Seminar -I

PLANT RESPONSE TO ABIOTIC STRESS

Deepak Barsaiya GuptaM.Sc(Ag), 3rd semesterDepartment of Ag. Biochemistry

Seminar leader & ChairmanProf. A Chakravorty Prof. Sri Kumar PalDepartment of Agriculture biochemistryBidhan Chandra Krishi Vishwavidyalaya

Department of Agriculture Biochemistry Faculty of Agriculture,

Mohanpur-741252, Nadia, West Bengal, India.

Course No.- ABC-591

INTRODUCTION• Plant stress is defined as any change in

environmental conditions that adversely affect development, growth and productivity.

• Two types of stress:– Abiotic stress– Biotic stress

ABIOTIC STRESSAbiotic stress arising from an

excess or deficit in the physical or chemical environment.

• Water logging• Drought• Salinity stress• Oxidative stress• High or low temperature• Inadequate mineral nutrients in the

soil

Source: Biochemistry & molecular biology of plants 2007,22 1158-1159.

STRESS RESISTANCE MECHANISMS

Mechanism that permit stress survival are termed stress resistance mechanisms.

Stress resistance mechanisms can be grouped into three categories

• Avoidance mechanisms - which prevent exposure to stress.• Tolerance mechanisms - which permit the plant to withstand

the stress.• Acclimation - Alter the physiology in response stress (drew et al. 1997).

Changes in gene expression to stress

• A stress response is initiated when plants recognizes stress at the cellular level.

• Stress recognition activates signal transduction pathways that transmit information within the individual cell and throughout the plant.

• Changes in gene expression may modify growth and development and even influence reproductive capabilities.

Regulation of ion (e.g., Na+ and K+) homeostasis by the sos(Salt Overly Sensitive) pathway

Source :-Na+ uptake by plant cells 1999;29:75–112.

PHOSPHOLIPID SIGNALING

Source : Inositol phosphate and cell signaling. Nature. 1989;341:197–205.

GENE EXPRESSION RESULTS IN

• Increase amounts of specific mRNA• Enhance translation• Stabilize proteins• Altered protein activity

Source: Biochemistry & molecular biology of plants 2007,22 1158-1159.

WATER STRESS Water related stresses could affect plants if the environment contains insufficient water to meet basic needs.Water loggingDrought condition

WATER LOGGING

Water logging cause:• hypoxia i.e. shortage of oxygen • anoxia i.e. total lack of oxygen Which causes the reduced growth, inhibits the

metabolic processes and finally reduces the yield of plant.

When soil is completely saturated with water is in general referred to the water logging.

DROUGHT CONDITION

Source: Biochemistry & molecular biology of plants 2007,22 1164-1165.

A prolonged period of abnormally low rainfall, leading to a shortage of water.

SOLUTES THAT CONTRIBUTES TO OSMOTIC ADJUSTMENTS

SALT STRESS• Plant salt stress is a condition where excessive salts

in soil solution cause inhibition of plant growth or plant death.

• salt stress Osmotic forces exerted on plants when they are growing in a salt marsh or under other excessively saline conditions.

• Sodium chloride (NaCl):NaCl ambiguously found in nature

• deserts, coastal areas.

Source: Protein Contribution to Plant Salinity Response and Tolerance Acquisition, 2013

PINITOL RESPONSE TO SALT STRESS

source: Biochemistry & molecular biology of plants 2007,22 1168-1169.

MANNITOL RESPONSE TO PLANT STRESS

Plant inhibit sucrose synthesis and promotes accumulation of manitol in salt stress condition.

Source: Biochemistry & molecular biology of plants 2007,22 1168-1169.

OXIDATIVE STRESS• Oxidative stress is a complex chemical and

physiological phenomenon that accompanies virtually all biotic and abiotic stresses in higher plants and develops as a result of overproduction and accumulation of reactive oxygen species (ROS).

• Oxidative stress result from conditions promoting the formation of active oxygen species that damage or kill cells.

FACTOR CAUSED OXIDATIVE STRESS

HEAT STRESS• Heat stress is often defined as a period in which temperatures are

hot enough for a sufficient period of time to cause irreversible damage to plant function or development. Plants can be damaged by either high day or high night temperatures and by either high air or soil temperatures.

HIGH TEMPERATURE STRESS

• Heat stress is a decrease in the synthesis of normal proteins, accompanied by an accelerated transcription band translation of new proteins known as heat shock proteins (HSPs)

• Heat stress has been shown to cause problems in mitochondrial functions and can result in oxidative damage. Activators of heat stress receptors and defenses are thought to be related to ROS.

NUTRIENT DEFICIENCYA lack of one or more essential elements needed by plants for optimum growth lead to plant stress.

NUTRIENT DEFICIENCY SYMPTOMS

Other Factors• Chemical Injury• Mechanical Injury• Transplant Shock• Chilling injury

Conclusion • None of the mechanisms by which higher plants precive

abiotic stresses has been elucidated. Progress in this crucial area will advance substantially our knowledge of stress initiated signal transduction events stress related signal propagated by several different agents in some cases, these signal transduction events involve at least one of the five best harmones ABA, Auxin, cytokinins ethylene, and gibberellins. However perhaps signaling molecules not yet identified also participate in controlling plant response to the environment.

Thank You