Acquired Immunity

Question 1

Acquired immunity

Answer 1

Plant resistance induced by stimulus
Enables plants to acquire long lasting and broad spectrum resistance
Develops distal from sites where innate immunity expressed
Happens upon recoveru of previous stress exposure

Question 2

Augments basal resistance

Answer 2

Controlled by many genes
Different disease phenotypes - some plants more resistance than others
Makes basal resistance more efficient so more plants becomming efficient
Not as effective as qualitative resistance and protection rarely complete

Question 3

Signals

Answer 3

Similar signals to innate immunity

Question 4

Systemic acquired resistance

Answer 4

Devlops after infection of lower leaves
Upper leaves more resistant over time

Question 5

Augementation of basal resistance

Answer 5

Use components of innate immunity to increase efficiency
Augment resistance that is dependent on SA after localised attack
Local tissues generate long distance signals
Induce resistance in distal parts
Augment SA dependent resistance

Question 6

Herbivore induced volatiles

Answer 6

Airborne volatives to so neighbours respond quickly and induce resistance
Augments JA defences
Signals will result in lower caterpillar growth in neighbouring plants

Question 7

Beneficial Soil microbes

Answer 7

Non pathogenic rhizobacteria and MC colonise root in mutualistic way
Induces resistance to necrotrophs and insects through JA
Help mobilise critical nutrients

Question 8

Selected chemicals

Answer 8

Mimic biological resistance phenomena

Question 9

BABA

Answer 9

Non protein amino acid found in stressed plants in low conc
Induces resistance against many pathogens and abiotic stress - effective and long term
Based on priming of SA dependent and independent defence mechanisms - enhances basal defence
Recognised by specific plant receptor
Faster induction of SA defences

Question 10

Effectiveness of BABA

Answer 10

No trade offs w growth - tradeoffs when innate immunity but not acquired

Question 11

Defences aren’t upregulated

Answer 11

Acquired immunity uses same infrastructure as innate but not prolonged upregulation
Plants are primed so can allocate more energy to growth when happy - costly defences not expressed so don’t drain energy

Question 12

Primed plants

Answer 12

Higher defence activity than unprimed plants as exposed to previous stimulus
Downregulated in distal parts and over time
Mount faster and stronger defence later in life cycle
No major trade offs
Primed plants are fitter and grow more when under disease pressure - slightly reduced growth when no disease pressure but benefits of priming outweigh this

Question 13

BABA

Answer 13

Promote earlier and stronger defence reactions when pathogens attack
Augment induction of SA dependent defence genes
Wrong conc of BABA causes reduced growth and yield

Question 14

IBI mutants

Answer 14

Hyper sensitive to BABA induced stress
IBI1 is a receptor of BABA - forces enzyme to lead to defence priming and resistance
IBI1 controls defence priming
Plants become more tolerant to IBI1 and more sensitive to BABA induced resistance

Question 15

IBI signalling

Answer 15

No priming: IBI1 confined to endoplasmic reticulum
Primed w BABA and no pathogen: IBI1 confined still - treating w BABA along doesn’t change localisation of IBI1
No priming and pathogen present: Some movement of IBI1 to cytoplasm - basal defence
Priming and pathogen: All of IBI1 moved to cytoplasm - augmented defence

Question 16

VOZ

Answer 16

Regulate SA independent priming of cell wall defence
Tf activate early acting defence against pathogens
Inhibit ABA induced tolerance genes - protection against abiotic stress

Question 17

Downy mildew

Answer 17

Activates ABA signalling - decoy
Plant invests in tolerance to abiotic stress to plant more susceptible to pathogen
Treating w BABA results in energy into defence instead so pathogen doesn’t succeed

Question 18

Seedlings treated w BABA

Answer 18

Induced resistance passed onto new cells forming new tissues

Question 19

JA priming

Answer 19

Defence against herbivores
Seedlings exposed to JA or caterpillar feeding remain immune over logn timer period

JA works w BABA:
Increases resistance to herbivores due to loss of water from damaged tissues
MYC dependent pathway

JA works w ET:
Resistance to necrotrophs to accelerate senescence and cell death

Memory induced in some cells passed on through cell division to new ones

Question 20

Epigenetic trait

Answer 20

Heritable trait that can’t be explained by variation in DNA sequence
Progenies partially primed to stress suffered by parent
Reduced growth but some resistance
Passed on through meiosis to next gen

Question 21

DNA methylation

Answer 21

Methylation of cytosons passed on
3 diff sequence contexts
Diff pathways to ensure sufficient DNA methylation

Question 22

Transposable elements

Answer 22

Hostile DNA that can become active and jump into other genes
Don’t want them expressed
Silence them by methylating DNA at all sequence contexts - tightly packs DNA to TE can’t be expressed

Question 23

DNA demethylases

Answer 23

Removes methylation at all 3 sequence contexts

Question 24

Something about mutations?

Answer 24

Too many mutations damages plant
Transposons become active and expressed
Deregulation of other genes
Find mutations that reduce expression of genes

Question 25

DNA methylation

Answer 25

More methylation = impaired to transgeneration resistance so more vulnerable to disease

Less methylation = plant susceptibility

Question 26

DDM1 mutation???

Answer 26

Removing this reduced DNA methylation - sick plant but survives