Course

Practical

• Measurement of soil and plant water
• Drought stress imposition and measurement of physiological and biochemical changes in plants under stress –gas exchange and fluorescence
• Determination of water use efficiency as a drought resistant
• Drought Susceptibility Index (DSI) -precise field technique to identify productive genotypes under
• Approaches to quantify root characters
• Determination of stomatal parameters and canopy temperature as a reflection of transpiration and root
• Determination of Salinity Tolerance Index.
• Studying acclimation response – Temperature induction
• Heat tolerance and membrane integrity- Sullivans heat tolerance
• Quantification of osmolytes – proline under
• Oxidative stress imposition- Quantification of oxidative stress
• Quantification of ROS under
• Estimation of ABA content in leaf and root tissues under
• Determination of Sodium and Potassium in plant tissue grown under salt
• Estimation of antioxidant

Unit I

Theory

Block 1: Abiotic Stresses

Introduction to Abiotic Stresses

Abiotic stresses major constraints to realize potential yields of crop plants, yield losses. Drought prone areas in India- Frequency of occurrence of drought, Rainfed- kharif, Rabi, Areas affected by salinity, heavy metals, water logging, high temperature scenario due to global warming.

Block 2: Drought Stress

Unit I: Moisture Stress Responses in Plants

Drought-characteristic features; water potential in the soil-plant-air continuum. Physiological and biochemical processes affected by drought. Oxidative stress-generation of ROS and other cytotoxic compounds, their effect on cellular process. Effect on total carbon gain- decrease in photosynthetic area and function, protein turn over and lipid characters, phenology-reproductive aspects, critical stages.

Unit II

Stress Perception and Molecular Responses of Plants to Drought Stress

Stress perception and signal transduction leading to expression of regulatory genes, stress specific kinases, stress specific transcription factors, functional genes associated with adaptive mechanisms.

Unit III

Plant Adaptive Mechanisms to Drought

Escape and desiccation avoidance mechanism Concept of stress escape- exploiting genetic variability in phenology, Drought avoidance mechanisms- Maintenance of cell turgor, water mining by root characters. Moisture conservation- Regulation of transpiration- traits reducing heat load, Stomatal factors guard cell metabolism, moisture conservation by waxes. Water use efficiency (WUE) and concept of water productivity- regulation of transpiration efficiency-stomatal conductance, mesophyll efficiency, relevance of WUE and Passioura’s model. Desiccation tolerance- Concept of acquired tolerance. Decreased turgor mediated upregulation of cellular tolerance mechanisms, Osmolytes, managing cytotoxic compounds, ROS, RCC, scavenging – enzymatic and non-enzymatic, protein turnover, stability, chaperones, membrane stability, photo- protection of chlorophylls.

Unit IV

Approaches to Improve Drought Tolerance

Development of genetic resources- donor genotypes for specific traits, Genomic resources- genes, QTL’s regulating adaptive mechanisms, Conventional, transgenic and molecular breeding approaches to improve relevant adaptive traits, concept of trait introgression.

Unit V

Block 3: Salt, Heavy Metal, Water Logging, Temperature and Light Stress

Unit I: Salt Stress

Soil salinity-Effect of salt stress, ionic and osmotic effects; species variation in salt tolerance; glycophytes and halophytes, Salt tolerance mechanisms – exclusion, extrusion and compartmentalization, Signaling during salt stress – SOS pathway, Approaches to improve salt tolerance.

Unit II: Heavy Metal Stress and Water Logging

Heavy metal toxicity in plants (eg., Al, Cd), tolerance mechanisms and approaches to improve. Plant response to water logging, role of hormones- ethylene, mechanism of tolerance and approaches to improve.

Unit III: Temperature and Light Stress

High and low temperatures; effect on plants; adaptive mechanisms, evaporation cooling, concept of cellular tolerance, protein stability, chaperones, HSPs, HSFs, membranes. High light and high ionizing radiation- photo oxidation and photo- inhibition; mechanisms of tolerance, plant adaptation to low light, concept of shade avoidance response (SAR).

This course aims to describe students the abiotic-stress physiology and their effects on plant growth and productivity. This will also help students gain insights into latest developments in stress physiology and stress tolerance mechanisms, approaches for crop improvement under stressful environment.