Abscisic Acid Determines Basal Susceptibility of Tomato to Botrytis cinerea and Suppresses Salicylic Acid-Dependent Signaling Mechanisms

• Published in: Plant physiology (Bethesda) Vol. 128; no. 2; pp. 491 - 501
• Main Authors: Audenaert, Kris, De Meyer, Geert B, Hofte, Monica M
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.02.2002; American Society of Plant Physiologists
• Subjects: Abscisic Acid - pharmacology; Agronomy. Soil science and plant productions; Ammonia; benzo(1,2,3)thiadiazole-7-carbothioic acid; Biological and medical sciences; Botrytis; Botrytis - pathogenicity; Botrytis cinerea; Cyclopentanes - pharmacology; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Fungi; Genetics and breeding of economic plants; Hormones; Immunity, Innate - drug effects; Infections; Inoculation; Leaves; Lesions; Lycopersicon esculentum; Lycopersicon esculentum - drug effects; Lycopersicon esculentum - genetics; Lycopersicon esculentum - microbiology; Mutation; NahG protein; Oxylipins; Pathogens; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Pest resistance; Phenylalanine Ammonia-Lyase - metabolism; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - microbiology; Plant Growth Regulators - pharmacology; Plant interaction; Plant pathogens; Plants; Plants Interacting with Other Organisms; Plants, Genetically Modified; PR1a gene; Salicylic Acid - metabolism; Signal Transduction; Spores; Thiadiazoles - pharmacology; Tomatoes; Varietal selection. Specialized plant breeding, plant breeding aims; Phenylalanine ammonia-lyase; Botrytis cinerea; Lyases; Fungi; Signal transduction; Disease resistance; Regulation(control); Dicotyledones; Sesquiterpenes; Angiospermae; Lycopersicon esculentum; Abscisic acid; Plant growth substance; Mould; Transgenic plant; Fungi Imperfecti; Solanaceae; Intraspecific comparison; Thallophyta; Salicylic acid; Enzyme; Genetic variant; Host agent relation; Fungus resistance; Carbon-nitrogen lyases; Infection; Ammonia-lyases; Sensitivity resistance; Vegetable crop; Genetic improvement; Defense mechanism; Spermatophyta; Mutation
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.010605

Abscisic acid (ABA) is one of the plant hormones involved in the interaction between plants and pathogens. In this work, we show that tomato (Lycopersicon esculentum Mill. cv Moneymaker) mutants with reduced ABA levels (sitiens plants) are much more resistant to the necrotrophic fungus Botrytis cinerea than wild-type (WT) plants. Exogenous application of ABA restored susceptibility to B. cinerea in sitiens plants and increased susceptibility in WT plants. These results indicate that ABA plays a major role in the susceptibility of tomato to B. cinerea. ABA appeared to interact with a functional plant defense response against B. cinerea. Experiments with transgenic NahG tomato plants and benzo(1,2,3)thiadiazole-7-carbothioic acid demonstrated the importance of salicylic acid in the tomato-B. cinerea interaction. In addition, upon infection with B. cinerea, sitiens plants showed a clear increase in phenylalanine ammonia lyase activity, which was not observed in infected WT plants, indicating that the ABA levels in healthy WT tomato plants partly repress phenylalanine ammonia lyase activity. In addition, sitiens plants became more sensitive to benzo(1,2,3)thiadiazole-7-carbothioic acid root treatment. The threshold values for PR1a gene expression declined with a factor 10 to 100 in sitiens compared with WT plants. Thus, ABA appears to negatively modulate the salicylic acid-dependent defense pathway in tomato, which may be one of the mechanisms by which ABA levels determine susceptibility to B. cinerea.