lecture 22

Question 1

what is a metabolite?

Answer 1

a low molecular weight compound, which is an intermediate or product of metabolism; an organic compound

Question 2

what are the kinds of plant metabolites?

Answer 2

1. primary
2. hormones
3. secondary / specialized

Question 3

what are primary metabolites?

Answer 3

compounds common to majority of plants and life forms
- essential amino acids for biopolymers
- nucleotides
- sugars
- micronutrients (vitamins)

necessary for life; mutations affecting biosynthesis would be fatal

Question 4

what is the function of secondary metabolites?

Answer 4

1. defense
2. plant to plant communication
3. species-specific / lineage-specific

you can live without it!

Question 5

what is anthocyanin?

Answer 5

a secondary metabolite found in strawberries

Question 6

how do plants communicate using metabolites?

Answer 6

• root to root
• touch
• volatile organic compounds

Question 7

what are the root-to-root intermediaries?

Answer 7

• soil
• ionic gradients
• microbes
• direct root-to-root contact

Question 8

example: in a line of pea plants, if the first plant is not watered …

Answer 8

drought stress –> closed stomata, and the rest of the plants, whether they are watered or not, will have a closed stomata because the message from the first pea plant has been conveyed via secondary metabolites (root-to-root)

Question 9

what are volatile organic compounds and what do they do?

Answer 9

a subset of secondary metabolites, mostly terpenes.
exuded from aerial organs and trigger reactions from adjacent plants

Question 10

what kind of metabolites are responsible for the smell we associate many plants with?

Answer 10

small metabolites

Question 11

terpenoids are an example of …

Answer 11

secondary metabolites

Question 12

what can the release of volatile organic compounds change? how?

Answer 12

micro-climates;
VOCs released by plant, react with ozone and other particles forming secondary organic aerosols (SOA), which can act as cloud condensation nuclei (CCN)

Question 13

what can VOCs be applied to in plant biotechnology?

Answer 13

• applied to surfaces
• antimicrobials
• prime plant immunity
• prolong / promote growth
• weed control

Question 14

how is herbivore deterrence shown?

Answer 14

chemicals in plants can be unpalatable or toxic

Question 15

example of herbivore deterrence?

Answer 15

Hipomane mancinella / Manchineel tree : aka the death apple, sap contains a toxic mixture that can cause blisters if handled. eating the fruit can be fatal

Question 16

how does Capsicum plants exhibit herbivore deterrence?

Answer 16

protect seeds from mammals, contain anti-herbivory content, aka capsaicin (spicy)

Question 17

what is allelopathy?

Answer 17

the production of compounds that inhibit the growth of other plants

Question 18

what is involved in active allelopathy?

Answer 18

secondary metabolites, spending energy and resources (nitrogen, sulfur), actively secreting compounds

Question 19

what is passive allelopathy?

Answer 19

the process by which secondary metabolites are already broken down, and leach into soil

Question 20

how do walnuts exhibit allelopathy?

Answer 20

due to a secondary metabolite called juglone. the presence of juglone in the soil beneath walnut trees leads to foliar yellowing / wilting of plants trying to grow

Question 21

significance of antimicrobials derived from plants:

Answer 21

wide range and diversity, 25-50% of current pharmaceuticals are derived from plants. antimicrobials are toxic to DNA replication processes, disrupt biosynthetic processes e.g. glycolysis, and disrupt physical structures