Lecture 18: Plant Biotechnology

Question 1

highly effective method have been developed to

Answer 1

transform plants & for plant tissue culture & regeneration

Question 2

Golden rice

Answer 2

• milled rice doesn’t contain BETA-CAROTENE
• vitamin A deficiency afflicts over 200million children&woman
• ~500,000children go blind
• 2million children under 5 years die each year

Question 3

Isopentenyl pathway

Answer 3

metabolite that gives rise to all colour in plants

Question 4

Golden Rice: pathway

Answer 4

Isopentenyl pathway –>Geranyl geranyl pyrophosphate –phytoene synthase (plant)–>Phytoene–carotene desaturate (bacterial)–>Lycopene–>carotene—>Vitamin A

Understanding plant & bacterial biochemistry combined with GM tech allows manipulation of carotene biosynthesis in rice

Question 5

Timeline Golden Rice:

Answer 5

1984: initial research on transgenic rice
(1992:First GMO plant approved for consumption)
1996: First Golden Rice prototype
2004: First field trials
2004: Intellectual property rights agreed
2005: Golden rice 2
Bill&Melinda Gates Foundation Funding
2013: ongoing field trials trashed in the philippines

after 30yrs Golden Rice is still not acc being used

Question 6

Example of GM crops: Bt toxin

Answer 6

• Bt toxin used as commercial insecticide since 1960’s
• natural toxin produced by Bacillus thuringiengis
• 1990s: Bt gene transferred into crop plants (maize, cotton)

Question 7

Example of GM crops:

herbicide tolerant plants

Answer 7

in plants pathway where NO3–>NO2–>NH4–glutamine synthetase–>glutamine–>amino acids

Phosphinothricin - herbicide (ACITVE) inhibits Glutamin synthetase enzyme

PAT converts Phosphinothricin (active) to Acetyl-Phosphinothricin (inactive)

resistant plants have PAT so inactivates Active herbicide

Question 8

Phosphinothricin tolerant plants: - herbicide Phosphinothricin & non-transgenic (e.g. weed)

Answer 8

GROWTH

Question 9

Phosphinothricin tolerant plants: -herbicide Phosphinothricin & transgenic with PAT gene

Answer 9

GROWTH e.g. maize

Question 10

Phosphinothricin tolerant plants: + herbicide Phosphinothricin & non-transgenic (e.g.weed)

Answer 10

NO GROWTH

Question 11

Phosphinothricin tolerant plants: +herbicide Phosphinothricin & transgenic with PAT gene (e.g. maize)

Answer 11

GROWTH

Question 12

Glyphosate tolerant plants

Answer 12

-Glyphosate inhibits aromatic amino acid biosynthesis
in the chloroplast
-Bacterial mutant EPSP synthase retains affinity for PEP substrate but does not bind glyphosate
-ROUNDUP READY SOYBEANS
— Facilitates no-till agriculture
—But yields have not usually increased and new weed species have emerged

Question 13

using transgenics to provide resistance to pathogens: Phytophera infestans

Answer 13

• potato blight
• S. tuberous (sensitive)
• S. bulbocastanum
• -sexual crossing no longer possible

-inoculate with fungus s.b = resistant

Question 14

__% crop loss/year due to disease

Answer 14

30-40

Question 15

wheat stem rust:

Answer 15

•A new, highly pathogenic strain emerged in Uganda in 1999 – it is called Ug99.
•Most wheat has no resistance to this strain.
•Without resistance and chemical control, a rust
outbreak can lead to loss of 90% of the crop
-spores can easily spread all over world

Question 16

plant growth is often limited by

Answer 16

drought stress.

- Mild drought stress reduces the rate of photosynthesis and growth, whereas extreme drought stress is lethal.

Question 17

a plant drought tolerance can be altered by a

Answer 17

single gene.
-HDG11 encodes a transcription factor.
Overexpressing the transcription factor leads to drought tolerance in Arabidodopsis

Question 18

wheat yield 1961-200 __% increase but has come at a cost

Answer 18

300

-All the chemicals we put on the crops. Bt-cotton can lead to >50% decrease in pesticide use but glyphosate resistant weeds are increasing

Question 19

GM plant could allow us to grow plants in __ climates.

or develop resistance __ to novel pathogens

Answer 19

drier

quickly

Question 20

all crops are the result of selective breeding: (maize)

Answer 20

• ancient maize (teosinte)

- modern maize (Zea mays)

Question 21

fertiliser is an _____ resource

Answer 21

energy-demanding limiting

• Crops need fertilizer – potassium, phosphate, nitrogen, and other nutrients
• Potassium and phosphate are non- renewable, mined resources
• Synthesis of nitrogen fertilizers requires huge amounts of energy
• Need to get agriculture to work more efficiently

Question 22

many of the solution to increasing yield sustainability require an…

Answer 22

understanding of plant development.

• roots and N2
• changing leaf structure to enable more efficient photosynthesis (C4)

Question 23

Rhizobium infection leads to N2 fixation

Answer 23

Nodules are formed - bacteria take over programme for lateral root formation
-Requires a specific host- derived
structure, the nodule. -Developmentally related to lateral root.

Question 24

C3 vs C4 plants

Answer 24

C3

• Chloro in M cells
• LARGE distance between BS
• SMALL proportion of BS tissue

C4

• Chloro in BS cells
• SMALL distance between BS
• LARGE proportion of BS tissue