Enhanced resistance to the rice blast fungus Magnaporthe grisea conferred by expression of a cecropin A gene in transgenic rice

• Published in: Planta 2006-02, Vol.223 (3), p.392-406
• Main Authors: Coca, M, Penas, G, Gomez, J, Campo, S, Bortolotti, C, Messeguer, J, San Segundo, B
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animals; Antifungals; Antimicrobial Cationic Peptides - analysis; Antimicrobial Cationic Peptides - genetics; Antimicrobial Cationic Peptides - metabolism; antimicrobial peptides; Biological and medical sciences; blast disease; Blasts; cecropin A; disease resistance; Fundamental and applied biological sciences. Psychology; Fungal spores; gene expression regulation; Genetic Vectors; Genetics and breeding of economic plants; Hyalophora cecropia; Immune response; Immunity, Innate; insect proteins; Leaves; Magnaporthe - pathogenicity; Magnaporthe grisea; molecular sequence data; Moths - genetics; nucleotide sequences; Oryza - genetics; Oryza - metabolism; Oryza - microbiology; Oryza sativa; Pathogens; Peptides; Pest resistance; Phenotype; Plant diseases; Plant Diseases - microbiology; Plant growth; plant pathogenic fungi; Plant pathogens; Plants; Plants, Genetically Modified - anatomy & histology; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - microbiology; Proteins; Recombinant Fusion Proteins - metabolism; resistance mechanisms; Rice; Transformation, Genetic; Transgenes; Transgenic plants; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-005-0069-z

Cecropins are a family of antimicrobial peptides, which constitute an important key component of the immune response in insects. Here, we demonstrate that transgenic rice (Oryza sativa L.) plants expressing the cecropin A gene from the giant silk moth Hyalophora cecropia show enhanced resistance to Magnaporthe grisea, the causal agent of the rice blast disease. Two plant codon-optimized synthetic cecropin A genes, which were designed either to retain the cecropin A peptide in the endoplasmic reticulum, the ER-CecA gene, or to secrete cecropin A to the extracellular space, the Ap-CecA gene, were prepared. Both cecropin A genes were efficiently expressed in transgenic rice. The inhibitory activity of protein extracts prepared from leaves of cecropin A-expressing plants on the in vitro growth of M. grisea indicated that the cecropin A protein produced by the transgenic rice plants was biologically active. Whereas no effect on plant phenotype was observed in ER-CecA plants, most of the rice lines expressing the Ap-CecA gene were non-fertile. Cecropin A rice plants exhibited resistance to rice blast at various levels. Transgene expression of cecropin A genes was not accompanied by an induction of pathogenesis-related (PR) gene expression supporting that the transgene product itself is directly active against the pathogen. Taken together, the results presented in this study suggest that the cecropin A gene, when designed for retention of cecropin A into the endoplasmic reticulum, could be a useful candidate for protection of rice plants against the rice blast fungus M. grisea.