Micropropagation

• Useful if desirable plant doesn’t readily produce seeds or respond well to natural cloning, is required to be ‘pathogen-free’, is very rare and if it is genetically modified or selectively bred
• There are many ways plants can be micropropagated, but basic principles remain same
• 1 Small meristem (because it is totipotent) tissue sample taken from plant’s shoot tips/axial buds in sterile conditions (explant)
• 2. Explant is sterilised (to kill microgoranism, that would grow using agar) with dilute bleach or alcohol, then placed on a sterile growth medium (agar gel)
• 3. Gel contains glucose, amino acids, phosphates, and high concentrations of plant hormones stimulating mitosis (stimulate growth/proliferation of cells)
• 4. Cells proliferate, form callus; divided into larger number of individual cells/clumps and put in new sterile growth medium
• 5. Each growth medium has different ratios (to promote different tissues) of plant hormones, auxin and cytokinin; stimulate root and shoot development to form plantlets
• 6. Once tiny plantlets have formed, they are potted into compost where they grow to small plants, young plants are grown in a greenhouse to acclimatise to normal growing conditions (provide optimum growth conditions)
• Advantages: - Rapid production of large numbers with known genetic make up, can produce disease free plants and viable numbers of plants after genetic modification - Can produce large seedless numbers, and grow relatively infertile plants or those difficult to grow from seeds, also increase numbers of rare/endangered plants
• Disadvantages: - Monoculture: Genetic variation lack; all plants susceptible to same disease/ environmental conditions, also it is expensive, and requires skilled workers - They’re vulnerable to moulds and other diseases in production, if source material is infected, all clones will also be infected, and sometimes large numbers are lost in process
• Application

  • Bananas are commonly grown with natural asexual reproduction to produce a seedless fruit
  • One species was wiped out in early 20th century due to disease susceptibility, another disease is now destroying species commonly grown now