Identification Of The New Cry1A Binding Proteins Of Helicoverpa Armigera And Their Alterations In Cry1A-resistant H.armigera Larvae

Transgenic cotton that expresses a gene derived from the bacterium Bacillus thuringiensis has been a key measure for keeping cotton bollworm Helicoverpa armigera (Hiibner), an important worldwide agricultural insect pest, under control. But H. armigera are selected under the pressure of high-dose Bt toxin produced by Bt cotton for a long time, therefore the resistance risk should not be ignored. To date, several resistant H. armigera strains have been selected in the laboratory and Helicoverpa zea from the field had developed resistance to Cry toxins. The evolvement of insect resistance to the Cry toxins is considered as the major threat to the long-term effectiveness of Bt cotton. Binding of the Cry toxins to specific receptors of the larval midgut is required for toxicity. Alterations of toxin-binding receptors are reported as main mechanisms of Bt resistance. It is indispensable to study the binding proteins in the midgut for farther understanding the molecular mechanisms of Bt resistance.We compared the differences of proteins in H. armigera brush border membrane vesicles (BBMV) between three resistant strains and the susceptible strain. The different proteins were identified by biological mass spectrometry technology. The relation between these different proteins and resistance were discussed. The results were follows:1. The results of 2D-DIGE:There were 13 proteins showed significant changes (P<0.05) in expression level in the Group Gel01, compared with susceptible strain, there had 8 proteins which expression levels were up-regulated and 5 proteins were down-regulated in BtR strain, the differences were 1.37 to 3.53-fold and 1.64 to 7.22-fold separately. There were 17 proteins showed significant changes (P<0.05) in expression level in the Group Gel02, therein 9 proteins were up-regulated and 8 proteins were down-regulated in the BtI strain, the differences were 1.22 to 2.87-fold and 1.36 to 7.72-fold respectively. Over 47 proteins showed significant changes (P<0.05) in expression level in the Group Gel03, in which 33 proteins were up-regulated and the differences were 1.22 to 3.29-fold in the IS strain,14 proteins were down-regulated and the differences were 1.25 to 2.15-fold.2.13 Differential proteins were selected and analysed by MALDI-TOF/TOF and 7 different proteins were successfully identified. The results of MALDI-TOF/TOF showed there included TER94, alkaline phosphatase 2, PREDICTED:similar to COP9 signalosome complex subunit 4, ATP synthase and trypsin 2. The relationship between these different proteins and resistance was discussed.