Artificial elevation of glutathione contents in salicylic acid‐deficient tobacco (Nicotiana tabacum cv. Xanthi NahG) reduces susceptibility to the powdery mildew pathogen Euoidium longipes

• Published in: Plant biology (Stuttgart, Germany) Vol. 22; no. 1; pp. 70 - 80
• Main Authors: Künstler, A., Kátay, G., Gullner, G., Király, L., Noctor, G.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.01.2020
• Subjects: Acids; Airborne microorganisms; Aqueous solutions; Ascomycota - drug effects; Ascomycota - physiology; Carboxylic acids; Disease resistance; Disease Resistance - drug effects; Elevation; Euoidium longipes; Gene expression; Gene Expression Regulation, Plant; Glutathione; Glutathione - metabolism; Glutathione - pharmacology; Inoculation; Leaves; NahG; Nicotiana - chemistry; Nicotiana - microbiology; Nicotiana tabacum; Pathogenesis; Pathogens; Plants, Genetically Modified - chemistry; Plants, Genetically Modified - microbiology; Powdery mildew; Salicylic Acid; Tobacco; Disease resistance; powdery mildew; NahG; glutathione; salicylic acid; tobacco; Euoidium longipes
• ISSN: 1435-8603; 1438-8677
• DOI: 10.1111/plb.13030

The effects of elevated glutathione levels on defence responses to powdery mildew (Euoidium longipes) were investigated in a salicylic acid‐deficient tobacco (Nicotiana tabacum cv. Xanthi NahG) and wild‐type cv. Xanthi plants, where salicylic acid (SA) contents are normal. Aqueous solutions of reduced glutathione (GSH) and its synthetic precursor R‐2‐oxothiazolidine‐4‐carboxylic acid (OTC) were injected into leaves of tobacco plants 3 h before powdery mildew inoculation. SA‐deficient NahG tobacco was hyper‐susceptible to E. longipes, as judged by significantly more severe powdery mildew symptoms and enhanced pathogen accumulation. Strikingly, elevation of GSH levels in SA‐deficient NahG tobacco restored susceptibility to E. longipes to the extent seen in wild‐type plants (i.e. enhanced basal resistance). However, expression of the SA‐mediated pathogenesis‐related gene (NtPR‐1a) did not increase significantly in GSH or OTC‐pretreated and powdery mildew‐inoculated NahG tobacco, suggesting that the induction of this PR gene may not be directly involved in the defence responses induced by GSH. Our results demonstrate that artificial elevation of glutathione content can significantly reduce susceptibility to powdery mildew in SA‐deficient tobacco. Glutathione suppresses hyper‐susceptibility to the powdery mildew Euoidium longipes in salicylic acid‐deficient tobacco.