Breeding for Drought tolerance in Pearl Millet
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Breeding for Drought tolerance in Pearl Millet

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Breeding for Drought Tolerance in pearl millet

Breeding for Drought Tolerance in pearl millet

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Breeding for Drought tolerance in Pearl Millet Breeding for Drought tolerance in Pearl Millet Presentation Transcript

  • //o Name of speaker : Patel Satishkumar Reg. no. : 04-1313-2010 Major advisor : Dr. J.A. Patel Date : 14/03/2012 Time : 1600 hrs
  •  Introduction  Mechanism of Drought Tolerance  Screening Methods  Case studies on Drought Tolerance Physiological Variability and Correlation Biochemical  Biotechnological Studies  Breeding approaches  Achievements  Limitations  Conclusion  Future thrust 2
  • INTRODUCTION Botanical Name: Synonyms: Pennisetum glaucum (L.) R. Br. Pennisetum typhoides (Burm. F.) Stapf. and Hubbard Pennisetum typhoideum Rich., Pennisetum americanum L. Leeke Common Names:- Bajra, Bulrush millet, Spiked millet, Cat tail millet Family: - Poeaceae Sub family: Panicoideae Tribe: Paniceae Origin :- Sahel zone of West Africa Chromosome No.: 2n=14 Uses:- Feed: Fodder, Fuel, Fencing,  Cross pollinated Crop Spices due to its protogynous flowering nature  Annual C4 crop species.  Stable diet for the vast majority of poor farmers 3
  • Table:-1 Area, Production And Productivity (2010-11) Area (million hectare) Production (million tonns) Productivity (kg /hectare) India 8.75 8.89 1015 Gujarat 0.92 1.31 1365 Source: Directorate of Economics and Statistics, Department of Agriculture and Cooperation. 4
  • State wise Bajra production (2010-11) Rajasthan 31% Uttar Pradesh 22% Haryana 14% Gujarat 13% MH 12% MP 4% Karnataka 2% Tamil Nadu 1% Andhra Pradesh 1% State Production (Million Tonnes) Productivity (kg/ha) Rajasthan 2.03 394 Uttar Pradesh 1.39 1638 Haryana 0.93 1593 Gujarat 0.92 1365 Maharashtra 0.77 741 Madhya Pradesh 0.25 1495 Karnataka 0.15 502 Tamil Nadu 0.08 1513 Andhra Pradesh 0.05 1178 Source: Directorate of Economics and Statistics, Department of Agriculture and Cooperation. 5
  • Drought  Drought is event which implies the absence of a period of time, long enough to cause moisture-depletion in soil and water deficit with decrease of water potential in plant tissues.  Drought is highly heterogenous in time, space, degree of stress, growth stage and time of stress exposure, and it is unpredictable. 6
  • Types of Drought • Meteorological Drought:- It is related to deficiencies in rainfall compared to the average mean seasonal rainfall in an area. • Agricultural Drought:- Deficit rainfall over cropped areas during their growth cycle can destroy crop or lead to poor crop yields. • Hydrological Drought:- It is a deficiency in surface and sub-surface water supply. It is measured as stream flows and also as lake, reservoir and groundwater levels. 7
  • Drought affected area in the world The major bajra growing countries are Senegal, Mali, Niger, Nigeria, Sudan and India. 1.3 Billions people are under drought-prone areas (India/Africa) 8
  • Source: www.milletindia.org Source : http://www.mapsofindia.com Major Bajra Growing Regions of India Severely Affected Moderately Affected States affected by Drought Bajra is a major cereals in northwestern zone as it represents approximately 25 % of the total acreage of the crop in the country. The chronically drought-prone areas around 33 % -receive less than 750 mm of rainfall, while 35 % classified as “drought-prone ” receive rainfall of 750-1,125 mm (in India). 9
  • 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 all stresses. Drought resistance is a genetically controlled physiological property of plant species. Breeding for drought tolerance is a major objective in arid and semiarid regions of the world due to inadequate precipitation, shortage of irrigation water and high water demand for crop evapotranspiration in such climates Main features of drought 10
  • • Drought resistance : Ability of a plant to live, grow and yield satisfactorily with limited water supply or under periodic water deficits. • Drought escape : Ability of plant to mature before water stress becomes a serious limiting factor. • Drought avoidance: Ability of a plant to withstand water deficit as measured by degree and duration of low plant water potential. water savers-closing of stomata water spenders- extract more water from soil • Drought tolerance: Ability of a plant to recover from a dry period by producing new leaves from buds, and those were able to survive the dry spell. Gupta et al., 1986 11
  • Symptoms of Drought • Reduced leaf area • Early senescence of older leaves • Effect on flowering, largely delay in flowering (Cause abscission of flowers.) Injury Mechanism • Water stress directly affects cellular processes, membrane structures and structure of macromolecules. • Cause severe embolism formation in the xylem vessels. 12
  • Morphological traits Physiological factors Higher rate of photosynthesis Lower rate of transpiration Higher leaf turgidity Higher osmotic concentration Earliness Stomatal characters :- Shrunken type, small size, less number per unit area, rapid closing nature Leaf character:- Waxy leaves, small thick leaves, hairiness Root characters:- Root length, root density, R/S ratio Growth habit:- Indeterminate Biochemical factors Proline content ABA content in Leaf 13
  • Drought avoiding plant must maintain High water potential Thick and highly impermeable cuticle Closure of stomata More waxier leaves Higher root -shoot ratio 14
  • Measurement of drought tolerance 1. Change in growth patterns 2. Change in seed production 3. Electrolyte leakage from leaf segments 4. Leaf wilting 5. Relative leaf water content 6. Change in the transcriptome Traits investigated in pearl millet References Grain and stover yield and quality Ibrahim et al. (1985), Kumari S (1988). Bidinger et al. (1987, 2007), Singh and Singh (1995), van Oosterom et al (1996), Nepolean et al. (2006), Yadav et al. (I999a,b, 2002, 2003. 2004) Serraj et al. (2005) ABA accumulation Henson et al. (1981). Henson (1983). Henson et al. (1983). Henson(1984) Water potential Henson (1982) Osmotic potential Henson (1982) Osmolytes Patil et al. (2005), Kholova et al. (2008) Antioxidative enzymes Patil et al. (2005), Kholova et al. (2008) Photosynthetic pigments Ibrahim et al. (1985), Ashraf et al. (2001) Transpiration related traits Ibrahim et al. (1985), Squire (1979), Black and Squire (1979), Henson et al. (1981), Henson (1984), Kholova et al. (2008, 2010 a, b.c) Canopy temperature Singh and Kanemasu (1983) 15
  • Drought Tolerance Physiolo gical processes Expression Profiling Reverse Genetics Allele Mining for natural Variation MAS/Tran sformation Map Based Cloning Forward Cloning Forward Genetics Comparative mapping Fig. 1 Drought tolerance improvement tools and processes 16
  • Screening Criteria 17
  • Screening Criteria The selection criteria primarily based on morphological characters could be selection of parents as well as desirable segregants followed by hybridization. During selection, characters have high heritabilities and high correlation with yield under stress across the environments. Grain yield under stress conditions is usually the primary traits for selection. A suitable secondary traits should have (Edmeades et al. 2001). 1) Genetically association with grain yield under drought, 2) High heritability, 3) Stable and feasible to measure, 4) Lack of association with yield loss under ideal growing conditions. 18
  • Screening methods for Drought tolerance in Pearl millet 19
  • Laboratory method  In Laboratory method to identify genotypic difference in germinability, osmotic solutions like polyethylene glycol (PEG) is used.  The osmotic effect of drought are known to be comparable to true drought effects Field method:  The field is uniformly irrigated with overhead system using perforated pipes.  Also used sprinkler method.  The percentage of seedling that emerge is computed. Tested Material Tested Material Line source irrigation method Increasewaterstress Water Source/chennel 20
  • Case Studies 21
  • Table 2 :-Effect of osmotic stress on seedling traits of pearl millet genotype during drought induced by PEG in Vitro condition. ICRISAT (A. P.) Govindaraj et al. (2010) 22
  • Genotype Germination % Root length (cm) Seedling height (cm) Dry mass of seedling (g) Vigor index Normal Stress Normal Stress Normal Stress Normal Stress Normal Stress X7 99.5 98.0 10.89 6.53 17.90 10.71 0.058 0.074 1781.3 1049.6 X6 97.0 96.0 10.23 6.17 17.48 10.65 0.070 0.080 1695.6 1022.4 Co7 98.3 95.5 9.28 5.58 16.17 9.03 0.073 0.094 1589.5 862.4 WC-C75 99.8 98.3 11.18 4.64 18.43 7.75 0.093 0.101 1839.3 761.8 CD (P<0.05 %) T 0.636** 0.650** 0.755** 0.0065** 72.133** V 0.900** 0.919 (NS) 1.068** 0.0092* 102.002 (NS) T X V 1.272 (NS) 1.300* 1.510** 0.0131 (NS) 144.268 (NS) Table 3 :- Germination and physiological parameters under normal (N) and induced stress (PEG) (S) treatments (T) in pearl millet cultivars (V) Vijayalakhsmi et al. (2000) Coimbatore (T.N.) 23
  • Treatment Plant height (cm) Plants/m Tillers/m Effective tillers/m Length of ear (cm) Weight of ear (g) 1000 Grain weight (g) Average Yield (kg/ha) Percent Reduction T1, control 154 5.0 15.9 8.1 24.2 30.4 9.45 2101 - T2, Rain out during crop establishment 149 4.8 17.5 6.2 22.2 28.8 9.27 1852 11.80 T3, Rainout during tillering stage 144 4.8 11.8 5.8 20.4 26.3 8.89 1629 22.50 T4, Rainout during earing and flowering stage 139 5.2 11.6 6.3 21.2 27.8 8.67 1707 18.80 T5, Rainout during grain-filling and maturity stage 152 4.7 16.2 5.8 20.5 28.2 7.75 1970 6.20 CD (P < 0.05 %) NS NS 2.23 0.30 0.78 NS 0.25 - - Table 4:-Average growth and yield attributes of pearl millet as affected by different treatments Agra (U.P.) Prakash et al. (2008) 24
  • WW (36 %) MS(21 %) SS (9 %) Ethiopia Yalew and Yemane (2011) WW (36 %) MS(21 %) SS (9 %) Fig. 2 Response of pearl millet cultivars (Dadda and Shella ) to post-flowering drought stress. WW= Well Water MS= Moderately Stress SW= Severely Stress WW (36 %) MS(21 %) SS (9 %) 25
  • Yalew and Yemane (2011)Ethiopia Fig.3 Potential quantum yield of two cultivars of Pearl millet subjected to three soil moisture levels. WW= Well Water (36 %) MS= Moderately Stress ( 21 %) SW= Severely Stress ( 9 %) Dadda Shella 26
  • Table 5:- Grain yield and physiological parameters as influenced by terminal moisture stress in B-line and inbreds Pearl millet lines Days to flower Grain yield (kg/ha) Harvest index Threshing Relative Water content (%) Drought susceptibility Index 81B 70.8 136.1 4.7 22.0 74.9 1.196 + 0.06 218B 65.7 234.4 8.7 28.4 63.4 1.259 + 0.12 89111B 59.3 263.3 11.2 26.0 77.4 1.104 + 0.12 95444B 58.7 628.9 22.4 47.7 74.2 0.812 + 0.06 J-108 57.8 648.9 18.2 40.0 72.0 0.846 + 0.10 J-998 62.8 353.3 9.3 29.7 69.0 1.057 + 0.04 J-2290 68.0 375.0 8.2 31.7 75.7 1.099 + 0.09 J-2296 59.2 376.7 15.4 37.7 75.0 0.880 + 0.08 J-2340 58.8 806.7 18.1 44.4 77.8 0.761 + 0.18 LSD (P=0.05) 4.7 304.2 5.2 13.5 6.5 - CV % 3.9 39.7 36.4 19.0 7.1 - Joshi et al. (2005)Jamnagar (Gujarat) 27
  • Table 6:- Physiological parameters in pearl millet hybrids as influenced by high temperature and receding soil moisture at seedling stage Entries/ Hybrids Root Dry mass (mg/plant) Shoot dry mass (mg/plant) Total Dry Mass (mg/plant) Root /shoot ratio (dry wt. basis) Survival (%) at 19-22 DALI* Leaf elongatio n Rate (cm/day) index at 15 DALI* Chlorophyll Stability GHB-558 26.3 30.9 57.1 0.9 44.9 0.35 0.111 + 0.016 GHB-559 29.5 26.4 55.7 1.2 68.4 0.48 0.079 + 0.007 GHB-316 26.9 25.9 52.8 1.1 61.3 0.47 0.096 + 0.019 GHB-526 38.7 37.4 76.1 1.1 76.4 0.59 0.053 + 0.016 GHB-538 32.8 34.9 67.8 1.0 72.9 0.55 0.058 + 0.014 LSD (P=0.05) NS 5.3 NS NS 16.4 0.09 - CV (%) 10.5 15.1 10.8 17.9 9.1 17.3 - * DALI – Days after last Irrigation, NS- Non significant Joshi et al. (2005)Jamnagar (Gujarat) 28
  • 29
  • Character GCV % PCV % h2 (B.S.) % Genetic Advance GA % of Mean E % 12.83 13.52 90.1 20.783 25.09 FSL 12.21 12.85 90.3 2.806 23.89 FRL 12.57 13.65 98.7 4.987 25.73 FSW 16.32 16.60 96.6 0.02 33.05 FRW 21.36 21.91 95.0 0.015 42.87 DSW 22.48 23.14 94.4 0.002 44.99 DRW 24.99 25.32 97.4 0.002 50.79 R/S 22.87 24.03 90.6 0.203 44.83 Table 7:- Estimates on GCV, PCV, heritability in broad sense(h2 B.S.), Genetic advance as percentage of mean (GA %) of seedling traits in 63 pearl millet genotypes Coimbatore (T.N.) Arulselvi and Selvi (2009) E %=Emergence %, EI= Emergence index, ERI= Emergence rate, FSL=Fresh Shoot Length, FRL= Fresh Root Length, FSW=Fresh Shoot Weight, FSL= Fresh Root Weight, DSW= Dry Shoot Weight, DRW= Dry Root Weight. 30
  • Table 8:-Character contribution towards genetic divergence Sr. No. Character Contribution (%) 1 Emergence % 4.86 2 Fresh Shoot Length 2.66 3 Fresh Root Length 39.63 4 Fresh Shoot Weight 26.73 5 Fresh Root Weight 2.05 6 Dry Shoot Weight 7.32 7 Dry Root Weight 16.28 8 Root/Shoot 0.36 Coimbatore (T.N.) Arulselvi and Selvi (2009) 31
  • Source df E % EI ERI FSL FRL FSW FRW DSW DRW R/S Replications 1 6.2222 0.002 0.000007 0.0287 0.0229 0.00001 0.000059 0.000002 0.000001 0.0178 Genotypes 62 238.3574** 0.0069 0.000027 4.3309** 11.9518** 0.000201** 0.000107** 0.000002** 0.000001** 0.0226** Error 62 12.4158 0.0035 0.000014 0.2211 0.0778 0.000003 0.000003 0.0000001 0.0000001 0.0011 SE 2.4717 0.0414 0.0027 0.3298 0.1956 0.0013 0.0012 0.0002 0.0001 0.0234 CD @ 5% 4.9409 0.0828 0.0053 0.6593 0.3911 0.0026 0.0023 0.0004 0.0001 0.0468 Mean 82.8254 1.0956 0.0139 11.7437 19.3833 0.0609 0.0338 0.0047 0.0021 0.4528 Table 9:- Mean Square from analysis of variance for seedling traits conferring drought tolerance in pearl millet genotypes. ** Significant at 0.01 probability level Coimbatore (T.N.) Arulselvi and Selvi (2009) E %=Emergence %, EI= Emergence index, ERI= Emergence rate, FSL=Fresh Shoot Length, FRL= Fresh Root Length, FSW=Fresh Shoot Weight, FSL= Fresh Root Weight, DSW= Dry Shoot Weight, DRW= Dry Root Weight. 32
  • Traits FSL FRL FSW FRW DSW DRW R/S E % 0.2782 0.4332** 0.4555** 0.5009** 0.4479** 0.3204** -0.0508 FSL 0.4688** 0.7518** 0.5672** 0.5909** 0.5542** 0.0606 FRL 0.5536** 0.4769** 0.5793** 0.5411** 0.0506 FSW 0.7682** 0.8105** 0.6978** -0.0060 FRW 0.5633** 0.8800** 0.4457** DSW 0.5176** -0.3404** DRW 0.6158** Table 10:- Simple Correlation coefficients Between seedling traits (conferring Drought Tolerance ) among 63 pearl millet genotypes. Arulselvi and Selvi (2009)Coimbatore (T.N.) ** Significant at 0.01 probability level E %=Emergence %, EI= Emergence index, ERI= Emergence rate, FSL=Fresh Shoot Length, FRL= Fresh Root Length, FSW=Fresh Shoot Weight, FSL= Fresh Root Weight, DSW= Dry ShootWeight, DRW= Dry Root Weight. 33
  • Table 11:-Means and F ratios of genotypes for growth and yield components measured in the irrigated control (c) and drought stress (s) treatments. Characters 1988 (34 Genotypes) 1989 (34 Genotypes) 1990 (32 Genotype) Treatment Means F ratio Means F ratio Means F ratio Time to flowering (days) Control 64 5.80** 66 5.92** 67 11.90** Stress 62 5.40** 65 5.99** 68 15.60** Biomass (g m-2) Control 621 3.02** 858 1.79** 662 2.49** Stress 437 2.49** 585 3.28** 598 2.76** Stover (g m-2) Control 398 3.29** 482 1.91** 431 6.50** Stress 300 4.38** 359 4.57** 423 3.91** Panicle (g m-2) Control 223 2.54** 378 1.77** 230 0.97 Stress 137 2.05** 228 2.19** 175 1.41 Grain yield (g m-2) Control 156 2.30** 271 1.66** 158 1.07 Stress 83 2.48** 140 2.64** 121 0.78 Panicle No. m m-2 Control 9.8 1.58* 11.5 3.61** 10.3 1.50* Stress 8.2 1.47 10.0 2.33** 8.4 1.51* Panicle yield (g) Control 16.2 4.02** 23.7 3.81** 15.0 2.46** Stress 9.8 3.00** 13.7 3.23** 14.2 0.72 No. Grains panicle-1 Control 2440 4.47** 3090 3.75** 2260 1.96** Stress 1840 1.90** 2300 3.16** 2330 0.72 Grain mass (g 100-1) Control 0.67 10.39** 0.77 3.96** 0.66 5.90** Stress 0.53 7.30** 0.53 2.86** 0.61 2.55** No. Grains m-2 (*103) Control 2.306 3.34** 35.3 1.93** 23.5 1.16 Stress 15.4 1.88** 23.3 2.43** 19.6 0.81 Harvest index Control 25.4 4.04** 32.0 3.20** 23.0 2.01** Stress 18.6 4.38** 24.0 3.81** 20.0 0.65 Threshing Percentage Control 70 3.61** 71 1.90** 67 2.30** Stress 58 3.44** 60 3.76** 69 0.61 Sadore Peter (1992) 34
  • Characters Correlation Coefficients Flowering DRI 1988 1989 1990 1988 1989 1990 Time to flowering (days) --- ----- --- -0.07 0.07 -0.02 Biomass (G m-2) 0.53** 0.47** 0.56** 0.56** 0.59** 0.20 Stover (G m-2) 0.76** 0.63** 0.77** 0.26. 0.37** 0.06 Panicle (G m-2) -0.31 -0.21 -0.35* 0.73** 0.74** 0.31 Grain yield (G m-2) -0.46** -0.35* -0.28 0.69** 0.71** 083** Panicle No. M-2 -0.55** -0.47** -066** 050** 0.11 0.10 Panicle yield (g) -0.29 -0.16 0.06 0.62** 0.78** 0.88** No. Grains per panicle 0.13 0.22 0.04 0.55** 0.63** 0.92** Grain mass (G) -0.47** -0.57** 0.04 0.28 0.36* -0.01 No. Grains m-2 (x103) -0.22 -0.08 -0.28 0.65** 0.62** 0.85** Harvest index -0.74** -069** -044* 0.44* 0.25 0.82** Threshing % -0.60** -057** -0.09 0.48** 0.44* 0.44* 0.91** Table 12 :- Correlations of yield parameters in the drought stress treatment to time to flowering under drought stress and Drought Response Index. ** P<0.01 * P<0.05 Peter (1992)Sadore 35
  • Character Days to 50 per cent Flowering Days to Maturity Ear head length (cm) Ear head girth (cm) No. of produc- tive tillers per plant Ear head weight per plant (g) Total biomass accumulati on per plant (g) Grain yield per plant (g) Harvest index Panicle harvest index Test weight (g) Root length per plant (cm0 Proline content (µ g g-1 f. w.) Drought response index (DRI) Days to 50 % Flowering 1.00 Days to Maturity 0.14** 1.00 Ear head length -0.22** -0.07 1.00 Ear head Girth -0.06 0.07 0.07 1.00 No of Productive tillers per plant -0.06 0.04 0.03 -0.18** 1.00 Ear head weight per plant -0.08 -0.08 -0.01 -0.16** 0.13* 1.00 Total biomass accumulation per plant -0.05 -0.08 -0.10 -0.06 0.20** 0.24** 1.00 Grain Yield per plant -0.06 -0.12 0.13* -0.20** 0.44** 0.48** 0.19** 1.00 Harvest index -0.18** -0.15** 0.27** -0.08 0.22** 0.11 -0.26** 0.65** 1.00 Panicle harvest index -0.14** -0.08 0.16** -0.08 0.39** -0.21** 0.03 0.74** 0.66** 1.00 Test weight -0.14** -0.15** 0.14** -0.12 0.23** 0.13* 0.09 0.59** 0.42** 0.55** 1.00 Root length per plant -0.00 0.03 0.17** 0.11 0.21** 0.04 0.09 0.35** 0.26** 0.36** 0.33** 1.00 Proline Content 0.04 -0.00 0.04 -0.09 0.36** 0.10 0.13* 0.49** 0.31** 0.45** 0.50** 0.37** 1.00 Drought response index -0.01 0.00 -0.11 -0.30** 0.35** 0.53** 0.01 0.74** 0.28** 0.41** 0.30** 0.17** 0.35** 1.00 Table 13:-Phenotypic correlation coefficient for different characters under terminal drought condition in pearl millet. *, ** Significant at 5 and 1 percent level of probability, respectively AAU (Anand) Patil and Jadeja (2005) 36
  • Transpiration Rate 37
  • Fig 4:-Water Conserving mechanisms with the terminal drought tolerance of pearl millet Kholova et al. ( 2010)ICRISAT (A.P.) Drought Tolerant PRTL 2/89-33 863B-P2 Drought Sensitive H 77/833-2 ICMB-841-P3 38
  • ABA content in Leaf 39
  • Fig. 5:- ABA content in pearl millet test cross hybrids (Drought Tolerant Drought Sensitive) in well-water (WW) and water stress (WS) condition Vegetative Stage Reproductive Stage NIL-QTLs Drought Tolerant PRTL 2/89-33 863B-P2 Drought Sensitive H 77/833-2 ICMB-841-P3 Kholova et al. ( 2010) ICRISAT (A.P.) 40
  • Drought Tolerance QTL under salt stress 41
  • 0 2 4 6 8 10 12 14 16 843A X H 77/833- 2 (Drought sensitiveparent) 843A X 01029 (QTL-NIL) 843A X PRTL 2/89-33 (Drought tolerant parent) pH 8.5 pH 9.0 pH 9.4 LeafNa(mg/gdrywt.) FIG. 6:- Na+ accumulation in the leaves of drought- sensitive and drought-tolerant parents, at three Alkalinity levels. Sharma et al. (2010)CSSRI (Karnal) 42
  • LeafNa(mg/gdrywt.) 0 5 10 15 20 25 843A X H77/833-2 (Drought Sensitive parent) 843A X 01029 (QTL-NIL) 834A X PRTL 2/89-33 (Drought tolerant parent) EC 2 ds/m EC 9 ds/m EC 12 ds/m FIG. 7:- Na+ accumulation in the leaves of drought- sensitive and drought-tolerant parents, at three salinity levels. CSSRI (Karnal) Sharma et al. (2010) 43
  • Table 14:- Correlation analysis between enzymatic activities and pigments contents and ratios under well water and water stress condition. Water stress Chlorophyll a Chlorophyll b Carotenoids Chl a/Chl b Chl/Car APX (Ascorbic peroxidase) APX 2 ns ns ns ns 0.9344* APX 4 ns ns ns ns 0.9037*/0.9881* APX 8 ns ns -0.9104* ns ns APX 9 ns ns ns ns 0.8929* SOD (Superoxide dismutase) Mn-SOD2 ns ns ns ns 0.969** Mn-SOD3 ns ns ns ns 0.9516* CAT (Catalse) CAT1 ns ns ns ns 0.9439* CAT2 ns ns ns ns 0.8911* Well-watered Chlorophyll a Chlorophyll b Carotenoids Chl a/Chl b Chl/Car APX (Ascorbic peroxidase) APX5 ns ns ns ns -0.8821* APX 6 ns ns ns ns -0.8972* APX Sum ns ns ns ns -0.9417* Kholova et al. ( 2011)ICRISAT (A.P) 44
  • Fig. 8:- Gene networks involved in drought stress response and tolerance Function in stress tolerance Signal transduction and gene expression Shinozaki and Shinozaki (2007)Japan 45
  • Breeding Strategies 46
  • Lines of pearl millet used in crosses to developed genetic maps Lines Characteristics 1 H 77/833-2 Elite male parent of grain hybrids in north-western India, Susceptible to downy mildew but with seedling thermotolerance, high tillering capacity and earliness 2 PRLT 2/89-33 Inbred 33 in ICRISAT potential R- line Trail conducted in 1989; derived by selfing in the ICRISAT bold seeded Early Composite, low tillering, large seeds, drought tolerant which is largely based on lniadi landrace germplasm from West Africa. 47
  • Fig. 9:- Strategy for development of Genetic linkage map to identify QTLs linked to traits Yadav et al. 2010ICRISAT 48
  • Fig:-10 Genetic map Genetic map of a pearl millet population that segregates for drought tolerance showing the distribution of molecular marker on the different linkage group. The highlighted regions indicate parts of the genome controlling grain yield, and its components, during drought stress. 49
  • Linkage Group (QTL on) Drought Response for Grain yield Genetic Background References LG2 Up to 32 % H 77/833-2 x PRTL 2/89-33 Yadav et al., 1999,2002 LG 3 & 4 11.6-17.3 % ICMB 841 x 863 B Bidinger et al., 2007 LG 5 14.8 % ICMB 841 x 863 B Yadav et al., 2004 LG 6 & 1 QTL has Pleiotropic to decreased panicle number H 77/833-2 x PRTL 2/833 Yadav et al., 2010 Table:- 15 QTLs associated with drought tolerance of grain yield 50
  • Fig:-11 Marker Assisted Backcross Breeding for Drought Tolerance 51
  • Fig. 12:- Fine mapping population or High Resolution Cross Yadav et al. 2010 Objective of HRC 1. To fine map the DT-QTL interval on LG 2 2. To Pyramid this DT-QTL with the Downy-mildew resistance QTLs on LG 1 & 4 52ICRISAT
  • Table 16:-Comparison of the DT-QTL based and Field performance- based Hybrids. Moisture Environment Crop Trait QTL topcross Hybrids Field topcross hybrids LSD (P=0.05) Non- Stress Flowering (d) 39.1 41.3 0.19 Biomass (g /m2) 777 845 15.6 Harvest Index (%) 49.6 45.9 0.55 Grain Yield (g/m2) 381 393 7.7 Terminal Stress Flowering (d) 41.1 43.5 0.15 Biomass (g /m2) 581 619 11.4 Harvest Index (%) 41.7 38.3 0.60 Grain Yield (g/m2) 245 239 5.6 Line Source Flowering (d) 35.1 38.1 0.12 Biomass (g /m2) 537 562 7.9 Harvest Index (%) 49.5 43.8 0.5 Grain Yield (g/m2) 268 255 5.1 Serraj et al.(2005)ICRISAT 53
  • Fig. 13:-Marker Assisted Selection 1. Marker-assisted selection. Genetic composition at the drought tolerance QTL ( to constitute a MAS TCP) 2. Phenotypic selection. Field performance (best 16) in the drought trials used to identify QTLs (to constitute a phenotype TCP) 3. A Random control. A random sample from within the mapping population (to constitute a random TCP). Bidinger et al. (2005)ICRISAT 54
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  • The mapped progeny were phenotyped as testcross hybrids rather than as the skeleton-mapped F2 plants. • To restore heterotic vigour to partially inbred mapping progeny that might otherwise be too weak for effective screening under stress conditions (Inbreeding depression) • To reduced variation in flowering time among the test units, in order to focus the mapping on specific drought tolerance traits rather than traits or responses associated with variation on capacity for drought escape • To have test units that approximate the genetic structure of the F1 hybrids grown by farmers rather than partially inbred F3 or F4 lines. 56
  • Framework of an integrated strategy for genetic enhancement of crop grain yield (GY) and its components under water-limited conditions at ICRISAT. TR=total plant water transpired; TE=transpiration efficiency; HI= harvest index. 57
  • Breeding Approaches  Breeding under optimum (water-stress free) condition  Breeding under actual drought condition  Breeding under artificially created environment  Incorporation of drought tolerance 58
  • 1. Introduction (PRLT 2/89-33, lniadi landrace germplasm from West Africa.) 2. Interspecific and intergeneric hybridization Single backcross Three way cross (Gene pyramiding) 3. Pedigree selection 4. Back cross breeding 5. Mutation breeding 6. Ideotype breeding : Breeding activity aimed at producing new genotypes with novel morpho-physiological features that fit a pre-defined architecture thought to be advantageous based on experimental physiology and/or modelling. Breeding Methods 59
  • 7. Marker assisted breeding 8. Marker-assisted backcrossing (MABC): Repeated backcrossing of the F1’s to reconstitute the recipient genome without losing the desirable gene. 9. Tissue culture (in vitro Screening by using PEG 6000) 10.Development of Transgenic 60
  • Achievements 61
  • Table:-17 Recommended drought-tolerant/drought-avoiding hybrids/varieties of pearl millet in India State Hybrids Varieties Maharashtra Nandi 35,Saburi, PAC 903 PPC 6, HC 20, JBV 2, ICTP 8203, ICMV 221, AIMP 92901 Tamil Nadu GHB 558, CoH (Cu)8, X7 Co7, ICMV 221, ICMV 155 Andhra Pradesh PB 106, GHB 558 AIMP 92901, ASP-1, ICTP 8203 Karnataka PB 106, GHB 558 ICMV 221, ICTP 8203 Rajasthan HHB 67, RBH 121, GHB 538, PB 180 CZP 9802, Raj 171 Gujarat GHB 577, GHB 526, PB 172, PB 112, ICMB 356 JBV 2, HC 20 Haryana HHB 67, GHB 538, HHB 117, ICMB 356 CZP 9802 ICRISAT REPORT (2007) 62
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  • Limitations • There is no single major gene, which has a remarkable effect on the drought tolerance • Drought tolerance is an environmental and developmental stage specific character • Drought reduces nutrients uptake, and is associated with temperature stress and at higher elevation with cold. This associations make the breeding programme more complicated. • Most of the physiological and metabolic processes are affected by water deficits: cell growth, stomatal regulation, photosynthesis, translocation, etc. • Large number of genes regulated up- or down- by drought • Large genetic populations and replicates are required • Even drought component traits are often complex and difficult to screen 64
  • Conclusion • Tillering stage (30-45 DAS) is most susceptible to drought; wherein 23-25 % of yield reductions occurres, followed by drought at grain filling and maturity stage. • The osmotic (PEG 6000) stress at the seedling stage is the most suitable method for drought tolerance screening owing to their significant relationship with declining the germination percentage, root and shoot length. • Selection for seedling traits conferring drought tolerance such as root length, root weight and root shoot ratio will be useful for identifying genotypes with drought tolerance capacity. • Post-flowering drought stress is one of the most important environmental factors reducing the grain yield and yield stability of pearl millet and increasing the incidence of crop failure in dryland production environments • Marker Assisted Selection is the most appropriate method to improve drought tolerance genotype. 65
  • Future thrust • Consolidation of yield grains through multiple resistance to various abiotic and biotic stresses. • To develop a plant ideotype by restructuring the morphological attributes these can withstand drought conditions. • Need to saturate QTL areas to increase the efficiency • Pyramiding with other QTLs • In pearl millet, it need to be tested whether high leaf ABA content and the lower Tr are linked or not. • Need to develop Transgenic for Drought Tolerance, though difficult because of polygenic inheritance. 66
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