3.2 - Plant & Animal Breeding

• Plant field trials


  Used to investigate the performance of different plant cultivars or treatments under the same set of environmental conditions and the effect different environmental conditions have on a new cultivar of a crop plant. When designing a plant field trial, considerations include the selection of treatments used, number of replicates, and randomisation of treatments
• Selecting and breeding


  Over many years, farmers and breeders have selected the plants and animals with the best characteristics to be the parents of the next generations. This allows them to bring together the desired alleles of two organisms, producing offspring superior to the parents
• Inbreeding


  Involves two closely related relatives reproducing. This is done for several generations until the population breeds true to the desired type due to the elimination of heterozygotes
• While inbreeding can be used to develop desired characteristics, there can be negative results
• Population breeding


  Done for several generations until the population breeds true to the desired type due to the elimination of heterozygotes
• Crossbreeding animals


  New alleles introduced by crossbreeding individuals from different breeds to produce a new crossbred population with improved characteristics
• Crossbreeding plants


  Hybridisation between two different homozygous inbred plants results in an F1 generation of hybrids that create a relatively uniform heterozygous crop with increased vigour, yield, and fertility
• Genetic sequencing allows scientists to determine the precise sequence of DNA nucleotides for a living organism
• Using genetic technology in breeding programmes


  Identifying organisms with desired characteristics through genetic sequencing and inserting single genes for desirable characteristics into crop plants to create genetically modified plants with improved traits
• What are the effects of inbreeding depression?

  Increase in frequency of recessive deletorous alleles. They will do less well at surving and reproducing.
• What is crossbreeding?

  Crossing a cultivar or breed with an individual who has a different desired genotype. May produce a new crossbreed with improved characteristics.
• Hybrid vigour causes an increase of vigour, yield and fertility
• What is genetic sequencing?

  Genetic sequencing techniques can be used to identify organisms that possess particular alleles for a desired characteristic. This organism can then be selected for use in a breeding programme
• What is genetic transformation?

  Breeding programmes can involve crop plants that have been genetically modified using recombinant DNA technology.

  Single genes for desirable characteristics can be inserted into the genomes of crop plants, creating genetically modified plants with improved characteristics.