Characterization of cDNAs encoding three trypsin-like proteinases and mRNA quantitative analysis in Bt-resistant and -susceptible strains of Ostrinia nubilalis.

摘要: Our previous studies suggested that Bacillus thuringiensis (Bt) resistance in a Dipel-resistant strain of Ostrinia nubilalis was primarily due to reduced trypsin-like proteinase activity. In this study, we demonstrated 254-fold Cry1Ab protoxin but only 12-fold trypsin-activated toxin the strain. Significantly higher than further supports hypothesis activity leading activation Bt is major mechanism To understand molecular basis activity, three cDNAs, OnT2, OnT23, and OnT25, encoding full-length proteinases, were sequenced Bt-resistant -susceptible O. larvae. Although number nucleotide differences found sequences from strains, not consistent with However, mRNA levels OnT23 resistant 2.7- 3.8-fold lower those susceptible as determined by northern blotting real-time quantitative PCR, respectively. Thus, may be attributed expression nubilalis. study provides new insights into management strategies, mediated would ineffective if insects ingest fully activated form toxin, either spray formulations or transgenic crops.