Salicylic acid and cysteine contribute to arbutin-induced alleviation of angular leaf spot disease development in cucumber

• Published in: Journal of plant physiology 2015-06, Vol.181, p.9-13
• Main Authors: Kuźniak, Elżbieta, Wielanek, Marzena, Chwatko, Grażyna, Głowacki, Rafał, Libik-Konieczny, Marta, Piątek, Milena, Gajewska, Ewa, Skłodowska, Maria
• Format: Article
• Language: English
• Subjects: ARB; ARB+PSL; arbutin; Arbutin - pharmacology; CSH; Cucumis sativus - drug effects; Cucumis sativus - genetics; Cucumis sativus - metabolism; Cucumis sativus - microbiology; cysteine; Cysteine - metabolism; cysteine synthase; Cysteine synthase complex; dai; days after inoculation; Gene Expression Regulation, Plant - drug effects; p-CSH; PAL; phenylalanine ammonia lyase; Phenylalanine Ammonia-Lyase - metabolism; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - microbiology; Plant Proteins - genetics; Plant Proteins - metabolism; plants treated with arbutin and infected; protein-bound cysteine; Pseudomonas syringae - drug effects; Pseudomonas syringae - physiology; Pseudomonas syringae pv lachrymans; PSL; SAC; salicylic acid; Salicylic Acid - metabolism; salicylic acid conjugates; Salicylic acid signaling; SAT; serine acetyltransferase
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2015.03.017

Arbutin induced suppression of angular leaf spot disease in cucumber resulting from lower populations of Pseudomonas syringae pv lachrymans in the infected tissues. This study provides insight into mechanisms that may potentially account for this effect. In the absence of the pathogen, exogenous arbutin-induced expression of PR1, the marker of salicylic acid signaling, increased the content of salicylic acid and modulated the cysteine pool. This suggested that arbutin promoted cucumber plants to a “primed” state. When challenged with the pathogen, the arbutin-treated plants showed strongly reduced infection symptoms 7 days after inoculation. At this time point, they were characterized by higher contents of free and protein-bound cysteine due to higher cysteine biosynthetic capacity related to increased activities of serine acetyltransferase and cysteine synthase when compared with plants infected without arbutin treatment. Moreover, in the arbutin-treated and infected plants the contents of free salicylic acid and its conjugates were also increased, partly owing to its biosynthesis via the phenylpropanoid pathway. We suggest that arbutin-induced abrogation of angular leaf spot disease in cucumber could be mediated by salicylic acid and cysteine-based signaling.