Three cadherin alleles associated with resistance to Bacillus thuringiensis in pink bollworm.
Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. Because inheritance of resistance to the Bt toxins in transgenic crops is typically recessive, DNA-based screening for resistance alleles in heterozygotes is potentially much more efficient than detection of resistant homozygotes with bioassays. Such screening, however, requires knowledge of the resistance alleles in field populations of pests that are associated with survival on Bt crops. Here we report that field populations of pink bollworm (Pectinophora gossypiella), a major cotton pest, harbored three mutant alleles of a cadherin-encoding gene linked with resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Each of the three resistance alleles has a deletion expected to eliminate at least eight amino acids upstream of the putative toxin-binding region of the cadherin protein. Larvae with two resistance alleles in any combination were resistant, whereas those with one or none were susceptible to Cry1Ac. Together with previous evidence, the results reported here identify the cadherin gene as a leading target for DNA-based screening of resistance to Bt crops in lepidopteran pests.
Morin
Shai
S
Department of Entomology, University of Arizona, Tucson, AZ 85721, USA.
Biggs
Robert W
RW
Sisterson
Mark S
MS
Shriver
Laura
L
Ellers-Kirk
Christa
C
Higginson
Dawn
D
Holley
Daniel
D
Gahan
Linda J
LJ
Heckel
David G
DG
Carrière
Yves
Y
Dennehy
Timothy J
TJ
Brown
Judith K
JK
Tabashnik
Bruce E
BE
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001413:Bacillus thuringiensis / Q000472:pathogenicity*; D001681:Biological Assay; D015820:Cadherins / Q000737:chemistry / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D007915:Lepidoptera / Q000235:genetics / Q000382:microbiology*; D008297:Male; D008969:Molecular Sequence Data; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D015820:Cadherins