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.

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 Transcriptomic Responses of Fall Armyworms (Spodoptera frugiperda) Feeding on a Resistant Maize Inbred Line Xi502 with High Benzoxazinoid Content

Agronomy ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2503
Author(s):  
Saif ul Malook ◽  
Xiao-Feng Liu ◽  
Caiyan Ma ◽  
Jinfeng Qi ◽  
Wende Liu ◽  
...  
Keyword(s):  
Inbred Line ◽  
Spodoptera Frugiperda ◽  
Genetic Material ◽  
Resistance Mechanism ◽  
Fall Armyworm ◽  
Structural Analog ◽  
Defense Responses ◽  
Preliminary Evidence ◽  
Maize Inbred Line ◽  
Detoxification Mechanisms

The fall armyworm (Spodoptera frugiperda) is a devastating invasive insect herbivore. Its success on its preferred host plant, maize (Zea mays), is supported by numerous specialized detoxification mechanisms that suppress the defense responses of maize. In this study, we used a resistant Chinese maize cultivar, Xi502, which showed slower growth and lower yield-related phenotypes compare with maize inbred line B73. Comparative transcriptomic analyses demonstrated that B73-fed fall armyworm larvae have a significantly faster transcriptomic re-configuration toward maturation compared to their siblings fed with Xi502 leaves, whereas a number of putative aromatic breakdown -related DEGs were specifically induced when feeding on Xi502. Targeted metabolomic quantification demonstrated that Xi502 contains significantly higher levels of various benzoxazinoid compounds. Artificial feeding with the structural analog of a benzoxazinoid compound preferentially accumulated in Xi502 demonstrated a significant growth inhibition effect on FAW larvae. These results provide important genetic material and preliminary evidence for further dissection of the FAW-resistance mechanism in maize.

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 Host plant defense produces species-specific alterations to flight muscle protein structure and flight-related fitness traits of two armyworms

2020 ◽  
Vol 223 (16) ◽  
pp. jeb224907 ◽  
Author(s):  
Scott L. Portman ◽  
Gary W. Felton ◽  
Rupesh R. Kariyat ◽  
James H. Marden
Keyword(s):  
Plant Defense ◽  
Host Plant ◽  
Host Plants ◽  
Molecular Mechanisms ◽  
Flight Muscle ◽  
Troponin T ◽  
Muscle Protein ◽  
Muscle Metabolism ◽  
Spodoptera Eridania ◽  
Flight Muscles

ABSTRACTInsects manifest phenotypic plasticity in their development and behavior in response to plant defenses, via molecular mechanisms that produce tissue-specific changes. Phenotypic changes might vary between species that differ in their preferred hosts and these effects could extend beyond larval stages. To test this, we manipulated the diet of southern armyworm (SAW; Spodoptera eridania) and fall armyworm (FAW; Spodoptera frugiperda) using a tomato mutant for jasmonic acid plant defense pathway (def1), and wild-type plants, and then quantified gene expression of Troponin t (Tnt) and flight muscle metabolism of the adult insects. Differences in Tnt spliceform ratios in insect flight muscles correlate with changes to flight muscle metabolism and flight muscle output. We found that SAW adults reared on induced def1 plants had a higher relative abundance (RA) of the A isoform of Troponin t (Tnt A) in their flight muscles; in contrast, FAW adults reared on induced def1 plants had a lower RA of Tnt A in their flight muscles compared with adults reared on def1 and controls. Although mass-adjusted flight metabolic rate showed no independent host plant effects in either species, higher flight metabolic rates in SAW correlated with increased RA of Tnt A. Flight muscle metabolism also showed an interaction of host plants with Tnt A in both species, suggesting that host plants might be influencing flight muscle metabolic output by altering Tnt. This study illustrates how insects respond to variation in host plant chemical defense by phenotypic modifications to their flight muscle proteins, with possible implications for dispersal.

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 Disease Interactions in a Shared Host Plant: Effects of Pre-Existing Viral Infection on Cucurbit Plant Defense Responses and Resistance to Bacterial Wilt Disease

PLoS ONE ◽  
2013 ◽  
Vol 8 (10) ◽  
pp. e77393 ◽  
Author(s):  
Lori R. Shapiro ◽  
Lucie Salvaudon ◽  
Kerry E. Mauck ◽  
Hannier Pulido ◽  
Consuelo M. De Moraes ◽  
...  
Keyword(s):  
Viral Infection ◽  
Plant Defense ◽  
Host Plant ◽  
Bacterial Wilt ◽  
Defense Responses ◽  
Wilt Disease ◽  
Plant Defense Responses ◽  
Bacterial Wilt Disease ◽  
Plant Effects

scholarly journals Spodoptera exigua caterpillar feeding induces rapid defense responses in maize leaves

2017 ◽  
Author(s):  
Vered Tzin ◽  
Yuko Hojo ◽  
Susan R. Strickler ◽  
Lee Julia Bartsch ◽  
Cairo M. Archer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Inbred Line ◽  
Time Course ◽  
Spodoptera Exigua ◽  
Defense Responses ◽  
Chemical Defenses ◽  
Maize Inbred Line ◽  
Beet Armyworm ◽  
Specialized Metabolites ◽  
Maize Leaves

ABSTRACTInsects such as beet armyworm caterpillars (Spodoptera exigua) cause extensive damage to maize (Zea mays) by consuming foliar tissue. Maize plants respond to such insect attack by triggering defense mechanisms that involve large changes in gene expression and the biosynthesis of specialized metabolites and defense signaling molecules. To investigate dynamic maize responses to herbivore feeding, leaves of maize inbred line B73 were infested with S. exigua caterpillars for 1 to 24 hours, followed by comprehensive transcriptomic and metabolomic characterization. Our results show that the most significant gene expression responses of maize to S. exigua feeding occur at early time points, within 4 to 6 hours after caterpillar infestation. However, both gene expression and metabolite profiles continued changing during the entire 24-hour experiment while photosynthesis genes were gradually decreased. The primary and specilaze metabolism shift maught be temporal and dynamic processes in the infested leaf tissue. We analyzed the effects of mutating genes in two major defense-related pathways, benzoxazinoids (Bx1 and Bx2) and jasmonic acid (Lox8), using Dissociation (Ds) transposon insertions in maize inbred line W22. Together, these results show that maize leaves shift to implementation of chemical defenses within one hour after the initiation of caterpillar attack. Thus, the induced biosynthesis of specialized metabolites can have major effects in maize-caterpillar interactions.HIGHLIGHTA comprehensive transcriptic and metabolomic profiling time course of maize foliar responses to caterpillar feeding identifies genes for the synthesis of benzoxazinoids and phytohormones.

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