Molecular Plant-Microbe Interactions 2005 18 (9), pp. 960-972

Pathogen-Induced Production of the Antifungal AFP Protein from Aspergillus giganteus Confers Resistance to the Blast Fungus Magnaporthe grisea in Transgenic Rice.

Ana Beatriz Moreno (1), Gisela Peñas (2), Mar Rufat (1), Juan Manuel Bravo (1), Montserrat Estopà (2), Joaquima Messeguer (2), and Blanca San Segundo (1). Consorcio Laboratorio CSIC-IRTA de Genética Molecular Vegetal: (1) Departamento de Genética Molecular, Instituto de Biología Molecular de Barcelona, CSIC. Jordi Girona 18, 08034 Barcelona, Spain; (2) Departamento de Genética Vegetal, IRTA Centro de Cabrils. Carretera de Cabrils s/n, Cabrils 08348, Barcelona, Spain. MPMI 18:960-972. Submitted 23 February 2005. Accepted 24 April 2005. Copyright 2005 The American Phytopathological Society.

Rice blast, caused by Magnaporthe grisea, is the most important fungal disease of cultivated rice worldwide. We have developed a strategy for creating disease resistance to M. grisea whereby pathogen-induced expression of the afp (antifungal protein) gene from Aspergillus giganteus occurs in transgenic rice plants. Here, we evaluated the activity of the promoters from three maize pathogenesis-related (PR) genes, ZmPR4, mpi, and PRms, in transgenic rice. Chimeric gene fusions were prepared between the maize promoters and the beta-glucuronidase reporter gene (gus A). Histochemical assays of GUS activity in transgenic rice revealed that the ZmPR4 promoter is strongly induced in response to fungal infection, treatment with fungal elicitors, and mechanical wounding. The ZmPR4 promoter is not active in the seed endosperm. The mpi promoter also proved responsiveness to fungal infection and wounding but not to treatment with elicitors. In contrast, no activity of the PRms promoter in leaves of transgenic rice was observed. Transgenic plants expressing the afp gene under the control of the ZmPR4 promoter were generated. Transformants showed resistance to M. grisea at various levels. Our results suggest that pathogen-inducible expression of the afp gene in rice plants may be a practical way for protection against the blast fungus. Additional keywords: Oryza sativa, Zea mays.