title: Synergistic activity of a Bacillus thuringiensis delta-endotoxin and a bacterial endochitinase against Spodoptera littoralis larvae.
abstract: In an attempt to increase the insecticidal effect of the delta-endotoxin crystal protein CryIC on the relatively Cry-insensitive larvae of Spodoptera littoralis, a combination of CryIC and endochitinase was used. CryIC comprising the first 756 amino acids from Bacillus thuringiensis K26-21 and endochitinase ChiAII encoded by Serratia marcescens were separately produced in Escherichia coli carrying the genes in overexpression vectors. The endochitinase on its own, even at very low concentrations (0.1 microgram/ml), perforated the larval midgut peritrophic membrane. When applied together with low concentrations of CryIC, a synergistic toxic effect was obtained. In the absence of chitinase, about 20 micrograms of CryIC per ml was required to obtain maximal reduction in larval weight, while only 3.0 micrograms of CryIC per ml caused a similar toxic effect in the presence of endochitinase. Thus, a combination of the Cry protein and an endochitinase could result in effective insect control in transgenic systems in which the Cry protein is not expressed in a crystalline form.
authors.affiliation: Department of Botany, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Regev
authors.forename: M
authors.initials: M
authors.lastname: Keller
authors.forename: N
authors.initials: N
authors.lastname: Strizhov
authors.forename: B
authors.initials: B
authors.lastname: Sneh
authors.forename: E
authors.initials: E
authors.lastname: Prudovsky
authors.forename: I
authors.initials: I
authors.lastname: Chet
authors.forename: I
authors.initials: I
authors.lastname: Ginzberg
authors.forename: Z
authors.initials: Z
authors.lastname: Koncz-Kalman
authors.forename: C
authors.initials: C
authors.lastname: Koncz
authors.forename: J
authors.initials: J
authors.lastname: Schell
authors.forename: A
authors.initials: A
authors.lastname: Zilberstein
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology / Q000633:toxicity; D001427:Bacterial Toxins; D002462:Cell Membrane / Q000187:drug effects; D002688:Chitinases / Q000235:genetics / Q000494:pharmacology; D004357:Drug Synergism; D004731:Endotoxins / Q000235:genetics / Q000494:pharmacology / Q000633:toxicity; D004926:Escherichia coli / Q000235:genetics; D006460:Hemolysin Proteins; D007814:Larva; D010572:Pest Control, Biological / Q000379:methods*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012706:Serratia marcescens / Q000201:enzymology; D018411:Spodoptera
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D002688:Chitinases; C094590:chitinase ChiA