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1.
Sci Rep ; 11(1): 20500, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34654848

RESUMO

Pesticides and pathogens are known drivers of declines in global entomofauna. However, interactions between pesticides and viruses, which could range from antagonistic, over additive to synergistic, are poorly understood in ants. Here, we show that in ants the impact of single and combined pesticide and virus stressors can vary across castes and at the colony level. A fully-crossed laboratory assay was used to evaluate interactions between a sublethal dose of the neonicotinoid thiamethoxam and Acute bee paralysis virus (ABPV) in black garden ants, Lasius niger. After monitoring colonies over 64 weeks, body mass, neonicotinoid residues and virus titres of workers and queens, as well as worker behavioural activity were measured. ABPV, but not thiamethoxam, reduced activity of workers. Neonicotinoid exposure resulted in reduced body mass of workers, but not of queens. Further, thiamethoxam facilitated ABPV infections in queens, but not in workers. Overall, virus exposure did not compromise detoxification and body mass, but one colony showed high virus titres and worker mortality. Although the data suggest additive effects at the level of individuals and castes, co-exposure with both stressors elicited antagonistic effects on colony size. Our results create demand for long-term holistic risk assessment of individual stressors and their interactions to protect biodiversity.

2.
Plant Cell Environ ; 44(12): 3502-3514, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34505297

RESUMO

Plant-soil feedbacks refer to effects on plants that are mediated by soil modifications caused by the previous plant generation. Maize conditions the surrounding soil by secretion of root exudates including benzoxazinoids (BXs), a class of bioactive secondary metabolites. Previous work found that a BX-conditioned soil microbiota enhances insect resistance while reducing biomass in the next generation of maize plants. Whether these BX-mediated and microbially driven feedbacks are conserved across different soils and response species is unknown. We found the BX-feedbacks on maize growth and insect resistance conserved between two arable soils, but absent in a more fertile grassland soil, suggesting a soil-type dependence of BX feedbacks. We demonstrated that wheat also responded to BX-feedbacks. While the negative growth response to BX-conditioning was conserved in both cereals, insect resistance showed opposite patterns, with an increase in maize and a decrease in wheat. Wheat pathogen resistance was not affected. Finally and consistent with maize, we found the BX-feedbacks to be cultivar-specific. Taken together, BX-feedbacks affected cereal growth and resistance in a soil and genotype-dependent manner. Cultivar-specificity of BX-feedbacks is a key finding, as it hides the potential to optimize crops that avoid negative plant-soil feedbacks in rotations.

3.
New Phytol ; 232(6): 2491-2505, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34510462

RESUMO

Plants are able to detect insect eggs deposited on leaves. In Arabidopsis, eggs of the butterfly species Pieris brassicae (common name large white) induce plant defenses and activate the salicylic acid (SA) pathway. We previously discovered that oviposition triggers a systemic acquired resistance (SAR) against the bacterial hemibiotroph pathogen Pseudomonas syringae. Here, we show that insect eggs or treatment with egg extract (EE) induce SAR against the fungal necrotroph Botrytis cinerea BMM and the oomycete pathogen Hyaloperonospora arabidopsidis Noco2. This response is abolished in ics1, ald1 and fmo1, indicating that the SA pathway and the N-hydroxypipecolic acid (NHP) pathway are involved. Establishment of EE-induced SAR in distal leaves potentially involves tryptophan-derived metabolites, including camalexin. Indeed, SAR is abolished in the biosynthesis mutants cyp79B2 cyp79B3, cyp71a12 cyp71a13 and pad3-1, and camalexin is toxic to B. cinerea in vitro. This study reveals an interesting mechanism by which lepidopteran eggs interfere with plant-pathogen interactions.

4.
J Chromatogr A ; 1655: 462507, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34487880

RESUMO

Pesticide metabolites are frequently detected in groundwater at concentrations often exceeding those of their parent pesticides. A well-known example is the metabolites of chlorothalonil, a non-systematic, broad spectrum fungicide. Some of the chlorothalonil metabolites occur frequently and at elevated concentrations in groundwater, which is why the use of chlorothalonil was recently banned in the European Union. To estimate the long-term evolution of the concentration of the chlorothalonil metabolites in groundwater after this ban, it is important to know if metabolite residues in soil and unsaturated zone can affect the concentrations in groundwater. We developed and validated a method for the determination of 5 chlorothalonil metabolites in soil (R471811, R417888, SYN507900, SYN548580 and R611968), including those which are frequently detected in groundwater. The developed protocols, based on a solid phase extraction approach (for R471811, R417888, SYN507900, SYN548580) or a QuEChERS approach (for R611968) followed by UHPLC-MS/MS analysis, provided excellent sensitivity (LOQ of 0.5 µg/kg for all metabolites), precision (RSD<10 % at low, medium and high concentrations) and accuracy (84-115 %). In addition, we developed a simple but highly sensitive (LOQ of 5-10 ng/L) direct-injection method for the analysis of these 5 metabolites in water to compare their occurrence in soil and groundwater. The application of these methods to agricultural soil samples and groundwater samples showed that the detection frequency of the 5 chlorothalonil metabolites in soil and groundwater seems to be inversed and dependent on their sorption coefficient. The latter might control the amount of the chlorothalonil metabolites which is retained in the soil or which leaches towards groundwater. Our results provide insights to estimate the retention of the different chlorothalonil metabolites in soil and unsaturated zone and therefore, to assess the influence of the soil and unsaturated zone on the long-term concentration evolution of these metabolites in groundwater.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Nitrilas , Solo , Espectrometria de Massas em Tandem , Água , Poluentes Químicos da Água/análise
5.
Front Plant Sci ; 12: 709858, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34413869

RESUMO

In response to herbivore attack, plants release large amounts of volatiles that can serve as attractants for the natural enemies of the attacking herbivores. Such responses are typically triggered by damage- and insect-associated factors. Cotton plants are somewhat peculiar because they release specific blends of volatiles in two waves in response to caterpillar attack. They first emit constitutively stored volatile compounds, and after about 24 h a second wave that includes various de novo synthesized compounds. The relative importance of damage-associated and insect associated-factors in this induction of cotton volatile emissions is not yet fully clear. We evaluated how cotton plants respond to mechanical damage and to the application of the oral secretion from the generalist lepidopteran pest Spodoptera exigua, by measuring the local and systemic emissions of volatile compounds from their leaves. Our results confirm that cotton plants respond to damage-associated molecular patterns (DAMPs) as well as to herbivore-associated molecular patterns (HAMPs) present in the caterpillars' oral secretion. Interestingly, a stronger response was observed for cotton plants that were treated with oral secretion from cotton-fed caterpillars than those fed on maize. We tested the possibility that volicitin, a common fatty acid-derived elicitor in caterpillar regurgitant plays a role in this difference. Volicitin and volicitin-like compounds were detected in equal amounts in the oral secretion of S. exigua fed on either cotton or maize leaves. We conclude that other elicitors must be involved. The identification of these eliciting cues is expected to contribute to the development of novel strategies to enhance the resistance of cotton plants to insect pests.

6.
Plants (Basel) ; 10(8)2021 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-34451771

RESUMO

Viscum album L., commonly known as European mistletoe, is a hemi-parasitic plant of the Santalaceae family. The in vitro and in vivo effects of V. album differ, according to its host tree. However, little is known about the host-dependent phytochemical diversity in V. album. In this study, the metabolic profiles of V. album ssp. album from Malus domestica Bork., Quercus robur L., and Ulmus carpinifolia Gled were compared. Leaves, stems, and berries were collected in Switzerland, by the same procedure, in September 2016 and 2017. The methanolic extracts were analyzed by ultra-performance liquid chromatography, coupled to electrospray quadrupole time-of-flight mass spectrometry in positive ionization mode. The data were submitted to partial-least square discriminant analysis (PLS-DA) and the results showed that the V. album ssp. album samples were clustered into three groups, according to the three distinct host trees. Seven compounds, with high VIP scores (variable importance in projection), were responsible for this differentiation. The following four compounds were detected in both the harvest years: arginine, pipecolic acid or lysine, dimethoxycoumarin, and sinapyl alcohol, suggesting their use as host specific V. album biomarkers. The present work highlights the importance of standardized harvest and analytical procedures for the reproducibility of the chemical results of herbal materials.

7.
Plant Physiol Biochem ; 166: 950-957, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34247109

RESUMO

Durable disease resistance genes such as the wheat gene Lr34 are valuable sources of resistance for agricultural breeding programs. Lr34 encodes an ATP-binding cassette transporter protein involved in the transport of the phytohormone abscisic acid. Lr34 from wheat is functionally transferable to barley, maize, rice and sorghum. A pleiotropic effect of Lr34 induces the development of a senescence-like phenotype, referred to as leaf tip necrosis. We used Lr34-expressing wheat and transgenic barley plants to elucidate the role of abscisic acid in the development of leaf tip necrosis. Leaf tips in Lr34-expressing wheat and barley showed an accumulation of abscisic acid. No increase of Lr34 expression was detected in the leaf tip. Instead, the development of ectopic, Lr34-induced leaf tip necrosis after removing the leaf tip suggests an increased flux of abscisic acid towards the tip, where it accumulates and mediates the development of leaf tip necrosis. This redistribution of abscisic acid was also observed in adult transgenic barley plants with a high Lr34 expression level growing in the field and coincided with leaf tip necrosis as well as complete field resistance against Puccinia hordei and Blumeria graminis f. sp. hordei. In a barley transgenic line with a lower Lr34 expression level, a quantitative resistance against Puccinia hordei was still observed, but without a significant redistribution of abscisic acid or apparent leaf tip necrosis. Thus, our results imply that fine-tuning the Lr34 expression level is essential to balance disease resistance versus leaf tip necrosis to deploy transgenic Lr34 in breeding programs.


Assuntos
Basidiomycota , Hordeum , Ácido Abscísico , Ascomicetos , Resistência à Doença/genética , Hordeum/genética , Melhoramento Vegetal , Doenças das Plantas/genética , Folhas de Planta/genética , Triticum/genética
8.
Horm Behav ; 135: 105034, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34320418

RESUMO

Despite widespread interest in the evolution of cooperative behaviour, the physiological mechanisms shaping their expression remain elusive. We tested the hypothesis that glucocorticoid (GC) hormones affect cooperative behaviour using captive Damaraland mole-rats (Fukomys damarensis), a cooperatively breeding mammal. Within groups, individuals routinely contribute to public goods that include foraging tunnels, which provide all group members access to the tubers of desert plants they feed on, communal food stores and nests. We found that experimental increases in glucocorticoid concentration (GCc) in non-breeding female helpers led them to be active for longer and to burrow more while active, raising their daily contributions to burrowing, but not food carrying or nest building. However, experimentally induced increases in burrowing did not lead to elevated GCc in helpers of both sexes. These results suggest that heightened GCc may stimulate some cooperative behaviours that are energetically demanding (a characteristic shared by many types of cooperative activities across species) but that the cooperative behaviours affected by GCc can also be regulated by other mechanisms.


Assuntos
Glucocorticoides , Ratos-Toupeira , Animais , Comportamento Cooperativo , Feminino , Masculino , Comportamento Sexual Animal
9.
Mass Spectrom Rev ; 2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34145627

RESUMO

In recent years, metabolomics has emerged as a pivotal approach for the holistic analysis of metabolites in biological systems. The rapid progress in analytical equipment, coupled to the rise of powerful data processing tools, now provides unprecedented opportunities to deepen our understanding of the relationships between biochemical processes and physiological or phenotypic conditions in living organisms. However, to obtain unbiased data coverage of hundreds or thousands of metabolites remains a challenging task. Among the panel of available analytical methods, targeted and untargeted mass spectrometry approaches are among the most commonly used. While targeted metabolomics usually relies on multiple-reaction monitoring acquisition, untargeted metabolomics use either data-independent acquisition (DIA) or data-dependent acquisition (DDA) methods. Unlike DIA, DDA offers the possibility to get real, selective MS/MS spectra and thus to improve metabolite assignment when performing untargeted metabolomics. Yet, DDA settings are more complex to establish than DIA settings, and as a result, DDA is more prone to errors in method development and application. Here, we present a tutorial which provides guidelines on how to optimize the technical parameters essential for proper DDA experiments in metabolomics applications. This tutorial is organized as a series of rules describing the impact of the different parameters on data acquisition and data quality. It is primarily intended to metabolomics users and mass spectrometrists that wish to acquire both theoretical background and practical tips for developing effective DDA methods.

10.
Plant Cell Physiol ; 62(6): 959-970, 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34037236

RESUMO

Most land plants entertain a mutualistic symbiosis known as arbuscular mycorrhiza with fungi (Glomeromycota) that provide them with essential mineral nutrients, in particular phosphate (Pi), and protect them from biotic and abiotic stress. Arbuscular mycorrhizal (AM) symbiosis increases plant productivity and biodiversity and is therefore relevant for both natural plant communities and crop production. However, AM fungal populations suffer from intense farming practices in agricultural soils, in particular Pi fertilization. The dilemma between natural fertilization from AM symbiosis and chemical fertilization has raised major concern and emphasizes the need to better understand the mechanisms by which Pi suppresses AM symbiosis. Here, we test the hypothesis that Pi may interfere with AM symbiosis via the phytohormone gibberellic acid (GA) in the Solanaceous model systems Petunia hybrida and Nicotiana tabacum. Indeed, we find that GA is inhibitory to AM symbiosis and that Pi may cause GA levels to increase in mycorrhizal roots. Consistent with a role of endogenous GA as an inhibitor of AM development, GA-defective N. tabacum lines expressing a GA-metabolizing enzyme (GA methyltransferase-GAMT) are colonized more quickly by the AM fungus Rhizoglomus irregulare, and exogenous Pi is less effective in inhibiting AM colonization in these lines. Systematic gene expression analysis of GA-related genes reveals a complex picture, in which GA degradation by GA2 oxidase plays a prominent role. These findings reveal potential targets for crop breeding that could reduce Pi suppression of AM symbiosis, thereby reconciling the advantages of Pi fertilization with the diverse benefits of AM symbiosis.


Assuntos
Giberelinas/metabolismo , Micorrizas/fisiologia , Petunia/fisiologia , Fosfatos/metabolismo , Tabaco/fisiologia , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/microbiologia , Plantas Geneticamente Modificadas , Transdução de Sinais , Simbiose
11.
Plant Cell Environ ; 44(8): 2672-2686, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33748996

RESUMO

Plant leaves that are exposed to herbivore-induced plant volatiles (HIPVs) respond by increasing their defenses, a phenomenon referred to as priming. Whether this phenomenon also occurs in the roots is unknown. Using maize plants, Zea mays, whose leaves respond strongly to leaf HIPVs, we measured the impact of belowground HIPVs, emanating from roots infested by the banded cucumber beetle, Diabrotica balteata, on constitutive and herbivore-induced levels of defense-related gene expression, phytohormones, volatile and non-volatile primary and secondary metabolites, growth and herbivore resistance in roots of neighbouring plants. HIPV exposure did not increase constitutive or induced levels of any of the measured root traits. Furthermore, HIPV exposure did not reduce the performance or survival of D. balteata on maize or its ancestor teosinte. Cross-exposure experiments between HIPVs from roots and leaves revealed that maize roots, in contrast to maize leaves, neither emit nor respond strongly to defense-regulating HIPVs. Together, these results demonstrate that volatile-mediated defense regulation is restricted to the leaves of maize. This finding is in line with the lower diffusibility of volatiles in the soil and the availability of other, potentially more efficient, information conduits below ground.

12.
Nat Commun ; 12(1): 956, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33574268

RESUMO

Plasma membrane-associated and intracellular proteins and protein complexes play a pivotal role in pathogen recognition and disease resistance signaling in plants and animals. The two predominant protein families perceiving plant pathogens are receptor-like kinases and nucleotide binding-leucine-rich repeat receptors (NLR), which often confer race-specific resistance. Leaf rust is one of the most prevalent and most devastating wheat diseases. Here, we clone the race-specific leaf rust resistance gene Lr14a from hexaploid wheat. The cloning of Lr14a is aided by the recently published genome assembly of ArinaLrFor, an Lr14a-containing wheat line. Lr14a encodes a membrane-localized protein containing twelve ankyrin (ANK) repeats and structural similarities to Ca2+-permeable non-selective cation channels. Transcriptome analyses reveal an induction of genes associated with calcium ion binding in the presence of Lr14a. Haplotype analyses indicate that Lr14a-containing chromosome segments were introgressed multiple times into the bread wheat gene pool, but we find no variation in the Lr14a coding sequence itself. Our work demonstrates the involvement of an ANK-transmembrane (TM)-like type of gene family in race-specific disease resistance in wheat. This forms the basis to explore ANK-TM-like genes in disease resistance breeding.


Assuntos
Repetição de Anquirina/genética , Resistência à Doença/genética , Genes de Plantas/genética , Proteínas de Membrana/genética , Doenças das Plantas/genética , Triticum/genética , Basidiomycota/patogenicidade , Regulação da Expressão Gênica de Plantas , Pool Gênico , Inativação Gênica , Haplótipos , Mutagênese , Melhoramento Vegetal , Proteínas de Plantas/genética , Tabaco/genética
13.
Elife ; 102021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33629953

RESUMO

Light triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Using Serial Block Face Scanning Electron Microscopy (SBF-SEM), we generated a series of chloroplast 3D reconstructions during differentiation, revealing chloroplast number and volume and the extent of envelope and thylakoid membrane surfaces. Furthermore, we used quantitative lipid and whole proteome data to complement the (ultra)structural data, providing a time-resolved, multi-dimensional description of chloroplast differentiation. This showed two distinct phases of chloroplast biogenesis: an initial photosynthesis-enabling 'Structure Establishment Phase' followed by a 'Chloroplast Proliferation Phase' during cell expansion. Moreover, these data detail thylakoid membrane expansion during de-etiolation at the seedling level and the relative contribution and differential regulation of proteins and lipids at each developmental stage. Altogether, we establish a roadmap for chloroplast differentiation, a critical process for plant photoautotrophic growth and survival.

14.
Proc Natl Acad Sci U S A ; 118(3)2021 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-33431671

RESUMO

To cope with environmental challenges, plants produce a wide diversity of phytochemicals, which are also the source of numerous medicines. Despite decades of research in chemical ecology, we still lack an understanding of the organization of plant chemical diversity across species and ecosystems. To address this challenge, we hypothesized that molecular diversity is not only related to species diversity, but also constrained by trophic, climatic, and topographical factors. We screened the metabolome of 416 vascular plant species encompassing the entire alpine elevation range and four alpine bioclimatic regions in order to characterize their phytochemical diversity. We show that by coupling phylogenetic information, topographic, edaphic, and climatic variables, we predict phytochemical diversity, and its inherent composition, of plant communities throughout landscape. Spatial mapping of phytochemical diversity further revealed that plant assemblages found in low to midelevation habitats, with more alkaline soils, possessed greater phytochemical diversity, whereas alpine habitats possessed higher phytochemical endemism. Altogether, we present a general tool that can be used for predicting hotspots of phytochemical diversity in the landscape, independently of plant species taxonomic identity. Such an approach offers promising perspectives in both drug discovery programs and conservation efforts worldwide.


Assuntos
Metaboloma , Compostos Fitoquímicos/classificação , Plantas/química , Plantas/classificação , Altitude , Biodiversidade , Clima , Conservação dos Recursos Naturais/métodos , Descoberta de Drogas/métodos , Ecossistema , Europa (Continente) , Concentração de Íons de Hidrogênio , Filogenia , Compostos Fitoquímicos/biossíntese , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Plantas/genética , Plantas/metabolismo , Solo/química , Temperatura
15.
Plant Cell Environ ; 44(4): 1165-1177, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-32996129

RESUMO

Upon herbivore attack, plants emit herbivore-induced plant volatiles (HIPVs). HIPVs can prime defences and resistance of intact plants. However, how HIPVs are decoded and translated into functional defence responses is not well understood, especially in long-lived woody plants. Here, we investigated the impact of the aromatic HIPV indole on defence-related early signalling, phytohormone accumulation, secondary metabolite biosynthesis and herbivore resistance in tea plants. We find that tea plants infested with tea geometrid caterpillars release indole at concentrations >450 ng*hr-1 . Exposure to corresponding doses of synthetic indole primes the expression of early defence genes involved in calcium (Ca2+ ) signalling, MPK signalling and jasmonate biosynthesis. Indole exposure also primes the production of jasmonates and defence-related secondary metabolites. These changes are associated with higher herbivore resistance of indole-exposed tea plants. Chemical inhibition of Ca2+ and jasmonate signalling provides evidence that both are required for indole-mediated defence priming and herbivore resistance. Our systematic assessment of the impact of indole on defence signalling and deployment shows that indole acts by boosting Ca2+ signalling, resulting in enhanced jasmonate-dependent defence and resistance in a woody plant. Our work extends the molecular basis of HIPV-induced defence priming from annual plants to an economically important tree species.


Assuntos
Camellia sinensis/metabolismo , Indóis/farmacologia , Defesa das Plantas contra Herbivoria , Transdução de Sinais , Animais , Camellia sinensis/efeitos dos fármacos , Camellia sinensis/fisiologia , Catequina/metabolismo , Hidroxibenzoatos/metabolismo , Larva , Mariposas , Defesa das Plantas contra Herbivoria/efeitos dos fármacos , Reguladores de Crescimento de Plantas/metabolismo , Metabolismo Secundário/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transcriptoma , Compostos Orgânicos Voláteis/metabolismo
16.
New Phytol ; 229(3): 1755-1767, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-32981048

RESUMO

Biologists still strive to identify the ecological and evolutionary drivers of phytochemical variation that mediate biotic interactions. We hypothesized that plant species growing at sites characterized by high herbivore pressure would converge to produce highly toxic blends of secondary metabolites, independent of phylogenetic constraints. To address the role of shared evolutionary history and ecological niches in driving variation in plant phytochemistry, we combined targeted metabolomics with insect herbivore bioassays and with a set of growth-related traits of several Cardamine species growing along the entire elevational gradient of the Alps. We observed that Cardamine phytochemical profiles grouped according to previously established growth form categorizations within specific abiotic conditions, independently of phylogenetic relationship. We also showed that novel indices summarizing functional phytochemical diversity better explain plant resistance against chewing and sap-feeding herbivores than classic diversity indices. We conclude that multiple functional axes of phytochemical diversity should be integrated with the functional axis of plant growth forms to study phenotypic convergence along large-scale ecological gradients.


Assuntos
Herbivoria , Insetos , Animais , Filogenia , Compostos Fitoquímicos , Plantas
17.
New Phytol ; 229(6): 3481-3496, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33231304

RESUMO

The intimate association of host and fungus in arbuscular mycorrhizal (AM) symbiosis can potentially trigger induction of host defence mechanisms against the fungus, implying that successful symbiosis requires suppression of defence. We addressed this phenomenon by using AM-defective vapyrin (vpy) mutants in Petunia hybrida, including a new allele (vpy-3) with a transposon insertion close to the ATG start codon. We explore whether abortion of fungal infection in vpy mutants is associated with the induction of defence markers, such as cell wall alterations, accumulation of reactive oxygen species (ROS), defence hormones and induction of pathogenesis-related (PR) genes. We show that vpy mutants exhibit a strong resistance against intracellular colonization, which is associated with the generation of cell wall appositions (papillae) with lignin impregnation at fungal entry sites, while no accumulation of defence hormones, ROS or callose was observed. Systematic analysis of PR gene expression revealed that several PR genes are induced in mycorrhizal roots of the wild-type, and even more in vpy plants. Some PR genes are induced exclusively in vpy mutants. Our results suggest that VPY is involved in avoiding or suppressing the induction of a cellular defence syndrome that involves localized lignin deposition and PR gene induction.


Assuntos
Micorrizas , Petunia , Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lignina , Micorrizas/genética , Petunia/genética , Raízes de Plantas , Simbiose
18.
Sci Total Environ ; 757: 143822, 2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33246718

RESUMO

Synthetic pesticides such as neonicotinoids are commonly used to treat crops in tropical regions, where data on environmental and human contamination are patchy and make it difficult to assess to what extent pesticides may harm human health, especially in less developed countries. To assess the degree of environmental and human contamination with neonicotinoids we collected soil, water and people's hair in three agricultural regions of the Philippines and analysed them by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS-MS). Five neonicotinoids, namely acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam were targeted. Residues of neonicotinoids were found in 78% of 67 soil samples from the three provinces. Total neonicotinoid loads ranged on average between 0.017 and 0.89 µg/kg in soils of rice, banana and vegetable crops, and were 130 times higher (113.5 µg/kg) in soils of a citrus grove. Imidacloprid was the most prevalent compound at an average of 0.56 µg/kg in soil while thiacloprid was below the limit of detection. Half of the eight water samples from a rice field and nearby creek contained residues of imidacloprid (mean 1.29 ng/L) and one contained thiamethoxam (0.15 ng/L). Residues of neonicotinoids were found in 81% of 99 samples of people's hair from the surveyed regions (average total concentrations 0.14 to 1.18 ng/g, maximum 350 ng/g). Hair residue levels correlated well with the concentrations of thiamethoxam and total residues in soils from the same locality (r = 0.98). The presence of thiacloprid in 15% of the hair samples but not in soil samples suggests an additional route of exposure among people, which is most likely to be through ingestion of agricultural food and drinks available in the market.


Assuntos
Inseticidas , Solo , Humanos , Inseticidas/análise , Neonicotinoides , Nitrocompostos , Filipinas , Água
19.
Horm Behav ; 128: 104910, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33309816

RESUMO

In cooperatively breeding cichlid fish, the early social environment has lifelong effects on the offspring's behaviour, life-history trajectories and brain gene expression. Here, we asked whether the presence or absence of parents and subordinate helpers during early life also shapes fluctuating levels of cortisol, the major stress hormone in the cichlid Neolamprologus pulcher. To non-invasively characterize baseline and stress-induced cortisol levels, we adapted the 'static' holding-water method often used to collect waterborne steroid hormones in aquatic organisms by including a flow-through system allowing for repeated sampling without handling of the experimental subjects. We used 8-year-old N. pulcher either raised with (+F) or without (-F) parents and helpers in early life. We found that N. pulcher have a peak of their circadian cortisol cycle in the early morning, and that they habituated to the experimental procedure after four days. Therefore, we sampled the experimental fish in the afternoon after four days of habituation. -F fish had significantly lower baseline cortisol levels, whereas stress-induced cortisol levels did not differ between treatments. Thus, we show that the early social environment has life-long effects on aspects of the physiological stress system of the Hypothalamic-Pituitary-Interrenal (HPI) axis. We discuss how these differences in physiological state may have contributed to the specialization in different social and life-history trajectories of this species.


Assuntos
Ciclídeos , Hidrocortisona , Animais , Cruzamento , Meio Social , Estresse Fisiológico
20.
Science ; 370(6523): 1469-1473, 2020 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-33335062

RESUMO

Herbivory and plant defenses exhibit a coupled decline along elevation gradients. However, the current ecological equilibrium could be disrupted under climate change, with a faster upward range shift of animals than plants. Here, we experimentally simulated this upward herbivore range shift by translocating low-elevation herbivore insects to alpine grasslands. We report that the introduction of novel herbivores and increased herbivory disrupted the vertical functional organization of the plant canopy. By feeding preferentially on alpine plants with functional traits matching their low-elevation host plants, herbivores reduced the biomass of dominant alpine plant species and favored encroachment of herbivore-resistant small-stature plant species, inflating species richness. Supplementing a direct effect of temperature, novel biotic interactions represent a neglected but major driver of ecosystem modifications under climate change.


Assuntos
Mudança Climática , Pradaria , Herbivoria , Plantas , Animais , Biomassa , Espécies Introduzidas
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