title: Insect resistance of transgenic tobacco expressing an insect chitinase gene.
abstract: Chitinase expression in the insect gut normally occurs only during moulting, where the chitin of the peritrophic membrane is presumably degraded. Thus, insects feeding on plants that constitutively express an insect chitinase gene might be adversely affected, owing to an inappropriately timed exposure to chitinase. This hypothesis was tested by introducing a cDNA encoding a tobacco hornworm (Manduca sexta) chitinase (EC 3.2.1.14) into tobacco via Agrobacterium tumefaciens-mediated transformation. A truncated but enzymatically active chitinase was present in plants expressing the gene. Segregating progeny of high-expressing plants were compared for their ability to support growth of tobacco budworm (Heliothis virescens) larvae and for feeding damage. Both parameters were significantly reduced when budworms fed on transgenic tobacco plants expressing high levels of the chitinase gene. In contrast, hornworm larvae showed no significant growth reduction when fed on the chitinase-expressing transgenics. However, both budworm and hornworm larvae, when fed on chitinase-expressing transgenic plants coated with sublethal concentrations of a Bacillus thuringiensis toxin, were significantly stunted relative to larvae fed on toxin-treated non-transgenic controls. Foliar damage was also reduced. Plants expressing an insect chitinase gene may have agronomic potential for insect control.
authors.affiliation: Department of Plant Pathology, Kansas State University, Manhattan 66506-5502, USA.
authors.forename: X
authors.initials: X
authors.lastname: Ding
authors.forename: B
authors.initials: B
authors.lastname: Gopalakrishnan
authors.forename: L B
authors.initials: LB
authors.lastname: Johnson
authors.forename: F F
authors.initials: FF
authors.lastname: White
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: T D
authors.initials: TD
authors.lastname: Morgan
authors.forename: K J
authors.initials: KJ
authors.lastname: Kramer
authors.forename: S
authors.initials: S
authors.lastname: Muthukrishnan
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002688:Chitinases / Q000235:genetics* / Q000378:metabolism; D004731:Endotoxins; D006460:Hemolysin Proteins; D018402:Manduca / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D009036:Moths / Q000254:growth & development*; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics*; D010947:Plants, Toxic; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics*; D014170:Transformation, Genetic; D019076:Transgenes
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D002688:Chitinases