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Plant responses to pathogens (365 - 367) -…
Plant responses to
pathogens (365 - 367)
Passive defences
Physical barriers
Example; cuticle, cell walls + small stomata
Inhibit pathogen entry
Thicker cuticle = harder to break down
Extra protection against pathogens
Prevents those from invading + reaching food sources
Vertical hanging leaves
Do not accumulate a water film
Reduce likelihood of pathogen reservoirs
Stomata
Regulate water balance in plant
Potential port of entry for pathogens
Chemical barriers
Presence of chemical compounds in tissues
Reduce fungal + bacterial growth
Ward off vectors of viruses
Examples; glucosides + saponins
May produce enzymes
Break down pathogen-derived toxins
Chemical receptors on plant cells
Detect the presence of a pathogen
Activate the next stage of defence
Active defences
Pathogen recognition
Detect physical + chemical signals
Fragments from cell walls - bacteria + fungi
Genes within cells of plants
Thought to regulate plant responses
Rapid response
Proteins on surface of cells
Causes changes in permeability
Allows movement of certain ions
Triggers defence responses
Activates expression of certain genes
Release of hydrogen peroxide
Oxidative burst kills microbes directly
Indication of immune response
Cluster of dead cells isolate pathogen
Delayed response
Limit the spread of pathogens
Lysozyme-like chemicals released
Have an antimicrobial action
Salicylic acid
Signalling agent of subsequent infections
Play a role in plants memory or particular pathogen
Systemic acquired resistance
Limits severity of subsequent infections