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Breeding for abiotic stress resistance in vegetable crops

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Breeding for abiotic stress resistance in vegetable crops

  1. 1. BREEDING STRATEGIES FOR ABIOTIC STRESS TOLERANCE IN VEGETABLE CROPS DOCTORAL SEMINAR- II VSC - 849 Speaker-Subhrajyoti Chatterjee PhD 2nd year, 3rd sem. Reg.No: VSC/D-1745/2017 Department. of Vegetable Science Course Leaders: Prof. A. Chattopadhyay Dr. P. Choudhuri
  2. 2. STRESS  The effect that is having negative effect on the other entity is termed as stress. Stress is any factor of environment that interferes with the complete expression of the genotypic potential of the plant (Singh, 2000).  An external conditions that adversely effect plants growth, development and productivity. John et al. (1989) defined stress as “an overpowering pressure of some adverse forces that prevent or decrease the normal system of functioning”.
  3. 3. Environment Stress Biotic (Human, animals, insects fungi , bacteria, viruses etc.) Abiotic Atmospheric Air pollution Light stress Temperature stress Edaphic (soil) Water Stress Salt Stress
  4. 4. ABIOTIC STRESS • Abiotic stress is best defined as any factor exerted by the environment on the optimal functioning of a plant. • Situations where environmental stimuli that normally influence plant development, growth, and productivity, exceed thresholds (species-specific), damaging the plant. Most commonly encountered abiotic stresses are:- 1)DROUGHT 2)WATERLOGGING 3)HEAT STRESS 4)COLD STRESS 5)SALINITY
  5. 5. PERCENT OF GEOGRAPHICAL AREA POTENTIALLY AND ACTUALLY ARABLE Region Arable (cultivable) area (% of geographical area) Potential arable area Actual arable area World Asia India 24.2% 24.1% 56.0% 10.6 18.9 43.6 Abiotic Stress Fraction (%) arable land Drought Mineral (toxicity/deficiency) Freezing No stress Other stresses 26 20 15 9 39 FRACTION OF WORLD’S ARABLE LAND SUBJECTED TO ABIOTIC STRESSES (Source: WVC,2012)
  6. 6. DROUGHT
  7. 7. EFFECT OF WATER STRESS ON GROWTH AND DEVELOPMENT OF VEGETABLES VEGETABLES CRITICAL STAGE IMPACT OF WATER DEFICIT Tomato Flowering and fruit enlargement Flower shedding, BER, reduced fruit size, fruit splitting Eggplant Flowering and fruit development Less yield , poor color development Chilli and capsicum Flowering and fruit set Shedding of flower and fruits Cabbage and cauliflower Head/curd formation, enlargement Tip burning, splitting of head and riceyness in cauliflower Root crops Root enlargement Distorted, rough and poor roots, splitting, Forking Cucumber Flowering and fruit development Bitterness and deformity in fruits Pea & Beans Flowering and pod filling Less root nodulation, poor grain filling
  8. 8. WATERLOGGING  The term water logging is defined as “the condition of soil where excess water inhibits gas exchange of roots with atmosphere.” • Plants shift its metabolism to anaerobic mode from aerobic mode. The important biological consequence of waterlogging are:  Deficiency of oxygen in soil environment (hypoxia)  Complete absence of oxygen in soil environment (anoxia)
  9. 9. Waterlogging Gas diffusion limitation Oxygen deficit Anaerobic respiration Metabolic toxins (soil or roots) Reduced respiration (Energy deficiency) Reduced root conductivity to water Carbon dioxide excess Ethylene excess Mineral nutrient deficiency (Leaching induced)
  10. 10. HEAT STRESS • Heat stress is often defined as the rise in temperature beyond a threshold level for a period of time sufficient to cause irreversible damage to plant growth and development (Wahid et al., 2007). • A transient elevation in temperature, usually 10-15◦C above ambient, is considered heat shock or heat stress. EFFECTS OF HEAT STRESS ON PLANT
  11. 11. COLD STRESS • Tropical plants suffer cold damage when exposed to temperature below 200C. • When temp is above freezing point (>00C)Chilling injury • When temp is below freezing point (<00C)Freezing injury- Low temp may  Reduce germination  Reduce vegetative growth  Metabolic imbalances  Prevent reproductive development
  12. 12. SALT STRESS • Mostly caused by sodium saltsSALINESOILS • pH: 7.0-8.5 • EC : >4dsm-1 • ES : <15 % • Soil Structure is Stable • Gypsum is present in sufficient amount SALINESODICSOILS • pH: > 8.5 • EC : >4dsm-1 • ES : >15 % • Soil Structure is Unstable • Gypsum present in sufficient amount ALKALI/SODICSOILS • pH: 8.5-10 • EC : < 4dsm-1 • ES : >15 % • Soil Structure is Unstable • Gypsum is absent
  13. 13. WHY there is a need for stress tolerant plants ??? Serious concern for food security of developing countries. To improve protection of crops to stresses. As earth population increases, new means of improving crop productivity must be found to increase the available resources. Global climate change is altering environmental conditions.
  14. 14. BREEDING STRATEGIES FOR ABIOTIC STRESS RESISTANCE Mainly depends upon the availability of resistance sources and genetics of tolerance of traits. Should be incorporated into materials with high genetic potential for yield. Can be developed through exposition to sub- optimal growing conditions: the acclimation processs.
  15. 15. Genetic Sources of Resistance/ Tolerance Germplasm Collection & Screening Related/Wild species A known Variety Mutation
  16. 16. CONVENTIONAL BREEDING METHODS Breeding Methods For Cross Pollinated Crops A. Mass selection B. Recurrent Selection 1. Simple Recurrent Selection 2. Recurrent Selection For General Combining Ability 3. Recurrent Selection For Specific Combining Ability 4. Reciprocal Recurrent Selection Breeding Methods For Self Pollinated Crops 1. Introduction 2. Pureline Selection 3. Mass Selection 4. Pedigree Method 5. Backcross Breeding 6. Mutation
  17. 17. • When abiotic stress resistance is available in an exotic variety, such variety can be introduced and after thorough testing if found suitable can be released in the new area. INTRODUCTION • When genes for resistance occur in existing or indigenous/ commercial varieties, landraces or mixed populations. Either pure line or mass selection is adopted. SELECTION HYBRIDIZATION When resistant genes are available in germplasm or wild species, breeder resort to hybridization. • Superior genotypes are selected from segregating generations • Proper record of ancestry of selected plants are made in each generation. PEDIGREE METHOD BREEDING METHODS
  18. 18. Parent A ( Recurrent Parent) X Parent A ( BC1 )F1 AB X Number of backcrosses depends on homozygosity of desired characters of the recurrent parent. Parent B ( Donor of Resistance) BC1 X Parent A ( BC2 ) BC2 X Parent A ( BC3 ) BC3 X Parent A ( BC4) BACKCROSS BREEDING METHODOLOGY Lines with good agronomic characters having gene (s) for resistance
  19. 19. MUTATION BREEDING When resistance sources are not available in germplasm, then one strategy is to introduce inheritable changes or mutations in crop plants and to select rare mutants having resistance to particular stresses. BREEDING FOR DROUGHT TOLERANCE
  20. 20. DYNAMIC BREEDING SCHEME FOR DROUGHT RESISTANCE Step-I 1. Multilocation evaluation under stress to identify stable and drought resistant lines to be used as parents for hybridization 2. Crosses are made between the selected drought resistant lines and agronomically superior cultivars: to combine high yield potential with drought resistance 3. F1, F2 and F3 grown under non stress condition 4. In F3 Individual Plant Progenies are evaluated for yield attributes and selection is done 5. In F4 selected progenies evaluated under stress( to identify stress resistant lines) as well as non stress condition (for seed multiplication) 6. Stress resistant progenies are identified and grown in F5. 7. In F5 selected progenies handled as F4. 8. Ultimately selected lines are subjected to multilocation tests and released for commercial cultivation. Step-2 1. Selected F5 lines are crossed to identified sources for desired drought resistance traits. 2. Procedures listed under items 3-6 are exceuted. Source: Singh (2004)
  21. 21. SCREENING CRITERIA FOR DROUGHT TOLERANCE • Screening of germplasm for drought tolerance based on screening criteria like – Yield potential – Leaf characteristics like leaf rolling – Water retention by leaf – Leaf stomata – Root characters: root mass and distribution – Seed germination, seedling emergence, survival, vigour and recovery – Photosynthetic rates – Membrane stability and Water use efficiency CHARACTERS OF A DROUGHT TOLERANT VARIETY Short life span (drought escape), High stomatal tolerance, High water use efficiency (drought avoidance), Increased and stabilized yield during water stress period (drought tolerance)
  22. 22. DROUGHT TOLERANT SPECIES AND GENOTYPES OF VEGETABLES (Kumar et al., 2012)
  23. 23. BREEDING FOR SALINITY TOLERANCE Improving Yield Level of Salt Tolerant Cultivars Transfer of Salt Tolerant Genes To High Yielding Cultivars Traditional cultivars of salt affected area are improved for their productivity without affecting their salt tolerance ability.  By transferring salt tolerance genes from salt tolerant cultivars through Hybridization and Selection in stress target environment Two approaches are followed for salinity tolerance breeding:-
  24. 24. METHODS OF SCREENING FOR SALT TOLERANCE 1. Germination test in a saline medium 2. Sand culture irrigated salt concentration 3. Seedling root dip 4.Natural selection-planting genotypes in salt affected fields 5. Hydroponics-increasing salt concentration 6. Young seedling screening 7. Cell membrane stability SALT STRESS TOLERANT SPECIES AND GENOTYPES OF VEGETABLES Crop Resistance Source Tomato S. cheesmanii, S. pimpinellifolium, S. peruvianum, S. hirsutum and S. pennellii, Sabour Suphala Okra Pusa Sawani Onion Hissar 2, Punjab Selection Bean Gevas Sirik 57 (GS57) Brinjal Pusa Bindu, CO-1, S. macrocarpon, S. gilo Source: Vegetable Breeding Principles & Practises by: Hari Har Ram
  25. 25. •An initial screening experiment of 780 globally distributed Pisum sp. L. accessions was conducted. •Lines with relatively higher tolerance as compared to commercial varieties grown in Australia were most frequently identified within landraces originating from the central, eastern and southern provinces of China. •The most tolerant identified accession was an unadapted landrace ‘ATC1836’ originating from Greece.
  26. 26. BREEDING FOR WATER LOGGING TOLERANCE • Collection and Evaluation of Germplasm – Water logging can appear at any stage of plant development due to excess rainfall so evaluation of genetic diversity should be done at different stage of development • Study of genetics of tolerance • Hybridization  Waterlogging tolerant genotype identified in vegetable crops – Tomato – L-123 (Kuo &Chen, 1979) – Potato- Gem, Jasper (Martin, 1984) BREEDING APPROACHES FOR HEAT STRESS TOLERANCE  Traditional breeding of heat resistant crops is basically based on :- • Screening • Selection  The common technique of selecting crops for heat stress resistance is: • To grow breeding materials in a hot target production environment and detect individuals/ lines with higher yield.
  27. 27. SELECTION CRITERIA FOR HIGH TEMP TOLERANCE • Germination: – Percent germination under stress • Growth development – Longer hypocotyl – Internodes elongation – Early vigour of seedlings – Dry matter content – Yield • Sensitivity of reproductive phase – Fruit setting – Pollen fertility • Membrane stability – Solute leakage as measured by conductivity test • Photosynthesis sensitivity – Chlorophyll content • Selection can be done under – Natural environment – Artificial created environment i.e. protected conditions
  28. 28. SOURCES OF HEAT TOLERANCE Crop Genotypes Reference Bean G 122, G5273 Shonnard & Gepts, 1994 GUNI 59 Udomprasert et al., 1995 Haibushi Suzuki etal., 2001 Cornell 503 Rainey & Griffiths, 2005 Chinese cabbage Qngyan 1 Li et al., 1999 Tomato Moneymaker, Red Cherry Johijma et al., 1995 Sonali, Hotset, Kewalo, Saladette, NDTVR-60 Nainer et al., 2004 CROP DONOR Tomato S. cheesmanii, S. cerasiformae (Cherry tomato), Phillipines, Punjab Tropics, EC 130042, EC 162935, Brinjal S. macrocarpon, S. gilo Potato S. chaconense, Kufri Surya Okra A. manihot var manihot Shah et al., 2018
  29. 29. SCREENING AND SELECTION OF COLD TOLERANT GENOTYPES S. No. Selection Criteria Screening technique Remarks 1. Chlorophyll loss Leaf/seedling colour Effect of light intensity 2. Growth under stress Dry weight, stem/leaf dry weight ratio Commonly used 3. Germination Field emergence/germination in incubators under stress Extensively used 4. Membrane stability Leakage of solute determined by conductivity meter Quite useful 5. Photosynthesis Variable chlorophyll florescence at 685 nm Promising technique 6. Seedling mortality Seedling survival under stress Simple 7. Seed/fruit set Fruit/seed produced under stress Simple 8. Pollen fertility Pollen sterility under stressed plants Indirect selection
  30. 30. SOURCES OF COLD TOLERANCE CROP DONOR Tomato S. habrochites, S. pimpinellifolium, Cold Set, Pusa Sheetal Potato S. acaule French Bean P. filliformis, P. angustissimus Okra A. angulosus PHYSIOLOGICAL TRAITS OF CHILLING TOLERANCE IN TOMATO 1) Short dense glandular hairs 2) High photosynthetic rate 3) Densely hairy stem, leaves and fruits (S. hirsutum) 4) Narrow leaflets (S. peruvianum) 5) Deep root system (S. chilense)
  31. 31. LIMITATIONS OF CONVENTIONAL METHODS 1) Longer time required to develop resistant cultivars. 2) More effort and labour requirements. 3) Transfer of non desirable genes along with resistance genes by Hybridization. 4) Identification of plants with stress tolerance is technically difficult in segregating population. 5) Marginal success due to the complexity of stress tolerance traits. MODERN BREEDING APPROACHES  In-vitro Screening Somaclonal Variation Marker Assisted Breeding Transgenics or GMO
  32. 32.  Four cultivars of lettuce (two romaine: ‘Verte Maraîchère’ and ‘Blonde Maraîchère’; and two Batavia: ‘Pierre Benite’ and ‘Great Lakes 118’) were sown in MS medium.  Seven days-old seedlings were transferred to medium containing different NaCl levels (0, 50, 100, 200, 300, 400 and 500 mM) and placed upside down. After 7 days, seedlings were transferred again to an NaCl free medium.  Results showed that ‘Great Lakes 118’ is the most tolerant cultivar followed respectively by ‘Verte Maraîchère’, ‘Blonde Maraîchère’and Batavia ‘Pierre Benite’. IN VITRO CULTURE USED FOR SCREENING SALT STRESS TOLERANT LETTUCE CULTIVARS A. Maamouri, Y. Trifa, K. Kouki , K. Aounallah, C. Karmous Acta Hort. (2012)
  33. 33. SOMACLONAL VARIATION • Selection of somaclonal variant strains from callus culture is supplementary tools to traditional breeding for production of stress resistant plants. • Meaningful tool for determining the tolerance and also for screening and developing salt tolerant genotypes. • It depends on the potentiality of callus induction and green plantlet regeneration.
  34. 34. MARKER ASSISTED SELECTION • Marker assisted selection (MAS) refers to the use of DNA markers that are tightly-linked to target loci as a substitute for or to assist phenotypic screening. • MAS can be performed in early segregating population and at early stages of plant development. • Marker assisted selection or identification can be used to pyramid the major genes including resistance genes with the ultimate goal of producing varieties with more desirable characters.
  35. 35. QTL MAPPING Used to identify specific chromosome segments that contain candidate genes for stress tolerance. Allow loci to be identified that are linked to stress tolerance. Identification of markers linked to QTLs enables breeding of stress- tolerant crops by combining or “pyra- miding”QTLs for tolerance to various stresses.
  36. 36. GENETIC ENGINEERING/TRANSGENIC APPROACH  Genes of resistance are introduced from unrelated species through recombinant DNA technology to overcome the genetic barriers.  Organisms with foreign genes (Transgenes) are called genetically modified organisms or GMOs.  Can be transferred by:-  Direct Method  Indirect Method RECENT SUCCESS • In Network Project on Transgenic Crops at IIVR (NPTC), water- deficit stress tolerant transgenic tomato was developed using AtDREB1A gene. • Another BcZAT12 transformed tomato line was useful for improving its quality in heat, drought or salt stressed conditions. Source: Annual report IIVR 2013-14 and 2015-16
  37. 37. GRAFTING • Grafting of vegetables can protect against abiotic stresses. • A special method of adapting plants to counteract environmental stresses by grafting elite, commercial cultivars onto selected vigorous rootstocks (Lee and Oda, 2003). • Rapid alternative tool to the relatively slow breeding methodology (Flores et al., 2010). Tomato grafted over eggplant rootstock like IC354557 and IC 111056 can alleviate waterlogging stress of 4 days. Due to vigorous root system, eggplant rootstock may also be useful for drought tolerance and higher nutrient use efficiency. (Source: Indian Hort: 2016) RECENT SUCCESS Experiment at IIVR, Varanasi
  38. 38. ROOT STOCK USED SCION REMARKS Fig Leaf gourd Cucumber, Watermelon, Melon and Summer Squash Tolerance to low soil temperature Rootstocks of the high- altitude accession LA 1777 of S. habrochaites Tomato scions Low root-temperature stress (Venema et al., 2008) Interspecific hybrid of S. lycopersicum × S. habrochaites Tomato scions Low root-temperature stress (Okimura et al., 1986) Shin-tosa-type (an interspecific squash hybrid, Cucurbita maxima × C. moschata) Watermelon Advance the planting date during cool periods (Davis et al., 2008) Sweet pepper rootstocks Chilli Scions Highest yield under high- temperature conditions (Palada and Wu 2008) Chilli accessions ‘PP0237 7502’,’ PP0242-62’ and ‘Lee B’ Pepper Flooding tolerance (WVC,2009)
  39. 39. FUTURE THRUST  Molecular breeding or transgenic approaches are suggested.  Detailed analysis of underlying physiological and molecular mechanisms for stress tolerance using functional genomics is an important area of future research for developing transgenic plants for stress tolerance.  Abiotic stress tolerant plants can only be developed by combining traditional and molecular breeding approaches.
  40. 40. • Development of resistant or tolerant cultivars is one of the best options to minimize the losses due to abiotic stresses. • Adoption of strategies for maximum crop stand and economic returns under stressful environments is to be followed. • Broadening the genetic base (wild relatives, landraces, and exotic germplasm of crops in their hybridization programs) in search of resistance genes against various abiotic stresses is needed. • Modern plant breeding methods like transgenic approach, somaclonal variation and Marker Assisted breeding have to be used in future . CONCLUSION
  41. 41. THANK YOU

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