title: A QTL that enhances and broadens Bt insect resistance in soybean.
abstract: Effective strategies are needed to manage insect resistance to Bacillus thuringiensis (Bt) proteins expressed in transgenic crops. To evaluate a multiple resistance gene pyramiding strategy, eight soybean (Glycine max) lines possessing factorial combinations of two quantitative trait loci (QTLs) from plant introduction (PI) 229358 and a synthetic Bt cry1Ac gene were developed using marker-assisted selection with simple sequence repeat markers. Field studies were conducted in 2000 and 2001 to evaluate resistance to corn earworm (Helicoverpa zea) and soybean looper (Pseudoplusia includens), and detached leaf bioassays were used to test antibiosis resistance to Bt-resistant and Bt-susceptible strains of tobacco budworm (TBW; Heliothis virescens). Based on defoliation in the field and larval weight gain on detached leaves, lines carrying a combination of cry1Ac and the PI 229358 allele at a QTL on linkage group M were significantly more resistant to the lepidopteran pests, including the Bt-resistant TBW strain, than were the other lines. This is the first report of a complementary additive effect between a Bt transgene and a plant insect resistance QTL with an uncharacterized mode of action that was introgressed using marker-assisted selection.
authors.affiliation: Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Walker
authors.forename: James M
authors.initials: JM
authors.lastname: Narvel
authors.forename: H Roger
authors.initials: HR
authors.lastname: Boerma
authors.forename: John N
authors.initials: JN
authors.lastname: All
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Parrott
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics* / Q000633:toxicity; D001427:Bacterial Toxins / Q000235:genetics* / Q000633:toxicity; D004731:Endotoxins / Q000235:genetics* / Q000633:toxicity; D006460:Hemolysin Proteins; D007305:Insecticide Resistance / Q000235:genetics; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D018598:Minisatellite Repeats / Q000235:genetics; D009036:Moths / Q000187:drug effects / Q000254:growth & development; D010572:Pest Control, Biological / Q000379:methods*; D030821:Plants, Genetically Modified; D040641:Quantitative Trait Loci; D012641:Selection, Genetic; D013025:Glycine max / Q000235:genetics*; D019076:Transgenes / Q000235:genetics
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis