Enhanced Disease Resistance Caused by BRI1 Mutation Is Conserved Between Brachypodium distachyon and Barley (Hordeum vulgare)

This study investigated the impact of brassinosteroid (BR)-insensitive 1 (BRI1) mutation, the main receptor of BR in both Brachypodium distachyon and barley, on disease resistance against a range of fungal pathogens of cereals exhibiting different trophic lifestyles. Results presented here show that i) disruption of BRI1 has pleiotropic effects on disease resistance in addition to affecting plant development. BR signaling functions antagonistically with mechanisms of disease resistance that are effective against a broad range of cereal pathogens. ii) Disruption of BRI1 results in increased disease resistance against necrotrophic and hemibiotrophic pathogens that exhibit only a marginal asymptomatic phase but has no effect on biotrophic pathogens or those with a prolonged asymptomatic phase, and iii) disruption of BRI1 has a similar effect on disease resistance in B. distachyon and barley, indicating that defense mechanisms are conserved between these species. This work presents the first evidence for conservation of disease resistance mechanisms between the model species B. distachyon and the cereal crop barley and validates B. distachyon for undertaking model-to-crop translation studies of disease resistance.

Download Full-text

Zinc Induced Enzymatic Defense Mechanisms in Rhizoctonia Root Rot Infected Clusterbean Seedlings

Journal of Botany ◽

10.1155/2014/735760 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 7

Author(s):

Neha Wadhwa ◽

Udai Narayan Joshi ◽

Naresh Mehta

Keyword(s):

Enzyme Activity ◽

Disease Resistance ◽

Root Rot ◽

Defense Mechanisms ◽

Phenylalanine Ammonia Lyase ◽

Resistance Mechanisms ◽

Phenylpropanoid Metabolism ◽

Rhizoctonia Root Rot ◽

Tyrosine Ammonia Lyase ◽

Wet Weight

This investigation was planned to determine the effect of different concentrations of zinc (Zn) on biochemical constituents of clusterbean, which play an important role in disease resistance mechanisms. Clusterbean seedlings were grown with 0, 10, or 20 mg Zn kg−1 soil treatments in earthen pots filled with 700 g inoculated soil. Soil was inoculated by pretreatment with 250 mg (wet weight) of Rhizoctonia inoculums per pot. A similar set was maintained in uninoculated soil. Root rot incidence decreased to 41 and 27 per cent with 10 and 20 mg Zn kg−1 soil treatments, respectively, as compared to 68 percent at control. Antioxidative enzyme activity (polyphenol oxidase, peroxidase, phenylalanine ammonia lyase, and tyrosine ammonia lyase) increased in inoculated seedlings and was increased further by 20 mg Zn kg−1 soil treatment. Antioxidative enzymes play an important role against fungal invasion, as peroxidase is involved in the formation of barrier via lignifications at the site of pathogen penetration. PAL and TAL play a key role in phenylpropanoid metabolism and could perform defense-related functions. Zn acts as a cofactor for these enzymes, so it can be concluded that Zn may be used as a soil-nutritive agent to increase resistance in plants against fungal diseases.

Download Full-text

Genetic diversity and disease resistance: some considerations for research, breeding, and deployment

Canadian Journal of Forest Research ◽

10.1139/x00-136 ◽

2001 ◽

Vol 31 (4) ◽

pp. 596-606 ◽

Cited By ~ 31

Author(s):

Rowland D Burdon

Keyword(s):

Genetic Diversity ◽

Disease Resistance ◽

Fungal Pathogens ◽

Indirect Costs ◽

Resistance Mechanisms ◽

Genetic Management ◽

Breeding Populations ◽

Pathogen Fitness ◽

Population Sizes ◽

Cost Of Virulence

Fungal pathogens present a complex challenge for genetic management of forest trees. The need is for disease resistance that withstands mutations and genetic shifts in pathogens. Also desirable are defences against new and dangerous pathogens. An understanding of how hosts and pathogens can continue to coexist should help. Experience from agriculture has allowed modelling of pathosystems, the genetic variations within hosts and pathogens that permit coexistence. While it is impractical to construct a comprehensive model, two phenomena seem generally conducive to stability: a cost of "virulence" in pathogen fitness and a multiplicity of host resistance mechanisms. However, other factors, notably indirect costs of resistance, are very difficult to model. Overall, the diversity of behaviour of models, of the nature of resistance and virulence genes, and of biology of both hosts and pathogens precludes any unique formula for stability. For current crops, genetic diversity offers risk spread for susceptibility to a new and serious pathogen or pathotype. For longer-term breeding, relatively rare resistance may be useful, but pedigreed breeding populations typically entail very finite population sizes. Providing for selecting within improved production populations may therefore be needed. This would give breeders technical challenges, and give forest managers opportunity costs and major logistical challenges.

Download Full-text

Interplay between Candida albicans and the Antimicrobial Peptide Armory

Eukaryotic Cell ◽

10.1128/ec.00093-14 ◽

2014 ◽

Vol 13 (8) ◽

pp. 950-957 ◽

Cited By ~ 72

Author(s):

Marc Swidergall ◽

Joachim F. Ernst

Keyword(s):

Candida Albicans ◽

Defense Mechanisms ◽

Fungal Pathogens ◽

Pathogenic Fungi ◽

Resistance Mechanisms ◽

Immune Defense ◽

Basal Resistance ◽

Content Type ◽

Normal Human ◽

Molecular Patterns

ABSTRACTAntimicrobial peptides (AMPs) are key elements of innate immunity, which can directly kill multiple bacterial, viral, and fungal pathogens. The medically important fungusCandida albicanscolonizes different host niches as part of the normal human microbiota. Proliferation ofC. albicansis regulated through a complex balance of host immune defense mechanisms and fungal responses. Expression of AMPs against pathogenic fungi is differentially regulated and initiated by interactions of a variety of fungal pathogen-associated molecular patterns (PAMPs) with pattern recognition receptors (PRRs) on human cells. Inflammatory signaling and other environmental stimuli are also essential to control fungal proliferation and to prevent parasitism. To persist in the host,C. albicanshas developed a three-phase AMP evasion strategy, including secretion of peptide effectors, AMP efflux pumps, and regulation of signaling pathways. These mechanisms preventC. albicansfrom the antifungal activity of the major AMP classes, including cathelicidins, histatins, and defensins leading to a basal resistance. This minireview summarizes human AMP attack andC. albicansresistance mechanisms and current developments in the use of AMPs as antifungal agents.

Download Full-text

Prospects for Engineering Enhanced Durable Disease Resistance in Crops

Feeding a World Population of More Than Eight Billion People ◽

10.1093/oso/9780195113129.003.0020 ◽

1998 ◽

Author(s):

Chris Lamb

Keyword(s):

Disease Resistance ◽

Defense Mechanisms ◽

Durable Resistance ◽

Genetic Resistance ◽

Crop Productivity ◽

Resistance Mechanisms ◽

Postharvest Diseases ◽

Host Interactions ◽

Crop Diseases ◽

Plant Life Cycle

Plants have evolved a battery of defense mechanisms that in aggregate provide protection against a wide range of potential viral, bacterial, fungal, and other pathogens encountered throughout the plant life cycle. However, in the artificial setting of agriculture, disease, although the exception, can be costly and even devastating. Crop diseases have played significant roles in human history, exemplified by the widespread starvation and mass emigration triggered by the failure of European potato crops in the mid-nineteenth century as a result of late blight. Today, the use of pesticides, breeding for resistance, and integrated pest management provide important tools for reducing crop losses to pre-and postharvest diseases. However, agrichemicals are expensive, prohibitively so for many fanners in developing countries, and there are increasing concerns about environmental load from their intensive application. Likewise, major disease resistance (R) genes are in many cases not durable, resistance breaking down within one or two seasons as a result of selection pressure on the pathogen population, and most breeding efforts now rely on combinations of minor resistance genes, each giving partial protection. For a number of important diseases, such as take-all of wheat, there is no effective genetic resistance. Population growth, migration to cities, desertification, and climate change all now contribute to an urgent need to secure diversified food production against disease losses. In this chapter I discuss the prospects that genetic engineering of disease-resistance mechanisms can contribute to durable, broad protection and hence underpin enhanced crop productivity. Plants have a number of performed physical and chemical defensive mechanisms that help protect against the myriad potential pathogens to which plants arc exposed (Osbourn, 1996). However, superimposed upon this preexisting protective armory, plants respond to the perception of pathogen attack by activation of inducible defense mechanisms (Lamb et al., 1989; Staskawicz et al., 1995). Many of the most important crop diseases involve specialized interactions between pathogen and host. Interactions between specific plant cultivars and defined physiological races or strains of potential pathogens are described as compatible (host susceptible, pathogen virulent) or incompatible (host resistant, pathogen avirulent).

Download Full-text

Host Defenses Associated with Fruit Infection by Colletotrichum Species with an Emphasis on Anthracnose of Blueberries

Plant Health Progress ◽

10.1094/php-2013-1125-01-rv ◽

2013 ◽

Vol 14 (1) ◽

pp. 30 ◽

Cited By ~ 1

Author(s):

Timothy D. Miles ◽

Annemiek C. Schilder

Keyword(s):

Host Resistance ◽

Defense Mechanisms ◽

Fungal Pathogens ◽

Sugar Content ◽

Defense Responses ◽

Vaccinium Corymbosum ◽

Resistance Mechanisms ◽

Fruit Rot ◽

Tissue Type ◽

Postharvest Disease

Defense mechanisms in fruit against invasion by fungal pathogens fall into several categories, including fruit physiological factors, passive defense responses, and active defense responses. Colletotrichum spp. are common fruit rot pathogens on a variety of crops. The infection strategy of Colletotrichum pp. varies depending upon the host and the tissue type being colonized and range from hemibiotrophy to necrotrophy. Anthracnose fruit rot caused by C. acutatum is the most important postharvest disease of blueberries (Vaccinium corymbosum). In order to better understand host resistance mechanisms in blueberry fruits, the resistant cultivar Elliott was compared with the susceptible cultivar Jersey. Higher levels of hydrogen peroxide and differentially expressed defense-related genes were found in ‘Elliott’ than in ‘Jersey’ fruit after inoculation. Furthermore, higher levels of anthocyanins and flavonols, including two distinctive compounds, were observed in Elliott fruits and two unique flavonols were present in Elliott. Additionally, pH and sugar content were implicated as being involved in host resistance in blueberry fruits. The results from these studies provide a significant contribution to the understanding of the multiple factors that contribute to anthracnose fruit rot resistance in blueberry. Accepted for publication 15 August 2013. Published 25 November 2013.

Download Full-text

Light environment affects the levels of resistance hormones in Syngonium podophyllum leaves and its attack by herbivores and fungi

Botanical Sciences ◽

10.17129/botsci.1213 ◽

2017 ◽

Vol 95 (3) ◽

pp. 363 ◽

Cited By ~ 1

Author(s):

Graciela García-Guzmán ◽

Frida Domínguez-Velázquez ◽

Jaime Mendiola-Soto ◽

Martin Heil

Keyword(s):

Fungal Pathogens ◽

Physiological Mechanism ◽

Trophic Levels ◽

Abiotic Factor ◽

Los Tuxtlas ◽

Light Conditions ◽

Model Species ◽

Tropical Plants ◽

Tropical Plant ◽

Biotrophic Pathogens

Background: Little is known on factors determining infection of tropical plants by fungal pathogens, although multiple studies on model species show that light conditions affect the two major hormones that control resistance in plants to enemies. This is the first study using a natural population of a wild tropical plant to relate light conditions to resistance hormones and, the beneficial and detrimental interactions with insects and fungi.Hypothesis: Light conditions affect the endogenous levels of resistance hormones and thereby cause quantitative shifts among herbivores and nectrotrophic, biotrophic and endophytic fungi.Studied species: The tropical vine Syngonium podophyllum.Study site: Los Tuxtlas tropical rain forest, Mexico.Methods: We used GC-MS to quantify the concentration of the two resistance hormones in intact leaves and natural levels of herbivory and fungal disease in S. podophyllum plants growing naturally in the full sun or in the shade.Results: The proportion of leaves damaged by herbivores or infected by hemibiotrophic or necrotrophic pathogens was higher in shade than under full-light conditions. Damage caused by biotrophic pathogens was frequently observed in sun but not in shade. Levels of both hormones in phenotypically healthy leaves were higher in sun than in shade.Conclusions: (i) light has an effect on concentrations of plant resistance hormones in nature; (ii) these differences have consequences for fungi and animals that naturally interact with the plant, and (iii) the described effect can represent a physiological mechanism via which an abiotic factor affects the members of the guilds at higher trophic levels.

Download Full-text

Comparative Mapping of Three Bacterial, Three Fungal, and One Virus Disease-resistance Genes in Common Bean

HortScience ◽

10.21273/hortsci.33.3.547a ◽

1998 ◽

Vol 33 (3) ◽

pp. 547a-547

Author(s):

Geunhwa Jung ◽

James Nienhuis ◽

Dermot P. Coyne ◽

H.M. Ariyarathne

Keyword(s):

Disease Resistance ◽

Common Bean ◽

Pseudomonas Syringae ◽

Resistance Genes ◽

Fungal Pathogens ◽

Xanthomonas Campestris ◽

Virus Disease ◽

Disease Resistance Genes ◽

Brown Spot ◽

Viral Pathogen

Common bacterial blight (CBB), bacterial brown spot (BBS), and halo blight (HB), incited by the bacterial pathogens Xanthomonas campestris pv. phaseoli (Smith) Dye, Pseodomonas syringae pv. syringa, and Pseudomonas syringae pv. phaseolicola, respectively are important diseases of common bean. In addition three fungal pathogens, web blight (WB) Thanatephorus cucumeris, rust Uromyces appendiculatus, and white mold (WM) Sclerotinia sclerotiorum, are also destructive diseases attacking common bean. Bean common mosaic virus is also one of most major virus disease. Resistance genes (QTLs and major genes) to three bacterial (CBB, BBS, and HB), three fungal (WB, rust, and WM), and one viral pathogen (BCMV) were previously mapped in two common bean populations (BAC 6 × HT 7719 and Belneb RR-1 × A55). The objective of this research was to use an integrated RAPD map of the two populations to compare the positions and effect of resistance QTL in common bean. Results indicate that two chromosomal regions associated with QTL for CBB resistance mapped in both populations. The same chromosomal regions associated with QTL for disease resistance to different pathogens or same pathogens were detected in the integrated population.

Download Full-text

The Impact of Plant Bioactive Compounds on Aging and Fertility of Diverse Organisms: A Review

Mini-Reviews in Medicinal Chemistry ◽

10.2174/1389557520666200429101942 ◽

2020 ◽

Vol 20 (13) ◽

pp. 1287-1299

Author(s):

Muhammad Akram Mohd Noordin ◽

Mahanem Mat Noor ◽

Wan Mohd Aizat

Keyword(s):

Clinical Trial ◽

Bioactive Compounds ◽

Defense Mechanisms ◽

Healthy Aging ◽

Antioxidant Defense ◽

Senior Citizens ◽

Aging Population ◽

Human Clinical Trial ◽

Fertility Reduction ◽

The Impact

It is expected that in 2050, there will be more than 20% of senior citizens aged over 60 years worldwide. Such alarming statistics require immediate attention to improve the health of the aging population. Since aging is closely related to the loss of antioxidant defense mechanisms, this situation eventually leads to numerous health problems, including fertility reduction. Furthermore, plant extracts have been used in traditional medicine as potent antioxidant sources. Although many experiments had reported the impact of various bioactive compounds on aging or fertility, there is a lack of review papers that combine both subjects. In this review, we have collected and discussed various bioactive compounds from 26 different plant species known to affect both longevity and fertility. These compounds, including phenolics and terpenes, are mostly involved in the antioxidant defense mechanisms of diverse organisms such as rats, mites, fruit flies, roundworms, and even roosters. A human clinical trial should be considered in the future to measure the effects of these bioactive compounds on human health and longevity. Ultimately, these plant-derived compounds could be developed into health supplements or potential medical drugs to ensure a healthy aging population.

Download Full-text

Stress, Burnout, and Resilience among Healthcare Workers during the COVID-19 Emergency: The Role of Defense Mechanisms

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18105258 ◽

2021 ◽

Vol 18 (10) ◽

pp. 5258

Author(s):

Mariagrazia Di Giuseppe ◽

Gianni Nepa ◽

Tracy A. Prout ◽

Fabrizio Albertini ◽

Stefano Marcelli ◽

...

Keyword(s):

Healthcare Workers ◽

Defense Mechanisms ◽

Online Survey ◽

Healthcare Professionals ◽

Well Being ◽

Personal Accomplishment ◽

Traumatic Experience ◽

Psychological Resources ◽

Defensive Functioning ◽

The Impact

The experience of working on the frontlines of the COVID-19 healthcare crisis has presented a cumulative traumatic experience that affects healthcare professionals’ well-being. Psychological resources such as resilience and adaptive defense mechanisms are essential in protecting individuals from severe stress and burnout. During September 2020, 233 healthcare workers responded to an online survey to test the impact of demographic variables, COVID-19 exposure, and psychological resources in determining stress and burnout during the COVID-19 emergency. Frontline workers reported higher scores for stress, emotional exhaustion, and depersonalization (p < 0.001) as compared to colleagues working in units not directly serving patients with COVID-19. Mature defensive functioning was associated with resilience and personal accomplishment (r = 0.320; p < 0.001), while neurotic and immature defenses were related to perceived stress and burnout. Stress and burnout were predicted by lower age, female gender, greater exposure to COVID-19, lower resilience, and immature defensive functioning among healthcare professionals (R2 = 463; p < 0.001). Working on the frontlines of the COVID-19 pandemic appears to provoke greater stress and burnout. On the other hand, resilience and adaptive defense mechanisms predicted better adjustment. Future reaction plans should promote effective programs offering support for healthcare workers who provide direct care to patients with COVID-19.

Download Full-text

MicroRNA-Regulated Signaling Pathways: Potential Biomarkers for Pancreatic Ductal Adenocarcinoma

Stresses ◽

10.3390/stresses1010004 ◽

2021 ◽

Vol 1 (1) ◽

pp. 30-47

Author(s):

Maria Mortoglou ◽

David Wallace ◽

Aleksandra Buha Buha Djordjevic ◽

Vladimir Djordjevic ◽

E. Damla Arisan ◽

...

Keyword(s):

Pancreatic Ductal Adenocarcinoma ◽

Metabolic Stress ◽

Resistance Mechanisms ◽

Current Data ◽

Cellular Damage ◽

Ductal Adenocarcinoma ◽

Aberrant Expression ◽

Metabolic Alterations ◽

Limited Effectiveness ◽

The Impact

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive and invasive type of pancreatic cancer (PCa) and is expected to be the second most common cause of cancer-associated deaths. The high mortality rate is due to the asymptomatic progression of the clinical features until the advanced stages of the disease and the limited effectiveness of the current therapeutics. Aberrant expression of several microRNAs (miRs/miRNAs) has been related to PDAC progression and thus they could be potential early diagnostic, prognostic, and/or therapeutic predictors for PDAC. miRs are small (18 to 24 nucleotides long) non-coding RNAs, which regulate the expression of key genes by targeting their 3′-untranslated mRNA region. Increased evidence has also suggested that the chemoresistance of PDAC cells is associated with metabolic alterations. Metabolic stress and the dysfunctionality of systems to compensate for the altered metabolic status of PDAC cells is the foundation for cellular damage. Current data have implicated multiple systems as hallmarks of PDAC development, such as glutamine redox imbalance, oxidative stress, and mitochondrial dysfunction. Hence, both the aberrant expression of miRs and dysregulation in metabolism can have unfavorable effects in several biological processes, such as apoptosis, cell proliferation, growth, survival, stress response, angiogenesis, chemoresistance, invasion, and migration. Therefore, due to these dismal statistics, it is crucial to develop beneficial therapeutic strategies based on an improved understanding of the biology of both miRs and metabolic mediators. This review focuses on miR-mediated pathways and therapeutic resistance mechanisms in PDAC and evaluates the impact of metabolic alterations in the progression of PDAC.

Download Full-text