Plant Propagation

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Plant Propagation

• The Biology of Propagation

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Plant Characteristics

• Genotype sum total of all genetic
  characteristics controlled by genes.
• Phenotype overall appearance and performance of
  the organism. Includes size, vigor color
  seasonal patterns, shape, etc.

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Genetic Control in Propagation

• Sexual vs. Asexual

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Sexual vs. Asexual

• Sporophytic involves vegetative growth of plant
  body in size and structure. Asexual implying the
  maintenance of genotype via mitosis.
• Gametophytic involves special reproductive
  cells, Gametes, and provides opportunity to
  exchange genetic information. Implies process of
  meiosis.

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Mitosis and Asexual Reproduction

• Cell Components
• nucleus, cytoplasm, cell wall, plasmalemma
• chromosomes-gtgenes-gtalleles
• Mitosis -gtformation of daughter cells
• shoot tip, root tip
• cambium, cork cambium
• intercalary zones
• production of callus, adventitious tissue

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Meiosis and Sexual Reproduction

• Formation of male and female gametes
• Reduction division-gthaploid cells-gtgametes
• Pollen
• Pollination
• Fertilization
• Zygote
• Seed

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Gene Expression

• Heterozygous
• Homozygous
• Dominance
• Recessive
• Inheritance
• -gt

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Plant Breeding, Genetic Engineering and
Biotechnology

• Transformation
• Transgenic Plants
• Recombinant DNA technology
• Molecular Biochemical markers
• Micropropagation

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Plant Development

• Totipotency each living cell has potential to
  reproduce an entire organism since it contains
  all the necessary genetic information.
• Refers to zygote, meristematic cells in root and
  shoot

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Gene Expression

• Phenotypic variations that develop within a
  single individual result from the translation of
  genetic information encoded in genes to the
  formation of plant structure, growth patterns and
  function.

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Epigenetic Variation

• Processes by which information in the DNA of the
  chromosome is channeled to direct growth,
  development and plant structure because change
  does not occur in the basic genotype of the
  plant.
• Formation of specific structures
• control of developmental cycles
• induction of adventitious shoots, roots or embryos

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Contd

• Competency- potential of a particular cell or
  tissue to develop in a particular way. Uses
  internal memory within the cell. Signal from
  within cell or from environment.
• Determinism degree of commitment that a group
  of cells have towards a specific direction at a
  specific time. Growth and development of stems,
  leaves, etc.

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Hormonal Control of Growth and Development

• Auxin
• Gibberellin
• Cytokinin
• Ethylene
• Abscisic Acid

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Auxin

• Indole Acetic Acid-IAA (IBA, NAA)
• from L-tryptophan in leaf primordia
• moves from cell to cell in a basipetal direction
• invloved in bending of coleoptile toward light
• inhibition of lateral buds by terminal buds
  (apical dominance)
• formation of abscission layer in leaves and fruit
• activation of cambial cell growth
• Induction of adventitious roots on cuttings, etc.

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Cytokinin

• Promote cell division
• Delays senescence
• stimulates protein synthesis
• Interaction between auxin and cytokinin is one of
  the primary relationships in plant propagation.
• High cytokinin, low auxin favors shoot
  development.
• High Auxin, low cytokinin favors root
  development.
• High amounts of both, callus development

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Gibberellins

• Occurs in seeds, stem apicies, particularly leaf
  primordia, roots fruits and tubers.
• Involved in seed germination and dormancy.
• Promote shoot elongation via cell division and
  elongation.
• Application can overcome dwarfness.

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Abscisic Acid

• Classified as an inhibitor
• Synthesis occurs in chloroplasts
• present in most organs of the plant, even in
  phloem and xylem sap
• Controls dormancy in seeds, buds and abscission
  in leaves.
• Regulates stomatal closure, water and ion uptake.

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Ethylene

• Involved in epinasty, senescence and leaf and
  fruit abscission.
• Promotes flowering, stimulates lateral bud
  growth.
• Induce initiation of adventitious roots,
  stimulate germination of some seeds and overcome
  dormancy.

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Life Cycles

• Ontogenetic Changes
• annuals, biennials, perennials
• Phase Changes-juvenile to adult
• Clonal Life Cycle- eg. Apple, pear, citrus
• Apomictic Life Cycle-Apomixisembryo development
  from vegetative parts of the seed structure.
  Adventitious, recurrent apomixis and nonrecurrent
  apomixis.

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Adventitious Embryony

• Also known as Nucellar Embryony or Nucellar
  Budding.
• Originates from cells of the nucellus or within
  the embryo sac or from the integument.
• More than one embryo produced, one being sexual,
  the remainder apomictic.
• Typical for citrus and mango species

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BotanicalClassification

• Plantae
• Spermatophytes
• Angiospermae
• Monocotyledonae
• Dicotyledonae
• Gymnosermae
• Filicinae
• Families, Species, Cultivars/Varieties

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Legal Protection of Cultivars

• Patents
• Plant Variety Protection
• Trademarks
• Utility Patents