Laila Toum1, Gabriela Conti2, Francesca Coppola Guerriero3,4,5, Valeria P Conforte1, Franco A Garolla4, Sebastián Asurmendi2, Adrián A Vojnov1, Gustavo E Gudesblat3,4,5. 1. Instituto de Ciencia y Tecnología Dr. César Milstein, Fundación Pablo Cassará, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Saladillo, C.A.B.A., Argentina. 2. Instituto de Agrobiotecnología y Biología Molecular (IABIMO), CICVyA- Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de investigaciones Científicas y Tecnológicas (CONICET), Los Reseros y Nicolas Repeto, Hurlingham, Argentina. 3. Departamento de Fisiología, Biología Molecular y Celular "Profesor Héctor Maldonado"- Instituto de Biociencias, Biotecnología y Biología Translacional (IB3), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Pres. Dr. Raúl Alfonsín S/N, Ciudad Universitaria, C.A.B.A., Argentina. 4. Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Pres. Dr. Raúl Alfonsín S/N, Ciudad Universitaria, C.A.B.A., Argentina. 5. Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), CONICET, Argentina.
Abstract
BACKGROUND AND AIMS: Single-stranded DNA oligodeoxynucleotides (ssODNs) have been shown to elicit immune responses in mammals. In plants, RNA and genomic DNA can activate immunity, although the exact mechanism through which they are sensed is not clear. The aim of this work was to study the possible effect of ssODNs on plant immunity. KEY RESULTS: ssODNs IMT504 and 2006 increased protection against the pathogens Pseudomonas syringae pv. tomato DC3000 and Botrytis cinerea but not against Tobacco Mosaic Virus - Cg when infiltrated in Arabidopsis thaliana. In addition, ssODNs inhibited root growth and promoted stomatal closure in a dose dependent manner, with half maximal effective concentrations between 0.79 and 2.06 µM. Promotion of stomatal closure by ssODNs was reduced by DNase I treatment. It was also diminished by the NADPH oxidase inhibitor diphenyleneiodonium and by coronatine, a bacterial toxin that inhibits NADPH oxidase-dependent reactive oxygen species (ROS) synthesis in guard cells. In addition it was found that ssODN-mediated stomatal closure was impaired in bak1-5, bak1-5/bkk1, mpk3 and npr1-3 mutants. ssODNs also induced early expression of MPK3, WRKY33, PROPEP1 and FRK1 genes involved in plant defence, an effect that was reduced in bak1-5 and bak1-5/bkk1 mutants. CONCLUSIONS: ssODNs are capable of inducing protection against pathogens through the activation of defence genes and promotion of stomatal closure through a mechanism similar to that of other elicitors of plant immunity, which involves the BAK1 co-receptor, and ROS synthesis.
BACKGROUND AND AIMS: Single-stranded DNA oligodeoxynucleotides (ssODNs) have been shown to elicit immune responses in mammals. In plants, RNA and genomic DNA can activate immunity, although the exact mechanism through which they are sensed is not clear. The aim of this work was to study the possible effect of ssODNs on plant immunity. KEY RESULTS: ssODNs IMT504 and 2006 increased protection against the pathogens Pseudomonas syringae pv. tomato DC3000 and Botrytis cinerea but not against Tobacco Mosaic Virus - Cg when infiltrated in Arabidopsis thaliana. In addition, ssODNs inhibited root growth and promoted stomatal closure in a dose dependent manner, with half maximal effective concentrations between 0.79 and 2.06 µM. Promotion of stomatal closure by ssODNs was reduced by DNase I treatment. It was also diminished by the NADPH oxidase inhibitor diphenyleneiodonium and by coronatine, a bacterial toxin that inhibits NADPH oxidase-dependent reactive oxygen species (ROS) synthesis in guard cells. In addition it was found that ssODN-mediated stomatal closure was impaired in bak1-5, bak1-5/bkk1, mpk3 and npr1-3 mutants. ssODNs also induced early expression of MPK3, WRKY33, PROPEP1 and FRK1 genes involved in plant defence, an effect that was reduced in bak1-5 and bak1-5/bkk1 mutants. CONCLUSIONS: ssODNs are capable of inducing protection against pathogens through the activation of defence genes and promotion of stomatal closure through a mechanism similar to that of other elicitors of plant immunity, which involves the BAK1 co-receptor, and ROS synthesis.