We developed a DNA microarray representing 2,755 gut-specific transcripts from the European corn borer (ECB, Ostrinia nubilalis) larvae. Our microarray analysis putatively identified 174 genes whose expression changed by at least 2 folds after the early fourth-instar larvae of a Cry1Ab-susceptible strain were fed the artificial diet containing Cry1Ab protoxin. Among these, 17 up-regulated genes appeared to be involved in insect defense, signaling, and transport, and 43 down-regulated genes may be involved in binding and other biological processes. A total of 13 genes, putatively encoding 8 different serine proteases, 1 cadherin-like protein, 1 alkaline phosphatase, and 3 aminopeptidases, are potentially involved in Bt toxicity or/and resistance. We further compared the gut transcriptional responses to the ingestion of transgenic Cry1Ab corn (MON810-event) leaves in the early third-instar larvae between a laboratory-selected resistant (R) strain and a susceptible (S) strain. We putatively identified 398 genes from the S strain and 264 genes from the R strain with significantly increased or decreased expression (at least 2.0 folds) levels. When both the S and R larvae were fed transgenic corn leaves, the number of differentially expressed genes and the degree of their expression changes were generally greater in the S larvae than in the R larvae. Among these genes, 17 in the S larvae and 9 in the R larvae were potentially involved in Bt toxicity or/and resistance. Two aminopeptidase genes (contig 4776 and contig 1398) were down-regulated in the S larvae, but up-regulated in the R larvae as compared with the control larvae after they were fed transgenic corn leaves for 6 h. These studies represent the first large-scale surveys of Cry1Ab protoxin and transgenic Cry1Ab corn-induced transcriptional changes in the ECB larval gut and provide a platform for functional investigation of Bt-insect interactions.

Transcriptional responses to the ingestion of Cry1Ab protoxin and Cry1Ab corn leaves in the gut of Ostrinia nubilalis larvae

246th National Meeting (2013)

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