Microorganisms in Plant Growth and Pathogens

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Questions and Answers

Which of these factors was found to significantly improve the drought resistance of perennial ryegrass?

Bacillus amyloliquefaciens GB03

Super absorbent hydrogels

Both A and B (correct)

None of the above

What was the primary focus of the research by He et al.?

Studying the effect of mycorrhizal fungi on plant growth and disease resistance

Analyzing the role of effector proteins in fungal pathogenesis

Investigating the mechanism of host-specificity in plant-pathogenic fungi

Identifying genes involved in plant growth promotion and abiotic stress tolerance in a drought-tolerant bacterium (correct)

Which of the following is a characteristic of biotrophic plant-pathogenic fungi?

They are primarily found in soil

They produce toxins that kill plant cells

They rely on dead plant tissue for nutrition

They live in close association with their host plant (correct)

What is the primary function of effector proteins secreted by biotrophic fungi?

To suppress plant immune responses (C) Signup and view all the answers

In the study by Gao et al., what method was used to identify putative effector proteins in Fusarium proliferatum?

Transcriptome sequencing and analysis (D) Signup and view all the answers

Which of the following is NOT a mechanism by which microorganisms can improve plant fitness?

Reducing plant biomass production (B) Signup and view all the answers

What is the main idea presented in the passage?

Microorganisms play a crucial role in plant health and can be used to mitigate the challenges of climate change (A) Signup and view all the answers

Which of the following is an example of a biotrophic fungal pathogen?

Microbotryum lychnidis-dioicae (A) Signup and view all the answers

What is the potential significance of the CarO protein found in Fusarium fujikuroi?

It appears to be involved in the regulation of light-driven proton pumping (C) Signup and view all the answers

What is the main takeaway from the research by Wang et al. regarding the interaction of kiwifruit with Pseudomonas syringae pv. actinidiae?

The kiwifruit plant mounts a multifaceted defense response against the infection (C) Signup and view all the answers

What is a key characteristic of Streptomyces species that makes them more competitive than other microbes?

They can form spores and survive adverse conditions in the soil. (C) Signup and view all the answers

How do Streptomyces species contribute to the typical fragrance of fresh forest soil?

They produce volatile organic compounds. (C) Signup and view all the answers

What is the primary benefit of utilizing plant growth-promoting bacteria (PGPB) in phytoremediation?

PGPB can help plants withstand metal-induced stress and improve their growth. (D) Signup and view all the answers

Which of the following crops is mentioned as being particularly susceptible to drought and high salinity?

Lolium perenne (B) Signup and view all the answers

What is a key characteristic of Helianthus tuberosus that makes it suitable for bioethanol production?

It has a high biomass yield. (D) Signup and view all the answers

How do Streptomyces species qualify as biocontrol agents?

They can produce antibiotics that inhibit the growth of pathogens. (B) Signup and view all the answers

What is the primary way in which Streptomyces species contribute to plant growth promotion?

They facilitate the uptake of nutrients by plants through the breakdown of organic polymers. (B) Signup and view all the answers

Which of the following applications is NOT mentioned as a possible use for plant growth-promoting bacteria?

Increasing the tolerance of crops to certain herbicides. (B) Signup and view all the answers

What is the significance of the fact that Streptomyces species can colonize root and aerial parts of plants?

It suggests they can protect the plant from pathogens in multiple locations. (B) Signup and view all the answers

Why is it significant that plant growth-promoting bacteria (PGPB) can grow endophytically?

It allows them to access nutrients from within the plant. (B) Signup and view all the answers

Study Notes

Microorganisms and Plant Growth

Streptomyces species: Filamentous microbes that colonize soil, roots, and aerial plant parts. Produce antibiotics, volatile organic compounds (giving soil its smell), and lytic enzymes. Act as biocontrol agents and biofertilizers. Their spore formation and survival in adverse conditions make them competitive.
Plant growth-promoting bacteria: Beneficial bacteria that enhance plant growth and resistance to abiotic stresses (drought, salt). Can also be used in phytoremediation (remediating metal-contaminated soil). Examples include Bacillus amyloliquefaciens GB03 and bacteria isolated from other tolerant plants.
Arbuscular mycorrhizal fungi (AMF): Specifically, Rhizophagus irregularis CD1 enhances plant growth, especially cotton, and resistance to Verticillium dahliae wilt. This fungus may inhibit V. dahliae growth via unknown volatiles.

Plant Pathogens and Host Specificity

Fungal Plant Pathogens: A significant threat to plant health. Many are highly host-specific. Elucidating the host specificity factors for pathogen proliferation and disease formation is a crucial research topic.
Biotrophic Plant Pathogenic Fungi: Live in close contact with plant tissue, feeding on living plant parts and subvert plant defenses. One strategy is secreting effector proteins that interact with plant proteins to the pathogen's advantage. Examples include Microbotryum lychnidis-dioicae (anther smut) and Fusarium proliferatum (tomato disease).
Host specificity factors: Identification often involves comparing molecular characteristics of different strains or species. This usually results in a list of target genes potentially involved in host-specific virulence, requiring further verification and validation. Combining classical genetics, genomics, and transcriptomics (of both pathogen and host) is crucial.
Bacterial Plant Pathogens: Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker. Study of kiwifruit infected with Psa involved transcriptome analysis revealing upregulated genes involved in defense compounds, plant immunity, and metabolic processes.
Fungal Pathogens and Rhodopsins: Some phytopathogenic and phyto-associated ascomycetes contain rhodopsin-encoding genes. Fusarium fujikuroi, a rice plant pathogen, has two rhodopsins (CarO and OpsA). CarO, a light-driven proton pump, is shown to be positively regulated by indole-3-acetic acid and sodium acetate. Deletion of the CarO-encoding gene leads to hypervirulence.

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Description

Explore the vital role of microorganisms such as Streptomyces and plant growth-promoting bacteria in enhancing plant growth and resilience. Learn about arbuscular mycorrhizal fungi and their beneficial effects on crop health, along with insights into plant pathogens and their specific interactions with hosts.