adapting-like neurons did not. Interareal communications were also severely compromised. We propose that slow-adapting-like neurons and afferents in recovered area 3b and S2 mediate recovery of impaired grasping behavior after dorsal column tract lesion. SIGNIFICANCE STATEMENT Sensory feedback is essential for execution of hand grasping behavior in primates. Reactivations of somatosensory cortices have been attributed to recovery of such behavior after loss of sensory inputs via largely unknown mechanisms. In input-deprived area 3b and S2 cortex, after hand grasping behavior mostly recovered, we found slow-adapting-like neurons were greatly recovered, whereas rapid-adapting-like neurons did not. Communications between area 3b and S2 neurons were severely compromised. We suggest that recovery of slow-adapting-like neurons in input-deprived area 3b and S2 may mediate the recovery of hand grasping behavior., (Copyright © 2022 the authors.)

Common bean (Phaseolus vulgaris L.) is a major legume and is frequently attacked by fungal pathogens, including Fusarium solani f. sp. phaseoli (FSP), which cause Fusarium root rot. FSP substantially reduces common bean yields across the world, including China, but little is known about how common bean plants defend themselves against this fungal pathogen. In the current study, we combined next-generation RNA sequencing and metabolomics techniques to investigate the changes in gene expression and metabolomic processes in common bean infected with FSP. There were 29,722 differentially regulated genes and 300 differentially regulated metabolites between control and infected plants. The combined omics approach revealed that FSP is perceived by PAMP-triggered immunity and effector-triggered immunity. Infected seedlings showed that common bean responded by cell wall modification, ROS generation, and a synergistic hormone-driven defense response. Further analysis showed that FSP induced energy metabolism, nitrogen mobilization, accumulation of sugars, and arginine and proline metabolism. Importantly, metabolic pathways were most significantly enriched, which resulted in increased levels of metabolites that were involved in the plant defense response. A correspondence between the transcript pattern and metabolite profile was observed in the discussed pathways. The combined omics approach enhances our understanding of the less explored pathosystem and will provide clues for the development of common bean cultivars' resistant to FSP. [ABSTRACT FROM AUTHOR]