Plant Biotechnology Flashcards
Why are plants important?
They produce food (cheaper now than historically), oxygen, medicine, building materials and fuel
They are 83% of the Earth’s biomass (Bar-On et al, 2018) however since the 1st agricultural revolution, humans have halved the mass of plants to 1Tt (Eldacham et al, 2020)
There is a need for a 2nd agricultural revolution as global grain production is in decline with a growing population
Global energy consumption has increased to ~0.5 zJ from ~0.2 zJ in 1965
Name some examples of plants used medicinally
Mint -> gastrointestinal, bronchitis, motion sickness
Saffron -> depression, digestion
Parsley -> aphrodisiac, kidney cleanser diuretic
Olive -> omega-3 for improved brain functions no lowered LDL cholesterol, prevent strokes and diabetes
Fennel -> anti-inflammatory, stimulates appetite
Why are food plants important?
Meat production is very water intensive versus plants (per kg)
However photosynthesis only converts 5% of the sun energy to sugars thus is very inefficient
Whole food chain as animals eat plants
What are some dangers plants face?
Herbivore attacks such as aphid attack leads to plants producing signals to warn other plants of attack (aphids feed on sap and destroy plant)
Infections -> plant diseases such as blight cause plant tissue to die and can spread rapidly
Drought -> lack of moisture in the soil stresses the plant
How do plants communicate with each other?
Warning signals -> volatile organic compounds are released into the air
Defence response -> VOCs repel aphids and attract aphid hunting wasps
Closed stomata -> prevent water loss
Chemical communication -> stressed plant secretes soluble chemicals from roots which are absorbed by neighbours
Fungi network -> warning signals transmit through mycorrhizae
Give some statistics about malaria
Mosquitoes are moving further north due to climate change thus a larger population is exposed to the malaria parasite (Plasmodium)
212 million infections reported in 2015
Describe how artemisinin is produced in sweet wormwood
Produced in the trichomes (oil sacs) on leaves and contains 0.1-0.6 % artemisinin
Describe how antiviral drugs were produced in plants against SARS-CoV-2
100 natural polyphenols from plants were tested against SARS-CoV-2 via RdRp inhibition and 4 potential antiviral drugs were discovered
What are the 3 different levels plants can be grown at?
Field
Greenhouse
Bioreactor
Describe field growing conditions
Smaller footprint due to less space
Top leaves get more sunlight than lower leaves thus it is hard to equalise conditions
Describe greenhouse growing conditions
Bigger leaves are produced
Plants are easy to transform
More space but more yield than fields
Describe bioreactor growing conditions
A cell culture of one type of plant cell i.e. roots/leaves
More control
More expensive
What are 4 ways to increase product formation?
Select a high yield line
Start off with a producing part
Modify the media for growth and product fromation
Feed precursors or feed intermediates for bioconversion
What are the benefits of producing high value chemicals in a plant cell culture?
Consistency of output
No contamination from soil/viruses/heavy metals
Can be used for slow growing, rare and endangered plants
Higher yield of desired product per mass compared to growing the whole plant
Environmentally friendlier as less toxic solvents and less water and land are used
Cheap and made of film thus disposable
Why was Taxus baccata (English yew) grown in a cell culture?
Grows too slow to harvest the amount of paclitaxel required
Difficult to synthetically synthesise the paclitaxel pathway
Paclitaxel is an anti cancer drug
Plant Cell Fermentation Technology uses no hazardous solvents compared to direct plant extraction
What are the 4 factors that affect plant tissue cultures?
Minerals
Growth factors
Carbon source
Hormones
Describe the relationship between plants and hormones
All plant cells produce hormones whilst animal cells do not
Phytohormones affect and regulate all stages of plant life cycles
What is a callus and how is it produced?
Equimolar amounts of auxin and cytokinin stimulate cell division which leads to a mass proliferation of an unorganised mass of cells called a callus
How are calluses made into cell suspension cultures and why are this done?
Agitated in a liquid medium so that they break up
Suspensions are easier to bulk up than calluses since there is no manual transfer or solid support
Describe the growth kinetics of plant cell suspensions
Initial lag phase dependent on dilution
Exponential phase
Linear/deceleration phase with declining nutrients
Stationary phase where nutrients have been exhausted
What are some characteristics of plants
Large (10-100 mM)
Tend to occur in aggregates
Shear-sensitive
Slow growing
Easily contaminated
Low oxygen demand
Have a cell wall
Will not tolerate anaerobic conditions
Grow to high cell densities
Can form very viscous solutions
Describe mammalian cell production
High initial investment (>250 M)
Expensive stainless steel reactors
Strict controlled environments
Expensive maintenance
Risk of viral contamination
Describe plant cell production
Low initial investment (<250 M)
Inexpensive polyethylene bags
Inexpensive maintenance
Manufacturing at room temperature
Nor risk of viral contamination
Advantages and disadvantages of bacterial growth
+ easy genome sequencing and simple genetic content
+ rapid growth and more developed culture system
- impaired CYP450 due to no endoplasmic reticulum
-substrate and product inhibition
- difficult to deal with post-translational modification
Advantages and disadvantages of yeast growth
+ simple genetic content and easy transformation and scale-up
+rapid growth and more developed culture system
-requires carbon source and precursors
-multi gene engineering requires
-issues with post-transcriptional modification
Advantages and disadvantages of algae growth
+simple genetic content and scale-up
+post-transcriptional modification performed
+more developed culture system
- insufficient genetic engineering tools
-Long growth cycle
Advantages and disadvantages of plant cell growth
+ moderately rapid growth
+ Post-translational modification performed
+constant supply of products
-requires carbon source and sometimes precursors
-Complex genetic content
-genetic instability
Advantages and disadvantages of native plant growth
+ bio synthetic pathway construction not required
+ less gene modification required
+ more toxicity tolerance
+ large scale
-low yield
- slow growth
Advantages and disadvantages of chemical synthesis
+ scale up
+ easy synthesis
+ quick
- difficult to synthesise plant secondary metabolites with multiple chiral centres
- hazardous chemicals
- labelled as artificial
What are the prerequisites to genetically engineering plants?
Growth of individual plant cells
Regeneration of entire plants or organs from cells
Alteration of nucleus by inserting new genetic material
Screen for transformed plants
How does agrobacterium transform plants?
Ti plasmid carrying desired genes on agrobacterium tumefaceins
Cocultivation of plant pieces and agrobacterium so DNA is transferred to plant cells
Callus (cell multiplication)
Shoot regeneration followed by root regeneration
Plant with new trait
How are plants transformed using particle gun?
Gold or tungsten particles coated with DNA encoding required genes
Particle gun bombards plant pieces with particles
Cell multiplication
Shoot and root regeneration
Plant transformed
How can proteins be delivered orally?
Plant cellulose wall protect therapeutic protein from gastric fluid
