This document discusses breeding methods for improved drought tolerance in major crops like maize, sorghum, and redgram. It begins with definitions of drought and describes past and present drought trends. It then discusses the effects of drought on various crops and their response mechanisms. Various sources of drought tolerance are identified in wild relatives. The genetics and quantitative trait loci governing drought tolerance are described for different crops. Methods for creating drought environments, phenotyping traits, and conventional and molecular breeding approaches for developing drought tolerant varieties are explained. Promising drought tolerant varieties and future strategies are also mentioned.

1. BREEDING FOR IMPROVED DROUGHT TOLERANCE IN MAJOR
CROPS (MAIZE, SORGHUM, REDGRAM)
Bidush Ranjan Swar
M.Sc.(Ag.) 2nd year
RAM/18-64
Dept. of Genetics and Plant
Breeding
Dr. V. Swarnalatha
Senior Scientist(Genetics and
Plant Breeding )BSPU,SRTC,
Rajendranagar, Hyderabad.
CHAIRPERSON
PRESENTED BY
MASTER’S SEMINAR ON
COLLEGE OF AGRICULTURE, RAJENDRANAGAR, HYDERABAD

2. 1) What is drought
2) Past and present trends of drought
3) Effects of drought
4) Response to drought
5) Mechanism of drought tolerance
6) Sources of drought tolerance
7) Genetics of drought tolerance
8) Creation of drought environment
9) Drought phenotyping methods
10) Breeding methods and approaches of drought
tolerance
11) Promising drought tolerant varieties
12) Future strategies
13) Drought breeding limitations
TOPICS TO BE COVERED

3. WHAT IS DROUGHT ?
Condition of soil
moisture deficiency or
water scarcity during
the crop life cycle to
restrict full expression
of genetic yield
potential.

4. (SOURCE- An analysis of Hydro-met data,
IMD, Pune.)
• Decreasing rate of SW
monsoon and actual
average rainfall.
• Increasing rate of
drought year.
PAST AND PRESENT TRENDS OF DROUGHT

5. PAST AND PRESENT TRENDS OF DROUGHT cont..
(SOURCE - Indiastat)
In 2015-16 and 2017-18, No Dist. of Telangana was affected by
drought(https://farmer.gov.in/Drought/Droughtreport.asp)
SOURCE-Manual for Drought
management, DAC&FW, 2016

6. CROP LOSS DUE TO DROUGHT
CROP GROWTH STAGE LOSSES REFERENCE
MAIZE REPRODUCTIVE 63-87 % Kamara et al. (2003)
MAIZE GRAIN FILLING 79-81 % Monneveux et al. (2005)
MAIZE VEGETATIVE 25-60 % Atteya et al. (2003)
PIGEON PEA REPRODUCTIVE 40-55 % Nam et al. (2001)
SORGHUM VEGETATIVE > 36% Assefa et al. (2010)
SORGHUM REPRODUCTIVE > 55% Assefa et al. (2010)

7. EFFECTS OF DROUGHT ON PHOTOSYNTHESIS
AND PLANT SURVIVABILITY
• Drought stress leads to stomata closure
results in increases of internal
O2(Reactive Oxygen species ).
• High photo respiration.
• Photochemical efficiency decreases.
• Generation of ROS includes O2,
perhydroxyl radical (H2O·),
hydroxyl radicals O2
2-, (H2O2)
and alkoxy radical (RO).
• The ROS may react with
proteins, lipids and DNA,
causing oxidative damage to the
cell.
(Source- Farooq et al. 2008)

8. PLANT RESPONSE UNDER DROUGHT
(SOURCE- Kumar et al. 2018)

9. MECHANISM OF DROUGHT RESISTANCE
• AVOIDANCE-Conserve
leaf Wp as more savers
and less spenders.
• TOLERANCE-Ability to
withstand water deficit
by maintaining
physiological activities
stabilized.
• ESCAPE-Adjusting crop
life cycle before onset of
drought.
(SOURCE-Badiganavar et al. 2018)

10. • Activation of the
signalling cascades by
ABA, H2O2, Ca+2.
• Further activation of
kinases leads to
changes in gene
expression.
• Synthesis of
antioxidants and
osmoprotectants.
• stomatal closure.
MECHANISM OF DROUGHT TOLERANCE
(Source-Farooq et al. 2008)

11. EFFECTS OF DROUGHT ON SORGHUM
(Source-Badiganavar et al. 2018)

12. RESPONSE TO DROUGHT IN SORGHUM
MORPHOLOGICAL &
ANATOMICAL RESPONSES-
1. Deep root system
2. Sunken stomata
3. Epicuticular waxy
bloom
4. Leaf pubescence
5. Leaf angle adjustment
6. Leaf rolling
7. Stay green.
(SOURCE-Badiganavar et al. 2018)sunken stomata

13. ( SOURCE- Assefa et al. 2010 )
RESPONSE TO DROUGHT IN SORGHUM cont..

14. EFFECTS OF DROUGHT ON MAIZE
(SOURCE-Drought stress in maize, springer.)

15. EFFECTS OF DROUGHT ON MAIZE Cont..
• Anthesis silking interval (ASI)
increases
• Pollen viability, Specific gravity,
shape and dispersal affected.
• Pollen sterility (less invertase
activity;IVR2, ABA
accumulation)
• Less growth of pollen tube.
• Silk dehydration; PG
germination affected. Silking
delayed by 6-9 days (Dass et al.
2001)
• Silk elongation is checked.
• Early embryo abortion (settler
et al. 2001)

16. RESPONSE TO DROUGHT ON MAIZE
( SOURCE-Drought stress in maize, springer : pp 21)
5. Larger stem diameter
6. Stay green
7. Deep rooting
1. Shorter plant height
2. Reduced tassel size
3. Smaller leaves above ear.
4. Erect leaves(45-600)

17. EFFECT AND RESPONSE OF DROUGHT ON RED GRAM
(Source-Nadeem et al. 2019)

18. SOURCES OF DROUGHT TOLERANCE
Crop Wild species Reference
Pigeon pea C. albicans ICRISAT
repositories.
Cajanus
lineatus
Khoury et
al.2015
Cajanus
acutifolius
Khoury et
al.2015
Cajanus
sericeus
Khoury et
al.2015
Cajanus
reticulata
Giez et al.
2013
Maize Tripsacum
dactyloides
Nanduri et al.
2003
• Cultivated species
• Land races
• Wild species and wild
relatives.
(SOURCE- http://www.icrisat.org/what-we-
do/crops/PigeonPea/Archives/uwsppi.htm)

19. GENETICS OF DROUGHT TOLERANCE
SORGHUM
Root traits
Polygenic
inheritance
Root lentgh
Root number
Dominant gene
Dominant gene
Root thickness Recessive gene
Leaf rolling Monogenic
inheritance
Stay green
Dominant or
recessive based
on genetic back
ground
Osmotic
adjustment
Monogenic
inheritance
Monogenic
inheritance
Dominant gene
action in some
study based on
environment
(SOURCE-BELETE, 2018)

20. QTL GOVERNING DROUGHT TOLERANCE IN
SORGHUM
Traits Ch. No.
Stomatal conductance 10
Epicuticular wax 10
Stay green 3, 2, 5, 1
Stomatal density 2, 7
CO2 assimilation rate 1, 5, 9
Root dry weight 2, 5, 8
Root lentgh 4
Root to shoot ratio 10
Root volume 1, 4
(Source -Karen et al. 2019)

21. GENETICS OF DROUGHT TOLERANCE IN MAIZE
Monogenic
traits
1.plant height
2.Osmotic adjustment
3.Flowering time
4.Ear development
Polygenic
traits
1.Ear height
2.Grain yield
3.Ear development
(SOURCE-Drought stress in maize springer)
traits Ch. no No of qtl
Sugar
concentratio
n
6 1
Root traits,
biomass
1 3
Grain yield
under
drought
1, 5, 9 3
Leaf ABA 7 1
OP 1, 3, 9, 4
RWC 7 1
Leaf surface
area
3 and 9 9
ASI 1, 2, 5, 6, 8
10
6
DROUGHT TOLERANCE QTL IN MAIZE
(SOURCE-Rahman et al. 2011)

22. CREATION OF DROUGHT ENVIRONMENT
1. GH environment-most
precised.
2. Field environment-if
breeding site less than
100mm rainfall
supplemented irrigation
required.
3. Line source gradient-
 Rows perpendicular to
sprinkler line.
 Irrigation by furrows
 Topographical slope
4. Two different plots
(SOURCE-Plant Breeding principles and methods Singh B.D.)

23. RAIN-OUT SHELTER WITH LYSIMETER FACILITY
LEASYSCAN PHENOTYPING PLATFORM
(SOURCE-https://www.icrisat.org/research-facilities)
• The Rainout Shelter has a
lysimeter facility for
phenotyping.
• Lysimeters are PVC tubes filled
with soil to measure plant water
use.
• Provides soil depth and aerial
spacing similar to field
conditions.
• LeasyScan is a computer based
3D imaging high-throughput
phenotyping platform acquired
in 2014.
• Measures leaf area, dynamics
of leaf development, leaf
conductance etc.
• It can scan 1600 to 2400 plots
per hour.

24. SELECTION INDEX/PHENOTYPING
METHODS
SHOOT PHENOTYPING METHODS
1. Canopy temperature-measured after
solar noon by IR thermometer
2. Stomatal conductance, transpiration
rate and photosynthetic potential
measured by Li-cor 6400 photosynthetic
system
3. Stay green phenotyping
4. Carbon isotope discrimination-(C13/C12
ratio) estimation of water uptake and
transpiration efficiency.
5. Leaf rolling visual scoring (0 to 5)
6. Leaf firing-leaf senescence.
7. Leaf area/photosynthesis
8. Leaf RWC -(FW−DW)/(TW−DW)× 100
9. Proline content
10. Malondialdehyde(MDA) content
11. Osmotic potential measured by
osmometer.
Li-cor 6400 photosynthetic system
IR thermometer

25. ROOT PHENOTYPING METHODS
Minirhizotron
1. Trench method-soil slice with
roots is taken
2. Shovel method-to know
rooting depth 40×25cm depth
around rhizosphere is done.
3. Rhizotron method-software
based camera scanners.
4. Monolith method-
20×30×15cm depth soil is
taken and roots washed with 1
mm sieve.
5. Hydroponics with PEG as
drought stimulant.
(SOURCE-WWW.selectscience.net/)(SOURCE-Darai et al.2016)

26. PHENOTYPING OF MAIZE FOR DROUGHT TOLERANCE
TRAITS THROUGH CONVENTIONAL BREEDING
(SOURCE-Drought stress in maize, springer, PP 48 )

27. DROUGHT PHEONTYPING TRAITS IN PIGEON PEA
1. Stomatal conductance-most stable; can be
measured in optimum moisture.
2. Osmotic potential
3. Relative water content
4. Transpiration rate
5. Proline content
6. MDA content
7. Vegetative biomass/shoot dry weight.
8. Harvest index

28. BREEDING METHODS AND APPROACHES
Adaptation to specific environment
Selection under moisture stress
Adaptation to variable environment
Selection based on yield components under
stress to non stress condition.
Breeding Approaches
Breeding
methods
Conventional breeding
Marker assisted
breeding
Gene pyramiding
Genomics-based
integrated approach
Transgenic approach
(SOURCE-Drought stress in maize, springer, pp 46 )

29. Cross is made at optimal environment
1. Selfing in F1 till F3.
2. F3 individuals grown and harvested separately
3. Optimum moisture is given
1. F4 progeny evaluated under wide range of
environment
2. Selection of progenies with high mean yield
1. Selected progenies grown under optimum moisture
2. Individual plant selection for yield and yield
components.
Preliminary yield trial
Multilocation yield trials under a range of environments.
Seed multiplication and distribution
CONVENTIONAL BREEDING IN WIDE RANGE
ENVIRONMENT

30. CONVENTIONAL BREEDING IN OPTIMUM AND MOISTURE
STRESS ENVIRONMENT
F7 grown on moisture stress PYT is
carried out
Crossing of contrasting parents
Selfing until F3 in under optimum
moisture.
1. Space planting of F4 under
optimum moisture
2. Selection carried out for superior
individuals
1. F5 grown on moisture stress
condition.
2. Phenotyping for drought
traits(epicuticular wax, leaf
senescence etc.)
3. Selection of superior progenies.
1. F6 grown on optimum moisture
2. Selection based on yield and
yield parameters.
F8-F10 multilocation yield trial at
moisture stress
F11 seed multiplication and
distribution.

31. OBJECTIVE –To understand Stg QTLs role on
towards drought adaptation.
STUDY SITE-Southeast Queensland,
Australia.
MATERIAL USED-set of four NILS, with their
RP.
RESULT-stg QTL regulate canopy size
1. Reducing tillering by incresaed
lower leaves size.
2. Reducing upper leaves size.
3. Decreasing no. of leaves per culm.
4. Affect leaf anatomy and leaf growth
5. Reduced pre-flowering water
demand.

32. • Construction of RTx7000 NILs
containing BTx642 DNA from
the stay-green loci by BC
method upto BC4F2.
• 4 set of NILS (stg1,
stg2,stg3,stg4 ) with 2 RP
grown at 2 location in split
plot design.
• Experiment carried out In
lysimeter and pot culture.
• Total and fertile tiller number
per plant were recorded by
planimeter.

33. Less tillers stg1 NIL More tillers in RTX7000
CONCLUSION-
• Stg loci reduce canopy
size at flowering by
modifying tillering, leaf
number, and leaf size.
• It reduces pre-anthesis
water use, which under
post flowering increases
water availability during
grain filling and thus
grain yield.

34. CONVENTIONAL BREEDING FOR
DROUGHT TOLERANCE ???
1. Complex traits
2. expensive phenotyping
3. Scored in whole plant (selection index)
4. Scored under specific target environment
5. Long term process.
6. Quantitative inheritance
7. Low heritability
8. Higher G×E interaction
9. Rely on multi location& multi seasonal yield
stability evaluation.

35. MARKER ASSISTED BREEDING
(SOURCE-http://www.knowledgebank.irri.org)

36. OBJECTIVE-To improve drought tolerance
and grain yield (GY) in a biparental
population.
STUDY SITE-IITA substation,Ikenne
MATERIAL USED-Biparental mapping
population from 2 ellite drought tolerant
line. Test cross population of between S1
individuals of C0, C1 and C2.
MARKER USED-SNP
RESULT-Testcrosses derived from C2
produced Yield under DS at 7% per cycle
under DS and 1% under WW and 3% under
rainfed.
frequency of favourable marker alleles
increased from 0.510 at C0 to 0.515 at C2.

37. CONCLUSION-
MARS can then facilitate
rapid accumulation of such favourable
alleles linked to drought and yield
QTLs in a breeding population.

38. OBJECTIVE-To introgress and evaluate 4
stable stg QTL for drought.
STUDY SITE-ICRISAT, Hyderabad
MATERIAL USED-B35 (donor parent) and R
16 (recurrent parent), six BC1F4 and 3
BC2F3 progenies.
MARKER USED-SNP
RESULT-
• Introgression lines had higher leaf
chlorophyll levels at flowering.
• GLA % was higher during the latter part
of grain filling.

39. CONCLUSION-
Marker assisted back crossing can be highly beneficial for transfer of
stable stgs QTL, andsenescent background has a potential to increase
its drought adaptation.

40. GENOME BASED INTEGRATED APPROACH OF
DROUGHT TOLERANCE
Evaluation of germplasm
Drought associated Trait
discovery
Selection of germplasm with
contrast phenotype
Candidate gene discovery by
gene expression
studies(omics)
Knock out/genetic
transformation to confirm the
gene
MAS Transgenic
Site directed
mutagenesis
(SOURCE- Langridge et al. 2015)

41. OBJECTIVE-To increase genetic gain for
tolerance to drought
MATERIAL USED-
• DH lines
• Testers
TECHNIQUE USED- Genotyping by
selection (GBS) for QTL detection.
Using SNP genotyping.
RESULT-
Prediction accuracy of the model used for
genomic selection
was generally higher than phenotypic
variance explained by the sum of QTL for
individual traits.

42. CONCLUSION-
• Use QTL-MAS in forward breeding to enrich
the allelic frequency for a few desired traits
while GS-MAS could be used in more mature
breeding programs to capture alleles with
smaller additive effects.

43. TRANSGENIC APPROACH OF DROUGHT TOLERANCE
(SOURCE-https://plantcellbiology.com)

44. OBJECTIVE-To increase drought tolerance
in pigeonpea by transferring of vigna
acontifolia gene P5CSF129.
STUDY SITE-Hyderabad
MATERIAL USED-
• Pigeonpea cultivars LRG 30, LRG 41
and ICPL 85063.
• Agrobacterium tumefaciens strain
LBA4404
• Binary vector pCAMBIA1301
RESULT-
Transgenic plants showed
more proline accumulation than their non-
transformed plants.
Had lower levels of lipid peroxidation.
High relative water content and chlorophyll
content.

45. CONCLUSION-Expression of P5CSF129A
transgene in the primary generation and
its inheritance resulted in over
production and accumulation of proline
in transgenics that results in higher
drought tolerance.
a) Multiple shoot initiation
b) GUS expression in embryonic structure.
c) Shoot elongation
d) Rooting of plantlet
e) GUS assay in shoot.
f) Primary transformants at flowering stage
g) PCR analysis.

46. MAIZE
• Droughtgard hybrids of Monsanto released in 2013, 1st drought
tolerant transgenic contain cold shock protein B.
• 24% increase in growth rate under drought conditions
• Act as RNA chaperones, which binds unfolding tangled RNA
molecules during drought stress.
• MON87460, a drought-tolerant maize hybrid of Monsanto has
cold-shock protein gene (cspB) obtained from Bacillus subtilis.
• Pioneer Hi-Bred and Syngenta are also working on transgenic
drought-tolerant maize development.
• Pioneer Aquamax P1151 also a drought tolerant variety.
PIGEONPEA
• Expression of the Vigna aconitifolia P5CSF129A gene in
transgenic pigeonpea enhances drought tolerance by proline
accumulation.
SOME TRANSGENIC VARIETIES

47. PROMISING DROUGHT TOLERANT VARIETES
MAIZE
• VARUN- A drought tolerant variety with 90 to 105 duration
released from Maize Research station, Rajendranagar,
Hyderabad.
SORGHUM
• CSH 31- A drought tolerant rabi sorghum
• CSV 26 R – A terminal drought tolerant cultivar.
PIGEON PEA
• ICPL 14003 (PRG 176) terminal drought drought resistant
variety. from (RARS), Palem under the name Ujwala.
Developed by pedigree selection (ICPL 88034 x ICPL 88039 ).
yield potential of 2.5 tons per ha and matures in 130 days.
(Nagesh kumar et al. 2017)
• LRG 30, LRG41, ICPL 85063, ICPL 4575 and ICPL 332 due to
RWC, pods/plant and HI Stress yield.

48. BEST BREEDING APPROACH FOR DROUGHT TOLERANCE
• Integrated genome based breeding approach with
high throughput phenotyping is best method of
drought breeding under heavy funding.
• Under minimum resources marker assisted breeding
can be useful.
• With rapid changing climate only conventional
breeding has less success rate with only
morphological selection.

49. FUTURE STRATEGIES OF DROUGHT TOLERANCE
• Exploration of plant genetic resources,
characterization and introgression.
• Gene pyramiding as governed by complex trait.
• Search for drought related transgenes and
development of transgenic
• Deep understanding of biochemical pathways
governing drought.
• Identification of protein marker by assessing stress
proteins(LEA, dehydrin etc.)
• Multidisciplinary approaches.

50. OBJECTIVE-To understand the
molecular mechanism of
drought tolerance in
pigeonpea.
STUDY SITE-ICRISAT, Hyderabad
MATERIAL USED-
Three pigeonpea genotypes
(ICPL151, ICPL8755 ICPL227)
TECHNIQUE-qRT-PCR gene
expression.
RESULT-
• Two times more expression of 6, 8 and 18 number of
genes in ICPL151, ICPL8755 ICPL227.
• Total 2 times more regulation of 10 differentially
expressed genes in more drought tolerant cultivar.(ubp,
uspA, antiporter protein, uncharacterized protein).
• (LDT) genotypes, ICPL 151 and ICPL 8755 clustered
separately from the (MDT) genotype, ICPL 227.
• GenesC.cajan_29830andC.cajan_33874 found to be
candidate gene based on expression profile.

51. Expression analysis of drought identified genes C.cajan_29830 and C.cajan_33874 in the
root tissues of tolerant and susceptible genotypes of the four legumes.

52. 51 differentially expressed candidate genes in
drought condition; Green-suppressed genes.
Red-Induced genes.
CONCLUSION-Identification of drought
tolerant candidate genes boost crop
improvement exclusively.

53. DIFFICULTIES IN DROUGHT RESISTANCE BREEDING
• Clear definition of target environment (moisture
regime changes with time and location.)
• Creation of controlled moisture stress.(GH and field
result varies.
• Selection for varying character unlike pest.
• Drought traits scoring difficult.
• Drought traits may –ve correlated with yield
(earliness, stomatal sensitivity)
• Devise an elaborate breeding scheme for selection
in optimum and stress condition.

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