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Introduction to Maize Breeding

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Introduction to Maize Breeding Nathan Schnur Overview What is Plant Breeding? Basic Genetics Mendelian Genetics Principles of Breeding Maize Plant Breeding Methods ... – PowerPoint PPT presentation

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Title: Introduction to Maize Breeding


1
Introduction to Maize Breeding
  • Nathan Schnur

2
Overview
  • What is Plant Breeding?
  • Basic Genetics
  • Mendelian Genetics
  • Principles of Breeding Maize
  • Plant Breeding Methods

3
Plant Breeding
  • What is it?
  • Is the science and art of improving crop plants
    through the study and application of genetics,
    agronomy, statistics, plant pathology,
    entomology, and other related sciences.
  • Goals
  • Nutritional enhancement, yield improvement,
    environmental stress tolerance, improved plant
    structure, or pest and disease resistance

4
Basic Plant Genetics
  • DNA
  • Primary carries of heritable information
  • Composed of thousands of genes
  • Genes
  • Contain actual heritable information
  • There can be many versions of genes called
    alleles

5
Basic Plant Genetics Cont
  • There are two alleles for any gene
  • Dominant and Recessive
  • Two dominant alleles are denoted as AA and
    called homozygous dominant
  • Two recessive alleles are denoted as aa and
    called homozygous recessive
  • If one dominant and one recessive allele is
    present then it is denoted as Aa and called
    heterozygous.

6
Basic Plant Genetics Cont
  • Alleles which are heterozygous or homozygous
    affect the phenotypes and genotypes of plants
  • Phenotype
  • Visual appearance of the plant
  • Genotype
  • Genetic makeup of the plant

7
Mendelian Genetics
  • Gregor Mendel
  • Famous geneticist from 1800s
  • His research consisted of selectively breeding
    garden peas
  • He developed two important laws of genetics
  • Law of Segregation
  • Law of Independent Assortment

8
Mendelian Genetics Example
9
Principles of Breeding Maize
  • Three Main Principles
  • Inbreeding
  • Hybridization
  • Heterosis

10
Inbreeding
  • Main Goals
  • Increase the homozygosity at all or specific loci
    in the plant genome
  • Produce a plant which breeds true
  • Produce uniform plants

11
Hybridization of Maize
  • Hybridization occurs when inbred parents are
    mated (cross pollinated)
  • Creates a heterozygous individual
  • Benefits
  • Increased heterosis (vigor) in F1 generation

12
Heterosis (Hybrid Vigor)
  • Heterosis occurs when two homozygous individuals
    are cross pollinated.
  • This causes all loci to become heterozygous
  • The increased heterozygosity causes increased
    plant vigor
  • Benefits of Increased Vigor
  • Increased yield
  • Better standability
  • Better germination
  • Overall better plant performance

13
Maize Breeding Methods
  • Main Methods of Maize Breeding
  • Selfing (Inbreeding)
  • Sib Mating
  • Crossing
  • Test Crossing
  • Backcrossing

14
Selfing
  • Selfing is the process of pollinating a plant
    with its own pollen
  • Benefits
  • Increased homozygosity
  • Plants which breed true from generation to
    generation
  • Decreased Segregation
  • Disadvantages
  • Many generations of selfing lead to inbreeding
    depression

15
Crossing and Test Crossing
  • Crossing is useful when trying to create hybrid
    seed.
  • Ex. By crossing Inbred A x Inbred a you would
    obtain an F1 hybrid Aa
  • Crossing is used to produce the hybrid seed
    farmers use to plant in the spring
  • Test Crossing is useful to test general combining
    ability of an individual
  • Ex. Inbred A is x to a tester which has a diverse
    selection of genotypes

16
Backcrossing
  • Backcrossing is a method which is used to improve
    a trait which a plant is deficient in.
  • Method
  • A hybrid plant which has the trait of interest is
    crossed with one of its parents
  • The offspring are then crossed back to the
    parent, thus increasing the frequency of the
    trait.

17
Conclusion
  • Plant breeding is a complicated but beneficial
    process.
  • There are many processes involved which are used
    in the development of new varieties.
  • Remember if it wasnt for plant breeding we
    wouldnt have such high yielding crops

18
References
  • Fehr, W. Principles of Cultivar Development.
    1993. Volume 1
  • Photos Courtesy of
  • www.pioneer.com
  • www.britannica.com
  • www.psu.edu
  • http//imbgl.cropsci.uiuc.edu
  • www.nsf.gov
  • www.scienceclarified.com

19
Questions
  • Questions?
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