Insect–Plant Interactions: A Multilayered Relationship

2020 ◽  
Author(s):  
Garima Sharma ◽  
Praful Ashokrao Malthankar ◽  
Vartika Mathur
Keyword(s):  
Plant Resistance ◽  
Crucial Role ◽  
Chemical Cues ◽  
Defense Responses ◽  
Trophic Levels ◽  
Plant Interactions ◽  
Plant Metabolites ◽  
Specific Chemical ◽  
Plant Interaction ◽  
Morphological Defense

Abstract During herbivory, insects recognize their host plant based on specific chemical cues, whereas the plants induce various chemical and morphological defense responses to resist this attack. However, the seemingly bidirectional insect–plant interaction involves various confounding aspects that influence the performance and fitness of the two participants. These interactions are often mediated by associated microbiota, competitors, predators, and parasitoids that interact in either obligate or facultative manner. Insect endosymbionts play a crucial role in the perception, nutrition, metabolism as well as reproduction of their host, which together determine its survival and fitness on the plant. Endosymbionts also help their host to overcome plant defenses by detoxifying plant metabolites. On the contrary, plant-associated microbes contribute in induced systemic plant resistance by enhancing chemical and morphological defense. These interactions determine the association of insect and plant, not only with the high trophic levels but also with the ecosystem as a whole. Thus, insect–plant interaction is a multilayered relationship extending to various micro- and macro-organisms associated either temporally or spatially. All these relationships may be considered to obtain a wholesome perspective of the natural environment.

scholarly journals Morphological and Molecular Analyses of Host and Nonhost Interactions Involving Barley and Wheat and the Covered Smut Pathogen Ustilago hordei

2010 ◽  
Vol 23 (12) ◽  
pp. 1619-1634 ◽  
Author(s):  
Denis A. Gaudet ◽  
Yuanyuan Wang ◽  
Carolyn Penniket ◽  
Z. X. Lu ◽  
Guus Bakkeren ◽  
...  
Keyword(s):  
Lipid Transfer Protein ◽  
Expression Patterns ◽  
Fluorescent Microscopy ◽  
Defense Responses ◽  
Lipid Transfer ◽  
Defense Gene Expression ◽  
Basal Resistance ◽  
Morphological Defense ◽  
Pathway Expression ◽  
Ustilago Hordei

Ustilago hordei interactions on coleoptiles of barley host cultivars Odessa (compatible), Hannchen (incompatible, carrying the Ruh1 resistance gene), and on nonhost Neepawa wheat were studied using light and fluorescent microscopy. Autofluorescence, mainly caused by callose accumulation, was more rapidly expressed in nonhost wheat at 30 to 72 h compared with the incompatible reaction between 72 and 144 h. Microarray results demonstrated that more than half of the 893 differentially regulated genes were observed in Neepawa; of these genes, 45% fell into the defense- and stress-related classes in Neepawa compared with 25 and 37% in Odessa and Hannchen, respectively. Their expression coincided with the early morphological defense responses observed and were associated with the jasmonic acid and ethylene (JA/ET) signaling pathway. Expression patterns in Odessa and Hannchen were similar, involving fewer genes and coinciding with later morphological defense responses of these varieties. Although no visible hypersensitive response was apparent in Hannchen or Neepawa, specific upregulation of hypersensitivity-related proteins was observed, such as beta-VPE at 48 h. Expression levels of the callose synthase gene were closely associated with callose accumulation. Differential responses in defense-gene expression among disease reaction types included upregulation of PR-1.1b and downregulation of a nonspecific lipid transfer protein in the incompatible and compatible interactions, respectively. Transcript levels of EDS1 and PAD4, involved in both basal resistance and R-mediated resistance to avirulent pathogens, were up-regulated during both nonhost and Ruh1-mediated resistance. Application of methyl-jasmonate, salicylic acid and ET to leaves revealed that only PR1.1b is strongly up-regulated by all three compounds, while the majority of the defense-related genes are only slightly up-regulated by these signaling compounds.

scholarly journals A small cysteine-rich phytotoxic protein of Phytophthora capsici functions as both plant defense elicitor and virulence factor

2021 ◽  
Author(s):  
Zi-Hui Zhang ◽  
Jinghao Jin ◽  
Gui-Lin Sheng ◽  
Yu-Ping Xing ◽  
Wang Liu ◽  
...  
Keyword(s):  
Plant Defense ◽  
Virulence Factor ◽  
Phytophthora Capsici ◽  
Ectopic Expression ◽  
Defense Responses ◽  
Phytophthora Species ◽  
Plant Interactions ◽  
Defense Gene Expression ◽  
Callose Deposition ◽  
Defense Gene

Small cysteine-rich (SCR) proteins including fungal avirulence proteins play important roles in the pathogen-plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens, but their functions during the pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein, namely SCR82 with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologues of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially scr82 was weakly expressed during the mycelium, sporangium and zoospore stages, but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses including the induction of defense gene expression, reactive oxygen species burst and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and reduced significantly its resistance againstoxidative stress. Inversely, its overexpression increased the pathogen’s virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora species.

scholarly journals Inducible morphological defense in Daphnia pulex: food quantity effects revised

2020 ◽  
Author(s):  
Sandra Klintworth ◽  
Eric von Elert
Keyword(s):  
Chemical Cues ◽  
Daphnia Pulex ◽  
Food Concentration ◽  
Bacterial Degradation ◽  
Inducible Defenses ◽  
Chemical Cue ◽  
High Food ◽  
Food Quantity ◽  
Morphological Defense ◽  
Food Concentrations

Abstract In aquatic systems, organisms largely rely on chemical cues to perceive information about the presence of predators or prey. Daphnia recognize the presence of the predatory larvae of Chaoborus via a chemical cue, emitted by the larvae, a so-called kairomone. Upon recognition, neckteeth, an alteration of the carapace, are induced in Daphnia that reduce predation rates of Chaoborus. Neckteeth induction was often reported to entail costs. In a previous study, food quantity affected the level of neckteeth induction, with stronger neckteeth induction at low food concentrations and weak induction at high food concentrations. However, reducing neckteeth induction at high food quantities seems to be maladaptive and not in accordance with the concept that inducible defenses are associated with costs. Here, we hypothesized that weaker neckteeth induction at high food concentrations is caused by increased bacterial degradation of the kairomone. More specifically, we assume that higher algal food concentration is associated with higher bacterial abundances, which degrade the kairomone during the experiment. We tested our hypothesis by treating food algae with antibiotics before providing them as food to Daphnia. Antibiotics reduced bacterial abundances at high and low food concentrations. Reduced bacterial abundances at high food concentrations led to the same level of neckteeth induction as at low food concentrations. A linear regression revealed a significant correlation of neckteeth induction to bacterial abundances. We therefore conclude that differences in neckteeth induction at different food concentrations are not caused by the food quantity effects but by differences in bacterial degradation of the kairomone.

scholarly journals Aqueous Garlic Extract as a Plant Biostimulant Enhances Physiology, Improves Crop Quality and Metabolite Abundance, and Primes the Defense Responses of Receiver Plants

2018 ◽  
Vol 8 (9) ◽  
pp. 1505 ◽  
Author(s):  
Sikandar Hayat ◽  
Husain Ahmad ◽  
Muhammad Ali ◽  
Kashif Hayat ◽  
Muhammad Khan ◽  
...  
Keyword(s):  
Foliar Application ◽  
Fungal Infections ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Defense Responses ◽  
Garlic Extract ◽  
Control Treatment ◽  
Antioxidant Systems ◽  
Plant Metabolites ◽  
Crop Quality

Biostimulants are the next-generation choice for sustainable agricultural production and are gradually becoming an alternative to synthetic chemicals. Various botanicals are proposed to exert stimulatory effects, and garlic allelochemicals are among such botanicals; however, a peer-reviewed scientific evaluation is required to understand garlic-derived substances such as biostimulants. Current studies were therefore performed to identify the bioactivity of garlic extract as a biostimulant to improve crop quality, alter its physiological potential, and prime its defense responses against pathogenic fungal infections. 100 µg mL−1 aqueous garlic extracts (AGE) in consort with 1 mM of acetyl salicylic acid (ASA) and distilled water as a control treatment were applied to eggplant and pepper seedlings as foliar application and fertigation methods. The results revealed stimulatory responses in the growth of the vegetables with improved plant height, number of leaves, root growth, fresh and dry weight, etc., due to AGE and ASA applications. Moreover, significant alterations were indicated in plant metabolites such as chlorophyll, carotenoids, and soluble sugars. Additionally, stimulation of the antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD), as well as the root activity of these plants, was observed after treatment. Application of AGE and ASA also exerted priming effects on pepper plants, inducing defense responses prior to Phytopthora capsici inoculation, and the treated plants therefore successfully resisted infection through activated antioxidant systems, and probably carotenoid and other protectory metabolites. Stress-induced H2O2 content was extremely low in the treated plants, indicating successful resistance against pathogenic infection.

scholarly journals Epigenetic and Metabolic Changes in Root-Knot Nematode-Plant Interactions

2020 ◽  
Vol 21 (20) ◽  
pp. 7759
Author(s):  
Paola Leonetti ◽  
Sergio Molinari
Keyword(s):  
Plant Resistance ◽  
Gene Activation ◽  
Plant Interactions ◽  
Root Knot Nematode ◽  
Methyl Transferase ◽  
Over Expression ◽  
Defense Enzyme ◽  
Anti Oxidant ◽  
Total Dna ◽  
Plant Resistance Gene

Two wild-type field populations of root-knot nematodes (Mi-Vfield, Mj-TunC2field), and two isolates selected for virulence in laboratory on resistant tomato cultivars (SM2V, SM11C2), were used to induce a resistance reaction in tomato to the soil-borne parasites. Epigenetic and metabolic mechanisms of resistance were detected and compared with those occurring in partially or fully successful infections. The activated epigenetic mechanisms in plant resistance, as opposed to those activated in infected plants, were detected by analyzing the methylated status of total DNA, by ELISA methods, and the expression level of key genes involved in the methylation pathway, by qRT-PCR. DNA hypo-methylation and down-regulation of two methyl-transferase genes (CMT2, DRM5), characterized the only true resistant reaction obtained by inoculating the Mi-1.2-carrying resistant tomato cv Rossol with the avirulent field population Mi-Vfield. On the contrary, in the roots into which nematodes were allowed to develop and reproduce, total DNA was generally found to be hyper-methylated and methyl-transferase genes up-loaded. DNA hypo-methylation was considered to be the upstream mechanism that triggers the general gene over-expression observed in plant resistance. Gene silencing induced by nematodes may be obtained through DNA hyper-methylation and methyl-transferase gene activation. Plant resistance is also characterized by an inhibition of the anti-oxidant enzyme system and activation of the defense enzyme chitinase, as opposed to the activation of such a system and inhibition of the defense enzyme glucanase in roots infested by nematodes.

scholarly journals Hormone Signaling and Its Interplay With Development and Defense Responses in Verticillium-Plant Interactions

2020 ◽  
Vol 11 ◽  
Author(s):  
Nikhilesh Dhar ◽  
Jie-Yin Chen ◽  
Krishna V. Subbarao ◽  
Steven J. Klosterman
Keyword(s):  
Defense Responses ◽  
Hormone Signaling ◽  
Plant Interactions

Insect—plant interactions: the evolution of component communities

1996 ◽  
Vol 351 (1345) ◽  
pp. 1361-1366 ◽  
Keyword(s):  
Genetic Variation ◽  
Plant Resistance ◽  
Great Majority ◽  
Plant Interactions ◽  
Leaf Beetles ◽  
Natural Hosts ◽  
Biogeographic Regions ◽  
Plant Families ◽  
Highly Correlated ◽  
Host Associations

Because plant resistance to different herbivores seems generally not to be genetically highly correlated, selection by herbivores for plant resistance traits and for investment in such traits is likely to be strongly influenced by the species composition of a plant species’ associated community of enemies. We summarize evidence that the host associations of specialized herbivorous insects are often phylogenetically very conservative, and include an analysis of host associations of eastern North American leaf beetles (Chrysomelidae). The great majority of these feed on the same plant families as their congeners in other biogeographic regions. The phylogenetic evidence for conservatism is complemented by a survey of several species of Ophraella (Chrysomelidae) for genetic variation in feeding responses to and survival on host plants of congeric species. In about half the cases, no genetic variation was discerned. Genetic variation was displayed most often in responses to plants closely related to the species’ natural hosts. Biases in patterns of genetic variation may therefore underlie the phylogenetic conservatism of host use. Long-lasting associations of plants with specialized herbivores may provide opportunity for coevolution.

scholarly journals The Plant-Stress Metabolites, Hexanoic Aacid and Melatonin, Are Potential “Vaccines” for Plant Health Promotion

2021 ◽  
Vol 37 (5) ◽  
pp. 415-427
Author(s):  
Anne J. Anderson ◽  
Young Cheol Kim
Keyword(s):  
Plant Defense ◽  
Abiotic Stresses ◽  
Plant Stress ◽  
Defense Responses ◽  
Hexanoic Acid ◽  
Microbial Pathogens ◽  
Plant Metabolites ◽  
Protective Mechanisms ◽  
Stress Metabolites ◽  
Rapid Activation

A plethora of compounds stimulate protective mechanisms in plants against microbial pathogens and abiotic stresses. Some defense activators are synthetic compounds and trigger responses only in certain protective pathways, such as activation of defenses under regulation by the plant regulator, salicylic acid (SA). This review discusses the potential of naturally occurring plant metabolites as primers for defense responses in the plant. The production of the metabolites, hexanoic acid and melatonin, in plants means they are consumed when plants are eaten as foods. Both metabolites prime stronger and more rapid activation of plant defense upon subsequent stress. Because these metabolites trigger protective measures in the plant they can be considered as “vaccines” to promote plant vigor. Hexanoic acid and melatonin instigate systemic changes in plant metabolism associated with both of the major defense pathways, those regulated by SA- and jasmonic acid (JA). These two pathways are well studied because of their induction by different microbial triggers: necrosis-causing microbial pathogens induce the SA pathway whereas colonization by beneficial microbes stimulates the JA pathway. The plant’s responses to the two metabolites, however, are not identical with a major difference being a characterized growth response with melatonin but not hexanoic acid. As primers for plant defense, hexanoic acid and melatonin have the potential to be successfully integrated into vaccination-like strategies to protect plants against diseases and abiotic stresses that do not involve man-made chemicals.

scholarly journals Experimental evidence that habitat-specific chemical cues influence fish preference patterns

2016 ◽  
Author(s):  
Charles W Martin
Keyword(s):  
Chemical Cues ◽  
Habitat Preferences ◽  
Hydrilla Verticillata ◽  
Food Sources ◽  
Sediment Runoff ◽  
Specific Chemical ◽  
Anthropogenic Inputs ◽  
Sailfin Molly ◽  
Plant Chemical ◽  
Preference Patterns

Vegetated habitats provide numerous benefits to nekton, including structural refuge from predators and food sources. However, the sensory mechanisms by which fishes locate these habitats remain unclear for many species, especially when environmental conditions (such as increased turbidity) are unfavorable for visual identification of habitats. Here, a series of laboratory experiments test whether three species of adult fish (golden topminnow Fundulus chrysotus Günther 1866, sailfin molly Poecilia latipinna Lesueur 1821, and western mosquitofish Gambusia affinis Baird and Girard 1853) use plant chemical cues to orient to one of two habitats (hydrilla Hydrilla verticillata (L.f.) Royle or water hyacinth Eichhornia crassipes (Mart.) Solms). First, experiments in aquaria were conducted offering fish a choice of the two habitats to determine preference patterns. Next, a two-channel flume, with each side containing flow originating in one of the two habitats, was used to determine if preferences were still exhibited when fish could only detect habitats through olfactory means. While patterns among the three fish species tested here were variable, results did indicate consistent habitat preferences despite the lack of cues other than olfactory, suggesting that these organisms are capable of discriminating habitats via chemical exudates from plants. As such, olfactory mechanisms likely provide vital information about the surrounding environment and future work should be directed at determining how anthropogenic inputs such as eutrophication and sediment runoff affect the physiology of these sensory capabilities.

scholarly journals A novel plant-fungal association reveals fundamental sRNA and gene expression reprogramming at the onset of symbiosis

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Ena Šečić ◽  
Silvia Zanini ◽  
Daniel Wibberg ◽  
Lukas Jelonek ◽  
Tobias Busche ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nutrient Uptake ◽  
Stress Responses ◽  
Growth And Development ◽  
De Novo ◽  
Brachypodium Distachyon ◽  
Defense Responses ◽  
Grass Species ◽  
Global Changes ◽  
Plant Metabolites

Abstract Background Beneficial associations between plants and microbes are widespread in nature and have been studied extensively in the microbial-dominant environment of the rhizosphere. Such associations are highly advantageous for the organisms involved, benefiting soil microbes by providing them access to plant metabolites, while plant growth and development are enhanced through the promotion of nutrient uptake and/or protection against (a)biotic stresses. While the establishment and maintenance of mutualistic associations have been shown to require genetic and epigenetic reprogramming, as well as an exchange of effector molecules between microbes and plants, whether short RNAs are able to effect such changes is currently unknown. Here, we established an interaction between the model grass species Brachypodium distachyon (Bd, Pooideae) and the beneficial fungal root endophyte Serendipita indica (Si, syn. Piriformospora indica, Sebacinales) to elucidate RNA interference-based regulatory changes in gene expression and small (s)RNA profiles that occurred during establishment of a Sebacinalean symbiosis. Results Colonization of Bd roots with Si resulted in higher grain yield, confirming the mutualistic character of this interaction. Resequencing of the Si genome using the Oxford Nanopore technique, followed by de novo assembly yielded in 57 contigs and 9441 predicted genes, including putative members of several families involved in sRNA production. Transcriptome analysis at an early stage of the mutualistic interaction identified 2963 differentially expressed genes (DEG) in Si and 317 in Bd line 21-3. The fungal DEGs were largely associated with carbohydrate metabolism, cell wall degradation, and nutrient uptake, while plant DEGs indicated modulation of (a)biotic stress responses and defense pathways. Additionally, 10% of the upregulated fungal DEGs encode candidate protein effectors, including six DELD proteins typical for Sebacinales. Analysis of the global changes in the sRNA profiles of both associated organisms revealed several putative endogenous plant sRNAs expressed during colonization belonging to known micro (mi)RNA families involved in growth and developmental regulation. Among Bd- and Si-generated sRNAs with putative functions in the interacting organism, we identified transcripts for proteins involved in circadian clock and flowering regulation as well as immunity as potential targets of fungal sRNAs, reflecting the beneficial activity of Si. Conclusions We detected beneficial effects of Si colonization on Bd growth and development, and established a novel plant-mutualist interaction model between these organisms. Together, the changes in gene expression and identification of interaction-induced sRNAs in both organisms support sRNA-based regulation of defense responses and plant development in Bd, as well as nutrient acquisition and cell growth in Si. Our data suggests that a Sebacinalean symbiosis involves reciprocal sRNA targeting of genes during the interaction.

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