Commercial extract from the brown seaweed Ascophyllum nodosum reduces fungal diseases in greenhouse cucumber.

摘要

This study examined the effects of StimplexTM, a marine plant extract formulation from Ascophyllum nodosum, on some common cucumber fungal pathogens. Greenhouse cucumber plants were sprayed and/or root drenched using StimplexTM at 0.5% or 1% concentration twice at 10-day intervals. Treatments also included application of fungicide (chlorothalonil, 2 g L-1) alternating with StimplexTM application. Treated plants were inoculated with four cucumber fungal pathogens including Alternaria cucumerinum, Didymella applanata, Fusarium oxysporum, and Botrytis cinerea. StimplexTM application resulted in a significant reduction in disease incidence of all the pathogens tested. The disease control effect was greater for Alternaria and Fusarium infection, followed by Didymella and Botrytis. Combined spray and root drenching with StimplexTM was more effective than either spray or root drenching alone. The alternation of one fungicide application, alternated with StimplexTM application, was highly effective and found to be the best treatment in reducing the disease ratings. Plants treated with StimplexTM showed enhanced activities of various defense-related enzymes including chitinase, beta -1,3-glucanase, peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, and lipoxygenase. Altered transcript levels of various defense genes, including chitinase, lipoxygenase, glucanase, peroxidase, and phenylalanine ammonia lyase were observed in treated plants. Cucumber plants treated with StimplexTM also accumulated higher level of phenolics compared to water controls. These results suggest that seaweed extracts enhance disease resistance in cucumber probably through induction of defense genes or enzymes.