Abiotic Stress Flashcards
(24 cards)
Breeding has already provided adapted traits to environmental stress, name them.
Cold tolerance in wheat.
Cold tolerance in winter forage; kale
Salt tolerance in rice and wheat varieties
What are the global annual losses from salt-affected land?
$12 billion
What percentage of the world’s agricultural dryland is suffering from salination?
69%
How many hectares of the world is used for agricultural dryland?
%5.2 billion ha
How does salinization occur?
Water & Salt go into the soil.
Water evaporates (heat) or transpires through plant.
Salt remains behind
What crops have low salt-tolerance?
Sugar beets and Barley
What are Glycophytes?
Crops that pump salt back to the environment to reduce build up. These are the majority of crop plants.
What are Halophytes?
Plants that thrive in high salinity e.g quinoa
What can Freezing stress cause in plants?
Injury to plant cell membranes from freezing.
Injury by dehydration during freeze thaw cycles.
What are osmolytes?
Compounds that balance osmotic potential of externally increased osmotic pressure.
Give examples of Osmolyte compounds.
Quarternary amines, amino acids and sugar alcohols.
What is a naturally occurring osmolyte?
Trehalose; non reducing disaccharide.
Increased water retention and desiccation (drying) tolerance.
What is an AFP?
An Anti Freeze Protein;
Declines rate of ice crystal growth.
Lowers the efficiency of ice nucleation sites
Lowers temperature at which ice forms.
Give an example of an AFP.
Proline
What is the compromise between water and photosynthesis?
Sunlight causes evaporation in leaves.
This draws more water up through the xylem.
Water enters leaf cells by osmosis.
Water vapor diffuses out through stomata and air movement carries it away.
What controls stomatal closure?
Abscisic acid (ABA)
What allele is being introduced for drought resistance?
The deeper root allele (rice)
What are examples of excess moisture- resistant plants?
Wetland plants (rice & mangroves)
Flood-tolerant plants (maize)
What root condition is caused by flooding?
Anoxia; absence of oxygen.
What do flood-tolerant plants do to avoid anoxia?
They shift their metabolism from respiration to anaerobic glycolysis.
What is hyponasty?
Upward bending of leaves or stems caused by faster growth to raise above water level.
How does rice survive waterlogged conditions?
Adventitious roots; Increases aerenchyma (air spaces) which aerates roots.
How do hormones regulate abiotic stress in plants?
Antagonistic; stress hormones can oppose each other (ABA vs SA).
Synergistic; some act together.
