Plants Communiations Flashcards
what is thigmonasty?
plants response to touch
what controls plant size?
vacuole by osmosis
what happens when thigmonasty occurs?
ions flow into outer cells of pulvini. Up regulation of aquaporin & H+ - ATPases (proton pump).
what happens to turgor pressure upon touch ?
increases/ decreases due to osmosis, outside cells increase in size
What signals do plants use to respond to their environment ?
Electrical, hydraulic, chemical
What does the phloem do?
moves sugars produced by photosynthesis from their source to sinks (non-photosynthetic tissue)
what does the xylem do?
water from the soil to atmosphere.
hollow and dead.
can convey info needed about nutrient availability +soil microbes.
xylem in drought response?
signals from draught- stressed roots cause guard cells to close, reduce respiration, preserve water.
How do plants long distance communicate?
Vascular system
What molecule signals for more phosphate uptake?
microRNA (miR399)
shoot to root communication ?
roots are phosphate limited, microRNA (miR399) moves through phloem to root, signal for more uptake.
What protein do plants use to initiate reproduction?
Flowering Lotus T (FT)
Time to reproduce?
Correct season, FT and its orthologs move from leaves to shoot apex… reproductive growth.
How to plants locally communicate?
cell to cell via; Symplastic, Transcellular, Apoplastic.
Symplastic communication?
PLASMADESMATA, gap junctions, connects the cytoplasmic space between plant cells.
How do plasmadesmata open and close?
regulated by callose deposition in cell wall
Transcellular communication?
need specific carriers in membrane; transporters OR diffusers OR vesicle secretion.
Apoplastic communication?
Travel in extracellular space between plant cells.
Enter cytoplasm via transporters or carriers.
Might bind to receptors… further signalling
What are the 3 signalling steps in plants ?
Perception –> Transduction –> Response
Signal perception and Transduction basic pathway in plants: What are the 3 transduction pathways that can occur?
1) metabolic emzymes –> altered BioChemistry
2) cytoskeletal protein –> altered cell growth or shape
3) TF –> altered gene transcription
What signals are perceived by receptors to initiate signal transduction? X9
hormones peptides RNA molecules ions metabolites ROS gravity light oxygen
What is the first layer of plant immunity?
detection of MAMPS (Microbe Associated Molecular Patterns)
What is MAMPS?
conserved molecules in pathogens that can evoke an immune response as they activate receptor.
What are the key features or MAPS? X4
not required for infection.
not strictly found in pathogens
often surface exposed
not present in host
How are MAMPS recognised?
Via pattern Recognition Receptors (PRRs), triggers plant defence response.
Bacterial pathogen binding response in cell…?
1) Ca2+ influx –> kinase cascade leading to transcriptional response –> defence response.
2) ROS production either to transcription response or DIRECT to defence response.
Fungal pathogen binding response in cell…?
kinase cascade leading to transcription response –> defence response.
What are the 2 categories of PRR’s ?
1) LRR-RKs (Leucine-rich repeat receptor kinases)
2) lysM receptor proteins
Key feautures of a LRR-RKs ?
extracellular = leucine rich domain intracellular = kinase domain
Name the 3 PRRs
FLS2, EFR, XA21
Name the 3 MAMPs to the PRRs
flagellin, EF-tu, Ax21
Name the MAMPs of the lysM receptor proteins
Chitin, unknown
What kind of MAMPS receptors are used in plants vs animals? (taken from example in lecture)
Animals: LRR (TLR5)
Plants: LRR (FLS2 & BAK1)
What do the animal and plant receptors signal once bound to MAMPS sequence?
Animals: MyDD8 –> MAPks –> TFS
–> NF-kB
Both transcribe cytokine defence
Plants: Kinase –> MAPs –> WRKYs –> transcribe defence
related genes
What are effectors?
When a pathogen delivers molecules inside their host cell to interfere with immunity, these molecules are called effectors.
What is the second immune response ?
resistance protein (NLRs), second class receptor
What happens after Perception?
ROS production, MAPK cascade, antimicrobials, plant hormones.
In-depth process of PRR FLS2 receptor (via ROS)
Step 1…
PRR can recognise small fragments in flagellin of bacterium called Flg 22
In-depth process of PRR FLS2 receptor (via ROS)
Step 2…
activation of co-receptor complex BAK 1 protein.
In-depth process of PRR FLS2 receptor (via ROS)
Step 3…
Leads to phosphorylation of BIK1, inside cell.
In-depth process of PRR FLS2 receptor (via ROS)
Step 4…
In turn activates NADPH oxidase, RBOHD1, activate oxygen species.
In-depth process of PRR FLS2 receptor (via ROS)
Step 5…
Trigger oxygen production
antimicrobial activity + stress signal
What do phytohormones help with in a plant?
Synthesised when needed
Small molecules help with stress
How do phytohormones move in a plant?
move by xylem and phloem across cellular membranes
through regulated transport proteins
can be membrane bound or soluble
important in plant immunity
What are 2 phytohormones?
Salicylates and Jasmonates
What is the degrading enzyme for both phytohormones?
NahG; bacterial enzyme degrading
What is the receptor for Salicylic acid (SA)?
NPR 1 Oligermeric in cytosol
What happens when SA binds to its receptor
Changes from oligomeric to monomeric state and can enter nucleus.
Activate TF –> defence related gene expression.
What is the other outcome of SA binding to its receptor?
STRESS PROTEOME. In cytosol, NPR1 can condensate a protein complex and regulate.
What does SAR stand for ?
Systemic Acquired Resistance
What happens when a pathogen is recognised in a plant? (SAR)
STP (Signal Transduction Pathway)
What does STP cause in plant SAR?
hypersensitive response, kills infected plant cells.
What is released before death of cell in SAR?
antimicrobial molecules and SA
What is the effect of SA being released by many cells in the plant?
SA induces a signal transduction pathway and antimicrobials are produced.
What are the physiological responses of SAR?
strengthening cell wall
Antimicrobials
what are 3 examples of Antimicrobials ?
phytoalexins, chininases, PR proteins.
What is the receptor for Jasmonate?
COI-1
What is the repressor protein that binds to TF on JA response gene?
JAZ
What are the co-repressor proteins that bind to repressor called?
NINJA & TPL
What increases JA levels ?
Pathogen infection
What happens when JA levels increase ?
JA bind to COI-1 receptor
What molecules make up the receptor complex of JA receptor ?
COI-1 and SCF
What is the role of the receptor complex in JA receptor?
Catalyses unbiquitination of target protein to 26S proteasome for degradation
What happens when JA bind to receptor complex?
JAZ attracted to to JA. JAZ bind to JA and sent for degradation, transcription of JA response gene can occur.
