Plant defenses against pathogens Flashcards
What are some examples of Physical barriers to prevent the entry of disease in plants?
Waxy cutical
Bark of tree trunks
Cellulose cell walls
What is Callose?
Callose is a polysaccharide, made of beta
glucose monomers
Role of Callose in Plant Defence
Callose is deposited between cell walls
and cell membranes next to the infected
cells – this barrier prevents further spread.
Lignin is added to the callose to
strengthen the barrier
Callose also blocks the sieve cells of the
phloem preventing spread this way
Callose is also deposited in the
plasmodesmata of connecting cells
Outline the physical defence processes in plants in response to an infection of a pathogen
Reference to callose
Idea that callose acts as a barrier
Deposited between cell wall AND
cell membrane
Ligin – strengthening agent
Callose blocks sieve cells of
phloem
Callose blocks plasmodesmata of
adjacent cells
How do plants prevent damage from insects?
Insect repellents – e.g. pine resin and
citronella (from lemon grass)
Insecticides – e.g. pyrethrins acts as a
neurotoxin to insects. And caffeine which
is toxin to insects and fungi
How do plants fight against pathogens?
Antibacterial compounds containing
antibiotics:
Phenols - an antiseptic produced by
cotton plants
Defensins – plant proteins that
disrupt membranes of bacteria and
fungi
How do plants deal with fungal infections
Antibacterial compounds containing
antibiotics:
Phenols - an antiseptic produced by
cotton plants
Defensins – plant proteins that
disrupt membranes of bacteria and
fungi
What is Chitinases
enzyme that breaks down fungal cell walls
What is Glucanase?
It is an enzyme to break down glucans found in
in oomycetes
Describe the role of plant chemicals in
disease control
Named chemical defence:
Insect repellents / Insecticides
Antibacterials / antibiotics
Antifungals
Anti-oomycetes
Specific named toxin
Prevent insects from spreading
disease
Chemicals act to kill pathogens
Chemical disrupt pathogen function
