scholarly journals Chloroplasts at the Crossroad of Photosynthesis, Pathogen Infection and Plant Defense

2018 ◽  
Vol 19 (12) ◽  
pp. 3900 ◽  
Author(s):  
Yan Lu ◽  
Jian Yao
Keyword(s):  
Plant Defense ◽  
Defense Mechanisms ◽  
Bacterial Pathogens ◽  
Signaling Molecules ◽  
Biological Processes ◽  
Pathogen Infection ◽  
Primary Metabolites ◽  
Key Steps ◽  
A Site ◽  
Host Tissues

Photosynthesis, pathogen infection, and plant defense are three important biological processes that have been investigated separately for decades. Photosynthesis generates ATP, NADPH, and carbohydrates. These resources are utilized for the synthesis of many important compounds, such as primary metabolites, defense-related hormones abscisic acid, ethylene, jasmonic acid, and salicylic acid, and antimicrobial compounds. In plants and algae, photosynthesis and key steps in the synthesis of defense-related hormones occur in chloroplasts. In addition, chloroplasts are major generators of reactive oxygen species and nitric oxide, and a site for calcium signaling. These signaling molecules are essential to plant defense as well. All plants grown naturally are attacked by pathogens. Bacterial pathogens enter host tissues through natural openings or wounds. Upon invasion, bacterial pathogens utilize a combination of different virulence factors to suppress host defense and promote pathogenicity. On the other hand, plants have developed elaborate defense mechanisms to protect themselves from pathogen infections. This review summarizes recent discoveries on defensive roles of signaling molecules made by plants (primarily in their chloroplasts), counteracting roles of chloroplast-targeted effectors and phytotoxins elicited by bacterial pathogens, and how all these molecules crosstalk and regulate photosynthesis, pathogen infection, and plant defense, using chloroplasts as a major battlefield.

On the Role of Calpain and Rho Proteins in Regulating Integrin-induced Signaling

1999 ◽  
Vol 82 (08) ◽  
pp. 385-391 ◽  
Author(s):  
Joan Fox
Keyword(s):  
Signaling Molecules ◽  
Cytoskeletal Proteins ◽  
Adherent Cells ◽  
Rho Proteins ◽  
Ligand Interactions ◽  
Platelet Aggregate ◽  
And Migration ◽  
Key Steps ◽  
A Site ◽  
Induced Changes

SummaryThe integrin family of transmembrane receptors plays an essential role in inducing the adhesion of cells to the extracellular matrix. In some cases, members of this family of receptors can bind soluble ligands or can bind receptors on other cells and, in this way, mediate interactions between cells. In all cases, once an integrin has bound, ligand signals are transmitted across the occupied integrin. These signals culminate in changes in the behavior of the cell appropriate for the adherent state of the cell. For example, in the case of platelets, an end result of the signaling induced by binding of fibrinogen to αIIbβ3 in a platelet aggregate is a reorganization of the cytoskeleton that leads to retraction of externally-bound fibrin by clots.1,2 In the case of neutrophils, cytoskeletal changes following the integrininduced interaction of neutrophils with endothelial cells lead to the migration of neutrophils into a site of injury.3,4 Other examples of the consequences of integrin-induced signaling in adherent cells include the trafficking of lymphocytes and migration of cells during development, angiogenesis, and metastasis.5-7 Numerous signaling molecules have been shown to be activated following integrin-ligand interactions.8 Many of these associate in complexes with ligand-occupied integrin and cytoskeletal proteins. However, in general, little is known about the key steps involved regarding integrin-induced changes in the behavior of adherent cells. The present chapter reviews steps involved in integrin-induced signaling, describes the evidence that calpain is one of the signaling molecules involved in this signal transduction, and discusses potential mechanisms by which cleavage of cytoskeletal proteins and signaling molecules by calpain may regulate the integrin-induced changes in cell behavior.

scholarly journals Transcription Factors as the “Blitzkrieg” of Plant Defense: A Pragmatic View of Nitric Oxide’s Role in Gene Regulation

2021 ◽  
Vol 22 (2) ◽  
pp. 522
Author(s):  
Noreen Falak ◽  
Qari Muhammad Imran ◽  
Adil Hussain ◽  
Byung-Wook Yun
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Plant Defense ◽  
Systemic Acquired Resistance ◽  
Defense Mechanism ◽  
Regulation Of Gene Expression ◽  
Acquired Resistance ◽  
Biological Processes ◽  
Genetic Components ◽  
Transcriptional Changes

Plants are in continuous conflict with the environmental constraints and their sessile nature demands a fine-tuned, well-designed defense mechanism that can cope with a multitude of biotic and abiotic assaults. Therefore, plants have developed innate immunity, R-gene-mediated resistance, and systemic acquired resistance to ensure their survival. Transcription factors (TFs) are among the most important genetic components for the regulation of gene expression and several other biological processes. They bind to specific sequences in the DNA called transcription factor binding sites (TFBSs) that are present in the regulatory regions of genes. Depending on the environmental conditions, TFs can either enhance or suppress transcriptional processes. In the last couple of decades, nitric oxide (NO) emerged as a crucial molecule for signaling and regulating biological processes. Here, we have overviewed the plant defense system, the role of TFs in mediating the defense response, and that how NO can manipulate transcriptional changes including direct post-translational modifications of TFs. We also propose that NO might regulate gene expression by regulating the recruitment of RNA polymerase during transcription.

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 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 How to rewire the host cell: A home improvement guide for intracellular bacteria

2017 ◽  
Vol 216 (12) ◽  
pp. 3931-3948 ◽  
Author(s):  
Elias Cornejo ◽  
Philipp Schlaermann ◽  
Shaeri Mukherjee
Keyword(s):  
Host Cell ◽  
Signaling Pathways ◽  
Membrane Trafficking ◽  
Defense Mechanisms ◽  
Bacterial Pathogens ◽  
Innate Immune ◽  
Intracellular Bacteria ◽  
Immune Signaling ◽  
Innate Immune Signaling ◽  
The Unfolded Protein Response

Intracellular bacterial pathogens have developed versatile strategies to generate niches inside the eukaryotic cells that allow them to survive and proliferate. Making a home inside the host offers many advantages; however, intracellular bacteria must also overcome many challenges, such as disarming innate immune signaling and accessing host nutrient supplies. Gaining entry into the cell and avoiding degradation is only the beginning of a successful intracellular lifestyle. To establish these replicative niches, intracellular pathogens secrete various virulence proteins, called effectors, to manipulate host cell signaling pathways and subvert host defense mechanisms. Many effectors mimic host enzymes, whereas others perform entirely novel enzymatic functions. A large volume of work has been done to understand how intracellular bacteria manipulate membrane trafficking pathways. In this review, we focus on how intracellular bacterial pathogens target innate immune signaling, the unfolded protein response, autophagy, and cellular metabolism and exploit these pathways to their advantage. We also discuss how bacterial pathogens can alter host gene expression by directly modifying histones or hijacking the ubiquitination machinery to take control of several host signaling pathways.

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