Bacillus thuringiensis Cry1Ab domain III β-22 mutants with enhanced toxicity to Spodoptera frugiperda (J. E. Smith).

Bacillus thuringiensis Cry1Ab domain III β-22 mutants with enhanced toxicity to Spodoptera frugiperda (J. E. Smith). Appl Environ Microbiol. 2020 Sep 04;: Authors: Gómez I, Ocelotl J, Sánchez J, Aguilar-Medel S, Peña-Chora G, Lina-Garcia L, Bravo A, Soberón M Abstract The fall armyworm, Spodoptera frugiperda, is an invasive maize pest that has spread from the Americas into Africa and Asia causing severe crop damages worldwide. Most populations of S. frugiperda show low susceptibility to Bacillus thuringiensis (Bt) Cry1Ab or Cry1Ac toxins, which have been proved to be effective against several other lepidopteran pests. In addition, S. frugiperda has evolved resistance to transgenic maize expressing Cry1Fa toxin. Cry toxins specificity and toxicity is determined by their binding to different larvae midgut proteins such as aminopeptidase-N (APN), alkaline phosphatase (ALP) and cadherin (CAD), among other proteins, by means of exposed domain II loop regions and also by domain III β16-β22 region. Here we analyzed different Cry1Ab mutants in domain III β22 region. The alanine scanning mutagenesis of this region revealed that all mutants showed increased toxicity against a non-susceptible Cry1Ab S. frugiperda population. Further analysis of the mutant toxin Cry1AbS587A revealed that it showed significant increased toxicity, compared to Cry1Ab, to other three different S. frugiperda populations from Mexico but retained similar toxici...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research