Applications of Biotechnology in Plant Breeding

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Applications of Biotechnology inPlant Breeding

• Sadanand Dhekney, PhD
• University of Florida / IFAS
• Mid-Florida Research Education Center
• Apopka, FL 32703

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Limitations of Conventional Breeding

• Extreme heterozygosity and pronounced inbreeding
  depression in plant species
• F1 hybrid produced is of intermediate quality
• Long juvenile period of sp. makes screening of
  new selections tedious and time consuming

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Plant biotechnology

• What is plant biotechnology?
• Products on the market
• Benefits of biotechnology

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Plant biotechnology

• A precise process in which scientific techniques
• are adopted to develop useful and beneficial
  plants.

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Traditional plant breeding
Commercial variety
Traditional donor
New variety
DNA is a strand of genes, much like a strand of
pearls. Traditional plant breeding combines many
genes at once.
(many genes are transferred)

X
(crosses)
Desired Gene
Desired gene
Plant biotechnology
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What is Plant Tissue Culture?
Totipotency Single cell has the ability to
regenerate into a whole plant
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What conditions do plant cells need to multiply
in vitro?

• Freedom from competition
• Nutrients and removal of waste products
• A controlled environment

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Applications
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Seed culture

• Increasing efficiency of germination of seeds
  that are difficult to germinate in vivo
• Precocious germination by application of plant
  growth regulators
• Production of clean seedlings for explants or
  meristem culture

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Embryo culture

• Overcoming embryo abortion due to incompatibility
  barriers
• Overcoming seed dormancy and self-sterility of
  seeds
• Embryo rescue in distant (interspecific or
  intergeneric) hybridization where endosperm
  development is poor
• Shortening of breeding cycle

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Ovary or ovule culture

• Production of haploid plants
• A common explant for the initiation of somatic
  embryogenic cultures
• Overcoming abortion of embryos of wide hybrids at
  very early stages of development due to
  incompatibility barriers
• In vitro fertilization for the production of
  distant hybrids avoiding style and stigmatic
  incompatibility that inhibits pollen germination
  and pollen tube growth

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Anther and microspore culture

• Production of haploid plants
• Production of homozygous diploid lines through
  chromosome doubling, thus reducing the time
  required to produce inbred lines
• Uncovering mutations or recessive phenotypes

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Organ culture

• Any plant organ can serve as an explant to
  initiate cultures

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Shoot apical meristem culture

• Production of virus free germplasm
• Mass production of desirable genotypes
• Facilitation of exchange between locations
  (production of clean material)
• Cryopreservation (cold storage) or in vitro
  conservation of germplasm

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Somatic embryogenesis

• One major path of regeneration
• Mass multiplication
• Production of artificial seeds
• As source material for embryogenic protoplasts
• Amenable to mechanization and for bioreactors

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Embryogenic Culture System for Vitis

• Initiation from leaves on NB 2 medium (Gray,
  1995)

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Organogenesis

• One major path of regeneration
• Mass multiplication
• Conservation of germplasm at either normal or
  sub-zero temperatures

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Callus Cultures

• In some instances it is necessary to go through a
  callus phase prior to regeneration via somatic
  embryogenesis or organogenesis
• For generation of useful somaclonal variants
  (genetic or epigenetic)
• As a source of protoplasts and suspension
  cultures
• For production of metabolites
• Used in in vitro selection

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Initiation from Stamens and Pistils
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In vitro mutagenesis

• Induction of polyploidy
• Introduction of genetic variability

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Genetic transformation

• Introduction of foreign DNA to generate novel
  (and typically desirable) genetic combinations
• Many different explants can be used, depending on
  the plant species and its favored method of
  regeneration as well as the method of
  transformation
• Used to study the function of genes

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Genetic Transformation System

Co-cultivate 48 h
Callus induction medium
Embryo explants
Wash explants
Agro culture
Select transgenic embryos using GFP/NPT II system
Embryo development medium
Regenerate transgenic plants
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Applications

• Disease resistance
• Insect resistance
• Salinity tolerance
• Heavy metals tolerance
• Improved nutritional characteristics

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More than 50 biotech food products have been
approved for commercial use in the United States

• Canola (5)
• Corn (21)
• Cotton (12)
• Papaya
• Potato

• Soybeans (62)
• Squash
• Sugarbeets
• Sweet corn
• Tomato

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Advantages Limitations

• Advantages
• Food quantity
• Food quality
• Eco friendly
• Limitations
• Recent scientific advances
• Tangible benefits may not be long term