38th Annual Meeting of the Society for Invertebrate Pathology

We previously reported detection of alkaline phosphatase (HvALP) that bound Cry1Ac toxin in brush border membranes from Heliothis virescens. Both alkaline phosphatase-specific activity and HvALP protein levels were reduced in Cry1Ac-resistant larvae of the H. virescens YHD2 strain, but not in susceptible offspring from backcrosses, suggesting a direct correlation between HvALP levels and Cry1Ac resistance (Jurat-Fuentes and Adang 2004, Eur. J. Biochem., 271:3127-35).
In H. virescens brush border membrane proteins separated by 2-dimensional (2D) gel electrophoresis, we identified HvALP as a chain of protein spots recognized by antiserum against membrane-bound ALP. In qualitative comparisons of HvALP in susceptible (YDK) and resistant (YHD2, CXC, and KCBhyb) H. virescens strains using 2D immunoblots, reduced amounts of HvALP were detected in all resistant strains. Alkaline phosphatase activity was significantly reduced in all resistant strains when compared to susceptible samples, further evidence for a direct correlation between reduced HvALP levels and Cry1Ac resistance. Furthermore, HvALP and Cry1Ac, together with cadherin, are co-localized in lipid rafts in the brush border membranes of H. virescens. These results support the potential use of HvALP alterations as a marker for Cry1Ac resistance in H. virescens.