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Background: Cabbage Fusarium wilt (CFW) is a devastating disease caused by the soil-borne fungus Fusarium oxysporum f. sp. conglutinans (Foc). One of the optimal measures for managing CFW is the employment of tolerant/resistant cabbage varieties. However, the interplay between plant genotypes and the pathogen Foc in shaping the rhizosphere microbial community, and the consequent influence of these microbial assemblages on biological resistance, remains inadequately understood. Results: Based on amplicon metabarcoding data, we observed distinct differences in the fungal alpha diversity index (Shannon index) and beta diversity index (unweighted Bray–Curtis dissimilarity) within the rhizosphere of the YR (resistant to Foc) and ZG (susceptible to Foc) cabbage varieties, irrespective of Foc inoculation. Notably, the Shannon diversity shifts in the resistant YR variety were more pronounced following Foc inoculation. Disease-resistant plant variety demonstrate a higher propensity for harboring beneficial microorganisms, such as Pseudomonas, and exhibit superior capabilities in evading harmful microorganisms, in contrast to their disease-susceptible counterparts. Furthermore, the network analysis was performed on rhizosphere-associated microorganisms, including both bacteria and fungi. The networks of association recovered from YR exhibited greater complexity, robustness, and density, regardless of Foc inoculation. Following Foc infection in the YR rhizosphere, there was a notable increase in the dominant bacterium NA13, which is also a hub taxon in the microbial network. Reintroducing NA13 into the soil significantly improved disease resistance in the susceptible ZG variety, by directly inhibiting Foc and triggering defense mechanisms in the roots. Conclusions: The rhizosphere microbial communities of these two cabbage varieties are markedly distinct, with the introduction of the pathogen eliciting significant alterations in their microbial networks which is correlated with susceptibility or resistance to soil-borne pathogens. Furthermore, we identified a rhizobacteria species that significantly boosts disease resistance in susceptible cabbages. Our results indicated that the induction of resistance genes leading to varied responses in microbial communities to pathogens may partly explain the differing susceptibilities of the cabbage varieties tested to CFW. -meKq2qaHpqpKck3NvZ8m1 Video Abstract [ABSTRACT FROM AUTHOR]

When attacked by insect herbivores, plants emit blends of chemical compounds known as herbivore‐induced plant volatiles (HIPVs). Although HIPVs are produced both aboveground and belowground, how HIPVs vary across plant tissues remains unresolved, as do the selective forces shaping interspecific HIPV emission patterns. Here, we compared foliar and root HIPVs within and among closely related plant species and evaluated if different eco‐evolutionary forces, including plant domestication, coexistence histories with herbivores, or phylogenetic relatedness, explain HIPV blends. To examine aboveground and belowground patterns in HIPVs, we compared leaf and root volatile profiles for six species in the Cucurbitaceae that differed in domestication status and coexistence history with specialist insect herbivores. We predicted that within‐species HIPVs from different tissues would be more similar than HIPV blends among different species, and that plant volatile chemodiversity was reduced by domestication and enhanced by coexistence histories with herbivores. We found that herbivory induced both quantitative and qualitative changes in volatile emissions across all plant species, which were more pronounced aboveground than belowground. Each species produced tissue‐specific HIPVs, and foliar and root HIPVs differed among species. Contrary to our predictions, plant domestication enhanced foliar volatile diversity, while coexistence histories with herbivores reduced foliar and root volatile diversity. Additionally, phylogenetic relatedness did not correlate with aboveground or belowground volatiles. Overall, this work furthers our understanding of the eco‐evolutionary forces driving patterns in aboveground and belowground HIPV emissions, elucidating an important and previously undescribed component of within‐plant variation in chemodiversity. [ABSTRACT FROM AUTHOR]

Elicitor-induced defences are a new addition in plants’ armour to counter insect herbivory. It is unknown whether exogenously-applied jasmonic acid and salicylic acid (JA & SA) induced defence in pigeonpea (Cajanus cajan) can reduce Maruca vitrata (Fab.) herbivory. We exogenously treated one resistant (AL 1747) and one susceptible (MN 1) pigeon pea genotype with JA (100 µM) and SA (5 mM) at 50% flowering stage (five treatments each). Then, we quantified pigeon pea secondary plant metabolites and M. vitrata nutritional indices. Approximate digestibility, efficiency of conversion of ingested and digested food into body matter, and relative growth rate of M. vitrata larvae were significantly reduced on plants pre-treated with JA and then infested with M. vitrata (PJA + MV); however, consumption index was increased. SA applications also altered the nutritional indices of M. vitrata, but the effects were not as pronounced as JA applications. PJA + MV treatment rapidly increased the level of tannins, total phenols and total protease inhibitors in flowers of both genotypes one day after treatment (DAT); this induction was more noticeable in the resistant genotype. However, only constitutive levels of the aforesaid compounds were detected at 7 DAT. Thus, JA and SA can significantly enhance pigeonpea defences against M. vitrata, providing farmers with an environmentally friendly alternative to synthetic pesticides. Researchers can further explore the use of natural or synthetic elicitors in integrated pest management, potentially combining them with biological control. [ABSTRACT FROM AUTHOR]

ABSTRACT Satellite RNAs (satRNAs) are RNA molecules associated with many plant viruses and fully dependent on them for replication, encapsidation, and movement within the plant or transmission from plant to plant. Their classification is based on their length, functional protein‐coding capacity, and RNA structure (whether linear or circular). They have been of interest for a long time as some of them, in particular systems, cause significant changes in the pathogenesis and epidemiology of plant viruses. The outcomes of how satRNAs affect pathogenesis depend on the components of the pathosystem: host plant species or variety, virus species or even strain, and the sequence of satRNA. These can be additionally affected by biotic and abiotic factors, for example, environmental conditions such as the presence of their vectors or ambient temperature. satRNAs may interfere with primary metabolism, signalling, plant defence [including post‐transcriptional gene silencing (PTGS)], as well as the efficiency of virus transmission from plant to plant. In recent years, due to wider access to high‐throughput technologies and the extension of studies on satRNAs to include the involvement of external factors in plant–virus–satRNA systems, we are gaining a broader view of the consequences of the presence of these small molecules in viral infections. This review presents the state of the art of satRNA interactions with the helper virus and host plant as well as the influence of satRNAs on the insect vector's behaviour. Moreover, areas requiring further research are identified and knowledge gaps indicated. [ABSTRACT FROM AUTHOR]

Plant defence peptides are paramount endogenous danger signals secreted after a challenge, intensifying the plant immune response. The peptidic hormone Systemin (Sys) was shown to participate in resistance in several plant pathosystems, although the mechanisms behind Sys-induced resistance when exogenously applied remain elusive. We performed proteomic, metabolomic, and enzymatic studies to decipher the Sys-induced changes in tomato plants in either the absence or the presence of Botrytis cinerea infection. Sys treatments triggered direct proteomic rearrangement mostly involved in carbon metabolism and photosynthesis. However, the final induction of defence proteins required concurrent challenge, triggering priming of pathogen-targeted proteins. Conversely, at the metabolomic level, Sys-treated plants showed an alternative behaviour following a general priming profile. Of the primed metabolites, the flavonoids rutin and isorhamnetin and two alkaloids correlated with the proteins 4-coumarate-CoA-ligase and chalcone-flavanone-isomerase triggered by Sys treatment. In addition, proteomic and enzymatic analyses revealed that Sys conditioned the primary metabolism towards the production of available sugars that could be fuelling the priming of callose deposition in Sys-treated plants; furthermore, PR1 appeared as a key element in Sys-induced resistance. Collectively, the direct induction of proteins and priming of specific secondary metabolites in Sys-treated plants indicated that post-translational protein regulation is an additional component of priming against necrotrophic fungi. [ABSTRACT FROM AUTHOR]

Black rot (Guignardia bidwellii) and downy mildew (Plasmopara viticola) are two major grapevine diseases against which the development of efficient biocontrol solutions is required in a context of sustainable viticulture. This study aimed at evaluating and comparing the efficacy and modes of action of bacterial culture supernatants from Bacillus velezensis Buz14 and B. ginsengihumi S38. Both biocontrol agents (BCA) were previously demonstrated as highly effective against Botrytis cinerea in grapevines. In semi-controlled conditions, both supernatants provided significant protection against black rot and downy mildew. They exhibited antibiosis against the pathogens by significantly decreasing G. bidwellii mycelial growth, but also the release and motility of P. viticola zoospores. They also significantly induced grapevine defences, as stilbene production. The LB medium, used for the bacterial cultures, also showed partial effects against both pathogens and induced plant defences. This is discussed in terms of choice of experimental controls when studying the biological activity of BCA supernatants. Thus, we identified two bacterial culture supernatants as new potential biocontrol products exhibiting multi-spectrum antagonist activity against different grapevine key pathogens and having a dual mode of action. [ABSTRACT FROM AUTHOR]

Summary: In this study, the accumulation of hydrogen peroxide (H2O2) in different parts (healthy root, gall, root attached to gall, aerial parts) of healthy tomato plants and plants infected by the root-knot nematode, Meloidogyne javanica , was investigated after treating the roots with β -aminobutyric acid (BABA). In addition, the effects of different concentrations of H2O2 (0-2 mM) on mortality, body structures and the digestive system of second-stage juveniles (J2) were also investigated in in vitro experiments. Results showed that exposure to concentrations of more than 1 mM H2O2 is lethal for J2, while the digestive system is not able to tolerate concentrations of more than 0.2 mM. Evaluating the activity level of enzymes related to biosynthesis and removing H2O2 in treated plants also showed that the nematode has significant suppressive effects on the biosynthesis enzymes of this compound, and this effect is greater in the site of nematode activity than in other parts of the plant. By contrast, the activity of catalase enzyme, as one of the H2O2-removing enzymes, shows a significant increase in all parts of nematode infected plants (especially in galls). [ABSTRACT FROM AUTHOR]

Main conclusion: A gene-to-metabolite approach afforded new insights regarding defence mechanisms in oat plants that can be incorporated into plant breeding programmes for the selection of markers and genes related to disease resistance. Monitoring metabolite levels and changes therein can complement and corroborate transcriptome (mRNA) data on plant–pathogen interactions, thus revealing mechanisms involved in pathogen attack and host defence. A multi-omics approach thus adds new layers of information such as identifying metabolites with antimicrobial properties, elucidating metabolomic profiles of infected and non-infected plants, and reveals pathogenic requirements for infection and colonisation. In this study, two oat cultivars (Dunnart and SWK001) were inoculated with Pseudomonas syringae pathovars, pathogenic and non-pathogenic on oat. Following inoculation, metabolites were extracted with methanol from leaf tissues at 2, 4 and 6 days post-infection and analysed by multiple reaction monitoring (MRM) on a triple quadrupole mass spectrometer system. Relatedly, mRNA was isolated at the same time points, and the cDNA analysed by quantitative PCR (RT-qPCR) for expression levels of selected gene transcripts associated with avenanthramide (Avn) biosynthesis. The targeted amino acids, hydroxycinnamic acids and Avns were successfully quantified. Distinct cultivar-specific differences in the metabolite responses were observed in response to pathogenic and non-pathogenic strains. Trends in aromatic amino acids and hydroxycinnamic acids seem to indicate stronger activation and flux through these pathways in Dunnart as compared to SWK001. A positive correlation between hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyl transferase (HHT) gene expression and the abundance of Avn A in both cultivars was documented. However, transcript profiling of selected genes involved in Avn synthesis did not reveal a clear pattern to distinguish between the tolerant and susceptible cultivars. [ABSTRACT FROM AUTHOR]

Plants and insect herbivores are two of the most diverse multicellular groups in the world, and both are strongly influenced by interactions with the belowground soil microbiome. Effects of reciprocal rapid evolution on ecological interactions between herbivores and plants have been repeatedly demonstrated, but it is unknown if (and how) the soil microbiome could mediate these eco‐evolutionary processes on a shared host plant. We tested the role of a plant‐beneficial soil bacterium Acidovorax radicis in altering eco‐evolutionary interactions between different aphid genotypes (Sitobion avenae, genotypes Sickte and Fescue) feeding on barley Hordeum vulgare. We measured fecundity, longevity and population growth of two aphid genotypes reared separately or together (population mixture) on three different barley varieties that were inoculated with or without A. radicis. Results showed that across all plant varieties A. radicis increased plant growth and suppressed aphid populations via reduced longevity and fecundity. The strength of effect was dependent on aphid genotype and barley variety, while the direction of effect was altered by aphid population mixture. Using Lotka–Volterra modelling, we demonstrated that while A. radicis inoculation decreased growth rates for both aphid genotypes it increased the competitiveness of one genotype against the other. In general, in the presence of A. radicis, the Fescue aphid genotype became more inhibitory of Sickte aphids, while Sickte aphids facilitated the growth of Fescue aphids. Our work demonstrates that plant rhizosphere microbiomes exert community‐level influences by mediating eco‐evolutionary interactions between herbivores and host plants. By altering competitive interaction outcomes among aphids and thus impacting processes such as rapid evolution, soil microbes contribute to the short‐ and long‐term structure and functioning of terrestrial habitats. [ABSTRACT FROM AUTHOR]

Simple Summary: According to recent research, insect herbivory can be positively and negatively regulated by ET biosynthesis and perception. This review explores the defence mechanisms of plants against insect herbivory, including biosynthesis and signal transduction of ET. Furthermore, it discusses the role of ET in triggering defences against herbivory, the ET interaction with other phytohormones, and the external application of ET stimulation. Plants have evolved to establish insect herbivory defences by modulating their metabolism, growth, and development. Precise networks of phytohormones are essential to induce those herbivory defences. Gaseous phytohormone ET plays an important role in forming herbivory defences. Its role in insect herbivory is not fully understood, but previous studies have shown that it can both positively and negatively regulate herbivory. This review presents recent findings on crosstalk between ET and other phytohormones in herbivory responses. Additionally, the use of exogenous ETH treatment to induce ET in response to herbivory is discussed. [ABSTRACT FROM AUTHOR]

Plants have developed chemical defence strategies which can either be triggered in response to herbivory or by the exogenous application of phytohormones, such as methyl jasmonate (MeJa). Tuta absoluta is the main pest associated with tomatoes worldwide. However, studies on the impact of plant hormones on this system are still scarce. This study aimed to evaluate the chemotactic responses and oviposition of T. absoluta towards tomato plants induced by MeJa and herbivory injuries. We conducted dual‐choice olfactometry bioassays evaluating the response of virgin T. absoluta males and females exposed to plants with conspecifics (eggs and caterpillars) and sprayed with MeJa (0.5 mM) at 24, 48, 72 and 96 h after the treatments. We also evaluated the oviposition preference of mated T. absoluta with the chance of choosing plants exposed to water, herbivory and three phytohormone concentrations (0.1, 0.5 and 2.5 mM). The males were mostly responsive to plants with conspecifics, while the females preferred intact plants over those sprayed with MeJa and with the presence of eggs. Furthermore, plants with MeJa (0.5 and 2.5 mM) and injured by conspecifics had less oviposition by T. absoluta. The results show that spraying MeJa on tomato plants is a potential tool for managing and controlling the tomato moth. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max) is an important oilseed, protein and biodiesel crop. It faces significant threats from bacterial, fungal and viral pathogens, which cause economic losses and jeopardises global food security. In this article, we explore the relationship between soybeans and these pathogens, focusing on the molecular responses that are crucial for soybeans defence mechanisms. Molecular responses involve small RNAs and specific genes, including resistance (R) genes that are pivotal in triggering immune responses. Functional genomics, which makes use of cutting-edge technologies, such as CRISPR Cas9 gene editing, allows us to identify genes that provide insights into the defence mechanisms of soybeans with the focus on using genomics to understand the mechanisms involved in host pathogen interactions and ultimately improve the resilience of soybeans. Genes like GmKR3 and GmVQ58 have demonstrated resistance against soybean mosaic virus and common cutworm, respectively. Genetic studies have identified quantitative trait loci (QTLs) including those linked with soybean cyst nematode, root-knot nematode and Phytophthora root and stem rot resistance. Additionally, resistance against Asian soybean rust and soybean cyst nematode involves specific genes and their variations in terms of different copy numbers. To address the challenges posed by evolving pathogens and meet the demands of a growing population, accelerated soybean breeding efforts leveraging functional genomics are imperative. Targeted breeding strategies based on a deeper understanding of soybean gene function and regulation will enhance disease resistance, ensuring sustainable agriculture and global food security. Collaborative research and continued technological advancements are crucial for securing a resilient and productive agricultural future. [ABSTRACT FROM AUTHOR]

Abstract Oomycetes are filamentous organisms that resemble fungi in terms of morphology and life cycle, primarily due to convergent evolution. The success of pathogenic oomycetes lies in their ability to adapt and overcome host resistance, occasionally transitioning to new hosts. During plant infection, these organisms secrete effector proteins and other compounds during plant infection, as a molecular arsenal that contributes to their pathogenic success. Genomic sequencing, transcriptomic analysis, and proteomic studies have revealed highly diverse effector repertoires among different oomycete pathogens, highlighting their adaptability and evolution potential. The obligate biotrophic oomycete Plasmopara viticola affects grapevine plants (Vitis vinifera L.) causing the downy mildew disease, with significant economic impact. This disease is devastating in Europe, leading to substantial production losses. Even though Plasmopara viticola is a well-known pathogen, to date there are scarce reviews summarising pathogenicity, virulence, the genetics and molecular mechanisms of interaction with grapevine. This review aims to explore the current knowledge of the infection strategy, lifecycle, effector molecules, and pathogenicity of Plasmopara viticola. The recent sequencing of the Plasmopara viticola genome has provided new insights into understanding the infection strategies employed by this pathogen. Additionally, we will highlight the contributions of omics technologies in unravelling the ongoing evolution of this oomycete, including the first in-plant proteome analysis of the pathogen.

The aim of this study was to evaluate the plant defence-promoting ability of various nematophagous fungi like Arthrobotrys oligospora, Paecilomyces lilacinus and Pleurotus sp. against root-knot nematode Meloidogyne incognita in tomato by determining the plant defence-promoting biomolecules, viz. hydrogen peroxide, superoxide dismutase, catalase, peroxidase and polyphenol oxidase. It was observed that soil application of A. oligospora along with farmyard manure (FYM) enhanced the activity of defence-related biomolecules from day 30 to day 60 after transplant, thereby showing its immense potential in controlling root-knot nematodes in tomatoes. The highest mean defence-related enzyme activity in plants was recorded in the treatment containing nematode-infested soil + FYM + A. oligospora with 97.65 enzyme unit (EU) mg-1 protein min-1 of hydrogen peroxide, 1.54 EU mg-1 protein min-1 of superoxide dismutase, 4.57 EU mg-1 protein min-1 of catalase, 9.45 EU mg-1 protein min-1 of peroxidase and 5.89 EU mg-1 protein min-1 of polyphenol oxidase. The gall production in nematode-infested soil had also reduced drastically after the application of the nematophagous fungi. [ABSTRACT FROM AUTHOR]

Summary: The jasmonic acid (JA) signalling pathway plays an important role in the establishment of the ectomycorrhizal symbiosis. The Laccaria bicolor effector MiSSP7 stabilizes JA corepressor JAZ6, thereby inhibiting the activity of Populus MYC2 transcription factors. Although the role of MYC2 in orchestrating plant defences against pathogens is well established, its exact contribution to ECM symbiosis remains unclear. This information is crucial for understanding the balance between plant immunity and symbiotic relationships.Transgenic poplars overexpressing or silencing for the two paralogues of MYC2 transcription factor (MYC2s) were produced, and their ability to establish ectomycorrhiza was assessed. Transcriptomics and DNA affinity purification sequencing were performed.MYC2s overexpression led to a decrease in fungal colonization, whereas its silencing increased it. The enrichment of terpene synthase genes in the MYC2‐regulated gene set suggests a complex interplay between the host monoterpenes and fungal growth. Several root monoterpenes have been identified as inhibitors of fungal growth and ECM symbiosis.Our results highlight the significance of poplar MYC2s and terpenes in mutualistic symbiosis by controlling root fungal colonization. We identified poplar genes which direct or indirect control by MYC2 is required for ECM establishment. These findings deepen our understanding of the molecular mechanisms underlying ECM symbiosis. [ABSTRACT FROM AUTHOR]

SUMMARY: The intercellular space or apoplast constitutes the main interface in plant–pathogen interactions. Apoplastic subtilisin‐like proteases—subtilases—may play an important role in defence and they have been identified as targets of pathogen‐secreted effector proteins. Here, we characterise the role of the Solanaceae‐specific P69 subtilase family in the interaction between tomato and the vascular bacterial wilt pathogen Ralstonia solanacearum. R. solanacearum infection post‐translationally activated several tomato P69s. Among them, P69D was exclusively activated in tomato plants resistant to R. solanacearum. In vitro experiments showed that P69D activation by prodomain removal occurred in an autocatalytic and intramolecular reaction that does not rely on the residue upstream of the processing site. Importantly P69D‐deficient tomato plants were more susceptible to bacterial wilt and transient expression of P69B, D and G in Nicotiana benthamiana limited proliferation of R. solanacearum. Our study demonstrates that P69s have conserved features but diverse functions in tomato and that P69D is involved in resistance to R. solanacearum but not to other vascular pathogens like Fusarium oxysporum. Significance Statement: The Solanaceae‐specific P69 subtilase family participates in the interaction between tomato and the vascular bacterial wilt pathogen Ralstonia solanacearum. [ABSTRACT FROM AUTHOR]

Plants employ a multilayered immune system to combat pathogens. In one layer, recognition of Pathogen‐ or Microbe‐Associated Molecular Patterns or elicitors, triggers a cascade that leads to defence against the pathogen and Pattern Triggered Immunity. Secondary or specialised metabolites (SMs) are expected to play a role, because they are potentially anti‐fungal compounds. Tomato (Solanum lycopersicum) plants inoculated with Alternaria solani s.l. show symptoms of infection after inoculation. Plants inoculated with Alternaria alternata remain symptomless. We hypothesised that pattern‐triggered induction of resistance related metabolites in tomato contributes to the resistance against A. alternata. We compared the metabolomic profile (metabolome) of tomato after treatments with A. alternata, A. solani and the fungal elicitor chitin, and identified SMs involved in early defence of tomato plants. We revealed differential metabolome fingerprints. The composition of A. alternata and chitin induced metabolomes show larger overlap with each other than with the A. solani induced metabolome. We identify 65 metabolites possibly associated with PTI in tomato plants, including NAD and trigonelline. We confirm that trigonelline inhibits fungal growth in vitro at physiological concentrations. Thus, a true pattern‐triggered, chemical defence is mounted against A. alternata, which contains anti‐fungal compounds that could be interesting for crop protection strategies. Summary statement: Using an untargeted metabolomics approach, comparing virulent, avirulent interactions and elicitor ‐treated samples, we identify new antifungal compounds in tomato that can be associated with pattern‐triggered immunity. [ABSTRACT FROM AUTHOR]

Despite substantial research examining caterpillar–plant interactions, changes in the feeding behaviour of lepidopteran larvae as they develop are poorly understood. In this study, we investigated ontogenetic changes in the behaviour of Helicoverpa armigera larvae feeding on reproductive structures of pigeonpea (Cajanus cajan). Specifically, we examined the preference for and avoidance of pigeonpea flowers and pods of first, second, third, and fourth instar H. armigera larvae. We also conducted a no-choice assay to compare the ability of third and fourth instar larvae to penetrate pigeonpea pod walls, which act as a physical defence against herbivory. When presented with a choice between pigeonpea pods and flowers, different instars behaved differently. First and second instar larvae largely avoided pigeonpea pods, instead feeding on flowers; third instar larvae initially avoided pods, but by 24 h, did not strongly discriminate between the structures; and fourth instars demonstrated a preference for pods. When initially placed on pods, first instars were slower than other instars to leave these structures, despite pods being suboptimal feeding sites for small caterpillars. We identified a clear instar-specific ability to penetrate through the pod wall to reach the seeds. Most third instar larvae were unable to penetrate the pod wall, whereas most fourth instars succeeded. Third instars suffered a physiological cost (measured by relative growth rate) when boring through the pod wall, which was not observed in fourth instars. Our study further illuminates the insect–plant interactions of the H. armigera–pigeonpea system and provides evidence for the significant changes in feeding behaviour that may occur during lepidopteran larval development. [ABSTRACT FROM AUTHOR]

Introduction: Tan Spot (TS) disease of wheat is caused by Pyrenophora tritici-repentis (Ptr), where most of the yield loss is linked to diseased flag leaves. As there are no fully resistant cultivars available, elucidating the responses of wheat to Ptr could inform the derivation of new resistant genotypes. Objectives: The study aimed to characterise the flag-leaf metabolomes of two spring wheat cultivars (Triticum aestivum L. cv. PF 080719 [PF] and cv. Fundacep Horizonte [FH]) following challenge with Ptr to gain insights into TS disease development. Methods: PF and FH plants were inoculated with a Ptr strain that produces the necrotrophic toxin ToxA. The metabolic changes in flag leaves following challenge (24, 48, 72, and 96 h post-inoculation [hpi]) with Ptr were investigated using untargeted flow infusion ionisation-high resolution mass spectroscopy (FIE-HRMS). Results: Both cultivars were susceptible to Ptr at the flag-leaf stage. Comparisons of Ptr- and mock-inoculated plants indicated that a major metabolic shift occurred at 24 hpi in FH, and at 48 hpi in PF. Although most altered metabolites were genotype specific, they were linked to common pathways; phenylpropanoid and flavonoid metabolism. Alterations in sugar metabolism as well as in glycolysis and glucogenesis pathways were also observed. Pathway enrichment analysis suggested that Ptr-triggered alterations in chloroplast and photosynthetic machinery in both cultivars, especially in FH at 96 hpi. In a wheat-Ptr interactome in integrative network analysis, “flavone and flavonol biosynthesis” and “starch and sucrose metabolism” were targeted as the key metabolic processes underlying PF–FH–Ptr interactions. Conclusion: These observations suggest the potential importance of flavone and flavonol biosynthesis as well as bioenergetic shifts in susceptibility to Ptr. This work highlights the value of metabolomic approaches to provide novel insights into wheat pathosystems. [ABSTRACT FROM AUTHOR]

Plants live in environments where they are constantly, and often simultaneously, exposed to different types of biotic and abiotic stress, such as insect herbivory and water availability. How plants are adapted to abiotic conditions may determine how a surplus or shortage of water affects plant resistance to insect herbivory. Moreover, this effect may vary depending on the feeding mode of the herbivore.We explored how three closely related Rorippa plant species that vary in adaptations to different water levels, resist herbivory by four different insects (aphids: Myzus persicae, Lipaphis erysimi, and caterpillars: Pieris brassicae, Plutella xylostella) under waterlogging or drought conditions. We hypothesized that plants that are differently adapted to water availability will be disparately affected by water availability in their resistance to insect herbivory.On the semi‐aquatic plant species Rorippa amphibia, both aphid species reached a larger colony size under drought conditions. This indicates that R. amphibia was compromised in resistance to aphid feeding when under drought conditions, to which it is less well adapted. Water conditions did not affect aphid performance on the flood‐plain species Rorippa palustris. On the terrestrial plant species Rorippa sylvestris, aphids performed worse on waterlogged than drought‐treated plants. Neither caterpillar species was significantly affected by the water availability of their food plant.Our findings suggest that water availability can have distinct effects on plant–insect interactions. We propose that plant adaptations to water conditions can be a major predictor towards explaining the variation of effects that water availability can have on plant–insect interactions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Powdery mildew in grapevine is caused by Erysiphe necator and its control requires many chemical treatments. Numerous efforts are being made to improve disease management to achieve crop sustainability goals. The exogenous induction of plant immune responses is one of the most encouraging strategies currently being developed. The objective of this research was to analyse differences in phenolic compound concentrations in E. necator‐infected leaves of two varieties of Vitis vinifera, Tempranillo and Tempranillo Blanco, using ultra performance liquid chromatography coupled with mass spectrometry. To understand the susceptibility of the varieties, in vitro assays using whole leaves were done. RESULTS: Differences in susceptibility between varieties were found in the early stage of the disease. In both varieties, total phenolic compounds were higher in infected leaves; however, hydroxycinnamic acid, anthocyanins and stilbenes were higher only in Tempranillo. Twenty‐six compounds showed differential responses to the fungal disease in Tempranillo, but only two in Tempranillo Blanco: syringa resinol, which was not detected in diseased leaves; and gallocatechin, which increased at 5 days post inoculation. In Tempranillo, four anthocyanidins, six hydroxycinnamic acids, mainly feruloyl derivates, and epigallocatechin gallate were higher in infected leaves at the beginning of the infection, whereas (−)‐epicatechin and protocatechuic hexoside contents were lower. CONCLUSION: Disease‐induced changes in phenolic compound biosynthesis were found. The increase in anthocyanidin content and flavan‐3‐ol galloylation could have a role in delaying E. necator growth in Tempranillo. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Plant metabolism is a key feature of biodiversity that remains underexploited in functional frameworks used in agroecology. Here, we study how phytochemical diversity considered at three organizational levels can promote pest control. In a factorial field experiment, we manipulated plant diversity in three monocultures and three mixed crops of oilseed rape to explore how intra- and interspecific phytochemical diversity affects pest infestation. We combined recent progress in metabolomics with classic metrics used in ecology to test a box of hypotheses grounded in plant defence theory. According to the hypothesis of ‘phytochemically mediated coevolution’, our study stresses the relationships between herbivore infestation and particular classes of specialized metabolites like glucosinolates. Among 178 significant relationships between metabolites and herbivory rates, only 20% were negative. At the plant level, phytochemical abundance and richness had poor predictive power on pest regulation. This challenges the hypothesis of ‘synergistic effects’. At the crop cover level, in line with the hypothesis of ‘associational resistance’, the phytochemical dissimilarity between neighbouring plants limited pest infestation. We discuss the intricate links between associational resistance and bottom-up pest control. Bridging different levels of organization in agroecosystems helps to dissect the multi-scale relationships between phytochemistry and insect herbivory.

Pectobacterium atrosepticum (Pba) is a gram-negative bacterium that causes blackleg and tuber soft rot of potato but can also asymptomatically colonise other (non-host) plant species. The aim of this study was to investigate the molecular processes and responses involved in Pba-host (potato) and Pba-non-host (radish) interactions, under laboratory conditions. To achieve this, we used total mRNA-sequencing to measure the gene expression patterns from all three species: Pba, potato and radish. We employed an end-point dual transcriptome approach. We used hydroponically grown potato (Solanum tuberosum var. Estima) and oil radish (Raphanus sativa var. Bento) roots inoculated with Pba SCRI1039 for 14 days compared to un-inoculated control plants or cultured bacteria. Total RNA was extracted from replicates of the two plant species and the bacterium using a Macherey-Nagel Nucleospin Plant RNA kit. The RNA from the 17 samples was then subjected to total mRNA-sequencing (paired-end) on an Illumina NovaSeq 6000™ sequencing platform. This gave between 39.2-58.1M reads per sample. The high-quality reads obtained were mapped to the corresponding reference genomes using Bowtie2 and the percentages of bacterium and plant transcripts calculated. This dataset constitutes the raw read fastq files and can be used to inform on genes active in plant rhizosphere-microbe interactions.

Necrogenic Gram-negative bacterium Erwinia amylovora, which causes economic losses especially in pome fruits such as apple, pear, quince and loquat, some berries and many ornamental plants, causes fire blight disease. Copper compounds are used extensively in disease control programs and they can cause toxicproblems in terms of plant and environmental health. In addition, the formation of resistance to copper in the pathogen is frequently observed. In this study, plant activator phosphorous acid and biological control agent Bacillus subtilis, and 3 different copper compounds, Copper sulfate, Copper oxychloride and Copper hydroxide which are commonly used against E. amylovora, on apple cv. Gala with M9 rootstock were evaluated comparatively. When the new season shoot lengths of 3-year-old plants with homogeneous growth reached 20-25 cm, chemicals and B. subtilis were applied first time before one week ago from the pathogen inoculation, and after 2 times with 1 week intervals. The youngest two leaves at tips of actively growing terminal plant shoots were inoculated by cutting off using scissors dipped in suspension of E. amylovora str. EaARADY5 containing 108 CFU ml-1. Disease assessments were made after the disease severity (%) was determined on the basis of shoot blight after symptom development of the disease stopped, and the results were found to be statistically significant (p

Secondary metabolites (SMs) play vital roles in plant defence mechanisms, adaptation to environmental conditions, and interactions with other organisms. Biotic and abiotic stress factors can significantly influence the production, accumulation, and composition of SMs in plants. Understanding the intricate relationship between stress and SM production is crucial for enhancing plant resilience, agricultural productivity, and the development of novel phytopharmaceuticals. This research provides current knowledge regarding the impact of biotic and also abiotic stress on SMs in plants. Biotic stress factors such as pathogen infection, and herbivore attacks, as well as abiotic stress factors like drought, along with temperature extremes, and also salinity, can profoundly influence the biosynthesis and accumulation of SMs in plants. We discussed the methodology based on secondary sources underlying physiological, biochemical, and molecular mechanisms involved in stress-induced SM synthesis and highlight the potential implications for plant biology, agriculture, and human health. The study also emphasizes the functions of SMs in plants including defence against herbivores, pathogens, and abiotic stresses. The mechanism by which these compounds act as allelochemicals and signalling molecules is also discussed. [ABSTRACT FROM AUTHOR]

The phenylalanine ammonia‐lyase (PAL) enzyme catalyses the conversion of l‐phenylalanine to trans‐cinnamic acid. This conversion is the first step in phenylpropanoid biosynthesis in plants. The phenylpropanoid pathway produces diverse plant metabolites that play essential roles in various processes, including structural support and defence. Previous studies have shown that mutation of the PAL genes enhances disease susceptibility. Here, we investigated the functions of the rice PAL genes using 2‐aminoindan‐2‐phosphonic acid (AIP), a strong competitive inhibitor of PAL enzymes. We show that the application of AIP can significantly reduce the PAL activity of rice crude protein extracts in vitro. However, when AIP was applied to intact rice plants, it reduced infection of the root‐knot nematode Meloidogyne graminicola. RNA‐seq showed that AIP treatment resulted in a rapid but transient upregulation of defence‐related genes in roots. Moreover, targeted metabolomics demonstrated higher levels of jasmonates and antimicrobial flavonoids and diterpenoids accumulating after AIP treatment. Furthermore, chemical inhibition of the jasmonate pathway abolished the effect of AIP on nematode infection. Our results show that disturbance of the phenylpropanoid pathway by the PAL inhibitor AIP induces defence in rice against M. graminicola by activating jasmonate‐mediated defence. [ABSTRACT FROM AUTHOR]

The carnivorous plants in the order Caryophyllales co-opted jasmonate signalling from plant defence to botanical carnivory. However, carnivorous plants have at least 11 independent origins, and here we ask whether jasmonate signalling has been co-opted repeatedly in different evolutionary lineages. We experimentally wounded and fed the carnivorous plants Sarracenia purpurea (order Ericales), Cephalotus follicularis (order Oxalidales), Drosophyllum lusitanicum (order Caryophyllales), and measured electrical signals, phytohormone tissue level, and digestive enzymes activity. Coronatine was added exogenously to confirm the role of jasmonates in the induction of digestive process. Immunodetection of aspartic protease and proteomic analysis of digestive fluid was also performed. We found that prey capture induced accumulation of endogenous jasmonates only in D. lusitanicum , in accordance with increased enzyme activity after insect prey or coronatine application. In C. follicularis , the enzyme activity was constitutive while in S. purpurea was regulated by multiple factors. Several classes of digestive enzymes were identified in the digestive fluid of D. lusitanicum. Although carnivorous plants from different evolutionary lineages use the same digestive enzymes, the mechanism of their regulation differs. All investigated genera use jasmonates for their ancient role, defence, but jasmonate signalling has been co-opted for botanical carnivory only in some of them. [ABSTRACT FROM AUTHOR]

The brown marmorated stink bug (BMSB; Halyomorpha halys Stål.) is a highly destructive and polyphagous invasive pest that poses a serious threat to more than a hundred reported host plants. In the current study, the metabolic response of peach fruit of two cultivars—'Maria Marta' and 'Redhaven'—to BMSB infestation was studied using high-performance liquid chromatography (HPLC) and mass spectrometry (MS). In general, a strong phenolic response to BMSB infestation in peach flesh in the injury zone was observed, with flavanol content increasing by 2.4-fold, hydroxycinnamic acid content by 5.0-fold, flavonol content by 3.2-fold, flavanone content by 11.3-fold, and dihydrochalcones content by 3.2-fold compared with the undamaged tissue in the cultivar 'Maria Marta'. The phenolic response in the 'Redhaven' cultivar was even stronger. Consequently, the total phenolic content in the injured flesh also increased, 3.3-fold in 'Maria Marta' and 6.9-fold in 'Redhaven', compared with the uninjured flesh. Infestation with BMSB induced the synthesis of cyanidin-3-glucoside, which is not normally present in peach flesh. In comparison, the phenolic response was lower in peach peel, especially in the cultivar 'Maria Marta'. The study showed that both peach cultivars reacted to BMSB infestation with an increase in phenolic content in the peach flesh, but in a limited area of injury. [ABSTRACT FROM AUTHOR]

Plum fruit moth, Grapholita funebrana is one of the most important plum (Prunus domestica) pests. This project was carried from 2019 to 2021 to screen 26 cultivars and promising genotypes of plum in terms of pest larvae feeding tolerance index. The percentage of injury and the larvae population were measured every ten days until the end of October during the activity period of larvae. Then the biological stress sensitivity index was calculated. Time series models were used to investigate the correlation between injury percentage and larval population density, and the cluster analysis method was used to separate cultivars and genotypes based on tolerance index. The degree of influence of different fruit characters on tolerance was investigated by calculating Spearman's correlation coefficient. The results showed that the maximum effective day-larva index in the study years was in late July to early August. The values of cross correlation coefficient in Ghalo and Sosormi cultivars had maximum and minimum values, respectively. Finally, Queen Roza and Anjelo were the most sensitive, and Qomi, Gholaman, Faryar, G-Black, Zojlo, Gallo, G-100, G98, G99, Mortini, Black Amber and Kermanshah were the most tolerant cultivars to plum moth. Fruit surface area, sphericity index, average diameter of fruit engineering, fruit size index, fruit length and width had positive and significant correlation with tolerance indices. The results of this research are part of the breeding program of plum cultivars to develop the cultivation of this product in the country. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) threatens natural ecosystems globally. While ALAN research is increasing, little is known about how ALAN affects plants and interactions with other organisms. We explored the effects of ALAN on plant defence and plant–insect interactions using barley (Hordeum vulgare) and the English grain aphid (Sitobion avenae). Plants were exposed to 'full' or 'part' nights of 15–20 lux ALAN, or no ALAN 'control' nights, to test the effects of ALAN on plant growth and defence. Although plant growth was only minimally affected by ALAN, aphid colony growth and aphid maturation were reduced significantly by ALAN treatments. Importantly, we found strong differences between full-night and part-night ALAN treatments. Contrary to our expectations, part ALAN had stronger negative effects on aphid colony growth than full ALAN. Defence-associated gene expression was affected in some cases by ALAN, but also positively correlated with aphid colony size, suggesting that the effects of ALAN on plant defences are indirect, and regulated via direct disruption of aphid colonies rather than via ALAN-induced upregulation of defences. Mitigating ecological side effects of ALAN is a complex problem, as reducing exposure to ALAN increased its negative impact on insect herbivores. This article is part of the theme issue 'Light pollution in complex ecological systems'. [ABSTRACT FROM AUTHOR]

The Southeastern Coastal Hinterland geomorphic province of South Africa is dissected by deep valleys created by tectonic uplift in the early Miocene and late Miocene/early Pliocene. We hypothesised that seedlings of Vachellia nilotica, V. tortilis and V. karroo grown from seeds from different valleys would differ in growth and spinescence because of geographical separation. Ninety seedlings (30 per species) were grown for 3 months in uniform conditions in a greenhouse. Mean height of V. nilotica and V. tortilis seedlings was greatest for the Phongolo populations and lowest for the Thukela populations. Maximum stem diameter of both species was attained by individuals from the Phongolo population. Mean spine dry mass of V. nilotica seedlings was greatest for the Phongolo population, suggesting a growth‐defence trade‐off, but did not differ for V. tortilis. Results suggested that Phongolo populations of V. nilotica and V. tortilis may be characterised by morphotypes clearly distinct from those in the other valleys. Unclear and inconsistent results for V. karroo in this study suggested subtly different morphotypes occur in each valley. We propose that distinct Phongolo morphotypes of V. nilotica and V. tortilis are explained as evolutionary adaptations to moderate fire and high browsing pressure compared to populations South of Phongolo. [ABSTRACT FROM AUTHOR]

Summary: Glucosinolate content in the two major oilseed Brassica crops—rapeseed and mustard has been reduced to the globally accepted Canola quality level (<30 μmoles/g of seed dry weight, DW), making the protein‐rich seed meal useful as animal feed. However, the overall lower glucosinolate content in seeds as well as in the other parts of such plants renders them vulnerable to biotic challenges. We report CRISPR/Cas9‐based editing of glucosinolate transporter (GTR) family genes in mustard (Brassica juncea) to develop ideal lines with the desired low seed glucosinolate content (SGC) while maintaining high glucosinolate levels in the other plant parts for uncompromised plant defence. Use of three gRNAs provided highly efficient and precise editing of four BjuGTR1 and six BjuGTR2 homologues leading to a reduction of SGC from 146.09 μmoles/g DW to as low as 6.21 μmoles/g DW. Detailed analysis of the GTR‐edited lines showed higher accumulation and distributional changes of glucosinolates in the foliar parts. However, the changes did not affect the plant defence and yield parameters. When tested against the pathogen Sclerotinia sclerotiorum and generalist pest Spodoptera litura, the GTR‐edited lines displayed a defence response at par or better than that of the wild‐type line. The GTR‐edited lines were equivalent to the wild‐type line for various seed yield and seed quality traits. Our results demonstrate that simultaneous editing of multiple GTR1 and GTR2 homologues in mustard can provide the desired low‐seed, high‐leaf glucosinolate lines with an uncompromised defence and yield. [ABSTRACT FROM AUTHOR]

Abstract Background The dark septate endophytes (DSE) are endophytic and non-mycorrhizal fungi with the ability to impact and control some plant pathogens and promote plant growth. The aim of this study was to investigate the effectiveness of five different DSE fungal isolates in controlling white root rot disease (WRRD) caused by the plant pathogen, Rigidoporus microporus in Hevea brasiliensis in a nursery system. There are no previous reports on the role of DSE in controlling WRRD. In this study, the efficacy of five DSE isolates, including Acrocalymma vagum SBTBMDS 1, Clonostachys chloroleuca TMDS 2.1, Lasiodiplodia theobromae APDS 3.2, Penicillium oxalicum TMDS 3.2, and Fusarium falciforme TBMDS 2.4b, was tested for their ability to reduce the severity of WRRD in vivo. Results The results showed that all the DSE isolates were able to inhibit R. microporus, leading to a decrease in the disease severity of WRRD, with percentages ranging from 7.50 to 17.5% and percentage of disease inhibition from 57.67 to 83.33% than the controls, which had a severity percentage of 45%. The TMDS3.2 isolate showed high efficacy in increasing the girth (137%) and height (63.3%) of H. brasiliensis seedlings, while the isolates of P. oxalicum TMDS 3.2 and F. falciforme TMDS 2.4b enhanced the dry weight (123 and 122%, respectively) than the control. Two isolates of P. oxacilum TMDS 3.2 and C. chloroleuca TMDS 2.1 increased the root volume (120 and 107%, respectively) than the control. Gas chromatography–mass spectrometry (GC–MS) analysis showed the ability of three selected DSE isolates, L. theobromae APDS 3.2, F. falciforme TBMDS 2.4b, and P. oxacilum TMDS 3.2, to produce acetic acid butyl methyl-phosphinoylmethyl ester and ethanone, 1-(4-methyl-1H(imidazol-2-yl)—that previously reported as antimicrobials. Conclusion This study demonstrated that DSE fungal isolates had the potential to act as a biocontrol agent against R. microporus in H. Brasiliensis seedlings. In the future, the findings of this study could be utilized to prevent WRRD, one of the most serious problems in rubber plantations, in an environmentally friendly way by reducing the usage of fungicides.

Plants have evolved to establish insect herbivory defences by modulating their metabolism, growth, and development. Precise networks of phytohormones are essential to induce those herbivory defences. Gaseous phytohormone ET plays an important role in forming herbivory defences. Its role in insect herbivory is not fully understood, but previous studies have shown that it can both positively and negatively regulate herbivory. This review presents recent findings on crosstalk between ET and other phytohormones in herbivory responses. Additionally, the use of exogenous ETH treatment to induce ET in response to herbivory is discussed.

The accumulation of silicon (Si) is widely reported to have anti‐herbivore defensive properties in grasses. There is emerging, but fragmentary, evidence that Si could play a similar role in legumes.Here, we sought to understand the effects of Si supplementation on anti‐herbivore defensive properties in lucerne (Medicago sativa), especially in relation to other potential defences (i.e. phenolics) and the phytohormone that regulates anti‐herbivore defences, jasmonic acid or jasmonate (JA), which is also linked to Si accumulation.We determined how growth, root nodulation and chemistry (carbon, nitrogen and phenolic concentrations) of four genotypes of lucerne responded to Si supplementation, with and without the application of JA, and we used feeding assays to determine the subsequent effects on the feeding success of adult Sitona discoideus weevils.Si supplementation increased plant mass and root nodulation of M. sativa by 61% and 227%, respectively, and reduced relative consumption (RC) and frass production by S. discoideus by 38% and 30% respectively. Si supplementation had no effect on foliar nitrogen concentrations, most likely due to the dilution effects of increased plant growth and foliar carbon. Phenolic concentrations were negatively correlated with leaf RC; RC also decreased by 34% when JA was applied to plants. When Si was combined with JA application, phenolics were significantly enhanced, demonstrating the potential to stimulate multiple anti‐herbivore properties in M. sativa. Overall, the Si‐ and JA‐induced phytochemical and herbivore feeding responses were consistent between the four lucerne genotypes tested.Synthesis. The novel findings suggest that Si accumulation may play a more important role in legume resistance to herbivorous animals than previously thought. The ubiquity of soil Si and its emerging functional role in plant biology, including plant–animal interactions, suggest that these patterns could be common among legumes. [ABSTRACT FROM AUTHOR]

A central goal in ecology is to understand the mechanisms by which biological diversity is maintained. The diversity of plant chemical defences and the strategies by which they are deployed in nature may influence biological diversity. Trees in neotropical forests are subject to relatively high herbivore pressure. Such consistent pressure is thought to select for constitutive, non‐flexible defence‐related phytochemistry with limited capacity for inducible phytochemical responses. However, this has not been explored for volatile organic compounds (VOCs) that have a relatively low ratio of production costs to ecological benefits. To test this, I sampled VOCs emitted from canopy leaves of 10 phylogenetically diverse tree species (3 Magnoliids and 7 Rosids) in the Peruvian Amazon before and after induction with the phytohormone methyl jasmonate (MeJA). There was no phylogenetic signal in induction or magnitude of MeJA‐induced VOC emissions from intact leaves: all trees induced VOC profiles dominated by β‐ocimene, linalool, and α‐farnesene of varying ratios. Moreover, overall inducibility of VOCs from intact leaves was unrelated to phytochemical diversity or richness. In contrast, experimentally wounded leaves showed considerable phylogeny‐based and MeJA‐independent variation the richness and diversity of constitutive wound‐emitted VOCs. Moreover, VOC inducibility from wounded leaves correlated negatively with phytochemical richness and diversity, potentially indicating a tradeoff in constitutive and inducible defence strategies for non‐volatile specialised metabolites but not for inducible VOCs. Importantly, there was no correlation between any chemical profile and either natural herbivory or leaf toughness. The coexistence of multiple phytochemical strategies in a hyper‐diverse forest has broad implications for competitive and multitrophic interactions, and the evolutionary forces that maintain the exceptional plant biodiversity in neotropical forests. Summary Statement: Ten phylogenetically diverse, sympatric tree species in a neotropical forest maintain a phylogeny‐independent ability for oxylipin‐mediated signal cascades and inducible volatile emissions, inducing three dominant terpenes and species‐specific minor volatile compounds from intact leaves. [ABSTRACT FROM AUTHOR]

Background: The dark septate endophytes (DSE) are endophytic and non-mycorrhizal fungi with the ability to impact and control some plant pathogens and promote plant growth. The aim of this study was to investigate the effectiveness of five different DSE fungal isolates in controlling white root rot disease (WRRD) caused by the plant pathogen, Rigidoporus microporus in Hevea brasiliensis in a nursery system. There are no previous reports on the role of DSE in controlling WRRD. In this study, the efficacy of five DSE isolates, including Acrocalymma vagum SBTBMDS 1, Clonostachys chloroleuca TMDS 2.1, Lasiodiplodia theobromae APDS 3.2, Penicillium oxalicum TMDS 3.2, and Fusarium falciforme TBMDS 2.4b, was tested for their ability to reduce the severity of WRRD in vivo. Results: The results showed that all the DSE isolates were able to inhibit R. microporus, leading to a decrease in the disease severity of WRRD, with percentages ranging from 7.50 to 17.5% and percentage of disease inhibition from 57.67 to 83.33% than the controls, which had a severity percentage of 45%. The TMDS3.2 isolate showed high efficacy in increasing the girth (137%) and height (63.3%) of H. brasiliensis seedlings, while the isolates of P. oxalicum TMDS 3.2 and F. falciforme TMDS 2.4b enhanced the dry weight (123 and 122%, respectively) than the control. Two isolates of P. oxacilum TMDS 3.2 and C. chloroleuca TMDS 2.1 increased the root volume (120 and 107%, respectively) than the control. Gas chromatography–mass spectrometry (GC–MS) analysis showed the ability of three selected DSE isolates, L. theobromae APDS 3.2, F. falciforme TBMDS 2.4b, and P. oxacilum TMDS 3.2, to produce acetic acid butyl methyl-phosphinoylmethyl ester and ethanone, 1-(4-methyl-1H(imidazol-2-yl)—that previously reported as antimicrobials. Conclusion: This study demonstrated that DSE fungal isolates had the potential to act as a biocontrol agent against R. microporus in H. Brasiliensis seedlings. In the future, the findings of this study could be utilized to prevent WRRD, one of the most serious problems in rubber plantations, in an environmentally friendly way by reducing the usage of fungicides. [ABSTRACT FROM AUTHOR]

Plant strategies against herbivores are classically divided into chemical, physical, biotic defences. However, little is known about the relative importance of each type of plant defence, especially in the same species. Using the myrmecophyte Triplaris americana (both with and without ants), and the congeneric non-myrmecophyte T. gardneriana, we tested whether ant defence is more effective than other defences of naturally ant-free myrmecophytes and the non-myrmecophyte congeneric species, all spatially co-occurring. In addition, we investigated how plant traits vary among plant groups, and how these traits modulate herbivory. We sampled data on leaf area loss and plant traits from these tree groups in the Brazilian Pantanal floodplain, and found that herbivory is sixfold lower in plants with ants than in ant-free plants, supporting a major role of biotic defences against herbivory. Whereas ant-free plants had more physical defences (sclerophylly and trichomes), they had little effect on herbivory—only sclerophylly modulated herbivory, but with opposite effects depending on ants' presence and species identity. Despite little variation in the chemicals among plant groups, tannin concentrations and δ13C signatures negatively affected herbivory in T. americana plants with ants and in T. gardneriana, respectively. We showed that ant defence in myrmecophytic systems is the most effective against herbivory, as the studied plants could not fully compensate the lack of this biotic defence. We highlight the importance of positive insect-plant interactions in limiting herbivory, and therefore potentially plant fitness. [ABSTRACT FROM AUTHOR]

Background and aimsWe investigate patterns of evolution of genome size across a morphologically and ecologically diverse clade of Brassicaceae, in relation to ecological and life history traits. While numerous hypotheses have been put forward regarding autecological and environmental factors that could favour small vs. large genomes, a challenge in understanding genome size evolution in plants is that many hypothesized selective agents are intercorrelated.MethodsWe contribute genome size estimates for 47 species of Streptanthus Nutt. and close relatives, and take advantage of many data collections for this group to assemble data on climate, life history, soil affinity and composition, geographic range and plant secondary chemistry to identify simultaneous correlates of variation in genome size in an evolutionary framework. We assess models of evolution across clades and use phylogenetically informed analyses as well as model selection and information criteria approaches to identify variables that can best explain genome size variation in this clade.Key resultsWe find differences in genome size and heterogeneity in its rate of evolution across subclades of Streptanthus and close relatives. We show that clade-wide genome size is positively associated with climate seasonality and glucosinolate compounds. Model selection and information criteria approaches identify a best model that includes temperature seasonality and fraction of aliphatic glucosinolates, suggesting a possible role for genome size in climatic adaptation or a role for biotic interactions in shaping the evolution of genome size. We find no evidence supporting hypotheses of life history, range size or soil nutrients as forces shaping genome size in this system.ConclusionsOur findings suggest climate seasonality and biotic interactions as potential forces shaping the evolution of genome size and highlight the importance of evaluating multiple factors in the context of phylogeny to understand the effect of possible selective agents on genome size.

Despite substantial research examining caterpillar–plant interactions, changes in the feeding behaviour of lepidopteran larvae as they develop are poorly understood. In this study, we investigated ontogenetic changes in the behaviour of Helicoverpa armigera larvae feeding on reproductive structures of pigeonpea (Cajanus cajan). Specifically, we examined the preference for and avoidance of pigeonpea flowers and pods of first, second, third, and fourth instar H. armigera larvae. We also conducted a no-choice assay to compare the ability of third and fourth instar larvae to penetrate pigeonpea pod walls, which act as a physical defence against herbivory. When presented with a choice between pigeonpea pods and flowers, different instars behaved differently. First and second instar larvae largely avoided pigeonpea pods, instead feeding on flowers; third instar larvae initially avoided pods, but by 24 h, did not strongly discriminate between the structures; and fourth instars demonstrated a preference for pods. When initially placed on pods, first instars were slower than other instars to leave these structures, despite pods being suboptimal feeding sites for small caterpillars. We identified a clear instar-specific ability to penetrate through the pod wall to reach the seeds. Most third instar larvae were unable to penetrate the pod wall, whereas most fourth instars succeeded. Third instars suffered a physiological cost (measured by relative growth rate) when boring through the pod wall, which was not observed in fourth instars. Our study further illuminates the insect–plant interactions of the H. armigera–pigeonpea system and provides evidence for the significant changes in feeding behaviour that may occur during lepidopteran larval development.

A study published in the Plant Biotechnology Journal explores the use of immune-enhancing microRNA-encoded peptides (miPEPs) to combat plant diseases and improve crop yields. The researchers identified 17 miPEPs that decreased the expression of a gene associated with plant defense responses, and three miPEPs that increased its expression. These miPEPs were found to decrease fungal colonization in Arabidopsis thaliana plants without directly harming the fungi. The study also demonstrated that the miPEPs were effective in reducing the incidence of Botrytis cinerea infection in strawberry, bean, and tomato plants. Field trials with tomato plants treated with a specific miPEP showed a 35% improvement in crop yields. The research highlights the potential of miPEPs as an alternative to chemical fungicides in agriculture. [Extracted from the article]

A major goal in ecology is understanding the factors which determine the diversity and distribution of organisms. The outcome of the symbiotic relationship between plants and arbuscular mycorrhizal (AM) fungi is strongly influenced by soil phosphorus (P) availability. Despite this knowledge, there is still much to uncover about how soil P status can shape the taxonomic and phylogenetic assembly of root‐colonising AM fungi. Additionally, there is a paucity of understanding about the implications of these changes for the outcome of the AM symbiosis in terms of plant growth, nutrient status and defence traits.We conducted a factorial pot experiment where sorghum (Sorghum bicolor) was grown under three different P treatments (low, medium and high), in the presence or absence of a natural AM fungal community. By analysing the diversity and community structure of the fungal community colonising roots, we aimed to determine if and how soil P influences the relatedness of these communities and whether competitive exclusion or environmental filtering play a more significant role in their assembly. Additionally, we evaluated the concomitant outcomes for plant growth, nutrient acquisition and defensive chemistry (phenolics).Increasing P availability reduced AM fungal richness and increased community evenness. Root‐colonising AM fungal communities under the high P treatment had significantly reduced phylogenetic diversity and comparatively lower mean pairwise distances among all treatments. This indicated that AM fungal communities became more closely related (phylogenetically clustered) with increasing soil P. The mycorrhizal growth and mycorrhizal P responses of plants were positive under low and medium P, but this was lost under high P, however, plant phenolics were increased.Our results suggest that under high P conditions, environmental filtering plays an important role in AM fungal community assembly as host plants alter their selectivity of fungal functional groups prioritising those associated with enhancing plant stress resistance and defences, rather than nutrient acquisition. Here we demonstrated how soil P status can shape taxonomic and phylogenetic assembly of AM fungi and the associated functional outcomes for the host. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The studies of the long-term effects of insect infestations on plant anti-herbivore defences tend to focus on feeding-induced damage. Infestations by an entire insect generation, including egg depositions as well as the feeding insects, are often neglected. Whilst there is increasing evidence that the presence of insect eggs can intensify plants' anti-herbivore defences against hatching larvae in the short term, little is known about how insect infestations, including insect egg depositions, affect plant defences in the long term. We addressed this knowledge gap by investigating long-term effects of insect infestation on elm's (Ulmus minor Mill. cv. 'Dahlem') defences against subsequent infestation. In greenhouse experiments, elms were exposed to elm leaf beetle (ELB, Xanthogaleruca luteola) infestation (adults, eggs and larvae). Thereafter, the trees cast their leaves under simulated winter conditions and were re-infested with ELB after the regrowth of their leaves under simulated summer conditions. Elm leaf beetles performed moderately worse on previously infested elms with respect to several developmental parameters. The concentrations of the phenylpropanoids kaempferol and quercetin, which are involved in egg-mediated, short-term effects on elm defences, were slightly higher in the ELB-challenged leaves of previously infested trees than in the challenged leaves of naïve trees. The expression of several genes involved in the phenylpropanoid pathway, jasmonic acid signalling, and DNA and histone modifications appeared to be affected by ELB infestation; however, prior infestation did not alter the expression intensities of these genes. The concentrations of several phytohormones were similarly affected in the currently challenged leaves of previously infested trees and naïve trees. Our study shows that prior infestation of elms by a specialised insect leads to moderately improved defences against subsequent infestation in the following growing season. Prior infestation adds a long-term effect to the short-term enhancer effect that plants show in response to egg depositions when defending against hatching larvae. [ABSTRACT FROM AUTHOR]

Aims: Soil-borne pathogens severely damage the yield and quality of crops worldwide. Plant and soil microbiomes (e.g. in the rhizosphere) intimately interact with the plant, the pathogen and influence outcomes of disease infection. Investigation of how these microbiomes respond to disease infection is critical to develop solutions to control diseases. Methods: Here, we conducted a field experiment and collected healthy and crown rot disease infected (caused by Fusarium pseudograminearum, Fp) wheat plants. We investigated their microbiomes in different compartments, plant immune responses and interactions with the pathogen (Fp) aiming at advancing our knowledge on microbiome-mediated regulation of plant responses to pathogens. Results: We found that Fp colonised wheat plants significantly in terms of relative abundances, accounting for 11.3% and 60.7% of the fungal communities in the rhizosphere and roots, respectively. However, Fp presented with a small fraction of the leaf microbiome, up to 1.2%. Furthermore, Fp-infection led to significant changes in the composition of microbiomes in the rhizosphere and root while had little impact on leaves. We further found that wheat defence signalling pathways, microbiomes and the pathogen intimately correlated with each other in structural equation modelling. As such, we also identified ecological clusters explained changes in the wheat defence signalling pathways. Lastly, microbial co-occurrence network complexity was higher in Fp-infected plants relative to healthy plants, suggesting that Fp-infection may have led to changes in the wheat microbial community structure. Conclusions: We provide novel evidence that soil-borne diseases disrupt belowground plant microbiomes influencing the responses of plant immunity to pathogens. [ABSTRACT FROM AUTHOR]

Aim: Attempts over the past 30 years to explain geographical variation in the strength of herbivore pressure have given rise to ecological hypotheses like the latitudinal herbivory hypothesis. This hypothesis, however, has rarely been tested using community‐level data. Therefore, the aim of our study was to examine the patterns and potential mechanisms underlying geographical variation in community‐wide herbivory. Location: The Qinghai‐Tibetan Plateau. Time Period: July 2021. Major Taxa Studied: Plants. Methods: We selected 43 grassland sites along a 1500‐km latitudinal gradient (c. 27°N to 39°N) and a 2698‐m elevational gradient (1886–4584 m) on the Qinghai‐Tibetan Plateau. We evaluated geographical patterns in invertebrate herbivory pressure at the population and community levels, while also evaluating the importance of geographical variation in mediating the effects of abiotic and biotic factors on intraspecific variation (through changes in herbivory on component species) and species turnover effects (through changes in plant community composition). Results: Community‐wide herbivory decreased with latitude, mirroring intraspecific variation, while species turnover effects did not vary along any tested geographical gradients. Furthermore, we found that geographical variation in community‐wide herbivory was strongly positively correlated with soil nitrogen content. We also found a positive effect of soil nitrogen content on intraspecific variation and a negative effect of plant community biomass on species turnover effects. Main Conclusions: The latitudinal gradient in community‐wide herbivory was primarily mediated by intraspecific variation, which was in turn associated with a gradient in soil nitrogen content. Our findings highlight the need for community‐wide assessments of geographical variation in plant–herbivore interactions, decomposing community‐wide herbivory into intraspecific variation and species turnover effects. [ABSTRACT FROM AUTHOR]