The main distinctive insecticidal properties of B. thuringiensis lays on the production of specific proteins. The best known ones are accumulated during the sporulation phase in a compact aggregate in the parasporal body called “crystal”. Then, proteins present are called crystal proteins (or Cry proteins). In addition, other proteins are released in the vegetative phase (vegetative insecticidal proteins, or Vip) and they are not structurally related to the previous ones.
Cry or Vip proteins are not homogeneous groups and they are classified in more than 70 Cry types and 4 Vip types at the present moment. New NGS technologies are providing an increasing number of genes for which no studies on their expression or pesticidal characterization has been carried out. It has been reported some association about the type of gene and the toxicity to a group of insects (i.e Cry1A toxic to Lepidoptera), so it is possible to look for a gene toxic for a target in a group of genes with no known member toxic for such species.
The finding of novel genes that codify for novel insecticidal proteins will allow improving both Bt-based insecticides and Bt-crops (crops protected from insect attack by expressing a gene from Bt). Different screening programs based on protein gene detection and protein expression are being carried out resulting in the discovery of several novel genes, which are being cloned, sequenced and expressed to determine their insecticidal potential. We have an especial interest on new types of proteins from poorly characterized families.
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