Research on Allelochemicals with Material Properties Exuded by Submerged Freshwater Macrophyte <i>Elodea nuttallii</i>

Abstract

Elodea nuttallii is well-known for its successful invasion to Europe and Asia. In addition to its high growth rate and nutrient storage capacity, chemical defense was recently found to play an important role in excluding other aquatic organisms. To reveal the chemical nature of its allelopathic effects on cyanobacterial development, extraction of plant exudates with different solvents and eluted procedures followed by 72h bioassays with Microcystis aeruginosa was conducted. The results showed that the fraction eluted with methanol exhibited the strongest inhibitory effects, which indicated that the anti-cyanobacterial active allelochemicals released by E.nuttallii was hydrophilic. Then ten phenolic acids were identified in the purified methanol fraction of Elodea exudates by GC-MS analysis. Quantification of the four phenolic acids therein showed the release contents were lower than 10μg/L when E.nuttallii was cultivated at 10g FW/L, which increased with the increasing culture density. When the culture density was 100g FW/L, the detected contents of vanillic acid, protocatechuic acid, ferulic acid and caffeic acid in E.nuttallii culture water were 23.41μg/L, 17.56 μg/L, 12.31 μg/L and 18.93μg/L, respectively. These results were helpful to understand the allelopathy mechanisms of E.nuttallii in aquatic ecosystems and useful in control of harmful cyanobacterial blooms.

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