Breeding strategies for drought tolerance in wheat


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Breeding Strategies for Drought Tolerance in Wheat 1 Navdeep Singh Jamwal A-2011-40-005 Department of Crop Improvement 1


CONTENTS Introduction Drought stress What is stress Drought mechanism Different Factors Breeding strategies Approaches Methods of breeding Case studies Summary 2


INTRODUCTION Wheat Scenario (2011) AREA 284.6 lakh ha PRODUCTION 807.1 lakh ton PRODUCTIVITY 28.3 qtl /ha AREA 3.52 lakh ha PRODUCTION 5.68 lakh ton PRODUCTIVITY 18.8 qtl /ha INDIA HIMACHAL PRADESH 3 India ranks first in area and second in production after china Wheat is cultivated on 10.4 lakh ha in N-W Himalayas


Introduction Wheat ( Triticum aestivum L.) production is adversely affected by drought in 50% of the area under production in the developing countries ( Trethowan and Pfeiffer 2000) Drought tolerance is a quantitative trait, with complex phenotype and genetic control (Mc William, 1989) Low heritability, high genotype X environment interaction Variation and unpredictability of environmental conditions have hindered breeders efforts to select for drought tolerance. 4

Scenario of Drought in India:

Scenario of Drought in India Total arable area 143.8 mha Irrigated area 43.8 mha ( 30.5% ) Rainfed area 65.5 mha ( 45.5% ) Dryland area 34.5 mha ( 23.9% ) In North-West Himalayan regions 81% is under rainfed 5


Stress Stress is an external factor that exerts a disadvantageous influence on the plant and is measured in relation to plant survival, crop yield, growth (biomass accumulation), which are related to overall growth. Taiz and Zeiger (2006) 6

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26 % Blum (1988) and Dudal (1976) 7 Blum (1988)

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Drought :

Drought The inadequacy of water availability, including precipitation and soil moisture storage capacity, in quantity and distribution during life cycle of crop to restrict expression of its full genetic potential. ( Sinha , 1986) “Drought stress accounts for more production losses than all other factors combined” John Cushman, Biochemistry Professor at the University of Nevada, Reno 9


MAJOR REASONs OF DROUGHT Atmospheric factors -sudden & beyond control Soil Factors - slow & steady controlled by agronomic means 10

Different types of drought:

Different types of drought Meteorological drought Agricultural drought Hydrological drought 11 Physiological drought

Categorization of plants on the basis of drought:

Categorization of plants on the basis of drought Drought-escaping plants Germination and growth in moisture Seeds persist during times of drought Annuals- Arabidopsis thaliana Drought-evading plants Growth restricted in moisture stress Drought- deciduous shrubs Brittle bush ( Encelia farinosa ) Drought - enduring plants Maintain growth in water stress Extensive root systems Morphological and physiological adaptations Evergreen shrubs i.e. Creosote bush Drought - resisting plants Water stored in swollen leaves and stems succulent perennials Barrel Cactus 12

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How plants cope with drought stress Different survival mechanisms of plants at dry sites: 1) Drought escape 2) Dehydration avoidance 3) Dehydration tolerance Levitt, 1980 13

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Drought escape Ability of plant to complete its life cycle before on set of severe water deficit Rapid development of plant Early maturing varieties – Terminal drought stress Late maturing varieties – Early season drought stress Early or Late maturation of a crop variety has an adverse effect on its economic yield 14

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Drought (dehydration) avoidance Maintain realtively high water potential as long as possible under water stress. Two groups of drought avoiders: Water savers -Reduce water loss -Leaf characteristics -Stomatal senstivity -Cuticular wax ii ) Water spenders -Increase water uptake -Root characteristics Anatomical and morphological traits help the plant to avoid drought. 15

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Drought (dehydration) tolerance Ability to tolerate the water stress by the biochemical and physiological changes Capacity of protoplasm to tolerate severe water loss Physiological processes proceed even at high dehydration levels Tolerance mechanisms take over when tissues are no longer protected by avoidance mechanisms Drought tolerance usually found in xerophytes Tolerance aims at plant survival rather than plant growth 16


Morphological Physiological Biochemical ADAPTATIONS OF PLANT FOR DROUGHT STRESS 17


18 MORPHOLOGICAL ADAPATIONS Earliness :- Early maturing varieties are ready for harvest before the onset of drought Stomatal characters : -Various stomatal 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

Physiological factors:



20 BIOCHEMICAL FACTORS ABA Abscisic Acid content ABAR genes PROLINE CONTENT gene P5CS GLYCINE BETAINE CONTENT Gene bet A- choline dehydrogenase Gene bet B- betaine aldehyde dehydrogenase

ABA (Abscisic acid):

ABA ( Abscisic acid) ABA, a plant stress hormone Role Signal transduction of stress Induces the closure of leaf stomata thereby reducing water loss through transpiration and decreasing the rate of photosynthesis Promotion of root growth and increase root hydraulic conductivity These responses improve the water use efficiency of the plant on the short term 21

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Proline is the most widely distributed osmolyte ; it occurs in plant and in many other organisms. Its accumulation correlates with tolerance to drought stress Role Osmotic adjustment Membranes protection Reservoir of nitrogen and carbon source for post stress growth Regulate redox potentials Proline 22

Glycine Betaine:

Glycine Betaine Glycine betaine is a quaternary ammonium compound that functions as an osmoprotectant . Role Stabilizing complex protein structure Protecting transcriptional machinery Maintain integrity of membrane Maintenance of the water balance between the plant cell and the environment. 23

Fundamentals of Breeding:

Fundamentals of Breeding Genetic variation Source of the desired trait Transfer of trait Methods and approaches of breeding 24

Genetic sources :

Genetic sources Cultivated varieties Adapted variety No compromise on yield Breeding material Transfer of trait is easy and with minimum linkage drag Landraces problem of undesirable linkages Subjected to artificial and natural selection Wild relatives Aim is to survive not the yield Transfer of trait is major problem Transgenes Cloning of target gene Transfer requires technical expertise Aegilops Squarrosa Imperata cylindrica 25

Breeding approach:

Breeding approach FOUR APPROACHES Breeding for high yield under optimum condition No intentional selection for drought tolerance Breeding for other characters indirectly effect drought Screening for drought is done Lines perform well in optimal condition show decline in yield under drought Breeding for High yield under Stress condition Choice of Parents Selection under the stress environment Drought varies from year and location Breeding for High yield under both stress and non-stress environment Simultaneous selection Use of conventional method Multi disciplinary approach Integrate drought tolerant mechanisms Use of genomic tools 26

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27 27 Breeding methods for drought tolerance


CONVENTIONAL METHODS INTRODUCTION Primary Secondary SELECTION Desirable Adaptation HYBRIDIZATION LINE A High yielding LINE B Drought resistant F 1 Conventional breeding focus on drought avoidance than drought tolerance (Blum, 2005) 28


29 NON-CONVENTIONAL METHODS BIOTECHNOLOGY GENETIC ENGINEERING Agrobacterium mediated gene transfer Particle Bombardment (Gene Gun) Electroporation of protoplast MAS QTL Molecular Cytogenetics

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Roadmap for identification of drought TOLERANCE gene 30

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F 2 P 2 F 1 P 1 x large populations consisting of thousands of plants Drought Resistant Drought Susceptible MARKER-ASSISTED SELECTION (MAS) MARKER-ASSISTED BREEDING 31

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32 QTLs identified Seven root traits Average root diameter (AVD) Number of root crossings (CRS) Number of root forks (FRK) Number of root tips (TIP) Root volume (RV) Surface root area (SRA) Total root length (TRL) 32

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Dharwar dry drought tolerant Sitta drought suceptible 127 RILs XBE637912, Xwmc89, and Xwmc420 SSR marker linked to Grain Yield QTL 33

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Yield QTL at 4AL 34

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Braley HVA1 gene is introduced in bread wheat Agrobacterium -mediated genetic transformation 35

Work done at CSKHPKV:

Work done at CSKHPKV Rye is an ultimate source of drought tolerance 1RS translocations Himalayan rye source 1RS Kishore , N., Chaudhary , H.K ., Chahota , R.K., Kumar, V., Sood , S.P. and Jeberson , S. and Tayeng,T . 2011. Relative efficiency of maize- and Imperata cylindrica -mediated chromosome elimination approaches for the induction of haploids in wheat-rye derivatives. Plant Breeding 130:192-194 36

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37 Hexaploid wheat Rye F1 BC1 Hexaploid wheat Imperata cylindrica Homozygous wheat Lines with rye introgressions Tricitale Wheat F1/F2/BC1 Imperata cylindrica Homozygous Lines With rye introgressions Recombinant Wheat with Rye Introgressions Chaudhary H.K ., Sethi G.S., Singh S., Pratap A. and Sharma S. 2005. Efficient haploid induction in wheat by using pollen of Imperata cylindrica. Plant Breeding 124(1): 96-98.

Isolation of the drought tolerant & susceptible lines on overall basis of in vitro & in vivo evaluation at the physiological and biochemical level:

Highly tolerant Highly susceptible DH 100 DH 5 DH 106 DH 52 DH 114 DH150 DH 40 DH144 DH 65 DH89 C 306 VL 829 KWS 29 (Dixit and Chaudhary , 2009) Isolation of the drought tolerant & susceptible lines on overall basis of in vitro & in vivo evaluation at the physiological and biochemical level 38 Physiologica l Traits studied Germination percentage Root length Shoot length Coleoptile length Dry matter accumulation Biochemical traits Soluble Sugars Starch Proteins Free amino acids Proline Invertase Amylase content

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Summary Wheat is the second most important cereal crop of the India Drought stress is polygenic in nature for which breeding require much effort Only conventional breeding is not sufficient in development of drought tolerant wheat variety Non conventional approaches i.e. Molecular breeding can play a significant role in the sphere of abiotic stress mainly drought tolerance Genomic regions carrying drought tolerant gene can contribute for abiotic stress tolerance 39

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Identification of major QTLs linked to different abiotic stresses and their pyramiding with minor effects QTLs elite lines Molecular genetic dissection of the genomic regions to understand the physiological mechanism Marker assisted selection and Molecular cytogenetic techniques for efficient screening Transgenic with stress protein/TF gene over- expression The way to go … 40

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Thank you… Cereal production in the rain-fed areas still remains relatively unaffected by the impact of the green revolution, but significant change and progress are now becoming evident in several countries Norman Borlaug 41

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