Breeding Drought Tolerant Maize

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					    Breeders Club Seminar


Breeding Drought Tolerant Maize




           Bhupesh Vaid

            1-12-2008
Presentation Outline


  History of Maize

  Area Production Productivity

  Breeding for Drought

  Nairobi Tour Highlights
History of Genetic Modification
           in Maize
History of Maize
Tripsacum grass (big) and a teosinte (small)
 Maize worldwide
Country     Area (Mha)   Production   Productivity
                         (MMT)        (MT/ha)
USA         28.79        256.9        8.92
China       23.52        114.18       4.85
Brazil      12.94        47.81        3.70
Mexico      7.78         19.66        2.53
Argentina   2.32         15.04        6.47
India**     8.26         14.70        2.33
France      1.67         11.90        7.14
Indonesia   3.35         10.91        3.25
S.Africa    3.35         9.71         2.90
Canada      1.23         9.59         7.82
Nigeria     4.70         5.15         1.10
World       142.0        637.4        3.41
Maize Area & Productivity in India
                                                                                             • Total Area: 8.26 million ha
                                  4500.0
                                                                                             • Hybrid market: 45%
                                  4000.0                                                     • Growing across India
Area 000 ha/ Productivity Kg/Ha




                                  3500.0


                                  3000.0


                                  2500.0
                                                                                                                     Area 000 ha
                                                                                                                     Product ivit y Kg/ ha
                                  2000.0


                                  1500.0


                                  1000.0


                                   500.0


                                     0.0
                                            Rj   UP   MP   Bih   Kt   Gj     AP       J&K   Mh   HP   Pb   TN   Cg

                                                                           St at es
                                           Source : 50th Annual Progress Report 2007
                                           (All India Coordinated Maize Improvement Project)
Maize Uses
Question: Of 10,000 items in a typical grocery store, how many
        would you guess would contain corn in one form or
        another?
Answer: At least 2,500 items use corn in some form during the
        production or processing

                                 Export
                  Animal feed
                                      2%
                                12%

    Starch industry
                      12%
                                                       Poultry
                                            49%

                            25%

      Human consumption
Maize Botany
                 Tassel: The male
                 inflorescence at
Anther: The      the top of the
pollen           plant
producing
part of tassel




                  Cob: The female
                  inflorescence at
                  the middle of
                  the plant
 Silk: The
 stigma/style
 of the plant
                 Monoecious Plant
Breeding Drought Tolerant Maize
Breeding for Drought Tolerance
 “In many elite populations and
 varieties there exists stress-
 adaptive genes, but at low
 frequency” (Blum, 1983)


                      Basic
                   assumptions


                    “Careful selection aimed to identify
                    those genes and increasing their
                    frequency may result in reasonable level
                    of stress tolerance” (CIMMYT, 1994)
Maize Physiology under Drought
• High ABA accumulation:
   – A “root signal’ to reduce water losses.
   – Synthesized in root & translocated to leaves – causes
     rolling, stomatal closure & senescence
   – Regulate growth as per water regime, help in survival under
     drought
   – No contribution in productivity; ABA-regulated kernel
     abortion, specially at ear tip

• Mild stress - cell expansion inhibited,
   – Reduced LA expansion, stem elongation, root growth &
     poor silk growth,
   – Good recovery when stress withdrawn
• Severe stress - cell division inhibited
   – Irreversible losses

                                               Ref: P.H.Zaidi CIMMYT, India
Effect of drought on maize
                                         CROP STAGE
Traits            Germination Pre-flowering    Flowering      Post-
                                                           flowering
Plant number          ***
Leaf area                          ***                *
Leaf senescence                     *             **          ***
ASI                                 *             ***
Ear number                                        ***
Grain number                                      ***
per ear
Kernel size                                                   ***
Yield                 ***           *             ***         **
KEY COMPONENETS

• Susceptible stage(s)

• Source germplasm

• Selection environment

• Selection criteria
 Maize under drought stress
Growth stage     Susceptibility    Probability of    Probability of
                  of yield to          stress       breeding success
                    drought
Germination,         High           Usually high          Low
establishment
Pre-flowering        Low            Depending on       Medium?
                                  the environment
Flowering            High           Depending on         High
                                  the environment
Post-flowering     Medium           Usually high        Medium
Efficient germplasm for drought tolerance

• Better root system
• Shorter ASI
• Protogyny
• Early maturity
• Stay green
• Erect leaves
• Strong plant
• Ears per plant/non barrenness
Selection Environment
                        (Bruce et al., 2002)
Selection Environment ……..
 Large Scale Screening
 at managed stress field
 during rain-free winter
         season




                           Evaluation of selected entries
                              under rain-out shelter
                               during rainy season
 MANAGED DROUGHT STRESS
 Timing : exposure at
  targeted growth stage for a
  defined period
 Intensity : should be severe
  enough to express the traits
  important for stress
 Uniformity: should be
  uniform over space & time so
  that genetic differences can
  be easily observed.
Different Stress Schemes



 Flowering stage drought stress
        Irrigation               Irrigation



  Planting           Flowering                Harvest
Different Stress Schemes………..

Post-flowering stage drought
             Irrigation



 Planting                 Flowering    Harvest



Flowering & Post-flowering stage drought stress


  Planting                Flowering     Harvest
Different Approaches for Drought Breeding


  Conventional Breeding


  Marker Assisted Selection


  Transgenic Approach
Marker Assisted Selection


•   Marker assisted backcrossing – most common
    •   Gene assisted or marker assisted selection (3
        markers)
    •   Traget per trait - few genes upto 5 major QTLs

•   Marker assisted recurrent selection (MARS)
    •   An improvement of an F2 population by 1 cycle
        of selection based on both marker and
        phenotypic data followed by 3 cycles of marker-
        based selection
    •   20-35 markers associated with the trait
    •   Target QTLs: large
Modern Tools for screening genotypes for
drought
 1. Chlorophyll content meter/SPAD meter
 2. GreenSeeker Optical Sensor

Why these are needed ?
• Screening large number of genotypes
• Shortage of technical manpower
• Quick method
• Low cost
• Integrated results for large number of traits
Chlorophyll Content Meter/SPAD
                     • It is quick method to determine
                       the chlorophyll content
                     • Helps in screening of the large
                       no. of genotypes
                     • Chlorophyll is an important
                       indicator for photosynthesis,
                     • Linking the chlorophyll content
                       with DT associated traits like leaf
                       senescence etc.
                     • For reliable results the leaf at
                       same node in each genotype
                       should be taken
                     • It is a low cost technique
GreenSeeker Optical Sensor
                       • Total physical scan of the plant
                       • Measures Normalized
                        Difference Vegetation Index
                        (NDVI) that includes biomass,
                        greenness, stress etc. of the
                        plant
                       • Large scale field screening
                       • NDVI varies from 0 to 1
                       • Higher NDVI indicates for
                         better plant type for
                         greenness, biomass, LAI,
                         photosynthesis etc.
Nairobi Tour Highlights
Highlights


• CIMMYT provided good knowledge about
  protocol standardization for Drought
  screening

• Also provided filed training for drought
  screening

• Provided one software “Fieldbook”
Introduction to Fieldbook
• Developed at CIMMYT
• Developed by maize breeders
• Tailored to maize but could be adapted for
  other crops
• Excel based
  – Very flexible
  – Power of Excel at user’s disposal
• Not a database
Fieldbook Utilities (short list)
   Prepare seed for nurseries and trials
   Make field books
   Make field maps
   Generate stock lists for different pollinations
   Manage stocks
   Manage trial data
   Statistical analysis
   Apply selection index
   Maintain and manage pedigree information
   Generate shipment lists and labels
   Generate bar codes
Nairobi Photos
Nairobi City, Kenya
CIMMYT Drought Screening Site, Kiboko, Kenya
Field observation for drought traits, Kiboko, Kenya
Grain yield observations at KARI, Kiboco, Kenya
ICRAF Campus, Nairobi, Kenya
Participants are from India, S. Africa, Egypt, Iran,
Afghanistan, Bangladesh, USA, Uganda, Kenya, Tanzania
Thanks

				
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