Summary - Gene Constructs

  • When designing genes, genetic engineers must keep in mind:
    1. Timing of protein production - controlled by the promoter
    2. Location where the protein is needed - controlled by the promoter
    3. How much protein to produce - controlled by the promoter
    4. Which protein should be produced - controlled by the coding region.
  • Input traits are those that potentially alter inputs needed in production. Examples: Bt corn where the need to apply a pesticide to control European corn borer is eliminated, Roundup resistant crops that allow producers to spray Roundup for weed control without damaging crop plants.   
  • Output traits are those that alter the harvested product. Example - High-oleic acid soybeans, which have improved the product for food and industrial uses.
  • Gene constructs:
    • Gene: Bt
      1. Promoters - 35S or PEP Carboxylase
      2. Coding Regions - Cry1A(b), Cry1A(c), or Cry9c
      3. Expression - If 35S promoter, then ECB resistance in all tissues all the time. If PEP Carb. promoter, then ECB resistance in actively photosynthesizing (green) tissues only.
    • Gene: Roundup resistance
      1. Promoter - 35S
      2. Coding Region - EPSPS enzyme (Roundup resistance) + CTP region to send protein to chloroplasts
      3. Expression - Roundup resistance in all plant tissues all the time.
    • Gene: Liberty resistance
      1. Promoter - 35S
      2. Coding Region - PAT (Liberty resistance)
      3. Expression - Liberty resistance in all plant tissues all the time.
    • Yield drag occurs when production of the added gene uses too great a share of the limited pool of amino acids. As a result, there may not be enough amino acids to produce other proteins important for plant growth and yield and yield potential may actually decrease.
Previous Page