L9- Acquired immunity

Question 1

what is acquired immunity

Answer 1

a defence system that enables genetically susceptible individuals to acquire long-lasting and/or systemic resistance upon recovery of previous exposure to biotic stress

Question 2

how is acquired immunity in plants different to those in vertebtrates

Answer 2

• acquired immunity in plants does not involve dedicated immune cells (lymphocytes)
• acquired immunity in plants is less specific than in humans
  -acquired immunity in plants is less specific than in humans
• acquired immunity in plants is often referred to as “induced resistance”
• acquired immunity/induced resistance augments basal (quantitative) resistance

Question 3

how can basal resistance be improved

Answer 3

through acquired immunity
- basal resistance is often not sufficient to stop disease progression all together, but acquired immunity acts as form of innate immunity, when plants recover from disease shift to higher level of resistance, if this little increase in resistance is “passed down” it is beneficial

Question 4

how does environmental stress induce long lasting resistance

Answer 4

acquired immunity is induced to stress signals, these stress signals include (photo order)
-pathogens - SAR
- herbivore attack - volatiles
-soil microbes - ISR
- selected chemicals -BABA
these can induce systemic resistance (JA is required for systemic resistance), together these acquired immunities are effective against broad spectrum of stress even if inducer is irrelevant

Question 5

what is SAR

Answer 5

systemic acquired resistance, resistance through whole plants, this means if stress is localised in leaf it can still trigger whole plant (systemic) resistance

• induced by localised pathogens and MAMPS, required SA and NPR1
  -mostly effective against biotrophic pathogens

Question 6

what is VOC-IR

Answer 6

volatile organic compound-induced resistance

volatiles include-
- aromatic volatiles
-green leaf volatiles
- terpenoid volatiles

Question 7

what is ISR

Answer 7

induced systemic resistance

• non pathogenic rhizobacteria can trigger imunity
• required JA and often ET signalling
• mostly effective against necrotrophic pathogens and insects

Question 8

what is BABA-IR

Answer 8

Beta-amino-butyric acid induced resistance

induced by the non-protein amino acid, beta-amino-butyric acid, BABA is produced by stressed plants in low concs
-effective against an exceptionally broad range of pathogens, insects, and abiotic stress
- produced by plants under stress conditions and recognised by a specific plant receptor

Question 9

are inducible defence good
- what reduces this

Answer 9

inducible defence mechanisms, expression of innate immunity is very costly to plants, self destructive baso.

• but immune system of plant is not on or off, there is intermediate called priming, this is a sensitisation. when there is recurrent exposure activation is more efficient

Question 10

what is working model of immune priming

Answer 10

shows that priming means inducible defence, reacts quicker and stronger but is also downregulated quicker (as costly). this explains how plants do not suffer to greatly from activation cost. argued immunological memory

Question 11

what does BABA prime

Answer 11

BABA primes late acting SA defence
Treating a plant with BABA wont show any visible effect on plant, but effect can be viewed after a pathogen attack, as BABA treated plants respond much quicker and stronger
- it can also prime other defences such as cell wall reinforcements, papillae made of callose, these are activated in response to pathogen attack. prime plants with BABA vaccine, again plant is more effective against spores of downy mildew

Question 12

is their cost of priming

Answer 12

plants are not all automatically primed, because their is cost under no disease pressure primed plants performed minorly worse in growth and seed production, but performed significantly better in growth and seed production under disease pressure