Plant Pathogen Interaction | Signalling

Summary

This video delves into the intricate dynamics of plant-pathogen interactions, highlighting the role of pattern recognition receptors (PRRs) and pathogen-associated molecular patterns (PAMPs) in triggering plant immunity. It explains two immunity responses: effector-triggered immunity (ETI) and pattern/PAMP-triggered immunity (PTI). The script details how pathogen effectors are detected by resistance proteins, leading to hypersensitive response (HR) and systemic acquired resistance (SAR). It also covers the hormonal signaling pathways activated by different pathogens, resulting in the production of defense genes and proteins to combat infection.

Takeaways

• 🌿 The interaction between plant cells and pathogens involves the recognition of Pathogen-Associated Molecular Patterns (PAMPs) by the plant's Pattern Recognition Receptors (PRRs).
• 🛡️ Plant cells have a defense mechanism known as Effector-Triggered Immunity (ETI) and Pattern-Triggered Immunity (PTI) to combat pathogens.
• 🔍 PTI is initiated when the plant's PRRs bind to PAMPs on the pathogen, activating a signaling cascade that leads to the expression of defense genes.
• 🛑 The defense response can also be triggered by the detection of pathogen effectors by the plant's Resistance (R) proteins, which leads to a Hypersensitive Response (HR).
• 💥 HR results in an oxidative burst and the production of callose, lignin, and phytoalexins, which help to contain the infection and prevent its spread to neighboring cells.
• 🌱 Systemic Acquired Resistance (SAR) is an advanced form of immunity where the plant produces proteins like PR-1 and chitinases to degrade the pathogen's cell wall and exoskeleton.
• 🌱 Hormonal signaling pathways are activated in response to different types of pathogens, with biotrophic pathogens inducing the SA pathway and necrotrophic pathogens inducing the JA pathway.
• 🌟 The activation of these hormonal pathways leads to the transcription of Pathogenesis-Related (PR) genes, which in turn express PR proteins to combat the infection.
• 🌱 The production of PR proteins is part of the plant's immune response to contain and prevent the spread of pathogen infection.
• 📈 The video script provides an overview of the complex mechanisms of plant-pathogen interactions and the plant's immune system's strategies to defend against infections.

Q & A

What is the role of pathogen-associated molecular patterns (PAMPs) in plant-pathogen interactions?

PAMPs are molecules found on the surface of pathogens that are recognized by the plant's pattern recognition receptors (PRRs), initiating the plant's immune response.

What are the two types of immunity discussed in the script related to plant-pathogen interactions?

The two types of immunity discussed are effector-triggered immunity (ETI) and pattern or PAMP-triggered immunity (PTI).

How do pattern recognition receptors (PRRs) on a plant cell interact with pathogens?

PRRs on the plant cell surface bind to PAMPs of the pathogen, which triggers the PTI and initiates the plant's immune response.

What is the function of resistance proteins (R proteins) in the context of plant immunity?

Resistance proteins are part of the plant's immune system that detect pathogen effectors, leading to the activation of defense mechanisms such as the hypersensitive response (HR).

What is the significance of the hypersensitive response (HR) in plant defense?

The HR is a rapid response to pathogen invasion that results in localized cell death to prevent the spread of the pathogen, and it also triggers systemic acquired resistance (SAR).

How does the plant cell combat pathogen effectors that are injected to hijack the plant's cellular system?

The plant cell uses nucleotide-binding leucine-rich repeat (NB-LRR) proteins that act as sensor proteins to detect pathogen effectors, leading to the activation of R genes and the subsequent defense response.

What is the role of the MAPK cascade in the plant's immune response?

The MAPK cascade is activated by PTI and leads to the activation of defense genes in the plant cell, which helps in combating the pathogen.

What are the two types of hormonal signaling pathways that are activated by different types of pathogens?

The two types of hormonal signaling pathways are the salicylic acid (SA) pathway, induced by biotrophic pathogens, and the jasmonic acid (JA) pathway, induced by necrotrophic pathogens.

How do PR genes contribute to the plant's defense against pathogens?

PR genes encode for pathogenesis-related (PR) proteins, which are part of the plant's defense mechanism and help combat pathogen infection in various ways.

What is the purpose of the lignin and callose deposition in the cell walls of surrounding cells during the hypersensitive response?

The deposition of lignin and callose strengthens the cell walls of surrounding cells, preventing the spread of infection to other cells and thus containing the pathogen.

How does the plant's immune system respond to different types of pathogens, such as necrotrophic and biotrophic pathogens?

Different types of pathogens activate different hormonal pathways. Biotrophic pathogens induce the SA pathway, while necrotrophic pathogens induce the JA pathway, leading to the transcription of PR genes and the production of defense proteins.

Outlines

00:00

🌿 Plant-Pathogen Interaction Dynamics

This paragraph delves into the intricate dance of interaction between plants and pathogens. It begins by setting the stage for the discussion, introducing the key players: plant cells with their pattern recognition receptors (PRRs) and pathogens with their pathogen-associated molecular patterns (PAMPs) or microbe-associated molecular patterns (MAMPs). The script explains the initial recognition process where PAMPs are identified by PRRs, triggering a cascade of immune responses. Two types of immunity are highlighted: effector-triggered immunity (ETI) and pattern/PAMP-triggered immunity (PTI). The paragraph further explores the mechanisms of PTI, including the activation of the MAPK cascade and the expression of defense genes. It also touches on ETI, where pathogen effectors are detected by nucleotide-binding leucine-rich repeat (NB-LRR) proteins, leading to a hypersensitive response (HR) that isolates the infection. The HR is described as a short-term response that also triggers systemic acquired resistance (SAR), an advanced form of immunity. The paragraph concludes with a look at how different types of pathogens—necrotrophic and biotrophic—induce different hormonal signaling pathways, ultimately leading to the production of pathogenesis-related (PR) proteins that combat infection.

05:01

👍 Conclusion and Call to Action

The final paragraph serves as a conclusion to the video, summarizing the complex process of plant immunity against pathogens. It wraps up the discussion by emphasizing the plant's ability to encounter and combat pathogens effectively. The script invites viewers to engage with the content, encouraging them to like the video if they found it informative and to subscribe to the channel for more such insightful content. This paragraph acts as a bridge between the educational material presented and the viewer's experience, fostering a sense of community and continued learning.

Keywords

💡Plant Pathogen Interaction

This term refers to the complex relationship between plants and the pathogens that can cause disease in them. It is the central theme of the video, which explores how pathogens interact with plant cells and the various defense mechanisms plants employ to resist infection. The script discusses the different stages and types of immunity in plants, such as PTI and ETI, in the context of this interaction.

💡Pattern Recognition Receptors (PRRs)

Pattern Recognition Receptors are proteins found on the surface of plant cells that can recognize and bind to specific molecules on pathogens, known as pathogen-associated molecular patterns (PAMPs). In the script, PRRs are highlighted as the first line of defense in plant immunity, initiating the PTI response when they detect the presence of a pathogen.

💡Pathogen-Associated Molecular Pattern (PAMP)/Microbe-Associated Molecular Pattern (MAMP)

PAMPs or MAMPs are conserved molecular structures found on the surface of pathogens that are recognized by the host's PRRs. The script explains that the recognition of PAMPs by PRRs is a crucial step in triggering the plant's immune response.

💡Resistance Protein

Resistance proteins, also known as R proteins, are proteins expressed by plants in response to pathogen recognition. The video script mentions that these proteins are involved in the detection of pathogen effectors and are part of the plant's second layer of immunity, known as effector-triggered immunity (ETI).

💡Pathogen Effectors

Pathogen effectors are molecules secreted by pathogens that can manipulate the host's cellular processes to facilitate infection. The script describes how these effectors are detected by resistance proteins in the plant, leading to a defense response.

💡Effector-Triggered Immunity (ETI)

ETI is a form of plant immunity that is activated when resistance proteins recognize specific pathogen effectors. The script explains that ETI is a more specific and robust response compared to PTI, often leading to a hypersensitive response (HR) that helps to limit the spread of the pathogen.

💡Pattern-Triggered Immunity (PTI)

PTI is the initial immune response in plants that is triggered by the recognition of PAMPs by PRRs. The script details how PTI leads to the activation of defense genes and the MAPK cascade, which helps to strengthen the plant's defenses against the pathogen.

💡Hypersensitive Response (HR)

The hypersensitive response is a form of localized cell death at the site of infection, which is part of the ETI response. The script describes HR as a mechanism to contain the pathogen by producing reactive oxygen species and triggering the deposition of lignin and callose in the cell walls of surrounding cells.

💡Systemic Acquired Resistance (SAR)

SAR is a long-lasting, broad-spectrum resistance that is activated in the plant following a localized infection. The script mentions that SAR is induced by the HR and involves the transcription of certain proteins that can degrade the cell wall of pathogens and provide protection to the entire plant.

💡Hormonal Signaling Pathway

The script discusses how different types of pathogens activate different hormonal signaling pathways in plants, such as the salicylic acid (SA) pathway for biotrophs and the jasmonic acid (JA) pathway for necrotrophs. These pathways are crucial for the activation of PR gene expression and the production of defense proteins.

💡Pathogenesis-Related (PR) Proteins

PR proteins are a group of proteins that are produced in response to pathogen infection and are involved in the plant's defense mechanisms. The script explains that these proteins, such as chitinases, are expressed following the activation of PR genes and help to combat the pathogen by degrading its cell wall.

Highlights

Plant pathogen interaction involves the recognition of pathogen-associated molecular patterns (PAMPs) by plant cells.

Plant cells possess pattern recognition receptors (PRRs) that interact with PAMPs on the pathogen surface.

Pathogens have effector molecules that can hijack the plant cellular system.

Plant immunity includes two types: effector-triggered immunity (ETI) and pattern-triggered immunity (PTI).

PTI is initiated when PRRs bind to PAMPs, triggering a defense response in the plant cell.

The MAPK cascade is activated by PTI, leading to the expression of defense genes.

Pathogen effectors are detected by NB-LRR proteins, which act as sensor proteins in the plant.

Detection of pathogen effectors by NB-LRR proteins leads to a hypersensitive response (HR).

HR causes an oxidative burst and the production of callose, which helps contain the infection.

Systemic acquired resistance (SAR) is an advanced form of immunity triggered by HR.

SAR involves the transcription of proteins like PR1 and chitinases, which degrade pathogen cell walls.

Different pathogens activate different hormonal signaling pathways in plants.

Biotrophic pathogens induce the SA pathway, while necrotrophic pathogens induce the JA pathway.

Hormonal pathways activate the transcription of pathogenesis-related (PR) genes, which express defense proteins.

Defense proteins like chitinases combat pathogen infection by degrading their cell walls.

The video provides an overview of how the plant immune system works against pathogens.

The video concludes with an invitation for viewers to like, subscribe, and support the channel.

Transcripts

in this video we'll be discussing about

plant pathogen interaction what we will

see how pathogen interacts with the

plant cell before getting into the

interaction pathway first of all we will

see what are the proteins and petals

involved in the process of interaction

in plant cell we see it has got PR all

on its surface

that's pattern recognition receptors and

in pathogen we see it has got PMP or ma

MP pathogen associated molecular pattern

or microbe associated molecular pattern

and it's this PMP molecule which

recognizes PR or of the plant cell then

we see plant cell has got a gene which

expresses our protein terminus

resistance protein and in pathogens they

have got effector molecules called

pathogen effectors and these are

detected by our protein in the plant

cell now in plant immunity we come

across with two types of immunity one is

ETA that's effector triggered immunity

and other being the PGI thats pattern or

PMP trigger immunity for the pathogen

effectors evokes the EDI Wireless PMP or

ma MP evokes the PTI now let's get into

the detail of plant pathogen interaction

we see in this diagram we have a plant

cell which is getting in controlled by a

pathogen on the pathogen it has got

small molecules what we called as PMP or

ma MP Wireless on plant cell it has got

PR or molecules as shown in the diagram

and these PR or molecules will bind to

the PMP molecules of pathogen after PR R

recognizes and receives the PMP molecule

the signal is mediated and this signal

mediates or we can say triggers the PGI

that's pattern or PMP triggered immunity

and furthermore this PTI will initiate

the MAPK cascade which would eventually

activate the expression of defense genes

in plant cell this is one type of

immunity and its basic one but there is

another way how plant cell combats the

pathogen we see in the meantime pathogen

also secretes some molecules called

effector molecules or pathogen effect

doors and when these molecules are

injected into the cell by pathogen in

order to hijack the plant cellular

system these pathogen effectors are

detected by NB LR are proteins that's

nucleotide binding leucine-rich repeat

this n BL are are acts as a sensor

protein and this protein is a class of

our protein remember it that's

resistance protein so upon detection of

pathogen effectors

the our genes are activated which causes

ion flux while there is a flux of

hydroxide and potassium ions and influx

of calcium and hydrogen ions and this

ultimately causes HR that's

hypersensitive response the HR in turn

causes oxidative burst by producing

always with which the cell gets

distracted and it must be noted that

always also triggers the deep ocean of

lignin and Kalos to the walls of

surrounding cells with which infection

is not dispersed to the other cells so

in this way pathogen infection is

contained and nearby cells are not

getting infected

this is short-term response by plant but

not only this is a way to stop the

infection but there are other ways also

the hypersensitive response also

triggers other types of ETI with which

HR induces SAR that systemic occur your

resistance is a more advanced or

immunity in the plants in systemic

acquired resistance hypersensitive

response activates the transcription of

certain proteins like pi to alexander

and chitin eases both these compounds

degrades the cell wall of NJ and even

effects the exoskeleton of some

orthopods

so now the question is how these

defensive proteins are getting produced

within the plant cell when

hypersensitive response fails to

eradicate the infection it activates the

hormonal signaling pathway and different

pathogens activate different pathways

because we have two types of pathogens

one is necrotic pathogen which

completely destroyed the plant cell and

other is their bio tropic pathogen which

does not instantly caused much

destruction of the plant tissue so we

see here

Bell tropic pathogen induces the si

pathway that's silly silicic acid

pathway while a neurotropic pathogen

induces their J a pathway that's J's

monic pathway so both these different

types of pathogens initiate different

types of hormonal pathways and

furthermore these pathways activates the

transcription of PR gene pathogenesis

related to gene which are defense genes

in plant

so finally PR gene will Express PR

protein like chitin ASIS which will

combat the pathogen infection in several

ways so this is hop plant immune system

works when they encounter the pathogen I

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