A β-1,3-galactosyltransferase and brainiac/bre5 homolog expressed in the midgut did not contribute to a Cry1Ab toxin resistance trait in Ostrinia nubilalis

Post-translational glycosylation of midgut epithelial protein and lipid receptors may be required prior to binding of activated Bacillus thuringiensis (Bt) Cry toxins. A 931 bp cDNA encoding a putative 297-residue β-1,3-galactosyltransferase (β3GalT5) was cloned from larval Ostrinia nubilalis midgut tissue, and showed homology to Drosophila brainiac (brn) and Caenorhabditis elegans bre5 proteins. Single nucleotide polymorphisms (SNPs) were detected in coding and promoter regions of O. nubilalis β3GalT5 (Onb3GalT5), of which 3 of 31 CDS SNPs were non-synonymous. SNPs within HaeIII and MspI recognition sites were confirmed by PCR–RFLP, and are Mendelian inherited. Analysis of F2 pedigrees suggested an Onb3GalT5 SNP C660 fixed within a Cry1Ab-resistant colony was not correlated with Cry1Ab resistance traits, as measured by higher larval O. nubilalis weights when fed toxin-containing diet.