Drought resistance is important because drought can cause up to 50% yield loss in crops. About 36% of land area is arid or semi-arid and prone to drought. The document discusses important traits for drought resistance like early maturity and root traits. It describes techniques for screening drought tolerance like line source sprinkler systems. Breeding approaches discussed include selection, hybridization, backcrossing and distant hybridization to transfer drought resistance genes.
This presentation gives the insight idea about drought and its effect on the plant system also talks about development of drought-tolerant variety for ensuring food security.
This presentation gives the insight idea about drought and its effect on the plant system also talks about development of drought-tolerant variety for ensuring food security.
Micropropagation and commercial exploitation in horticulture cropsDheeraj Sharma
Micro-propagation – principles and concepts, commercial exploitation in horticultural crops. Techniques - in vitro clonal propagation, direct organogenesis, embryogenesis, micrografting, meristem culture. Hardening, packing and transport of micro-propagules.
Development of transgenics for the abiotic stress tolerance is the need of the hour as the existing plant types were prone to vagaries of climate change and therefore a new technology for the development of abiotic resistant varieties through genetic manipulation is imperative.
The concept of gene for gene hypothesis was first developed by Flor in 1956 based on his studies of host pathogen interaction in flax, for rust caused by Melampsora lini. The gene for gene hypothesis states that for each gene controlling resistance in the host, there is corresponding gene controlling pathogenicity in the pathogen. The resistance of host is governed by dominant genes and virulence of pathogen by recessive genes. The genotype of host and pathogen determine the disease reaction. When genes in host and pathogen match for all loci, then only the host will show susceptible reaction. If some gene loci remain unmatched, the host will show resistant reaction. Now gene – for –gene relationship has been reported in several other crops like potato, sorghum, wheat, etc. The gene for gene hypothesis is also known as “Flor Hypothesis.”
“Seed priming is a controlled hydration technique in which seeds are soaked in water or low osmotic potential solution to a point where germination related metabolic activities begin in the seeds but radical emergence does not occur.”
Author: Dr. T. M. Thiyagarajan, Dean Faculty of Agricultural Sciences, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu, India
Title: Understanding the System of Rice Intensification (SRI) for Sustainable Rice Production
Presented at: The International Conference on Climate Change, Biodiversity and Sustainable Agriculture
Venue: Assam Agricultural University, Jorhat, Assam, India
Date: December 13-16
Micropropagation and commercial exploitation in horticulture cropsDheeraj Sharma
Micro-propagation – principles and concepts, commercial exploitation in horticultural crops. Techniques - in vitro clonal propagation, direct organogenesis, embryogenesis, micrografting, meristem culture. Hardening, packing and transport of micro-propagules.
Development of transgenics for the abiotic stress tolerance is the need of the hour as the existing plant types were prone to vagaries of climate change and therefore a new technology for the development of abiotic resistant varieties through genetic manipulation is imperative.
The concept of gene for gene hypothesis was first developed by Flor in 1956 based on his studies of host pathogen interaction in flax, for rust caused by Melampsora lini. The gene for gene hypothesis states that for each gene controlling resistance in the host, there is corresponding gene controlling pathogenicity in the pathogen. The resistance of host is governed by dominant genes and virulence of pathogen by recessive genes. The genotype of host and pathogen determine the disease reaction. When genes in host and pathogen match for all loci, then only the host will show susceptible reaction. If some gene loci remain unmatched, the host will show resistant reaction. Now gene – for –gene relationship has been reported in several other crops like potato, sorghum, wheat, etc. The gene for gene hypothesis is also known as “Flor Hypothesis.”
“Seed priming is a controlled hydration technique in which seeds are soaked in water or low osmotic potential solution to a point where germination related metabolic activities begin in the seeds but radical emergence does not occur.”
Author: Dr. T. M. Thiyagarajan, Dean Faculty of Agricultural Sciences, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu, India
Title: Understanding the System of Rice Intensification (SRI) for Sustainable Rice Production
Presented at: The International Conference on Climate Change, Biodiversity and Sustainable Agriculture
Venue: Assam Agricultural University, Jorhat, Assam, India
Date: December 13-16
Ecology - Crop adaptation to its environment - Response of plants to climate change - Recent trends of Climate change - Effects of climate change - crop adaptation strategies
Ways to address moisture stress under dryland conditionsmuskanporwal6
Water has been inherently a scarce resource in the semi arid tropics. Agriculture has been the major user of this constantly limiting resource. The basic and foremost constraint of drylands is the uneven distribution of rains. Erratic rainfall results in widely fluctuating production, leading to production deficit and causing land degradation through soil erosion and reduced groundwater recharge. And the effect being crop failures. There are various approaches to deal with the moisture stress in drylands. Water harvesting, agronomic approaches for in-situ moisture conservation, conservation agriculture and measures for efficient utilization of the stored moisture through genetic approaches, selection of suitable crops and varieties and different planting methods etc.Thus with the collaboration with appropriate government policies and institutional support and development of various drought resistance varieties the and associated measures the moisture stress in dryland areas can be minimized effectively and efficiently.
India grows the largest number of vegetables in the world. Varied agro climatic conditions in India make it feasible to grow several vegetables round the year. Being short duration crops, vegetables are more susceptible to extremities in environment. And vegetable production is also not consistent due to weather extremities and diminishing natural resources. In countries like India it is a serious problem in view of large population depending on agriculture, excessive pressure on natural resources and poor cropping mechanisms. Vegetables play an important role in achieving the nutritional security as they encounter the malnutrition problems in India and also serve as a source of income for the small and marginal farmers. The major objectives of reducing malnutrition and alleviating poverty in developing countries through improved and consumption of safe vegetables that involves adaptation of current vegetable cropping systems like, multiple cropping, mixed farming, intercropping, and relay cropping systems. Integration of crop production, different farming systems with suitable soil and water conservation measures lead to sustainable production increase in income levels and towards better livelihoods. Major emphasis should be given on development of diverse technologies for optimization of farm resources, increased economic return and improved sustainability.
Moreover, increasing temperatures, reduced irrigation water availability, flooding, and salinity will be major limiting factors in sustaining and increasing vegetable productivity. Extreme climatic conditions will also negatively impact soil fertility and increase soil erosion. Measures to adapt to these climate change induced stresses are critical for sustainable tropical vegetable production. Adoption of suitable cropping system is one such measure which ensures maximum utilisation of natural resources and inputs. Farmers may get benefitted by following different cropping systems even under adverse climatic conditions. Success in mitigating climate change depends on how well agricultural crops and systems adapt to the changes and concomitant environmental stresses of those changes on the current systems. Thus, adoption of suitable cropping patterns/systems will be needed to maintain vegetable productivity.
28. Breeding for resistance to abiotic stresses – drought resistance – mechanisms of drought resistance (drought escape, avoidance, tolerance, and resistance) – features associated with drought resistance – sources of drought resistance – breeding methods for drought resistance – limitations – achievements; breeding for resistance to water logging – effects of water logging mechanism of tolerance – ideotype for flooded areas – breeding methods.
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sources in the solar corona and is highly structured. It is often described
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holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
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(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
2. Advanced Screening and Breeding Approaches for
Drought and Heat Tolerance
Deptt.of PlantBreeding&Genetics
Speaker : Dr. Champa Lal Khatik
3. • Introduction
• Main features of drought
• important traits related to drought resistance
• measurement of drought resistance
• Mechanism of Drought Resistance
• measurement of drought tolerance
• Screening techniques for drought tolerance
• Breeding approaches for drought tolerance
• Strategies for the genetic engineering of drought tolerance
• Difficulties in breeding for drought resistance
• Heat tolerance
• Wheat – High temperature stress
• Screening for heat tolerance
CONTENTS
4. Introduction
Drought:
Inadequacy of water availability, including
precipitation and soil moisture storage capacity,
in quantity and distribution during the life cycle of
a crop to restrict, expression of its full genetic
yield potential.
5. Main features of drought
About 36% of the land area constitutes arid and semi
arid zones. Arid and semi arid areas are more prone to
drought.
Drought leads to reduction in both yield and quality of
economic product in crop plants. It has adverse effect
on plant growth and development.
Drought damages chloroplasts and lowers
photosynthetic output.
There is an increase in proline level in the leaves of
plants which are subjected to drought.
Drought resistance is a genetically controlled
physiological property of plant species.
5
6. Plant responses to drought are very complex as stress
itself involves various climatic, edaphic and agronomic
factors, frequently complicated by major variation in
time of occurrence and duration intensity
Occurrence of drought depends on the amount and
distribution pattern of rainfall
Increase in abscisic acid content in leaves of barley,
and in ethylene level in cotton and wheat under drought
condition
6
Contd…..
7.
8. Drought Resistance
It is the true form of drought resistance
which refers to the ability of crop plants to
give good yield under moisture deficit
condition
10. Why is drought resistance important?
• Drought is a major limiting factor in crop
productivity; drought can cause yield loss of
up to 50% or more
• A large portion of arable land is arid (35%)
and the aridity and acreage is on the rise
12. MORPHOLOGICAL TRAITS
Earliness:- Early maturing varieties are ready for harvest before the
onset of drought.
Stomatal characters: -Various stomata characters such as sunken
type, small size, less number per unit area and rapid closing
nature.
Leaf characters:- Thick cuticle, waxiness of leaf surface, small and
thick leaves with thick layers of palisade tissue,
glossiness and hairiness.
Root characters:- Root length, root density, root dry weight and root
to shoot ratio are important trait.
Growth habit:- Indeterminate genotypes are suitable to drought
because determinate gives only one flush of flower and if
there is drought period during flowering, it may lead to very
heavy loss.
13. Physiological TRAITS
• RATE OF PHOTOSYNTHESIS
• RATE OF TRANSPIRATION
• HIGHER LEAF TURGIDITY
• OSMOREGULATION
16. Mechanism Of Drought
Resistance
• DROUGHT ESCAPE: Drought susceptible variety performs
well under drought environment simply by avoiding the
drought period.
• DROUGHT AVOIDANCE: It refers to the ability of the plant
to maintain a favorable internal water balance under
moisture stress.
• DROUGHT TOLERANCE: It refers to the ability of crop
plants to withstand at low tissue water content.
• DROUGHT RESISTANCE: It is the true form of drought
resistance which refers to the ability of crop plants to give
good yield under moisture deficit condition
(Drought tolerance+drought avoidance)
17. Drought tolerance
It refers to the ability of crop plants to withstand at low tissue
water content.
Various approaches to defining stress tolerance into four
hierarchical classes
Stable grain yield despite the occurrence of stress
Maintenance of normal developmental and growth
processes under stress
Biological mechanisms underlying these favorable
responses under stress
Loci or alleles that underlie these biological mechanisms
18. Drought tolerance
• It is a very complex trait
Two arguments
1. Most of the crucial plant traits that control plant
water status and plant production
2. Plant water status, more than plant function,
controls crop performance under drought
19. MEASUREMENT OF DROUGHT
TOLERANCE
• Seedling growth under PEG stress
• Growth under stress
• Plant phenology
• Grain filling by translocated stem reserve
• Cellular membrane stability under stress
20.
21. Selection of a screening environment
Stored moisture environment
Variable moisture environment
Optimal moisture environment
22. Screening techniques for drought
tolerance
• Multilocation testing- simple and convenient
• Drought plots
• Green house screening in plots
• Line source sprinkler system
24. Drought tolerance traits and their usefulness and ease of screening
Traits Usefulness Ease of screening
Drought escape
Phenological development Very high Easy
Drought tolerance
Early vigour High Easy
Transpiration efficiency High Easy, but costly
Stomatal control High Difficult
Osmotic adjustment High Difficult
Deeper and denser roots High Very difficult
Membrane stability Low Easy
Turner (2001)
24
25. Laboratory method
In this method to identify genotypic difference in germinability in
laboratory, osmotic solutions like polyethylene glycol (PEG) was
used.
The osmotic effect of drought are known to be comparable to true
drought effects only under non limiting of water movement where
the soil and seed contact is perfect.
In field condition, it is difficult to visualize a perfect seed and soil
contact. Therefore instead of osmotic solutions, soils brought to
different moisture tensions and packed in seed germination trays.
Results shows that seedlings failed to emerged in vertisol at soil
moisture content below 22%.
ICRISAT Saxena et al. (1984)
26. Field method:
The field testing was conducted on deep vertisol at ICRISAT
centre
The field is uniformly irrigated with overhead system using
perforated pipes.
The seedling is done at uniform depth of 5 cm on different
dates, to obtain contrasting difference in soil moisture contents
at time of seedling
During the course of experiment, no rainfall is received.
Counted number of seeds is sown in subplot. Soil moisture at 0-
10 cm soil depth was determined gravimetrically at three places.
The percentage of seedling that emerge is computed.
26
27. Screening cowpea for drought tolerance at the
seedling stage
Cowpea seedlings survival after 4 weeks of drought followed by 2 weeks of
daily re-watering. The drought tolerant parent Dan Ila and RIL-106 had a 60%
survival rate,
susceptible parent TVu 7778 and RIL-117 had 0% survival, while RIL-87 had a
100% survival rate
‘‘wooden box
technique’’
Agbicodo et al., 200
28. Screening approaches for drought tolerance in cowpea
Field screening of cowpea lines for drought
tolerance. The plants on the left are IT98 K-205-
8 (drought tolerant) and those on the right are,
IT98 K-555-1 (drought susceptible)
Agbicodo et al, 2009
32. F2
P2
F1
P1 x
large populations consisting of thousands
of plants
PHENOTYPIC SELECTION
Field trialsGlasshouse trials
DonorRecipient
CONVENTIONAL PLANT BREEDING
Salinity screening in phytotron Bacterial blight screening Phosphorus deficiency plot
33. • INTRODUCTION – identification of crop plants from the
place of their cultivation to such area where they never
grown
• SELECTION- process that favors survival and further
propagation of some plants having more desirable
characters than others
• PURELINE SELECTION- development of new variety
through identification and isolation of single best progeny
– Used in S.P., not in C.P. species
– for isolating the best genotypes for yield, quality and disease
resistance
– Takes 10 years in the development of new variety
34. • MASS SELECTION- individual plants are selected on the
basis of phenotypes from a mixed population, their seeds
are bulked and used to grow the next generation
– Used for both S.P. and C.P. species
– Takes 7-8 years for release of a new variety
• HYBRIDIZATION- refers to the crossing between
genetically dissimilar plants
• DISTANT HYBRIDIAZTION- crossing between two different
species of the same genus or two different genera of the
same family
– Transferring desirable genes into cultivated plants from related
species and genera
– Two types- interspecific and intergeneric hybridization
35. • BULK SELECTION- segregating population of S.P. species
is grown in bulk plot with or without selection, a part of the
bulk seed is used to grow the next generation and
individual plant selection is practised in F6 or later
generation
– No need to maintain pedigree record
– Simple and less expensive method
– Takes 15-16 years
• PEDIGREE METHOD- superior genotypes are selected from
segregating generations and proper record of the ancestry
of selected plants are maintained in each generation
– More commonly used for the improvement of polygenic traits than
oligogenic traits
– Takes 14-15 years for release a new variety
36. • BACKCROSS METHOD- repeated backcrosses are made to
transfer a specific character to a well adapted variety for
which the variety is deficient
– Used for both S.P. and C.P. species
– More commonly used for transfer of oligogenic characters than
polygenic traits
• MUTATION BREEDING- genetic improvement of crop plants
for various economic characters through the use of
induced mutations
– Commonly used in self pollinated and asexually propagated
species
38. MAS ( Marker assisted selection ) : It refers
to the identification of the genomic region that
are involved in the expression of the trait of
interest through molecular markers.
With the development of array of molecular
marker techniques and consequently dense
molecular genetic maps in various crop plants
MAS has become possible for both governed
by major and minor genes.
39. F2
P2
F1
P1 x
large populations consisting of thousands
of plants
ResistantSusceptible
MARKER-ASSISTED SELECTION (MAS)
MARKER-ASSISTED BREEDING
Method whereby phenotypic selection is based on DNA markers
40. SALIENT REQUIREMENTS OF MAS
The success of any marker based breeding programme
depends upon:
A genetic map with an adequate number of
uniformly spaced , polymorphic markers to
accurately locate desired QTL or major genes.
Close linkage between the QTL or major gene of
interest and adjacent markers, along with adequate
recombination between the marker and rest of the
genome.
An ability to analyze a large number of plants in
time and cost effective manner.
41. Plasmid method
Plasmids are extra chromosomal
elements
Replicate independently of
chromosomal DNA and are not
essential for normal growth and
function of a bacterium
Plasmids are used as cloning vectors
Soil-born bacterium, A. tumefaciens is
used for the development of transgenic
plants
43. Electroporation
Suspension of protoplast with
desired DNA are prepared, passes
from high electric shock
Cause temporarily pores in the
membrane of protoplast
Allows DNA to enter the cell
Foreign DNA gets incorporated with
the host genome
44. Microinjection
Plasmid DNA can also be delivered in to host
cells by mechanical means i.e. by microscopic
needle also called microscopic injections
Effectively used with different crop plants
Regeneration from protoplast is a basic
requirement
46. Breeding for Drought Tolerance in Tropical Maize–
Conventional Approaches and Challenges to Molecular
Approaches
• Identifying the genes underlying known
drought adaptive traits
• Exploring additional traits that confer
drought tolerance
• Cost-effectively deploying molecular
techniques that improve the drought
tolerance in adapted garmplasm
Banziger et al, 2000
47. SSR markers associated with
membrane stability in wheat
Sources of
variation
DF MS when grouped according to alleles
Xwmc9,
Xwmc596,
Xwmc603 or
Xbarc108 loci
Xbar121 locus Xgwm260
locus
Between
groups
1 786.4* 876.2NS 981.7NS
Within groups 60 131.4 230.7 269.0
Matilda and Elena (2009)
48. Difficulties in breeding for drought
resistance
• The drought environment prevailing in the region for which the
variety is to be developed must be clearly defined
• Selection for drought resistance has to be performed under
moisture stress
• Measurement of many drought resistance traits is difficult and
problematic
• The use of wiled relatives as sources of drought resistance is
problematic
• Develop a suitable and elaborate breeding scheme to develop
a drought resistance variety with high yield potential
• Many drought resistance traits may reduce yield, eg.
Earliness, stomatal sensitivity
49. Heat stress
• Adverse effects on plants of temperature
higher than the optimal is considered as
heat stress,
It affects the
• Survival
• Growth and development
• Physiological processes
50. Heat stress resistance
Ability of some genotypes to perform
better than others when they are subjected
to the same level of heat stress
Mechanisms
• Heat avoidance- ability of genotypes to dissipate the
radiation energy and thereby, to avoid a rise in plant
temperature to a stress level
• Heat tolerance- ability of some genotypes to better
perform than others when their internal temperatures are
comparable and in the realm of heat stress
54. Wheat – High temperature stress
• Continual HT
stress – Central,
Peninsular &
Southern India
• Terminal HT stress
– North Indian
plains
55. Genotypes with high heat
tolerance
Yield stability:
• T. aestivum: C306, LOK1, HUW234,
Raj3777, NI5439, NP846, Kalyansona, WH-
730, WH-1021, WH-1080
High grain weight:
• T. aestivum : Kundan, Lok1
• T. durum : HI8498
56. Screening of heat tolerant wheat varieties by membrane thermo
stability index in relation to yield and yield attributing traits
• (MSI) was taken as major parameter
• High MSI was recorded in HD-2733, K-9006, HP-1761,
NW-1067 and NW-1012 under heat stress
• varieties like Halna, K-8962, NW-1076 and NW-1014
showed less MSI
• Halna was found to be highly tolerant wheat variety
followed by K-8962, DBW-14, NW-1076 and NW-1014
under moderate to high stress condition
• Although variety HD-2733 gave high yield under control
condition but it also showed high susceptibility to stress
followed by HP-1761, NW-1012 and K-9006
Singh et al, 2007
57. Screening for heat tolerance- Polyhouse
• Growth Conditions
• Plants grown under natural environments
• Shifted to Temperature Controlled Poly house at 7 days after
heading
• Temperatures >32+20C/22 +2oC day and night
• Regularly watered to avoid moisture stress
• Re-randomised weekly to eliminate spatial effect.
58. Heat tolerant and susceptible lines inside the
plastic sheet tunnel
Wheat Research Institute, Faisalabad Rehman et al, 2009
59. Cell Membrane Stability: Combining Ability and
Gene Effects under Heat Stress Conditions
• The varieties, Hindi 62 and NIAW 34 were good general and
specific combiners in the tolerant group, while HD 2687 and
WH 147 were good specific combiners in the heat sensitive
group.
• Selection for heat tolerant inbred lines based on MTS in this
material may be more effective by reducing the dominance
variance after a few generation of selfing particularly in a self-
pollinated wheat crop.
• Electrolyte leakage or MTS was conducted at grain-filling
stage of plant growth as ambient temperature become high
enough to cause heat hardening of leaves.
DHANDA and MUNJAL 2009
60. Membrane thermo stability and heat tolerance in wheat
Relative injury as determined by the MTS test on flag leaf tissue
Genotypes year
1985 1986 Average
% relative injuryHeat tolerance
SGW104-1 56 79 67
SGW104-2 61 47 54
SGW104-1 29 49 39
SGW104-2 42 41 42
Mean 47 54 51
Heat sensitive
SGW104-3 82 82 82
SGW104-4 84 86 85
SGW104-3 72 64 68
SGW104-4 54 80 67
Mean 73 78 76
Shanahan et al., 1990
62. Conclusion
By use of biotechnology tools, our understanding of the
processes underlying plant responses to drought at
molecular and whole plant levels has rapidly
progressed.
Recent success on laboratory-production of drought
and heat stress-tolerant transgenic plants has been
achieved, which must be exploited in the future.
Molecular markers are being used to identify drought-
related QTL and efficiently transfer them into
commercially grown crop varieties of rice, wheat,
maize, pearl millet, and barley.
63. Contd….
• Breeding for drought and heat tolerance
requires the identification of traits for
phenology and those contributing to yield
• Urgent need for exploration of the plant
genetic resources with attributes related to
drought resistance
• Many different genes responsible for
biosynthesis of different solutes and
osmolytes conferring drought resistance
• Plant genetic engineering and molecular
marker approaches allow development of
drought and heat tolerant germplasm
