scholarly journals Sm1, a Proteinaceous Elicitor Secreted by the Biocontrol Fungus Trichoderma virens Induces Plant Defense Responses and Systemic Resistance

2006 ◽  
Vol 19 (8) ◽  
pp. 838-853 ◽  
Author(s):  
Slavica Djonović ◽  
Maria J. Pozo ◽  
Lawrence J. Dangott ◽  
Charles R. Howell ◽  
Charles M. Kenerley
Keyword(s):  
Plant Defense ◽  
Defense Mechanisms ◽  
Molecular Mechanisms ◽  
Pathogenic Fungi ◽  
Defense Responses ◽  
Systemic Resistance ◽  
Trichoderma Virens ◽  
Trichoderma Spp ◽  
Toxic Activity ◽  
Small Protein

The soilborne filamentous fungus Trichoderma virens is a biocontrol agent with a well-known ability to produce antibiotics, parasitize pathogenic fungi, and induce systemic resistance in plants. Even though a plant-mediated response has been confirmed as a component of bioprotection by Trichoderma spp., the molecular mechanisms involved remain largely unknown. Here, we report the identification, purification, and characterization of an elicitor secreted by T. virens, a small protein designated Sm1 (small protein 1). Sm1 lacks toxic activity against plants and microbes. Instead, native, purified Sm1 triggers production of reactive oxygen species in monocot and dicot seedlings, rice, and cotton, and induces the expression of defense-related genes both locally and systemically in cotton. Gene expression analysis revealed that SM1 is expressed throughout fungal development under different nutrient conditions and in the presence of a host plant. Using an axenic hydroponic system, we show that SM1 expression and secretion of the protein is significantly higher in the presence of the plant. Pretreatment of cotton cotyledons with Sm1 provided high levels of protection to the foliar pathogen Colletotrichum sp. These results indicate that Sm1 is involved in the induction of resistance by Trichoderma spp. through the activation of plant defense mechanisms.

scholarly journals The race goes on: A fall armyworm-resistant maize inbred line influences insect oral secretion elicitation activity and nullifies herbivore suppression of plant defense

2021 ◽  
Author(s):  
Saif ul Malook ◽  
Xiao-Feng Liu ◽  
Wende Liu ◽  
Jinfeng Qi ◽  
Shaoqun Zhou
Keyword(s):  
Plant Defense ◽  
Host Plant ◽  
Inbred Line ◽  
Defense Mechanisms ◽  
Molecular Mechanisms ◽  
Fall Armyworm ◽  
Defense Responses ◽  
Feeding Preference ◽  
Maize Inbred Line ◽  
Oral Secretion

Fall armyworm (Spodoptera frugiperda) is an invasive lepidopteran pest with strong feeding preference towards maize (Zea mays). Its success on maize is facilitated by a suite of specialized detoxification and manipulation mechanisms that curtail host plant defense responses. In this study, we identified a Chinese maize inbred line Xi502 that was able to mount effective defense in response to fall armyworm attack. Comparative transcriptomics analyses, phytohormonal measurements, and targeted benzoxazinoid quantification consistently demonstrate significant inducible defense responses in Xi502, but not in the susceptible reference inbred line B73. In 24 hours, fall armyworm larvae feeding on B73 showed accelerated maturation-oriented transcriptomic responses and more changes in detoxification gene expression compared to their Xi502-fed sibling. Interestingly, oral secretions collected from larvae fed on B73 and Xi502 leaves demonstrated distinct elicitation activity when applied on either host genotypes, suggesting that variation in both insect oral secretion composition and host plant alleles could influence plant defense response. These results revealed host plant adaptation towards counter-defense mechanisms in a specialist insect herbivore, adding yet another layer to the evolutionary arms race between maize and fall armyworm. This could facilitate future investigation into the molecular mechanisms in this globally important crop-pest interaction system.

Elicitor Recognition and Signal Transduction in Plant Defense Gene Activation

1990 ◽  
Vol 45 (6) ◽  
pp. 569-575 ◽  
Author(s):  
Dierk Scheel ◽  
Jane E. Parker
Keyword(s):  
Signal Transduction ◽  
Plant Defense ◽  
Transcriptional Activation ◽  
Molecular Mechanisms ◽  
Plant Protection ◽  
Plant Cells ◽  
Defense Responses ◽  
Plant Defense Responses ◽  
Defense Genes ◽  
Plant Defense Genes

Abstract Plants defend themselves against pathogen attack by activating a whole set of defense responses, most of them relying on transcriptional activation of plant defense genes. The same responses are induced by treatment of plant cells with elicitors released from the pathogen or from the plant surface. Several plant/elicitor combinations have been used successfully as experimental systems to investigate the molecular basis of plant defense responses. Receptor-like structures on the plasma membrane of plant cells appear to bind the elicitors. Thereby, intracellular signal transduction chains are initiated which finally result in the activation of plant defense genes. A better understanding of the molecular mechanisms of early processes in plant defense responses, as provided by these studies, may in the long term help to develop environmentally safe plant protection methods for agriculture.

scholarly journals Transcriptome analysis reveals ethylene-mediated defense responses to Fusarium oxysporum f. sp. cucumerinum infection in Cucumis sativus

2020 ◽  
Author(s):  
Jingping Dong ◽  
Yuean Wang ◽  
Qianqian Xian ◽  
Xuehao Chen ◽  
Jun Xu
Keyword(s):  
Fusarium Oxysporum ◽  
Cucumis Sativus ◽  
Fusarium Wilt ◽  
Defense Mechanisms ◽  
Molecular Mechanisms ◽  
Severe Disease ◽  
Defense Responses ◽  
Differentially Expressed ◽  
Pcr Analysis ◽  
Positive Role

Abstract Background: Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (Foc), is a severe disease affecting cucumber (Cucumis sativus L.) production worldwide, but the molecular mechanisms underlying Fusarium wilt resistance in cucumber remain unknown. To gain an improved understanding of the defense mechanisms elicited in response to Foc inoculation, RNA sequencing-based transcriptomic profiling of responses of the Fusarium wilt-resistant cucumber line ‘Rijiecheng’ at 0, 24, 48, 96, and 192 h after Foc inoculation was performed.Results: We identified 4116 genes that were differentially expressed between 0 h and other time points after inoculation. All ethylene-related and pathogenesis-related genes from among the differentially expressed genes were filtered out. Real-time PCR analysis showed that ethylene-related genes were induced in response to Foc infection. Importantly, after Foc infection and exogenous application of ethephon, a donor of ethylene, these genes were highly expressed. In response to exogenous ethephon treatment in conjunction with Foc inoculation, the infection resistance of cucumber seedlings was enhanced and endogenous ethylene biosynthesis increased dramatically. Conclusion: Collectively, ethylene signaling pathways play a positive role in regulating the defense response of cucumber to Foc infection. The results provide insight into the cucumber Fusarium wilt defense mechanisms and provide valuable information for breeding new cucumber cultivars with enhanced Fusarium wilt tolerance.

scholarly journals Seaweed-Based Compounds and Products for Sustainable Protection against Plant Pathogens

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 59
Author(s):  
Pushp Sheel Shukla ◽  
Tudor Borza ◽  
Alan T. Critchley ◽  
Balakrishnan Prithiviraj
Keyword(s):  
Plant Defense ◽  
Plant Pathogens ◽  
Systemic Acquired Resistance ◽  
Plant Immunity ◽  
Crop Protection ◽  
Defense Responses ◽  
Systemic Resistance ◽  
Environmental Damage ◽  
Plant Defense Responses ◽  
Seaweed Extracts

Sustainable agricultural practices increasingly demand novel, environmentally friendly compounds which induce plant immunity against pathogens. Stimulating plant immunity using seaweed extracts is a highly viable strategy, as these formulations contain many bio-elicitors (phyco-elicitors) which can significantly boost natural plant immunity. Certain bioactive elicitors present in a multitude of extracts of seaweeds (both commercially available and bench-scale laboratory formulations) activate pathogen-associated molecular patterns (PAMPs) due to their structural similarity (i.e., analogous structure) with pathogen-derived molecules. This is achieved via the priming and/or elicitation of the defense responses of the induced systemic resistance (ISR) and systemic acquired resistance (SAR) pathways. Knowledge accumulated over the past few decades is reviewed here, aiming to explain why certain seaweed-derived bioactives have such tremendous potential to elicit plant defense responses with considerable economic significance, particularly with increasing biotic stress impacts due to climate change and the concomitant move to sustainable agriculture and away from synthetic chemistry and environmental damage. Various extracts of seaweeds display remarkably different modes of action(s) which can manipulate the plant defense responses when applied. This review focuses on both the similarities and differences amongst the modes of actions of several different seaweed extracts, as well as their individual components. Novel biotechnological approaches for the development of new commercial products for crop protection, in a sustainable manner, are also suggested.

scholarly journals Validamycin A Induces Broad-Spectrum Resistance Involving Salicylic Acid and Jasmonic Acid/Ethylene Signaling Pathways

2020 ◽  
Vol 33 (12) ◽  
pp. 1424-1437
Author(s):  
Chuanhong Bian ◽  
Yabing Duan ◽  
Jueyu Wang ◽  
Qian Xiu ◽  
Jianxin Wang ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Jasmonic Acid ◽  
Plant Defense ◽  
Signaling Pathways ◽  
Broad Spectrum ◽  
Defense Responses ◽  
Systemic Resistance ◽  
Signal Pathways ◽  
Plant Defense Responses ◽  
Validamycin A

Validamycin A (VMA) is an aminoglycoside antibiotic used to control rice sheath blight. Although it has been reported that VMA can induce the plant defense responses, the mechanism remains poorly understood. Here, we found that reactive oxygen species (ROS) bursts and callose deposition in Arabidopsis thaliana, rice (Oryza sativa L.), and wheat (Triticum aestivum L.) were induced by VMA and were most intense with 10 μg of VMA per milliliter at 24 h. Moreover, we showed that VMA induced resistance against Pseudomonas syringae, Botrytis cinerea, and Fusarium graminearum in Arabidopsis leaves, indicating that VMA induces broad-spectrum disease resistance in both dicots and monocots. In addition, VMA-mediated resistance against P. syringae was not induced in NahG transgenic plants, was partially decreased in npr1 mutants, and VMA-mediated resistance to B. cinerea was not induced in npr1, jar1, and ein2 mutants. These results strongly indicated that VMA triggers plant defense responses to both biotrophic and necrotrophic pathogens involved in salicylic acid (SA) and jasmonic acid/ethylene (JA/ET) signaling pathways and is dependent on NPR1. In addition, transcriptome analysis further revealed that VMA regulated the expression of genes involved in SA, JA/ET, abscisic acid (ABA), and auxin signal pathways. Taken together, VMA induces systemic resistance involving in SA and JA/ET signaling pathways and also exerts a positive influence on ABA and auxin signaling pathways. Our study highlights the creative application of VMA in triggering plant defense responses against plant pathogens, providing a valuable insight into applying VMA to enhance plant resistance and reduce the use of chemical pesticides. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Plant Defense Responses to Biotic Stress and Its Interplay With Fluctuating Dark/Light Conditions

2021 ◽  
Vol 12 ◽  
Author(s):  
Zahra Iqbal ◽  
Mohammed Shariq Iqbal ◽  
Abeer Hashem ◽  
Elsayed Fathi Abd_Allah ◽  
Mohammad Israil Ansari
Keyword(s):  
Plant Defense ◽  
Biotic Stress ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Defense Responses ◽  
Light Environment ◽  
Microbial Pathogens ◽  
Signaling Cascade ◽  
Dark Light ◽  
The Impact

Plants are subjected to a plethora of environmental cues that cause extreme losses to crop productivity. Due to fluctuating environmental conditions, plants encounter difficulties in attaining full genetic potential for growth and reproduction. One such environmental condition is the recurrent attack on plants by herbivores and microbial pathogens. To surmount such attacks, plants have developed a complex array of defense mechanisms. The defense mechanism can be either preformed, where toxic secondary metabolites are stored; or can be inducible, where defense is activated upon detection of an attack. Plants sense biotic stress conditions, activate the regulatory or transcriptional machinery, and eventually generate an appropriate response. Plant defense against pathogen attack is well understood, but the interplay and impact of different signals to generate defense responses against biotic stress still remain elusive. The impact of light and dark signals on biotic stress response is one such area to comprehend. Light and dark alterations not only regulate defense mechanisms impacting plant development and biochemistry but also bestow resistance against invading pathogens. The interaction between plant defense and dark/light environment activates a signaling cascade. This signaling cascade acts as a connecting link between perception of biotic stress, dark/light environment, and generation of an appropriate physiological or biochemical response. The present review highlights molecular responses arising from dark/light fluctuations vis-à-vis elicitation of defense mechanisms in plants.

scholarly journals Transcriptional profiling reveals conserved and species-specific plant defense responses during the interaction of the early divergent plant Physcomitrium patens with Botrytis cinerea

2020 ◽  
Author(s):  
Guillermo Reboledo ◽  
Astrid Agorio ◽  
Lucía Vignale ◽  
Ramón Alberto Batista-García ◽  
Inés Ponce De León
Keyword(s):  
Immune Response ◽  
Botrytis Cinerea ◽  
Defense Mechanisms ◽  
Molecular Mechanisms ◽  
Defense Responses ◽  
Land Plants ◽  
Differentially Expressed ◽  
Microbial Pathogens ◽  
Limited Information ◽  
Pathogen Invasion

AbstractBryophytes were among the first plants that colonized earth and they evolved key defense mechanisms to counteract microbial pathogens present in the new environment. Although great advances have been made on pathogen perception and subsequent defense activation in angiosperms, limited information is available in early divergent land plants. In this study, a transcriptomic approach uncovered the molecular mechanisms underlying the defense response of the bryophyte Physcomitrium patens against the important plant pathogen Botrytis cinerea. A total of 3.072 differentially expressed genes were significantly affected during B. cinerea infection, including genes encoding proteins with known function in angiosperm immunity and involved in pathogen perception, signaling, transcription, hormonal signaling, metabolic pathways such as shikimate and phenylpropanoid, and proteins with diverse role in defense against biotic stress. Similarly as in other plants, B. cinerea infection leads to downregulation of genes involved in photosynthesis and cell cycle progression. These results highlight the existence of evolutionary conserved defense responses to pathogens throughout the green plant lineage, suggesting that they were probably present in the common ancestors of land plants. Moreover, several genes acquired by horizontal transfer from prokaryotes and fungi, and a high number of P. patens-specific orphan genes were differentially expressed during B. cinerea infection, indicating that they are part of the moss immune response and probably played an ancestral role related to effective adaptation mechanisms to cope with pathogen invasion during the conquest of land.Key MessageEvolutionary conserved defense mechanisms present in extant bryophytes and angiosperms, as well as moss-specific defenses are part of the immune response of the early divergent land plant Physcomitrium patens.

scholarly journals Involvement of Jasmonic Acid/Ethylene Signaling Pathway in the Systemic Resistance Induced in Cucumber by Trichoderma asperellum T203

2005 ◽  
Vol 95 (1) ◽  
pp. 76-84 ◽  
Author(s):  
Michal Shoresh ◽  
Iris Yedidia ◽  
Ilan Chet
Keyword(s):  
Jasmonic Acid ◽  
Pseudomonas Syringae ◽  
Defense Mechanisms ◽  
Plant Pathogens ◽  
Polymerase Chain Reaction Analysis ◽  
Systemic Resistance ◽  
Signal Molecules ◽  
Ethylene Signaling ◽  
Trichoderma Spp ◽  
Leaf Pathogen

Trichoderma spp. are effective biocontrol agents for a number of soilborne plant pathogens, and some are also known for their ability to enhance plant growth. It was recently suggested that Trichoderma also affects induced systemic resistance (ISR) mechanism in plants. Analysis of signal molecules involved in defense mechanisms and application of specific inhibitors indicated the involvement of jasmonic acid and ethylene in the protective effect conferred by Trichoderma spp. against the leaf pathogen Pseudomonas syringae pv. lachrymans. Moreover, examination of local and systemic gene expression by real-time reverse transcription-polymerase chain reaction analysis revealed that T. asperellum (T203) modulates the expression of genes involved in the jasmonate/ethylene signaling pathways of ISR (Lox1, Pal1, ETR1, and CTR1) in cucumber plants. We further showed that a subsequent challenge of Trichoderma-preinoculated plants with the leaf pathogen P. syringae pv. lachrymans resulted in higher systemic expression of the pathogenesisrelated genes encoding for chitinase 1, β-1,3-glucanase, and peroxidase relative to noninoculated, challenged plants. This indicates that Trichoderma induced a potentiated state in the plant enabling it to be more resistant to subsequent pathogen infection.

scholarly journals Differential Response of Tomato Plants to the Application of Three Trichoderma Species When Evaluating the Control of Pseudomonas syringae Populations

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 626 ◽  
Author(s):  
María E. Morán-Diez ◽  
Eduardo Tranque ◽  
Wagner Bettiol ◽  
Enrique Monte ◽  
Rosa Hermosa
Keyword(s):  
Pseudomonas Syringae ◽  
Molecular Mechanisms ◽  
Defense Responses ◽  
Marker Genes ◽  
Post Inoculation ◽  
Trichoderma Spp ◽  
Bacterial Populations ◽  
Oxidase Gene ◽  
Trichoderma Species ◽  
Tomato Plants

Trichoderma species are well known biocontrol agents that are able to induce responses in the host plants against an array of abiotic and biotic stresses. Here, we investigate, when applied to tomato seeds, the potential of Trichoderma strains belonging to three different species, T. parareesei T6, T. asperellum T25, and T. harzianum T34, to control the fully pathogenic strain Pseudomonas syringae pv. tomato (Pst) DC3000, able to produce the coronatine (COR) toxin, and the COR-deficient strain Pst DC3118 in tomato plants, and the molecular mechanisms by which the plant can modulate its systemic defense. Four-week old tomato plants, seed-inoculated, or not, with a Trichoderma strain, were infected, or not, with a Pst strain, and the changes in the expression of nine marker genes representative of salicylic acid (SA) (ICS1 and PAL5) and jasmonic acid (JA) (TomLoxC) biosynthesis, SA- (PR1b1), JA- (PINII and MYC2) and JA/Ethylene (ET)-dependent (ERF-A2) defense pathways, as well as the abscisic acid (ABA)-responsive gene AREB2 and the respiratory burst oxidase gene LERBOH1, were analyzed at 72 hours post-inoculation (hpi) with the bacteria. The significant increase obtained for bacterial population sizes in the leaves, disease index, and the upregulation of tomato genes related to SA, JA, ET and ABA in plants inoculated with Pst DC3000 compared with those obtained with Pst DC3118, confirmed the COR role as a virulence factor, and showed that both Pst and COR synergistically activate the JA- and SA-signaling defense responses, at least at 72 hpi. The three Trichoderma strains tested reduced the DC3118 levels to different extents and were able to control disease symptoms at the same rate. However, a minor protection (9.4%) against DC3000 was only achieved with T. asperellum T25. The gene deregulation detected in Trichoderma-treated plus Pst-inoculated tomato plants illustrates the complex system of a phytohormone-mediated signaling network that is affected by the pathogen and Trichoderma applications but also by their interaction. The expression changes for all nine genes analyzed, excepting LERBOH1, as well as the bacterial populations in the leaves were significantly affected by the interaction. Our results show that Trichoderma spp. are not adequate to control the disease caused by fully pathogenic Pst strains in tomato plants.

scholarly journals Spermine Is a Potent Plant Defense Activator Against Gray Mold Disease on Solanum lycopersicum, Phaseolus vulgaris, and Arabidopsis thaliana

2019 ◽  
Vol 109 (8) ◽  
pp. 1367-1377 ◽  
Author(s):  
Hamed S. Seifi ◽  
Adel Zarei ◽  
Tom Hsiang ◽  
Barry J. Shelp
Keyword(s):  
Arabidopsis Thaliana ◽  
Salicylic Acid ◽  
Phaseolus Vulgaris ◽  
Plant Defense ◽  
Solanum Lycopersicum ◽  
Stress Responses ◽  
Systemic Acquired Resistance ◽  
Defense Responses ◽  
Gray Mold ◽  
Systemic Resistance

Polyamines (PAs) are ubiquitous aliphatic amines that play important roles in growth, development, and environmental stress responses in plants. In this study, we report that exogenous application of spermine (Spm) is effective in the induction of resistance to gray mold disease, which is caused by the necrotrophic fungal pathogen Botrytis cinerea, on tomato (Solanum lycopersicum), bean (Phaseolus vulgaris), and Arabidopsis thaliana. High throughput transcriptome analysis revealed a priming role for the Spm molecule in the genus Arabidopsis, resulting in strong upregulation of several important defense-associated genes, particularly those involved in systemic-acquired resistance. Microscopic analysis confirmed that Spm application potentiates endogenous defense responses in tomato leaves through the generation of reactive oxygen species and the hypersensitive response, which effectively contained B. cinerea growth within the inoculated area. Moreover, co-application of Spm and salicylic acid resulted in a synergistic effect against the pathogen, leading to higher levels of resistance than those induced by separate applications of the two compounds. The Spm plus salicylic acid treatment also reduced infection in systemic nontreated leaves of tomato plants. Our findings suggest that Spm, particularly when applied in combination with salicylic acid, functions as a potent plant defense activator that leads to effective local and systemic resistance against B. cinerea.

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