Selective Breeding in Plants (Edexcel IGCSE Biology: Double Science)

• Selective breeding of plants takes place in the same way as selective breeding of animals
• Plants are selectively bred by humans for development of many characteristics, including:
  • Disease resistance in food crops
  • Increased crop yield
  • Hardiness to weather conditions (eg. drought tolerance)
  • Better tasting fruits
  • Large or unusual flowers

• An example of a plant that has been selectively bred in multiple ways is wild brassica, which has given rise to cauliflower, cabbage, broccoli, brussel sprouts, kale and kohlrabi:

An example of selective breeding in plants

Problems with selective breeding

• Selective breeding can lead to ‘inbreeding’
• This occurs when only the ‘best’ animals or plants (which are closely related to each other) are bred together
• This results in a reduction in the gene pool – this is a reduction in the number of alleles (different versions of genes) in a population
• As inbreeding limits the size of the gene pool, there is an increased chance of:
  • Organisms inheriting harmful genetic defects
  • Organisms being vulnerable to new diseases (there is less chance of resistant alleles being present in the reduced gene pool)