Introduction to Plant stress physiology

What is Plant physiology?

Defines and characterizes physiological processes in plant

physiological processes such as:

Stresses; external conditions that adversely affect growth, development or productivity

The positive, adaptive, stress response triggered by low doses of a stressor is named “eustress”

The negative stress response caused by high doses of a stressor is named “distress”

ØEu-stress / reversible stress = a mild, acclimative, often specific response to a stressor

ØDistress / irreversible stress = a strong often generic response to a stressor, involving substantial (sub)-cellular damage

Primary direct injury/plastic strain: tissues, organisms remain permanently deformed/injured after brief exposure to stress conditions. (Irreversible)
Primary indirect injury/elastic strain: in which the organism return to their normal physiological conditions after removal of the stress condition. (Reversible)

Drought, chilling, salinity, temperature, light etc

-Water stress induced by salinity/heat

-O2 stress induced by water logging

An extension of the range of conditions under which an organism can operate, i.e. prevention of distress
Plants have evolved different strategies
Stressor escape
Stressor avoidance
True stressor tolerance

1.Stress escape via opportunistic growth and reproduction cycles

2.Stress avoidance; tolerance based on mechanisms that prevent exposure of the cell content to stressors

Species have evolved mechanisms that can hasten, retard, or decrease the action of a stressor on cellular systems

Capability to re-imbibe and restart growth
Central role of ABA
Accumulation of compatible solutes and other stabilizing compounds (proline, glycine-betaine, but also sugars)
Upregulated, cellular anti-oxidant defences to give a broad stress tolerance