Plant Stress Physiology

Drought, salinity, flooding, heat, and cold all threaten plant survival, and plant stress physiology examines how plants sense these abiotic challenges and mount protective responses to tolerate them.

Definition

Plant stress physiology is the study of how plants respond and adapt to adverse abiotic conditions that disturb their normal functioning, and the mechanisms that confer tolerance.

Scope

This topic covers the major abiotic stresses — water deficit, salinity, temperature extremes, flooding, and oxidative stress — the mechanisms by which plants perceive them, and the physiological and molecular responses, including osmotic adjustment, abscisic acid signaling, and antioxidant defenses.

Core questions

• How do plants perceive water deficit, salinity, and temperature stress?
• What physiological and molecular mechanisms confer tolerance to these stresses?
• How do plants protect against the oxidative damage that accompanies many stresses?

Key theories

Abscisic acid–mediated stress response

Water-related stresses raise abscisic acid, which closes stomata and activates stress-responsive genes, coordinating the plant's defense against dehydration.

Osmotic adjustment and protection

Plants accumulate compatible solutes and protective proteins to maintain cell turgor and stabilize macromolecules, while antioxidant systems limit the reactive oxygen species generated under stress.

Mechanisms

Under water deficit or high salinity, plants synthesize abscisic acid, which is perceived by PYR/PYL receptors to inhibit protein phosphatases and trigger stomatal closure and stress-gene expression. Cells accumulate compatible osmolytes such as proline and glycine betaine to lower water potential without disrupting metabolism, and produce protective proteins like LEA proteins and chaperones. Because many stresses elevate reactive oxygen species, enzymatic and non-enzymatic antioxidant systems scavenge them; cold and heat additionally trigger membrane and protein-protective responses such as heat-shock proteins.

Clinical relevance

Abiotic stress is the leading cause of crop yield loss worldwide, so understanding stress physiology drives the breeding and engineering of drought-, salt-, and temperature-tolerant crops critical for food security under a changing climate.

History

Once largely descriptive, plant stress physiology became mechanistic through the identification of abscisic acid signaling components, stress-responsive transcription factors, and ion transporters, much of it through molecular genetics in model plants.

Key figures

• Hans Kende
• Jian-Kang Zhu

Seminal works

• taiz2015
• buchanan2015

Frequently asked questions

What is abiotic stress?

Abiotic stress is harm caused to plants by non-living environmental factors such as drought, salinity, extreme temperatures, and flooding, as opposed to biotic stress caused by pathogens and herbivores.

How does abscisic acid help plants survive drought?

When water is scarce, abscisic acid accumulates and signals guard cells to close the stomata, reducing water loss, while also switching on genes that protect cells from dehydration.