Triterpene derivatives from Euphorbia enhance resistance against Verticillium wilt of tomato

• Published in: Phytochemistry (Oxford) 2017-03, Vol.135, p.169-180
• Main Authors: Smaili, Amal, Mazoir, Noureddine, Rifai, Lalla Aicha, Koussa, Tayeb, Makroum, Kacem, Kabil, El Mostafa, Benharref, Ahmed, Faize, Mohamed
• Format: Article
• Language: English
• Subjects: Drug Resistance, Fungal - drug effects; Elicitor; Euphorbia officinarum; Euphorbia resinifera; Euphorbiaceae; Hydrogen Peroxide - analysis; Lycopersicon esculentum - drug effects; Lycopersicon esculentum - growth & development; Molecular Structure; Resistance; Solanaceae; Solanum lycopersicum; Triterpene derivatives; Triterpenes - chemistry; Triterpenes - isolation & purification; Triterpenes - pharmacology; Verticillium - drug effects; Verticillium dahliae
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2016.12.017

Oxidation of α-euphorbol and 31-norlanostenol, two triterpenic compounds isolated from the latex of Euphorbia resinifera and Euphorbia officinarum respectively, yielded four products named 3β-tosyloxy-4α,14α-dimethyl-5α-cholesta-7,9-diene; 4α,14α-dimethyl-5α-cholesta-7,9-dien-3β-ol; 24-methylen-elemo-lanosta-8,24-dien-3-one and elemo-lanost-8-en-3,11,24-trione. They were evaluated for protection of tomato plants against Verticillium dahliae in a greenhouse. The four semisynthesized products were phytotoxic at higher concentrations as they completely inhibited tomato germination at 100 and 500 μg/ml. However at lower concentrations (10 and 50 μg/ml) germination and root length were not affected. Disease resistance against Verticillium wilt was assessed in tomato plants derived from seeds that germinated in the presence of 10 and 50 μg/ml of the four products. All of them were able to reduce significantly disease severity, with 10 μg/ml being more effective than 50 μg/ml. Reduction of leaf alteration index and of stunting index ranged from 52 to 68% and from 43 to 67%, respectively, while vessel discoloration was reduced by at least 95%. The compounds were also able to elicit H2O2 accumulation before and after fungal inoculation and to significantly enhance peroxidase and polyphenol oxidase activities. These results suggest that the hemisynthetized triterpenes can be used as elicitors of disease resistance. Four triterpenes deriving from Euphorbia were synthetized and applied to tomato plants. Pre-treated plants were protected against Verticillium wilt disease and exhibited elevated H2O2 content and enhanced defense. [Display omitted] •Four triterpenes were hemisynthetized from α-euphorbol and 31-norlanostenol.•They were able to protect tomato plants against Verticillium wilt disease.•They were able to elicit production of H2O2 and to activate plant defense.