Multiple insect resistance in transgenic tomato plants over-expressing two families of plant proteinase inhibitors.
Protease inhibitors have been proposed as potential defense molecules for increased insect resistance in crop plants. Compensatory over-production of insensitive proteases in the insect, however, has limited suitability of these proteins in plant protection, with very high levels of inhibitor required for increased plant resistance. In this study we have examined whether combined used of two inhibitors is effective to prevent this compensatory response. We show that leaf-specific over-expression of the potato PI-II and carboxypeptidase inhibitors (PCI) results in increased resistance to Heliothis obsoleta and Liriomyza trifolii larvae in homozygote tomato lines expressing high levels (>1% the total soluble proteins) of the transgenes. Leaf damage in hemizygous lines for these transformants was, however, more severe than in the controls, thus evidencing a compensation response of the larvae to the lower PI concentrations in these plants. Development of comparable adaptive responses in both insects suggests that insect adaptation does not entail specific recognition of the transgene, but rather represents a general adaptive mechanism triggered in response to the nutritional stress imposed by sub-lethal concentrations of the inhibitors. Combined expression of defense genes with different mechanisms of action rather than combinations of inhibitors may then offer a better strategy in pest management as it should be more effective in overcoming this general adaptive response in the insect.
Abdeen
Ashraf
A
Departmento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-CSIC, Campus Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain.
Virgós
Ariadna
A
Olivella
Elisenda
E
Villanueva
Josep
J
Avilés
Xavier
X
Gabarra
Rosa
R
Prat
Salomé
S
D000818:Animals; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004175:Diptera / Q000201:enzymology / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D007313:Insecta / Q000201:enzymology / Q000254:growth & development*; D007422:Intestines / Q000201:enzymology; D007700:Kinetics; D007814:Larva / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism / Q000469:parasitology; D009036:Moths / Q000201:enzymology / Q000254:growth & development; D010447:Peptide Hydrolases / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics* / Q000469:parasitology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000469:parasitology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D030821:Plants, Genetically Modified; D011480:Protease Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D011198:Solanum tuberosum / Q000235:genetics
D010940:Plant Proteins; D011480:Protease Inhibitors; D002268:Carboxypeptidases; D010447:Peptide Hydrolases