Scientists Investigate Asian Corn Borer Larvae's Mechanism of Tolerance to Bt Toxins

A population of Asian corn borer with greater resistance (~100-fold) to Cry1Ab than a susceptible population exhibited high levels of cross-resistance to Cry1Ah (131-fold), but had no cross-resistance to Cry1le. It was suggested that the cross resistance was caused by a change on the receptors of Cry toxins present in the midgut of the Asian corn borer larvae. Another study was conducted by Lina Xu of Chinese Academy of Agricultural Sciences and colleagues to identify the proteins from the brush border membrane vesicles from the midgut of both resistant and susceptible Asian corn borer larvae interacting with biotinylated Bt proteins (Cry1Ab, Cry1Ah, and Cry1Ie).

2D-Electrophoresis with ligand blots were used and actual protein identities were characterized through MALDI-ToF/ToF mass spectrometry. The V-type proton ATPase catalytic subunit A and heat shock 70 kDa proteins were identified as interacting with the Cry toxins tested in the resistant and susceptible larvae. Results also showed that the biotinylated Bt proteins had stronger interactions with proteins in the resistant compared to the susceptible larvae, which implies that there is increased V-type proton ATPase catalytic subunit A and heat shock 70 kDa proteins in the resistant larvae. Cry1Ie interactions with the V-type proton ATPase catalytic subunit A in the susceptible larvae were not found.

Read the abstract at http://link.springer.com/article/10.1007/s11248-013-9718-3.