Biotic and Abiotic Interactions Flashcards Preview

Plant-Environment Interactions > Biotic and Abiotic Interactions > Flashcards

Flashcards in Biotic and Abiotic Interactions Deck (33):
1

Biotic interactions

interactions between living things

2

Abiotic interactions

interactions between organism and non-living factors

3

Biotroph

the pathogen is entirely dependent on the host for nutrition

4

Necrotroph

kills host tissue as grows through them

5

Steps of pathogen (disease)

Locate the host
Attachment/adhere
Penetration and entry
Colonization
Suppression or avoidance of host defences
Reproduction
Dispersal from host

6

What do pathogens produce that causes part or all of the disease syndrome?

produce toxins

7

Types of defences by host plant:

inducible and constitutive

8

Detection systems

Resistance gene (plant) interacts with product of avirulence gene (pathogen).

9

Detection systems

Resistance gene (plant) interacts with product of avirulence gene (pathogen). Elicitor activates defence response by plant receptor.

10

Responses to pathogen recognition

Hydrogen peroxide
Hydroxyl radical
(through NADPH-dependent oxidases)

11

What do hydrogen peroxide and hydroxyl radicals do in plant defence?

Initiate hypersensitive response
Directly kill

12

What is the hypersensitive response?

Cells kill themselves at the site of infection to prevent further spread.

13

When does the hypersensitive response work?

Biotrophs only

14

What is systemic acquired resistance?

plant survives infection at one site the plant develops increased resistance at subsequent attack at sites throughout the plant

15

What is the use of methyl salicylate in plant defence?

Important signalling molecule for systematic acquired resistance.
Thought to be important in local signalling of pathogen attack to other plants (transpiration from leaves).

16

How is methyl salicylate transported around plant?

mostly likely through the vascular system

17

What are pathogen-related proteins (plant)?

hydrolytic enzymes that destroy pathogens macromolecules

18

Example of constitutive defence

For insect herbivory (deters feeding):
Terpenes – stored in resin canals or glandular hairs on plant surface
E.g. menthol

19

Example of inducible defence

Triggered by substance in insect saliva, Jasmonic acid
-> Protease inhibitors (block protein digestion)
-> amylase (block starch digestion)
-> signals to local area (other plants)

20

What are alkaloids?

constitutive defence molecule produced and stored by plants. Has a dramatic effect on vertebrate animals.
E.g. caffeine/nicotene...

21

What are phenolic compounds?

constitutive defence
stored compounds that deter insect feeding or have anti-fungal effects
E.g. benzoic acid

22

What are cyanogenic glycosides?

constitutive defence
Present in the vacuole and enzymes required to release cyanide in the cytosol.
E.g. apple seeds

23

What are phytoalexins

Inducible defence
produced by de novo synthesis in response to stress, particularly pathogen attack
E.g. rishitin (potatoes)

24

Two categories for response to abiotic stress

Adaptation
Acclimation

25

Acclimation

aka plasticity
Physiological or metabolic response of individuals in response to changing environmental factors

26

Adaptation

Constant or recurrent environmental challenges exert selective pressure driving evolution of traits that increase fitness under stress. Occurs over generations and across populations.

27

Physio-chemical variables in the environment

Water (lack and excess)
Oxygen (and reactive derivatives)
Radiant energy
Mechanical influences

28

Response(s) to water deficit and osmotic stress

Vacuolar accumulation of salts
Cytoplasm and organelles accumulated compatible solutes(sol. @ high conc. and non-toxic)
Stomatal closure (abscisic acid)

29

Response(s) to flooding (excess water)

Generate ATP in glycolysis
Regenerate NAD+ through production of ethanol
Aerenchyma in roots to help O2 diffusion controlled by ethylene production
Suberin and lignin deposits at the hypodermis help stop O2 leaking out of the root

30

Response(s) to cold stress

Accumulation of compatible solutes (osmoprotectants) allows cellular water to ‘super cool’ without freezing down to -40ºC.

31

Response(s) to chilling sensitivity

more unsaturated fatty acids the membrane contains the lower the temperature at which the liquid to gel transition of cell membrane occurs.

32

Response(s) to excess light

Light receive by violaxanthin then given to chlorophyll
When too much light, violaxanthin can be converted into zeaxanthin (reversible).

33

Response(s) to high temperature stress

Heat shock proteins interact with proteins to:
- Stop aggregation of proteins
- Promote disaggregation of proteins
- Assist folding and refolding of proteins