Bt toxins kill insects by binding to various receptors at insect midgut
and creating pores on the midgut membranes. However, the application of
Bt toxins in agriculture is threatened by evolved resistance of insects.
Our understanding of molecular basis in insects involved in Bt toxin
binding is incomplete, especially in diamondback moth (DBM, Plutella
xylostella), a major agricultural pest. Identifying Bt toxin receptors
has remained challenging due to lacking sufficiently sensitive methods.
Here, we report a novel technique, on-membrane capture, that identified
numbers of previously unknown proteins, in addition to known receptors
like cadherin and APN2, from the DBM midgut as binding partners of three
Bt toxins Cry1Ac, Cry1Ab, and Cry1Bd. Among them, glucosinolate
sulfatases GSS1 and GSS2 are receptors specifically interacted with
Cry1Bd. Reduction in GSSs expression increased tolerance of DBM to Bt
toxins. Expressing DBM GSSs in silkworms dramatically decreased the
tolerance of the transgenic silkworms to Cry1Bd. Therefore, the
on-membrane capture provides a new solution to identify Bt toxin
receptors in insects.