Opposite Effects on Spodoptera littoralis Larvae of
High Expression Level of a Trypsin Proteinase Inhibitor in Transgenic
Plants |
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Authors: | Francesca De Leo Michel A Bonadé-Bottino Luigi R Ceci Raffaele Gallerani and Lise Jouanin |
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Institution: | Dipartimento di Biochimica e Biologia Moleculare, Università di Bari, Via Orabona 4, 70126 Bari, Italy (F.D.L., R.G.);Laboratoire de Biologie Cellulaire, Institut National de la Recherche Agronomique, 78026 Versailles cedex, France (M.A.B.-B., L.J.);Centro di Studio sui Mitocondri e Metabolismo Energetico-Consiglio Nazionale delle Richerche, Sezione di Trani, Via Corato 17, 70059 Trani, Italy (L.R.C.) |
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Abstract: | This work illustrates potential adverse effects linked with the expression of proteinase inhibitor (PI) in plants used as a strategy to enhance pest resistance. Tobacco (Nicotiana tabacum L. cv Xanthi) and Arabidopsis [Heynh.] ecotype Wassilewskija) transgenic plants expressing the mustard trypsin PI 2 (MTI-2) at different levels were obtained. First-instar larvae of the Egyptian cotton worm (Spodoptera littoralis Boisd.) were fed on detached leaves of these plants. The high level of MTI-2 expression in leaves had deleterious effects on larvae, causing mortality and decreasing mean larval weight, and was correlated with a decrease in the leaf surface eaten. However, larvae fed leaves from plants expressing MTI-2 at the low expression level did not show increased mortality, but a net gain in weight and a faster development compared with control larvae. The low MTI-2 expression level also resulted in increased leaf damage. These observations are correlated with the differential expression of digestive proteinases in the larval gut; overexpression of existing proteinases on low-MTI-2-expression level plants and induction of new proteinases on high-MTI-2-expression level plants. These results emphasize the critical need for the development of a PI-based defense strategy for plants obtaining the appropriate PI-expression level relative to the pest's sensitivity threshold to that PI. |
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