scholarly journals Old Enzyme, New Role: The β-Glucosidase BglC of Streptomyces scabiei Interferes with the Plant Defense Mechanism by Hydrolyzing Scopolin

Biophysica ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 1-7
Author(s):  
Benoit Deflandre ◽  
Sébastien Rigali
Keyword(s):  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Substrate Inhibition ◽  
Primary Metabolism ◽  
Saturation Curve ◽  
Thaxtomin A ◽  
Virulence Determinant ◽  
Plant Defense Mechanism ◽  
Streptomyces Scabiei ◽  
Beta Glucosidase

The beta-glucosidase BglC fulfills multiple functions in both primary metabolism and induction of pathogenicity of Streptomyces scabiei, the causative agent of common scab in root and tuber crops. Indeed, this enzyme hydrolyzes cellobiose and cellotriose to feed glycolysis with glucose directly and modifies the intracellular concentration of these cello-oligosaccharides, which are the virulence elicitors. The inactivation of bglC led to unexpected phenotypes such as the constitutive overproduction of thaxtomin A, the main virulence determinant of S. scabiei. In this work, we reveal a new target substrate of BglC, the phytoalexin scopolin. Removal of the glucose moiety of scopolin generates scopoletin, a potent inhibitor of thaxtomin A production. The hydrolysis of scopolin by BglC displayed substrate inhibition kinetics, which contrasts with the typical Michaelis–Menten saturation curve previously observed for the degradation of its natural substrate cellobiose. Our work, therefore, reveals that BglC targets both cello-oligosaccharide elicitors emanating from the hosts of S. scabiei, and the scopolin phytoalexin generated by the host defense mechanisms, thereby occupying a key position to fine-tune the production of the main virulence determinant thaxtomin A.

scholarly journals Strong Sour Tamarind Flavor of Methyl-2,3,4- trihydroxyhexanoate, a new compound isolated from Leaves of Tamarindus indica, L. plays a role in plant defense mechanisms

2012 ◽  
pp. 26-44
Author(s):  
Suprana Biswas ◽  
Nabanita Chakraborty ◽  
Supriya Chakraborty
Keyword(s):  
Antioxidant Activity ◽  
Plant Defense ◽  
Inhibitory Activity ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Aspergillus Tamarii ◽  
Methanol Fraction ◽  
Wide Range ◽  
Plant Defense Mechanism ◽  
Defensive Activity

Flavoring compounds of plants play a significant role in plant defense mechanism. Compound responsible for strong sour tamarind flavor has been isolated and identified from Methanol fraction of tamarind leaves (TrMF). Chromatographic and spectral analyses of TrMF revealed the compound to be methyl 2,3,4- trihydroxyhexanoate. This compound showed a strong antioxidant activity as well as strong antimicrobial activity. It showed significant antioxidant activity with Ic50 value of 2.5μg/ml whereas tert-butyl-1-hydroxytoluene and ascorbic acid revealed 26.0μg/ml and 5.0μg/ml, respectively. It also revealed strong inhibitory activity against Aspergellosis disease-causing fungi namely; Aspergillus fumigatus, Aspergillus tamarii and Aspergillus niger at all concentrations. Streptococcus aureus and Escherichia coli were much more sensitive to methyl-trihydroxy-hexanoate at all concentrations than Pseudomonas aeruginosa. This pure compound exhibited concentration dependent inhibitory and stimulatory activity on rice seeds germination and seedling growth. It showed strong inhibitory activity up to 62.5ppm concentration and below this concentration the effect was stimulatory. Methyl- trihydroxyhexanoate exhibited wide range of defensive activity against microbes and crop seeds and also possesses potent antioxidative activity. Thus play an important role in plant defense mechanism and can be utilized as a valuable source of bio-herbicides and pesticides.

scholarly journals Research on the involment of phenoloics in the defence of horticultural plants

2016 ◽  
Vol 107 (1) ◽  
pp. 183 ◽  
Author(s):  
Ana SLATNAR ◽  
Maja MIKULIČ-PETKOVŠEK ◽  
Robert VEBERIČ ◽  
Franci ŠTAMPAR
Keyword(s):  
Phenolic Compounds ◽  
Plant Defense ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Plant Protection ◽  
Research Work ◽  
Primary Metabolism ◽  
Infection Site ◽  
Horticultural Plants

Phenolic compounds are not directly involved in the primary metabolism of plants but possess a number of important roles: (1) serving as attractants for pollinators and various animals, involved in the transfer of seeds, (2) plant protection from herbivores and against pathogen infection, (3) defining plant-plant relationships and the symbiosis between plants and microbes. The present review of our research work stresses the role of phenolic compounds in the defense mechanism against different fungi and bacteria. It has been established, that the content of phenolics is greatly affected by the infection with pathogenic organisms. Studies on several horticultural plants have demonstrated that the response to infection differs among the analyzed plant species. Generally, an increase of phenolic compounds can be expected in tissues near the infection site. The comparison of healthy and infected tissue reflects an increase of phenolics in infected tissues. Higher levels of all analyzed phenolic groups have been measured in the latter, with the exception of the anthocyanins. Based on the findings of many-year research studies, it can be concluded that phenolic compounds are involved in the plant defense mechanisms, but the response varies among species.

scholarly journals A Mechanistic insight into chemical cues and interactions involved in herbivory induced jasmonate mediated plant defense mechanism

2021 ◽  
Author(s):  
Qudsia Yousafi ◽  
Amina Hafeez ◽  
Muhammad Saad Khan ◽  
Shabana Bibi ◽  
Muhammad Ajmal Shah ◽  
...  
Keyword(s):  
Plant Defense ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Salt Bridge ◽  
Structure Alignment ◽  
Interaction Partner ◽  
Allene Oxide ◽  
Important Amino Acid ◽  
Plant Defense Mechanism ◽  
Insect Attack

Abstract The first step in plant defense mechanism is to sense the insect attack stimulus. Plant sensitivity of an insect attack is the first step of defense. Molecules generated by the oral secretion of the insect interact with the plant receptors to trigger plant defense mechanisms. We selected some highly cited insect elicitors molecules, volicitin, caeliferin, bruchin which interact with plant defense by interacting with plant elicitors (systemin, inceptin and peps) located on the plant cell surface. This interaction activates plant receptors SYR1, LRR, PEPR and triggers downstream defense signaling. The octadecanoid pathways, involving enzymes allene oxide synthase (AOS) and Hydroxyperoxide lyase (HPL) are activated. These enzymes mediate production of green leafy volatiles and Jasmonic acid by interacting with hydroxperoxide molecules. We docked the elicitors with receptors and enzymes with substrates in the pathway of JA production. Phe was found to be an important amino acid that interacts with 13- hydroxyperoxides in the case of AOS to produce JA but not in the case of HPL. JA is converted to JA-Ile which shows strong binding with COI1 and COI1-JA-Ile complex docked with JAZ which showed strong interaction with five hydrogens and one salt bridge bond. AOS and HPL showed less than 40% identity for sequence and structure alignment. AOS and HPL had shown an interaction between each other and showed a common interaction partner of the Lipoxygenase family. HPL shows interaction with ADH2 (Alcohol dehydrogenase) involved in GLVs production. AOS also showed interaction partner AOC, COI1 and OPR1 which are involved in JA-induced plant defense mechanism.

The Use of the Defense Mechanism Test to Aid in Understanding the Personality of Senior Executives and the Implications for Their Careers

2009 ◽  
Vol 30 (1) ◽  
pp. 73-96 ◽  
Author(s):  
Olya Khaleelee
Keyword(s):  
Crisis Intervention ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Senior Executives ◽  
Ideal Types ◽  
The Individual ◽  
Test Profiles ◽  
Real Test

This paper describes the use of the Defense Mechanism Test as an aid in helping to assess senior executives in four areas: for selection, development, career strategy, and crisis intervention. The origins of this test, developed to measure the defense mechanisms used to protect the individual from stress, are described. The paper shows how it was used to predict the capacity of trainee fighter pilots to withstand stress and its later application to other stressful occupations. Finally, some ideal types of the test are shown followed by four real test profiles, two of them with their associated histories.

A Study of Memory and Psychological Defense Mechanism in Julian Barnes’s The Sense of an Ending

2019 ◽  
Author(s):  
Hossein Aliakbari Harehdasht ◽  
Zahra Ekbatäni
Keyword(s):  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Human Mind ◽  
The Novel ◽  
Psychological Defense ◽  
Julian Barnes ◽  
Self Image

In The Sense of an Ending, Julian Barnes portrays the mysterious workings of the human mind as it distorts facts towards the end of a self-image that one can live with. The protagonist in the novel deploys certain psychological defense mechanisms in order to protect himself from feelings of anxiety, only to experience even more profound anxiety due to his excessive use of them. The significance of the present paper lies in its novel view of the book. So far, the critique on the novel has mainly been focused on the workings of time on memory; however, the present paper investigates how psychological defense mechanisms blur the protagonist’s perception of reality and distort his memories. This paper also attempts to attract scholarly interest in the study of psychological defense mechanisms in the study of The Sense of an Ending which has so far been to the best of our knowledge overlooked

Comparison of Defense Mechanisms Utilized in Perception by Congenitally Blind and Sighted Respondents

1984 ◽  
Vol 55 (1) ◽  
pp. 228-230
Author(s):  
Sam Minskoff ◽  
John M. Curtis
Keyword(s):  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Ego Defenses ◽  
Congenitally Blind

The present study examined specific defense mechanisms involved in perceptions of congenitally blind and sighted respondents. The Defense Mechanism Inventory was given 30 blind and 30 sighted subjects, randomly selected. One-way analyses of variance on specific defenses indicated nonsignificant differences between the groups who tended to show comparable patterns of ego defenses. Findings suggest any discrepancies in perception between such groups are not likely based on differences in the use of various defense mechanisms as measured by the Defense Mechanism Inventory.

scholarly journals Mitochondrial Hormesis in PancreaticβCells: Does Uncoupling Protein 2 Play a Role?

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Ning Li ◽  
Suzana Stojanovski ◽  
Pierre Maechler
Keyword(s):  
Stress Responses ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Cell Function ◽  
Uncoupling Protein ◽  
Glucose Sensing ◽  
Mitochondrial Uncoupling ◽  
Mitochondrial Uncoupling Protein ◽  
Cellular Stresses ◽  
Excessive Nutrients

In pancreaticβcells, mitochondrial metabolism translates glucose sensing into signals regulating insulin secretion. Chronic exposure ofβcells to excessive nutrients, namely, glucolipotoxicity, impairsβ-cell function. This is associated with elevated ROS production from overstimulated mitochondria. Mitochondria are not only the major source of cellular ROS, they are also the primary target of ROS attacks. The mitochondrial uncoupling protein UCP2, even though its uncoupling properties are debated, has been associated with protective functions against ROS toxicity. Hormesis, an adaptive response to cellular stresses, might contribute to the protection againstβ-cell death, possibly limiting the development of type 2 diabetes. Mitochondrial hormesis, or mitohormesis, is a defense mechanism observed in ROS-induced stress-responses by mitochondria. Inβcells, mitochondrial damages induced by sublethal exogenous H2O2can induce secondary repair and defense mechanisms. In this context, UCP2 is a marker of mitohormesis, being upregulated following stress conditions. When overexpressed in nonstressed naïve cells, UCP2 confers resistance to oxidative stress. Whether treatment with mitohormetic inducers is sufficient to restore or ameliorate secretory function ofβcells remains to be determined.

scholarly journals AUDREY TURNER’S CONFLICTS AND DEFENSE MECHANISMS IN KINSELLA’S 'FINDING AUDREY'

2018 ◽  
Vol 3 (1) ◽  
pp. 45
Author(s):  
M. Aprianto Budie Nugroho ◽  
Sely Viladinia
Keyword(s):  
Anxiety Disorder ◽  
Research Design ◽  
Defense Mechanisms ◽  
Qualitative Method ◽  
Defense Mechanism ◽  
Narrative Research ◽  
Internal Conflict ◽  
Main Character

A story becomes interesting because of the existence of the characters’ conflicts. This research objectives were to investigate the conflicts and defense mechanisms in Audrey Turner, the main character of Finding Audrey novel written by Sophie Kinsella. This research was conducted in qualitative method by using narrative research design. The collected data were identified, categorized, and analyzed based on literature and psychology perspectives of Islam’s (2016) theory and defense mechanisms by Cramer (2006). The findings show that person vs him/herself as the internal conflict is found 52 times (67.5%). The first external conflict found is person vs person which appears 23 times (29.9%) It is followed by person vs society and person vs nature conflicts, each of which appears once only (1.3%). Three kinds of defense mechanisms are found as well. The denial defense mechanisms are found 72 times (54.1%) whereas projection and identification are each found as many as 48 times (36.1%) and 13 times (9.8%). It means that  Audrey, as the main character, mostly faces conflicts against her own self and feels of fears affected from her anxiety disorder and people around her. To deal with her conflicts, Audrey mostly uses denial as a defense mechanism to protect herself.

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