title: Expression of the maize proteinase inhibitor (mpi) gene in rice plants enhances resistance against the striped stem borer (Chilo suppressalis): effects on larval growth and insect gut proteinases.
abstract: The maize proteinase inhibitor (mpi) gene was introduced into two elite japonica rice varieties. Both constitutive expression of the mpi gene driven by the maize ubiquitin 1 promoter and wound-inducible expression of the mpi gene driven by its own promoter resulted in the accumulation of MPI protein in the transgenic plants. No effect on plant phenotype was observed in mpi-expressing lines. The stability of transgene expression through successive generations of mpi rice lines (up to the T(4) generation) and the production of functional MPI protein were confirmed. Expression of the mpi gene in rice enhanced resistance to the striped stem borer (Chilo suppressalis), one of the most important pests of rice. In addition, transgenic mpi plants were evaluated in terms of their effects on the growth of C. suppressalis larvae and the insect digestive proteolytic system. An important dose-dependent reduction of larval weight of C. suppressalis larvae fed on mpi rice, compared with larvae fed on untransformed rice plants, was observed. Analysis of the digestive proteolytic activity from the gut of C. suppressalis demonstrated that larvae adapted to mpi transgene expression by increasing the complement of digestive proteolytic activity: the serine and cysteine endoproteinases as well as the exopeptidases leucine aminopeptidase and carboxypeptidases A and B. However, the induction of such proteolytic activity did not prevent the deleterious effects of MPI on larval growth. The introduction of the mpi gene into rice plants can thus be considered as a promising strategy to protect rice plants against striped stem borer.
authors.affiliation: Departamento de Genética Molecular, Consorci CSIC-IRTA-Laboratori de Genética Molecular Vegetal, Instituto de Biología Molecular de Barcelona, IBMB-CSIC, Jordi Girona 18, 08034 Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Vila
authors.forename: Jordi
authors.initials: J
authors.lastname: Quilis
authors.forename: Donaldo
authors.initials: D
authors.lastname: Meynard
authors.forename: Jean Christophe
authors.initials: JC
authors.lastname: Breitler
authors.forename: Victoria
authors.initials: V
authors.lastname: Marfà
authors.forename: Isabel
authors.initials: I
authors.lastname: Murillo
authors.forename: Jean Michel
authors.initials: JM
authors.lastname: Vassal
authors.forename: Joaquima
authors.initials: J
authors.lastname: Messeguer
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Guiderdoni
authors.forename: Blanca
authors.initials: B
authors.lastname: San Segundo