Binding and toxicity of Bacillus thuringiensis protein Cry1C to susceptible and resistant in diamondback moth (lepidoptera: plutellidae)

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TypeArticle
Journal titleJournal of Economic Entomology
Volume93
Issue1
Pages16; # of pages: 6
Subjectenv; plutella xylostella; bacillus thuringiensis; Cry1C; resistance; mechanism; binding
AbstractWe studied mechanisms of resistance to Bacillus thuringiensis insecticidal crystal protein Cry1C in the diamondback moth, Plutella xylostella (L.). Binding assays with midgut brush border membrane vesicles prepared from whole larvae showed no signiÞcant difference between resistant and susceptible strains in binding of radioactively-labeled Cry1C. These results indicate that reduced binding of Cry1C to midgut membrane target sites did not cause resistance to Cry1C. Thus, the mechanism of resistance to Cry1C differs from that observed in several previously reported cases of resistance to Cry1A toxins in diamondback moth. We tested Cry1C toxin and Cry1C crystalline protoxin against resistant and susceptible larvae using leaf disk bioassays. After adjusting for the size difference between Cry1C toxin and protoxin, we found that with resistant larvae, toxin was signiÞcantly more toxic than protoxin. In contrast, with susceptible larvae, no signiÞcant difference in toxicity occurred between Cry1C toxin and protoxin. The resistance ratios for Cry1C were 19 for toxin and 48 for protoxin. These results suggest that reduced conversion of Cry1C protoxin to toxin is a minor mechanism of resistance to Cry1C. Because neither reduced binding nor reduced conversion of protoxin to toxin appear to be major mechanisms, one or more other mechanisms are important in diamondback moth resistance to Cry1C.
Publication date
LanguageEnglish
AffiliationNRC Biotechnology Research Institute; National Research Council Canada
Peer reviewedNo
NRC number41854
NPARC number3539918
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Record identifier6580fa43-1384-4424-ba86-63bb59315a8e
Record created2009-03-01
Record modified2016-05-09
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