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Questions and Answers
What structural feature do mycorrhizal plants form around the sites of pathogen infection?
What structural feature do mycorrhizal plants form around the sites of pathogen infection?
Which compound's accumulation is significantly enhanced in mycorrhizal tomatoes upon Phytophthora attack?
Which compound's accumulation is significantly enhanced in mycorrhizal tomatoes upon Phytophthora attack?
What type of pathogens did AM symbiosis induce systemic resistance against in tomato plants?
What type of pathogens did AM symbiosis induce systemic resistance against in tomato plants?
Which signaling pathway is confirmed to be required for AM-induced resistance against Botrytis cinerea in tomatoes?
Which signaling pathway is confirmed to be required for AM-induced resistance against Botrytis cinerea in tomatoes?
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In addition to the root system, where else has priming of defenses been shown in AM plants?
In addition to the root system, where else has priming of defenses been shown in AM plants?
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What is one direct mechanism by which AM fungi help reduce pathogenic fungi in plants?
What is one direct mechanism by which AM fungi help reduce pathogenic fungi in plants?
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Which of the following changes in the plant is associated with root colonization by AM fungi?
Which of the following changes in the plant is associated with root colonization by AM fungi?
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How do AM fungi influence plant defense mechanisms?
How do AM fungi influence plant defense mechanisms?
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Which statement best describes the competitive interaction between AM fungi and pathogenic microorganisms?
Which statement best describes the competitive interaction between AM fungi and pathogenic microorganisms?
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What role do changes in root exudates play in the relationship between AM fungi and pathogens?
What role do changes in root exudates play in the relationship between AM fungi and pathogens?
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Which effect of AM fungi has been observed regarding pathogenic oomycetes?
Which effect of AM fungi has been observed regarding pathogenic oomycetes?
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Which of the following is NOT a result of AM fungal influence on plants?
Which of the following is NOT a result of AM fungal influence on plants?
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What is the phenomenon called that results in the plant being in an 'alert' state, enhancing its response to attacks?
What is the phenomenon called that results in the plant being in an 'alert' state, enhancing its response to attacks?
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Which hormone is reported to play a central role in the functioning of arbuscular mycorrhizal (AM) symbiosis?
Which hormone is reported to play a central role in the functioning of arbuscular mycorrhizal (AM) symbiosis?
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How do AM fungi likely promote successful colonization of host plants?
How do AM fungi likely promote successful colonization of host plants?
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What is the main purpose of the autoregulation of symbiosis in plants?
What is the main purpose of the autoregulation of symbiosis in plants?
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Which of the following describes the relationship between salicylic acid (SA) and jasmonic acid (JA) in mycorrhizal plants?
Which of the following describes the relationship between salicylic acid (SA) and jasmonic acid (JA) in mycorrhizal plants?
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What occurs during the early stages of interaction between AM fungi and host plants?
What occurs during the early stages of interaction between AM fungi and host plants?
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What beneficial effect does priming provide to plants regarding pathogen attacks?
What beneficial effect does priming provide to plants regarding pathogen attacks?
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What type of plants tend to be more resistant to necrotrophs as a result of AM fungi interaction?
What type of plants tend to be more resistant to necrotrophs as a result of AM fungi interaction?
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In what way does the plant's defense mechanism change as a result of AM fungal colonization?
In what way does the plant's defense mechanism change as a result of AM fungal colonization?
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What are some of the consequences of the primed state in plants as influenced by AM fungi?
What are some of the consequences of the primed state in plants as influenced by AM fungi?
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Study Notes
Mechanisms of AM Fungi in Plant Protection
- AM fungi protect plants against biotic stresses through direct competition and indirect, plant-mediated effects.
- Direct effects involve competition for resources like carbon, nitrogen, and infection sites, reducing pathogenic fungi abundance in roots.
- Pathogenic fungi and AM fungi exploit common resources, leading to negative correlations between their structures in roots and soil.
- Root colonization by AM fungi alters root system architecture, morphology, and exudates, impacting pathogen dynamics and microbial community favorability.
Changes Induced by AM Fungi
- Root exudation modifications affect microbial pathogens and nematodes directly.
- AM fungi can reprogram plant gene expression, influencing plant primary and secondary metabolism related to defense.
- Initial colonization by AM fungi activates plant defense responses, which may be suppressed for successful symbiosis, leading to a state known as priming.
- Priming enhances plant defenses, resulting in faster and stronger responses to subsequent attacks, improving plant fitness and resistance.
Modulation of Host Plant's Immune System
- AM fungi are recognized as alien organisms, prompting the plant's immune response which must be managed for successful colonization.
- Plants maintain a feedback system to prevent excessive AM fungal colonization, termed autoregulation of the symbiosis.
- Initial immune responses, including a transient increase in salicylic acid and defensive compounds, are limited compared to pathogen interactions.
- AM fungi secrete effector proteins that may suppress plant defenses, facilitating colonization while modulating defense pathways.
Induced Systemic Resistance (ISR)
- Mycorrhizal plants exhibit broad-spectrum resistance against various pathogens and herbivores, influenced by alterations in jasmonic acid and salicylic acid levels.
- Resistance to necrotrophic and chewing insects correlates with increased JA-dependent defenses, while biotrophs target SA-regulated defenses.
- Effective control of JA and SA signaling pathways is key for the protective benefits conferred by mycorrhizal associations.
Priming for Enhanced Defense
- AM fungi induce resistance without direct activation of defense mechanisms, leading to tissue sensitization for efficient response upon pathogen attack.
- Primed states involve moderate accumulation of regulatory molecules, such as transcription factors and MAP kinases.
- Mycorrhizal roots display stronger defense mechanisms against pathogens like Fusarium and Phytophthora, including specific structural and biochemical responses.
- AM fungi's priming effects extend beyond roots, enhancing defenses in aboveground tissues, demonstrated in studies of tomato plants against Botrytis cinerea.
Practical Implications
- Understanding the interactions between AM fungi and plant defenses provides insights into ecological benefits and potential agricultural applications.
- Research indicates that AM fungi can improve crop resistance, thereby enhancing productivity and reducing the need for chemical pesticides.
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Description
Explore the mechanisms through which arbuscular mycorrhizal (AM) fungi protect plants against biotic stresses. This quiz covers direct competition for resources, root colonization effects, and the reprogramming of plant gene expression. Understand how these interactions influence pathogen dynamics and enhance plant defense mechanisms.
