Abiotic Stress Flashcards
Name 5 abiotic stresses
Light, water, salinity, heavy metals, radiation
How much of crop yield is lost to abiotic stress?
50%
What percent of crops are currently being used to feed animals?
36%
What yield increase is required per annum to meet our demands?
2.4%
How will an annual plant react to stress (e.g. drought)
Transition to reproductive mode - more flowers and seed production
Name for acclimation in horticulture
Hardening
What is the role of genomics in plant science?
Allows scientists to look for markers and possible targets for manipulation
What % of worlds water is available for plants to use?
<1%
Money lost in US due to drought?
$130 million
What perecentage of cultivatable land is affected by salinity?
5%
What % of wheat belt is affected in Oz?
How much do wheat exports total?
How much do crop losses cost per year from salt stress?
70-80%
$4 Billion
>$500 million
What is meant by the dual function of Reactive Oxygen Species (free radicals)?
They act as a positive activator in signal pathways but have a negative impact on growth
What are the most common forms of ROS?
Superoxide anion, peroxyls, hydroxyls
Most common outcomes of ROS
Lipid peroxidation, DNA/RNA damage, protein oxidation
What are the 3 stages of increased oxidative modification of a protein?
Low oxidation protein can hold shape, moderate protein will unravel and become linear, high oxidation now hydrophobic protein will agregate with other proteins forming large inhibitory mess.
What 3 conditions can lead to osmotic stress?
Salt, drought, cold
Where are excess ions stored to avoid disruption of metabolic processes?
In the vacuole
What are the effects of drought on root phenotype?
Roots grow longer and less branched
What sites particularly produce ROS?
Sites of electron transport especially around the plastid/mitochondria since plants cannot regulate the transport
What is the role of a molceular chaperone?
Acts as a detoxifying method by assisting the folding of proteins
How does HSP60 assist in protein folding?
Barrel shaped structure sucks in amino acid chain into hydrophobic space and shoots out refolded protein.
How does HSP33, HSP31 and smallHSPs assist under stress?
Attempt to pull apart large aggregates of protein
How does HSP70 and 90 assist in protein folding?
Work alongside large HSP101 to dissaggregate large protein and reassemble protein (90 is magnet shaped) but this takes ATP.
What does mannitol do in an experiment?
Mimicks a drought environment by making water move out of the roots
How can we combat the drought effects of mannitol using genetic engineering?
Constant expression of HSP90
What is measured in the mannitol experiment to show the effect of HSP?
Chlorophyll levels
How does the technology in DroughtGuard improve dorught tolerance?
Processing bodies (degredation of mRNA) and stress granules (protect and stabilize mRNA under stress) are produced in the cytosol to deal with aggregating mRNA.
What does PolyacrylAmide Gel Electrophoresis help you determine?
Seperate proteins by size and isoelectric point
Where were binding proteins for mRNA known as cold shock proteins (used in DroughtGuard) first isolated from?
E-Coli in the 1980s
Describe the bacterial CSP-mRNA surveillance system
Under cold conditions, linear mRNA switches to structured mRNA which cannot be translated. Under these conditions, cspA is also produced which binds to mRNA, teasing apart the tight structure. Anything that does not get well linearised is degraded.
What was the step between CSP being expressed in bacteria to maize?
A model plant - Arapidopsis
What species was the specific CSP-B isolated from to be used in maize in Drought-Gard and why?
Bacillus Subtilus, it is already commonly used in fermented food so can be tested for safety.
How can movement of solutes into the vacuole help stress defence in plants?
In stress, the osmotic value outside of plants tends to be very low (with many solutes) causing water to move out. By moving solutes out of cytosol and into vacuole, it means water moves towards vacuole and water will continue to move into cell.
Which solute naturally builds up in cotton that can aid with stress?
Glycine Betaine
Describe the biosynthetic pathway that leads to glycine betaine IN PLANTS
Choline monooxygenase creates an aldehyde that then is converted to glycine betaine by a dehydrogenase enzyme.
Describe the biosynthetic pathway of GS IN E.COLI
Choline monooxygenase is subbed out for choline dehydrogenase (an enzyme targetted by genetic engineering)
Is the expression of choline dehydrogenase enzyme succesful in increasing plant yield?
Yes but no technology is currently on the market.
How does active transport in the roots limit salt stress in a plant?
Actively transport Na+ out of xylem and into root parenchhyma cells to reduce concentrations of Na+ in the leaves.
