Plant Reproduction

Fertilization

• Double fertilization occurs in flowering plants:
  • One sperm fuses with the egg cell to form a zygote (embryo)
  • Another sperm fuses with the central cell to form the endosperm
• Fertilization occurs in the embryo sac, which is the female gametophyte
• The resulting zygote develops into an embryo, while the endosperm provides nutrients

Pollination

• Pollination is the transfer of pollen from the anther to the stigma
• Types of pollination:
  • Self-pollination: pollen from the same flower or plant
  • Cross-pollination: pollen from a different plant
• Agents of pollination:
  • Insects (bees, butterflies, moths)
  • Birds
  • Bats
  • Wind
• Pollen-pistil interaction:
  • Pollen germination on the stigma
  • Pollen tube growth through the style
  • Fertilization occurs in the embryo sac

Gametophyte Development

• Male gametophyte (microgametophyte):
  • Develops from a microspore
  • Consists of two sperm cells and one vegetative cell
• Female gametophyte (megagametophyte):
  • Develops from a megaspore
  • Consists of seven cells: one egg cell, two synergid cells, three antipodal cells, and one central cell
• Both male and female gametophytes are haploid

Embryogenesis

• Embryo development:
  • Proembryo stage: formation of the apical meristem and cotyledons
  • Embryo proper stage: differentiation of root, stem, and leaves
• Pattern formation:
  • Radial pattern: organization of tissues in concentric layers
  • Apical-basal pattern: organization of tissues along the axis
• Embryo maturation:
  • Accumulation of storage products (e.g., starch, proteins)
  • Desiccation and dormancy