A P-Glycoprotein Is Linked to Resistance to the Bacillus thuringiensis Cry3Aa Toxin in a Leaf Beetle

Abstract

Chrysomela tremula is a polyvoltine oligophagous leaf beetle responsible for massive attacks on poplar trees. This beetle is an important model for understanding mechanisms of resistance to Bacillus thuringiensis (Bt) insecticidal toxins, because a resistant C. tremula strain has been found that can survive and reproduce on transgenic poplar trees expressing high levels of the Cry3Aa Bt toxin. Resistance to Cry3Aa in this strain is recessive and is controlled by a single autosomal locus. We used a larval midgut transcriptome for C. tremula to search for candidate resistance genes. We discovered a mutation in an ABC protein, member of the B subfamily homologous to P-glycoprotein, which is genetically linked to Cry3Aa resistance in C. tremula. Cultured insect cells heterologously expressing this ABC protein swell and lyse when incubated with Cry3Aa toxin. In light of previous findings in Lepidoptera implicating A subfamily ABC proteins as receptors for Cry2A toxins and C subfamily proteins as receptors for Cry1A and Cry1C toxins, this result suggests that ABC proteins may be targets of insecticidal three-domain Bt toxins in Coleoptera as well.

Investigation of Cry3Bb1 resistance and intoxication in western corn rootworm by RNA sequencing

“…A mapping study in WCR also identified a link between Cry3Bb1 resistance and a gene coding for ABCB2 (Flagel et al., ) , an ABC transporter of a different family than the families of ABC transporters identified in Lepidoptera. Moreover, an ABCB2 has been genetically linked to Cry3A resistance and to its mode of action in another Chrysomelid, Chysomela tremula Fabricius (Pauchet et al., ).…”

“…These authors also observed that the resistant L. decemlineata expressed different protease isoforms relative to the susceptible strain and that the overall toxin binding was decreased in the resistant midgut. In a laboratory‐selected strain of Chrysomela tremula Fabricius, Cry3A resistance was linked to a four base pair deletion in one of the intracellular domains of an ABCB transporter (Pauchet, Bretschneider, Augustin, & Heckel, ).…”

“…resistance was linked to a four base pair deletion in one of the intracellular domains of an ABCB transporter (Pauchet, Bretschneider, Augustin, & Heckel, 2016).…”

Knockout of a P‐glycoprotein gene increases susceptibility to abamectin and emamectin benzoate in Spodoptera exigua

“…In arthropods, recent studies have suggested that ABC transporters can actively export conjugated toxins out of the cell and contribute to xenobiotic resistance (Luo et al ., ; Tian et al ., ; Chen et al ., ; Xu et al ., ). Moreover, members of ABC transporter subfamilies C2 (Gahan et al ., ; Baxter et al ., ; Atsumi et al ., ; Park et al ., ; Xiao et al ., ), A2 (Tay et al ., ) and P‐gp (Pauchet et al ., ) have been reported as critical determinants of susceptibility to insecticidal proteins from the bacterium Bacillus thuringiensis (Bt).…”

“…In arthropods, recent studies have suggested that ABC transporters can actively export conjugated toxins out of the cell and contribute to xenobiotic resistance (Luo et al, 2013;Tian et al, 2013;Chen et al, 2016a;Xu et al, 2016). Moreover, members of ABC transporter subfamilies C2 (Gahan et al, 2010;Baxter et al, 2011;Atsumi et al, 2012;Park et al, 2014;Xiao et al, 2014), A2 (Tay et al, 2015) and P-gp (Pauchet et al, 2016) have been reported as critical determinants of susceptibility to insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). P-gp is an ABC transporter containing two cytosolic nucleotide-binding domains (NBDs), and two integral transmembrane domains, each consisting of five or six transmembrane segments (Tian et al, 2013).…”