Characterization of a Toxoneuron nigriceps (Viereck) (Hymenoptera: Braconidae) – derived chitinase and its potential for pest control

• Published in: Pesticide biochemistry and physiology Vol. 104; no. 2; pp. 96 - 102
• Main Authors: Rossi, Guilherme D., Labate, Mônica T.V., Labate, Carlos A., Vinson, S.B., Cônsoli, Fernando L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier Inc 01.10.2012; Elsevier
• Subjects: Antimicrobial agents; Asepsis; Biological and medical sciences; Biotechnology; Braconidae; calyx; Chitin; Chitinase; Chitolectins; Chitotriosidases; Colonization; complementary DNA; control methods; Cuticles; Digestion; endoparasitoids; Escherichia coli; females; Fundamental and applied biological sciences. Psychology; genes; Heliothis virescens; Herbivores; Hymenoptera; insect development; insect pests; Insects; Larvae; Leaves; Lepidoptera; Noctuidae; parasitism; Parasitoid; Parasitoids; Pathogens; Pest control; Pesticides; Pests; plant pathogens; plant pests; Polydnaviridae; Polydnavirus; Proteins; Secretions; Survival; Teratocytes; Tobacco; Toxoneuron nigriceps; Transgenic plants; Venom; venoms; Weapons; Biotechnology; Teratocytes; Parasitoid; Chitolectins; Chitotriosidases; Chitinase; Enzyme; Insecta; Pesticides; Potential; Glycosylases; Characterization; Pest management; Arthropoda; Glycosidases; Hydrolases; Hymenoptera; Invertebrata; Braconidae
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2012.07.005

[Display omitted] ► A chitinase of Toxoneuron nigriceps (TnChi) was expressed in tobacco plants. ► The binding efficiency of Tnchi to chitin is pH dependent. ► Tnchi lacks chitinolytic activity, but has insecticidal activity. ► Bioassays and bioinformatics indicated Tnchi as an inactive chitotriosidase with chitin binding properties. The larval endoparasitoid Toxoneuron nigriceps (Viereck) (Hymenoptera: Braconidae) has a toolbox of biological weapons to secure for host colonization and the successful parasitization of its host Heliothis virescens (F.) (Lepidoptera: Noctuidae). The cDNA of a putative chitinase has been previously isolated and initially characterized from teratocytes of this parasitoid among the plethora of molecules available in the venom and calyx fluids injected by females, oral and/or anal secretions released by the parasitoid larvae and/or produced by the expression of genes of the symbiotic associated polydnavirus. This putative chitinase has been initially associated with the host cuticle digestion to allow for parasitoid egression and with the asepsis of the host environment, acting as an antimicrobial. As chitinases are commonly expressed in plants against plant pathogens, the chitinase derived from the teratocytes of T. nigriceps is a potential tool for the development of insect pest control methods based on the disruption of the perithrophic membrane of herbivores. Therefore, we aimed to characterize the activity of the putative chitinase from teratocytes of T. nigriceps (Tnchi) produced using the Escherichia coli expression system and its potential to control H. virescens larvae when expressed into transgenic tobacco plants. The purified E. coli-produced Tnchi protein showed no chitinolitic activity, but was active in binding with colloidal and crystalline chitins in water and with colloidal chitin in buffered solution (pH=6.74). Transgenic tobacco plants showed no enhanced chitinolitic activity relative to control plants, but survival of three-day old larvae of H. virescens was severely affected when directly fed on transgenic tobacco leaves expressing the recombinant Tnchi protein. Some properties of the Tnchi protein and the potential use of Tnchi-transgenic plants to control plant pests are discussed.