A role of jasmonate in pathogen defense of Arabidopsis

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 95; no. 12; pp. 7209 - 7214
• Main Authors: Vijayan, P. (Washington State University, Pullman, WA.), Shockey, J, Levesque, C.A, Cook, R.J, Browse, J
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 09.06.1998; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: ACIDE JASMONIQUE; ACIDO JASMONICO; ARABIDOPSIS THALIANA; ARN MENSAJERO; ARN MESSAGER; Biological Sciences; BIOSINTESIS; BIOSYNTHESE; BIOSYNTHESIS; Botany; DEFENCE MECHANISMS; defense mechanisms; DERIVATIVES; DISEASE RESISTANCE; ENFERMEDADES FUNGOSAS; ESPORAS FUNGICAS; ESPORULACION; EXPRESION GENICA; EXPRESSION DES GENES; Flowers & plants; FUNGAL DISEASES; fungal diseases of plants; FUNGAL SPORES; Fungi; GENE EXPRESSION; Genes; Genetics; GROWTH RATE; HYPHAE; INDICE DE CRECIMIENTO; Infections; Inoculation; JASMONIC ACID; MALADIE FONGIQUE; MECANISME DE DEFENSE; MECANISMOS DE DEFENSA; MESSENGER RNA; METHYL JASMONATE; MICELIO; MUTANT; MUTANTES; MUTANTS; Mutation; MYCELIUM; OOSPORES; Pathogens; Plant cells; Plant growth; Plant roots; Plants; PODREDUMBRE DE LA RAIZ; POURRITURE DES RACINES; PYTHIUM; PYTHIUM MASTOPHORUM; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; root rot; ROOT ROTS; Rooting; SPORE FONGIQUE; SPORULATION; SUSCEPTIBILITY; TAUX DE CROISSANCE
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.95.12.7209

To investigate the role of jasmonate in the defense of plants against fungal pathogens, we have studied a mutant of Arabidopsis, fad3-2 fad7-2 fad8, that cannot accumulate jasmonate. Mutant plants were extremely susceptible to root rot caused by the fungal root pathogen Pythium mastophorum (Drechs.), even though neighboring wild-type plants were largely unaffected by this fungus. Application of exogenous methyl jasmonate substantially protected mutant plants, reducing the incidence of disease to a level close to that of wild-type controls. A similar treatment with methyl jasmonate did not protect the jasmonate-insensitive mutant coil1 from infection, showing that protective action of applied jasmonate against P. mastophorum was mediated by the induction of plant defense mechanisms rather than by a direct antifungal action. Transcripts of three jasmonate-responsive defense genes are induced by Pythium challenge in the wild-type but not in the jasmonate-deficient mutant. Pythium species are ubiquitous in soil and root habitats world-wide, but most (including P. mastophorum) are considered to be minor pathogens. Our results indicate that jasmonate is essential for plant defense against Pythium and, because of the high exposure of plant roots to Pythium inoculum in soil, may well be fundamental to survival of plants in nature. Our results further indicate that the fad3-2 fad7-2 fad8 mutant is an appropriate genetic model for studying the role of this important signaling molecule in pathogen defense