scholarly journals Friend or Foe? Orb-Weaver Spiders Inhabiting Ant–Acacias Capture Both Herbivorous Insects and Acacia Ant Alates

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Anna E Ledin ◽  
John D Styrsky ◽  
Jennifer Nesbitt Styrsky
Keyword(s):  
Plant Defense ◽  
Plant Protection ◽  
Herbivorous Insects ◽  
Ecological Role ◽  
Acacia Species ◽  
Additional Layer ◽  
Acacia Ants ◽  
Insect Predators ◽  
Prey Remains ◽  
Taxonomic Order

Abstract The orb-weaver spiders Eustala oblonga (Chickering) and Eustala illicita (O. Picard-Cambridge) (Araneae: Araneidae) inhabit the ant-defended acacias Vachellia melanocerus (Beurling) and Vachellia collinsii (Safford) (Fabales: Fabaceae), respectively, in Panama. These spiders do not capture patrolling Pseudomyrmex ants but exploit their plant-protection services to escape predation. What effect the spiders have on the ant-acacia mutualisms is unknown. They may provide an additional layer of plant defense by capturing flying herbivorous insects in their webs. Alternatively, the spiders may disrupt the ant–acacia mutualisms by capturing alate acacia ants during nuptial flights. We evaluated these two hypotheses by sampling insects flying through acacia foliage and by identifying prey remains in webs. The proportions of insects captured on sticky card traps and in webs varied with taxonomic order and ecological role. Herbivorous insects greatly outnumbered other groups captured on sticky cards and were captured in spiders’ webs in both acacia species but made up a minority of prey remains in webs. Instead, insect predators and parasitoids made up the majority of prey remains and were comprised primarily by alate ant mutualists of the host acacias. These results provide indirect support for both hypotheses and suggest that the spiders potentially both benefit and harm their host ant-acacia mutualisms. The net effect of spider exploitation, however, is unclear and is likely based on both the effectiveness of plant protection from herbivory provided by the spiders relative to that provided by acacia ants, as well as the overall proportion of the ant reproductive caste the spiders actually capture.

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.

Plant Resistance Genes for Fungal Pathogens - Physiological Models and Identification in Cereal Crops

1991 ◽  
Vol 46 (11-12) ◽  
pp. 969-981 ◽  
Author(s):  
Wolfgang Knogge
Keyword(s):  
Plant Defense ◽  
Resistance Genes ◽  
Fungal Pathogens ◽  
Plant Protection ◽  
Defense Responses ◽  
Avirulence Gene ◽  
Physiological Models ◽  
Plant Genes ◽  
Plant Pathogen Interaction

The complex biological phenomenon “resistance” can be reduced to single Mendelian traits acting on both the plant and the pathogen side in a number of pathosystems. According to the “gene-for-gene hypothesis”, the outcome of a plant/pathogen interaction in these cases is incompatibility if a plant carrying a particular resistance gene and a pathogen with the complementary avirulence gene meet. This suggests a causal role of resistance genes in a recognition process initiating active plant defense responses. Fundamentally different strategies are followed to identify these genes molecularly depending on the plant and pathogen species involved. Fungal diseases of crop plants, especially those of cereals, cause dramatic yield losses worldwide. It is assumed that a molecular characterization of plant genes conferring resistance to fungal pathogens will lead to a better understanding of the plant defense system in general permitting the development of new methods of crop plant protection.

scholarly journals Dual Mode of the Saponin Aescin in Plant Protection: Antifungal Agent and Plant Defense Elicitor

2019 ◽  
Vol 10 ◽  
Author(s):  
Lucie Trdá ◽  
Martin Janda ◽  
Denisa Macková ◽  
Romana Pospíchalová ◽  
Petre I. Dobrev ◽  
...  
Keyword(s):  
Plant Defense ◽  
Antifungal Agent ◽  
Plant Protection ◽  
Dual Mode

Jasmonate action in plant defense against insects

2019 ◽  
Vol 70 (13) ◽  
pp. 3391-3400 ◽  
Author(s):  
Jiaojiao Wang ◽  
Dewei Wu ◽  
Youping Wang ◽  
Daoxin Xie
Keyword(s):  
Transcription Factors ◽  
Plant Defense ◽  
Molecular Basis ◽  
Recent Progress ◽  
Herbivorous Insects ◽  
Role Perception ◽  
Rapid Synthesis ◽  
Defense Systems ◽  
F Box Protein ◽  
Insect Attack

Abstract Herbivorous insects represent one of the major threats to sessile plants. To cope with herbivore challenges, plants have evolved sophisticated defense systems, in which the lipid-derived phytohormone jasmonate plays a crucial role. Perception of insect attack locally and systemically elicits rapid synthesis of jasmonate, which is perceived by the F-box protein COI1 to further recruit JAZ repressors for ubiquitination and degradation, thereby releasing transcription factors that subsequently activate plant defense against insect attack. Here, we review recent progress in understanding the molecular basis of jasmonate action in plant defense against insects.

Dual role of the TYLCV protein V2 in suppressing the host plant defense

2013 ◽  
Author(s):  
Yedidya Gafni ◽  
Moshe Lapidot ◽  
Vitaly Citovsky
Keyword(s):  
Transcription Factor ◽  
Plant Defense ◽  
Host Plant ◽  
Bacterial Infections ◽  
Plant Protection ◽  
Cysteine Proteases ◽  
Host Protein ◽  
Disease Response ◽  
The Way

TYLCV-Is is a major tomato pathogen, causing extensive crop losses in Israel and the U.S. We have identified a TYLCV-Is protein, V2, which acts as a suppressor of RNA silencing. Intriguingly, the counter-defense function of V2 may not be limited to silencing suppression. Our recent data suggest that V2 interacts with the tomato CYP1 protease. CYP1 belongs to the family of papain-like cysteine proteases which participate in programmed cell death (PCD) involved in plant defense against pathogens. Based on these data we proposed a model for dual action of V2 in suppressing the host antiviral defense: V2 targets SGS3 for degradation and V2 inhibits CYP1 activity. To study this we proposed to tackle three specific objectives. I. Characterize the role of V2 in SGS3 proteasomal degradation ubiquitination, II. Study the effects of V2 on CYP1 maturation, enzymatic activity, and accumulation and, III. Analyze the effects of the CYP1-V2 interaction on TYLCV-Is infection. Here we describe results from our study that support our hypothesis: the involvement of the host's innate immune system—in this case, PCD—in plant defense against TYLCV-Is. Also, we use TYLCV-Is to discover the molecular pathway(s) by which this plant virus counters this defense. Towards the end of our study we discovered an interesting involvement of the C2 protein encoded by TYLCV-Is in inducing Hypersensitive Response in N. benthamianaplants which is not the case when the whole viral genome is introduced. This might lead to a better understanding of the multiple processes involved in the way TYLCV is overcoming the defense mechanisms of the host plant cell. In a parallel research supporting the main goal described, we also investigated Agrobacteriumtumefaciens-encoded F-box protein VirF. It has been proposed that VirF targets a host protein for the UPS-mediated degradation, very much the way TYLCV V2 does. In our study, we identified one such interactor, an Arabidopsistrihelix-domain transcription factor VFP3, and further show that its very close homolog VFP5 also interacted with VirF. Interestingly, interactions of VirF with either VFP3 or VFP5 did not activate the host UPS, suggesting that VirF might play other UPS-independent roles in bacterial infection. Another target for VirF is VFP4, a transcription factor that both VirF and its plant functional homolog VBF target to degradation by UPS. Using RNA-seqtranscriptome analysis we showed that VFP4 regulates numerous plant genes involved in disease response, including responses to viral and bacterial infections. Detailed analyses of some of these genes indicated their involvement in plant protection against Agrobacterium infection. Thus, Agrobacterium may facilitate its infection by utilizing the host cell UPS to destabilize transcriptional regulators of the host disease response machinery that limits the infection.

scholarly journals Potential Role of Flavobacterial Gliding-Motility and Type IX Secretion System Complex in Root Colonization and Plant Defense

2014 ◽  
Vol 27 (9) ◽  
pp. 1005-1013 ◽  
Author(s):  
Max Kolton ◽  
Omer Frenkel ◽  
Yigal Elad ◽  
Eddie Cytryn
Keyword(s):  
Plant Defense ◽  
Root Colonization ◽  
Plant Protection ◽  
Plant Root ◽  
Secretion System ◽  
Gliding Motility ◽  
Wild Type ◽  
In Planta ◽  
Clavibacter Michiganensis

Members of the Flavobacterium genus are often highly abundant in the rhizosphere. Nevertheless, the physiological characteristics associated with their enhanced rhizosphere competence are currently an enigma. Flavobacteria possess a unique gliding-motility complex that is tightly associated with a recently characterized Bacteroidetes-specific type IX protein secretion system, which distinguishes them from the rest of the rhizosphere microbiome. We hypothesize that proper functionality of this complex may confer a competitive advantage in the rhizosphere. To test this hypothesis, we constructed mutant and complement root-associated flavobacterial variants with dysfunctional secretion and gliding motility, and tested them in a series of in planta experiments. These mutants demonstrated significantly lower rhizosphere persistence (approximately 10-fold), plant root colonization (approximately fivefold), and seed adhesion capacity (approximately sevenfold) than the wild-type strains. Furthermore, the biocontrol capacity of the mutant strain toward foliar-applied Clavibacter michiganensis was significantly impaired relative to the wild-type strain, suggesting a role of the gliding and secretion complex in plant protection. Collectively, these results provide an initial link between the high abundance of flavobacteria in the rhizosphere and their unique physiology, indicating that the flavobacterial gliding-motility and secretion complex may play a central role in root colonization and plant defense.

The ecological role of microsymbionts in the interaction of plants and herbivorous insects

2017 ◽  
Vol 7 (6) ◽  
pp. 506-518 ◽  
Author(s):  
A. V. Sorokan ◽  
S. D. Rumyantsev ◽  
G. V. Benkovskaya ◽  
I. V. Maksimov
Keyword(s):  
Herbivorous Insects ◽  
Ecological Role

scholarly journals Optimization of Exopolysaccharides Production by Porphyridium sordidum and Their Potential to Induce Defense Responses in Arabidopsis thaliana against Fusarium oxysporum

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 282
Author(s):  
Marwa Drira ◽  
Jihen Elleuch ◽  
Hajer Ben Hlima ◽  
Faiez Hentati ◽  
Christine Gardarin ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Defense ◽  
Fusarium Oxysporum ◽  
Foliar Application ◽  
Plant Protection ◽  
Profile Analysis ◽  
Fungal Growth ◽  
Defense Responses ◽  
Expression Profile Analysis ◽  
Pathogenesis Related Protein

Polysaccharides from marine algae are one novel source of plant defense elicitors for alternative and eco-friendly plant protection against phytopathogens. The effect of exopolysaccharides (EPS) produced by Porphyridium sordidum on elicitation of Arabidopsis thaliana defense responses against Fusarium oxysporum was evaluated. Firstly, in order to enhance EPS production, a Box–Behnken experimental design was carried out to optimize NaCl, NaNO3 and MgSO4 concentrations in the culture medium of microalgae. A maximum EPS production (2.45 g/L) higher than that of the control (0.7 g/L) was observed for 41.62 g/L NaCl, 0.63 g/L NaNO3 and 7.2 g/L MgSO4 concentrations. Structurally, the EPS contained mainly galactose, xylose and glucose. Secondly, the elicitor effect of EPS was evaluated by investigating the plant defense-related signaling pathways that include activation of Salicylic or Jasmonic Acid-dependent pathway genes. A solution of 2 mg/mL of EPS has led to the control of fungal growth by the plant. Results showed that EPS foliar application induced phenylalaline ammonia lyase and H2O2 accumulation. Expression profile analysis of the defense-related genes using qRT-PCR revealed the up-regulation of Superoxide dismutases (SOD), Peroxidase (POD), Pathogenesis-related protein 1 (PR-1) and Cytochrome P450 monooxyge-nase (CYP), while Catalase (CAT) and Plant defensin 1.2 (PDF1.2) were not induced. Results suggest that EPS may induce the elicitation of A. thaliana’s defense response against F. oxysporum, activating the Salicylic Acid pathway.

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