This document discusses various types of abiotic stresses including salt tolerance, drought tolerance, waterlogging tolerance, heat tolerance, and cold tolerance. It defines each stress and describes the injury mechanisms, tolerance mechanisms, screening methods, and genes associated with tolerance. Salt tolerance mechanisms include cell membrane stability, osmotic adjustment, and ion accumulation. Drought tolerance is achieved through escape, avoidance, or tolerance. Waterlogging tolerance relies on phenology, morphology, and anaerobic metabolism. Heat and cold tolerance utilize membrane stability, osmoregulators, and molecular chaperones. The document provides details on screening rice, wheat, maize, chickpea and other crops for various abiotic stress tolerances.

2. Junagadh Agriculture
University
Assignment
Submitted By :-
Delvadiya Indrajay
R.
M.sc(Gpb)
indrajaydelvadiya@gmail.com
9033332413

3. Abiotic stress in vitro
Mutant gene

4. DEFINITIONS
 Abiotic stress is defined as negative impact of non-
living factor on the living organisms in specific
environment.
or
 Abiotic stress is a non-living enviromental factors ,
Example:
Drought, extreme cold or heat sun expose, salinity, high
metal toxicity such like adverse effect on environment.

5. VERSATILITY OF ABIOTIC STRESSES
STRESS
ABIOTIC
WATER DEFICIT
EXCESS
TEMPERATURE HIGH
LOW
SALT/ION
TOXICITY
DIFFICIENCY
AIR POLLUTION
OTHERS
BIOTIC
5

7. Types
1 Salt tolerance
2 Drought tolerance
3 Water logging tolerance
4 Cold tolerance
5 Heat tolerance

8. Salt tolerance

9. INTRODUCTION
 Soluble salts can cause an harm to plant if they are in
high concentrate in water or soils and it limit crop
cultivation world wide.
 Generally an array of stresses interplay in saline soils
and reduces productivity of salt sensitive crops.
 The optimum salt concentration of the growth of
halophytes is found to be about 0.5 M Nacl .

10. PLANT SYMPTOMS
 Tip and edge burn of leaves, slow growth, nutrient
deficienes, wilting and eventually death of plant can
occur.
 Increase salinity decrease and delay in seed
germination. Salinity stress decrease chlorophyll content,
total sugar, starch, potassium in seedling stage.

11. INJURY MECHANISMS
 Salt cause damage to the plants when it is absorbed
by the roots and accumulated in the plants to toxic
levels. salt stress has mainly three fold effects; it
reduces water potential, causes ion imbalance or
disturbance in ion homeostasis and toxicity. The
major causes of salt injury have been listed below,
 Reduce water potential
 Ionic imbalance
 Inhibition of enzymatic imbalance
 Change in physiological parameter
 Inhibition of translocation

12. TOLERANCE MECHANISM
 Salt tolerance denotes the ability of plant to prevent,
reduce or over come the possible injurious effects caused
directly or indirectly by excessive presence of soluble
salts in the soil liquid phase or growth medium.
 The possible mechanism of salinity tolerance by plant
have been listed below……..

13. 1 Cell membrane stability
2 Osmotic adjustment
i) Mannitol
ii) Glycinebetaine
iii) Proline
iv) Other amino acids
v ) Other osmoprotectant
3 Phytohrmone
4 Enzyme
5 Vitamins in salt tolerance
6 Ion accumulation and ion balance
7 Exclusion
8. Silicon supply
9. Leaf characteristics
10.Crop stages

14. SCREENING FOR SALT TOERANCE
 Success of breeding programme would depend upon
reliability estimation of salinity resistance various
genotype.
 For crop improvement programme, most
requirement is to gather information on natural
variability in crop tolerance behavior And whether
existing cultivated and wild resources have been
thoroughly screened. So far, different methods and
protocols have been discussed below……

16. GERMINATION TEST
 The simplest technique foe assessing germination
under stress is to plant seeds on filter papers wetted
with proper salt solution kept in container.
 A gradient of osmotic potential can be easily created
by making a series of small dilutions of a
concentrated salt solution.
 Seeds may be planted on a agar medium containing
suitable fungicide and the desired concentration of
salt solution.
 Significant differences among culture were observed
for ability to germinate under salt stress.

17. SAND CULTURE
 In this approach pots are filled with sand
subsequently irrigated with saline water. Polyethylene
bags filled with thoroughly washed river sand.
 The bags are wrapped with polyethylene sheet to
protect roots from exposure to light and to prevent
algal growth.
 The bags are flooded with Hoagland nutrient solution,
with salt mixture required to be added for salinization
and those bags were used to screen for salinity
resistance.

18. HYDROPONIC
 In hydroponic test for salt tolerance in plastic tanks .
The tank contain 16 bottom less growth pouch
arrange vertically in lines. The tank were filled with
known qauntity of salt solution, half Hoagland
nutrient solution added aerated continuously.
 The growth pouches permitted the seed to remain
above salt solution while imbibing salt water from
tank. Some fungicide may be use to retarted from
invension of the seed . Germination and seedling
growth were recorded.

19. YOUNG SEEDLING SCREENING
 Identification and evaluation of salt tolerant genotype
are important to improve production of crops in salt
affected in lands.
 The criteria used in the past for screening of plant
have failed to prove their legitimacy as the final
economic yield is not positively correlated with any
of these parameters.
 Thus, need of the hour is to have a simple , efficient,
economically viable and dependable techniques for
screening of salinity tolerant genotype of crop plants
that is reflected in economic yield as well.

20. YOUNG SEEDLING SCREENING
 Salinity affects more the rate of germination then the
ultimate germination percentag and suppresses
elongation of root then of shoot and in some other crop
more of shoot then roots.
 Minimum suppression in coleoptiles elongation has been
suggested as a better index for the screening of sorghum
variety.

21. SEEDLING ROOT DIP
 For laboratory screening root of 30 day old seedling can
be dipped in 0.5 % salt solution for 72 hours.
 Salt tolerance variety are characterized by lower
absorption of salt. While breeding for rice variety for
saline alkaline situation , one should selected for number
leaf tip burn , better root system and plant free from dark
bend at the juncture of the root and shoot.

22. OTHER METHOD OF
SCREENING
Many other methods of screening such as
terazolium test, paper towel method etc. have
been recorded to be utilized for screening against
salinity. A general reduction in shoot and root
length, vigour index and dry matter production
with increased salt concentration was observed in
the plants using paper towel method.

23. Drought tolerance

24. INTRODUCTION
 Drought has been defined as a the inadequacy of
water availability, including precipitation and soil
moisture storage capacity, in quantity and distribution
during the life cycle of crop to restrict expression of
it’s full genetic yield.
 It acts as a serious limiting factor in agricultural
production by preventing a crop from reaching the
genetically determined theoretical maximum yield.

25. INJURY MECHANISM
 At a cellular level, drought affects membrane
structures, and structure of macromolecules like
protein, nucleic acid, create pressure differential across
the membrane-cell wall complex.
 At low water potential, stomata close due to loss in
turgidity of guard cells leading cease in transpiration.
 In absence of transpiration, temperature of leaves
increase to lethal level and leaves die. Such low water
potential (cause high tension on xylem) are known to
cause severe embolism formation in the xylem vessels
of woody plants blocking water transport and
potentiality causing shoot die back.

26. TOLERANCE MECHANISM
 It should be grouped into three categories..
1 ) Drought escape
2 ) Dehydration avoidance
3 ) Dehydration Tolerance

27. BREEDING UNDER ARTIFICIAL
MEDIUM
 PEG creates artificial moister stress in plant growing
media .
 E.g. for screen maize F1 in 0.5 Mpa PEG we observed
non addictive variance important for germination percent
, shoot length and root: shoot ratio , while addictive gene
action play a major role of most of the drought related
trait in PEG.

28. SCREENING CRITERIA
 Selection for drought tolerance by a any selection
index requires vigours control over stress
environment, and needs to address moisture in terms
of growth stage and stress intensity along with
temperature gradient and radiation.
 Evidence of variation of moisture content within a
field implies a need for a reasonable level of drought
tolerance.

29.  Drought tolerance is an interactive result of different
morphological, physiological and biochemical traits
and thus this different components could be used as
selection criteria for screening appropriate plant type.
 A combinations of different traits of direct relevance,
rather than a single trait, should be used as selection
criteria.

30. GENES FOR DROUGHT
TOLERANCE
 Many genes have been identified and used for
drought tolerance in different crop plants.
 It reported that ABA biosynthesis signaling can be
regulated through AtGLR1.1 gene to trigger pre and
post emergation arrest and changes in whole plant
responses to water stress. They also suggested that
AtGLR1:1 integrates the different aspects of C,N
plant growth and development.
 Molecular characteristics of P5Cs (pyrroline 5-
carbohydrate synthases ) gene in sugarcane is related
to drought tolerance.

31. Waterlogging Tolerance

32. INTRODUCTION
 Waterlogging can be defined as a condition of soil where
excess water inhibits gas exchange of roots with
atmosphere.
Injury Mechanism
 Both root and shoot growth negatively affect by water
logging. It significantly decreases with chlorophyll
content, co2 assimilation rate, and mineral quantum
efficiency of photo system II.

33. Effect on plant
 Reduce gas exchange
 Water deficit in Aerial parts
 Nutrient imbalance
 Change in Phytohormone concentration and activity
 Disturbance in root metabolism
 Decreased leaf epidermal conductance
 Morpho-physiological changes

34. Tolerance Mechanism
 Physiological mechanisms for water logging
tolerance are ….
1) Phenology
2) Morphology and anatomy
3) Nutrition
4) Metabolism including anaerobic catabolism and
anoxia tolerance
5) Post toxic damage and recovery

35. SCREENING METHODS
 Screening without non water logged control obviously has
advantage since twice number of genotype evaluated.
 Positive impact of basin varietal selection are on such
screening strategy is that yield may be high in thus
germplasm when grow in water logged environment , how
ever this may have nothing to do with water logged
tolerance.
 Ex. :
In Lucerne two to three month old plants grown in half
strength Hogland nutrient solution for 16 days. At that time
all cultivars had significantly reduced fresh and dry weight
for both shoots and roots .

36. Heat tolerance

37. INTRODUCTION :
 Temperature is one of the most important environment
element influencing plant growth and development. it
has wide effect on photosynthesis and photo periodism.
All semi arid and arid crop effect on stress. Every plant
have a normal temperature for plant growth its called
Cardinal temperature.

38. INJURY MECHANISIM
 High temperature mainly affected two way
1) Growth and development of plant
2 ) Physiological process of plant
The nature and extend of heat energy may be depend on
temperature, plant species and other meteorological
function.

39. EFFECT
1. Effect of high temperature on plant growth and
development.
2. Physiological effect on high temperature,
I. Respiration
II. Photosynthesis
III. Protein Denaturation
IV. Membrane composite and stability

40. TOLERANCE MECHANISM
 The avability of plants to withstand high temperature and
perform better than the other under the same
environment condition is termed as heat tolerance. Based
on response of the plant high temperature , the various
mechanism of heat tolerance may be classified
HEAT AVOIDANCE
HEAT TOLERANCE

41. HIGH TEMPERATURE TOLERANCE
MECHANISIM
Molecular chaperones interacted to protect again heat
 Membrane stability
 Amylopectin content
 Osmoregulator content
 Plant growth regulator
 Repairing of injured cell

42. GENE FOR HEAT TOLERANCE
 The development of high temperature tolerent genotype of
crop plants if necessary to improve plant productivity
under high temperature stress environment.
 The chromosome number1A,2A,2B,3A,3B,3D,5D,6B
were associated with heat tolerant in wheat . Additive gene
action was more important than non additive efforts for
fruit set , flower drop and under developed ovaries as high
temperature.

43. SELECTION FOR HEAT TOLERANCE
1) Direct selection
2) Indirect selection
Artificially created environment :
 The prograame environment may be created in glass
house or in growth chamber , the critical tem. range can
be amend as per requirement at specific growth stage of
plant, high relative humidity is maintaing using
humidifiers or fogging facility in vitro lab. It is
important again water stress during screen for heat
tolerance ,it is costly but suitable for small population.

44. IN VITRO SCREENING
 Tissue culture for in vitro screening of germplasm for
heat tolerance used by many workers they studied the
tuberization for of potatoes for high temperature in tissue
culture system under temp. gradient, which ranges from
14-34 celcious in suggested that the system was
potentially useful for study of potato tuberization under
heat stress.
 In vitro screening of potato germplasm as heat
tolerance, heat tolerance germplasm was selected by
introducing stress at various stages of callus growth.

45.  To indentify heat tolerance ability of somaclone then
transfer somaclone into growth chamber somaclone were
screen based on leaf size, leaf number, pigment system,
root development.

46. COLD TOLERANCE

47. INTRODUCTION
 Low temperature is major factor for plant growth. Many
plant of tropical origin is suffer from cold damage, when
exposed to temperature below 20 celcious.
 Low temperature in growing season may be reduce
germination, retard vegetative growth by inducing
metabolic imbalance, and can delay or prevent
productive development .

48. TYPES OF INJURY
1. Chilling injury > 0’ celcious
2. Freezing injury < 0’ celcious
 Freezing injury maybe intracellular or extracellular.
 Intracellular freezing damage the protoplast structure
and ice- crystal kill cell once grow large enough to
detect microscopically.
 Intracellular freezing, protoplast of plant become
dehydrates because a plant water vapour deficit is
created as ice crystal forming between cell.

49. INJURY MECHANISM
 Membrane damage
 Prevents pollen germination
 Abnormal hormone metabolism
 Imbibitional chilling injury
 Reduction photosynthesis
 Oxidative stress

50. TOLERANCE MECHANISM
 Study of cold tolerance is in the fields is difficult rather than in
vitro
A. Biochemical and physical basis of tolerants.
I. Polyamine
II. Membrane lipid unsaturation
III. Phytohormone
IV. Vernalization
B. Morphological Basis of tolerance
I. Pollen Fertility
II. Enhance seed germination
III. Floral parts varation
IV. Cell size

51. GENETIC COLD TOLERANCE
CROP GENOTYPE
Chickpea ICCV- 88552
ICCV-88503
ICCV-88502
Wheat Albumin 114
( triticum aestivum ) Albumin 24
Odesskara 51
Rice Jumali
( oryza sativa ) Fujisaka-5
KH-998
Maize
(zea Mays )
CO-225
CO-304
Labo78

52. IN VITRO SCREENING
 The potential of tissue culture for effective genetic
modification has been stressed in number of research
paper.
 One approach to such genetic modification involved the
isolation of stable varient cell from established cell culture
either of directly or following mutagens treatments cold
tolrents cell lines can be selacted relatively easily and
tolerants plants can be regenerated from them.

53.  Cold tolerance lines have been produced from rice anther
cultural , some plants that were regenerated from
selection and tested under hydroponic condition showed
improve tolerance.

54. Bidhan Roy & Dr. Asit Kumar Basu ( 2009 )
Abiotic stress tolerance in crop plants
New India Publishing Agency
Page No. :- 5- 243
Reference