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Title: Suppression of cucurbit scab on cucumber leaves by photodynamic dyes

Author
item AVERYANOV, A - Russian Institute Of Phytopathology
item LAPIKOVA, V - Russian Institute Of Phytopathology
item PASECHNIK, T - Russian Institute Of Phytopathology
item ZAKHARENKOVA, T - Russian Institute Of Phytopathology
item POGOSYAN, S - Lomonosov University
item Baker, Con

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2011
Publication Date: 4/15/2012
Citation: Averyanov, A.A., Lapikova, V.P., Pasechnik, T.D., Zakharenkova, T.S., Pogosyan, S.I., Baker, C.J. 2012. Suppression of cucurbit scab on cucumber leaves by photodynamic dyes. Crop Protection. 30:925-930.

Interpretive Summary: Foliar plant diseases cause major crop losses for farmers each year. The goal of this study was to test the ability of photodynamic dyes to systemically suppress plant disease, specifically, scab of cucumber. It was a novel idea based on the knowledge that photodynamic dyes capture sunlight and produce toxic substances that cause localized tissue damage but signals other parts of the plant to activate their defenses. The dyes tested, or their derivatives, may offer a base for novel disease resistance inducers. This information will be of use to plant scientists who are devising new strategies to improve disease resistance in plants.

Technical Abstract: The goal of this study was to test the ability of the photodynamic dyes bengal rose, toluidine blue, and methylene blue, to protect systemically cucumber plants from cucurbit scab. At the stage of one true leaf, water or aqueous solutions of the dyes were applied to the leaf as droplets. When the second leaf appeared and was fully developed, it was inoculated with a spore suspension of Cladosporium cucumerinum. It was found that all dyes (at 0.5 to 200 µM) significantly suppressed symptoms of compatibility. The effect was preceded by development of local damage of the treated leaf. The degree of the damage as well as the disease suppression increased with dye concentration. Both indices were smaller if the plants were kept in darkness for the first day after the treatment. It is suggested that reactive oxygen photogenerated by dyes caused a local cell death, which induced resistance in distant leaves. The dyes tested, or their derivatives, may offer a base for novel disease resistance inducers.