clones in plants

• tissue culture


  • growing new tissues, organs or plants from certain tissues cut from from sample plants
• micro propagation


  • growing large numbers of plants from meristem tissue taken from a sample plant
• cuttings


  • to make a cutting a stem is cut between two leaf joints (nodes)
  • the cut end of the stem is then placed in soil where new roots will grow from the tissues in the stem
  • dipping the stem in rooting hormone helps to stimulate root growth
  • this produces large numbers of plants quickly
  • cuttings can also be made from roots, dormant twigs and leaves.
• micro propagation

  1. cells taken from shoot (called explant)
  2. cells sterilised before being placed onto nutrient medium
  3. explants placed on sterile growth medium. Forms a callus cultured divided to produce lots of small clumps or undifferentiated cells
  4. transferred to a new agar medium - plantlets grow
  5. plantlets are transferred into compost
• Advantages

  • Rapid compared to growing from seeds
  • Disease free plants
  • Increase number of rare plants
  • Large numbers of seedless plants
  • Naturally infertile plants can be grown
• Disadvantages

  • Monoculture - genetically identical - susceptible to same diseases
  • Expensive and requires skilled workers
  • Explains and plantlets are vulnerable to mould during the process
  • if source materials infected with a virus, all new plants are infected
• vegetative propagation

  natural plant cloning - plants can reproduce without fertilisation to produce genetically identical clones
• runner

  A clone is produced using an overground horizontal stem called a runner
• tuber

  A clone is produced using a swollen, underground piece of stem called a tuber
• bulb

  A clone is produced from an underground stem, enclosed by layers of leaves, called a bulb
• rhizome

  A clone is produced using an underground horizontal stem called a rhizome
• cutting

  Gardners can encourage plants to naturally clone. To do this, part of the stem of a healthy is removed, dipped in growth hormone and then placed in soil in a covered pot.
• micropropagation steps

  1. a small sample of meristem tissue, called an explant is taken from a healthy plant.
  2. the sample is sterilised to reduce the chances of contamination
  3.  the sample is cultured with growth hormones causing a mass of cells, called a callus to grow.
  4. this mass of cells is divided and grown in new cultures to form plantlets which are potted
• micropropagation

  advantages:

  • rapidly produces a large number of clones
  • plants can be grown at any time of the year
  • it can grow plants which are difficult to grow from seeds

  disadvantages:

  • requires expensive equipment
  • all clones are susceptible to the same diseases
  • requires a lot of skill