Block 3 - Plants Flashcards
Discuss the land used for agriculture and the 4 major crops.
Around 45% of habitable land on earth is agricultural.
Maize (corn) is the largest produced crop in the world.
Rice is the second largest produced crop in the world.
Wheat is the third largest produced crop in the world.
Potatoes are the fourth largest produced crop in the world.
Describe crop domestication using the example of cereal.
10,000 years ago crops were domesticated.
wild cereal —————-> cultivation and domestication ——> Landraces —>—->—> Selective breeding ———-> Modern day cereal
Describe the traits selected to increase grain yield.
Such as:
- Loss of seed shattering
- Loss of seasonal requirements
- Increased seed number
- Reduced height
- Reduced dormancy
Discuss the changes in developmental genes for crop domestication using the example qSH1.
Altered development is also important for breeding non-cereal crops.
rice gene qSH1 controls abscission zone formation at base of rice flower.
Single nucleotide polymorphism in 5’ regulatory region of a single transcription factor was responsible for non-shattering rice.
Discuss changes in developmental genes for domestication using the example of maize genes.
Altered development is also important for breeding of non-cereal crops.
two maize genes, both encode transcription factors; Teosinte glume architecture (TGA) promotes development of the tough case around a kernel, Teosinte Branched1 (TB1) suppresses branching to promote a single stalk.
This creates more space so that plants can be planted closer together in fields leading to denser fields and higher yields.
Describe the ‘population bomb’.
The Population Bomb has been characterized by critics as primarily a repetition of the Malthusian catastrophe argument that population growth will outpace agricultural growth unless controlled.
Describe the green revolution.
The green revolution = introduction of semi-dwarf varieties. Thus allowing for more crops to be tightly packed into a smaller area.
Green revolution and intensive farming practices pushed yields higher than ever before.
Green revolution varieties had defective gibberellin (GA) hormone biosynthesis or perception. This is one of the main growth hormones in plants.
Draw the GA signalling pathway.
[see notes for answer]
Describe the other major issue with current crop yields.
We are no close to maximum land use.
There is a yield gap for projected calorie demands, there is large difference between food availability and the baseline food availability projected to be necessary.
Outline the case study of submergence tolerance.
Case study of a current agricultural revolution – Submergence Tolerance
Flooding is a common problem in many rice-growing regions.
More than 16 million rice growing lands are lowland areas.
Deepwater areas unfavourably affected by floods.
Climate change will only increase this.
Sensitive rice cannot survive prolonged flooding.
Submergence-tolerant Sub1a rice growth arrests during flooding, enhancing survival.
Draw the signalling pathway in flooding rice.
[see notes for answer]
Describe the use of marker assisted selection (MAS).
Selects for DNA markers as its faster than selecting for phenotypes.
Markers allow use to see what genes are where as they are reassorted or shuffled every generation.
Describe the production of Swarna-Sub1a.
Cross Swarna with Sub1 donor and use MAS to select progeny with Sub1.
This allows for the Sub1 trait to be rapidly integrated into Swarna, thus keeping the original qualities of Swarna but making it tolerant to submergence as well.
Describe why plants moved environments >450 million years ago.
> 450 million years ago. Plant moved onto dry land. The aquatic environment they came from was competitive and filled with herbivores whereas initially land offered less competition and fewer herbivores.
Describe the systems plants have instead of a nervous system.
As sessile organisms, plants must sense and respond to stress, compared to most animals plants do not have a nervous system.
Xylem -> water moves from the soil to the atmosphere through the hollow dead cells of the xylem.
Phloem -> sugars produced by photosynthesis as well as other molecules move from their source to sinks (non-photosynthetic tissues) through the phloem.
Outline the use of vascular tissues for long distance signalling.
Vascular tissues are important for long distance signalling.
- Signals from drought-stressed roots cause guard cells to close by travelling in the xylem.
- Other xylem-borne signals convey information about nutrient availability and soil microbes.
- When leaves are phosphate-limited, a microRNA (miR399) moves through the phloem to the root and promotes phosphate uptake.
- Under appropriate day-length conditions (i.e. seasons) the protein flowering locus T (FT) and its orthologs move from leaves to the shoot apex via the phloem to promote the transition to reproductive growth.
Draw a diagram of cell-to-cell communication routes in plants.
[see notes for answer]
Draw a diagram describing the ROS wave.
The ROS wave accompanies other signals to alert the cells and tissues of stress.
RBOH = respiratory burst oxidase homolog
[see notes for answer]
Draw a diagram describing abiotic stress in a leaf affecting systemic leaves.
[see notes for answer]
Draw a diagram summarising the different kinds of signals plants use to respond to their environment.
[see notes for answer]
Draw a diagram detailing signal perception and transduction in plants.
[see notes for answer]
Describe Microbe Associated Molecular Patterns (MAMPs).
MAMPs (Microbe Associated Molecular Patterns): Conserved molecules in pathogens that can elicit immune responses.
1) Conserved across microbial generations.
2) Not required for infection, but important biological roles.
3) Not strictly found in pathogens (also other microbes).
4) Often surface exposed.
5) Not present in the host.
MAMP recognition via pattern recognition receptors (PRRs) triggers plant defence responses.
Draw a diagram depicting the use of MAMPs in plant cells.
[see notes for answer]
Describe PRRs in plants.
A variety of PRRs recognise different MAMPs from different organisms.
Several PRR/MAMP pairs have been identified.
[see notes detailing these pairs]
PRRs feature extracellular and intracellular domains for recognition and signalling respectively.
