1Key Laboratory of Plant Molecular Physiology Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
* E. Mail: yxli@ibcas.ac.cn
2 Correspondence author, College of Oceanography and Environmental Science, Xiamen University, Xiamen 361005, China
Online published on 12 March, 2012.
Allelopathy plays an important role in the formation and succession of algal communities; however, there are few studies on the allelopathic effects of terrestrial plants on algal blooms. We investigated the potential allelopathic effects of the halophyte Sesuvium portulacastrum against Skeletonema costatum (a unicellular marine diatom). In co-culture experiments, time-course growth curves of S. costatum showed that algal growth in both the lag and exponential phase was inhibited by S. portulacastrum. The inhibitory activity of S. portulacastrum was biomass-dependent, suggesting that S. portulacastrum can prevent or reduce the magnitude of algal blooms. A water extract and a petroleum ether extract were prepared from S. portulacastrum. When treated with either of these extracts, S. costatum showed abnormal cell morphology. In addition, both these extracts decreased the maximum cell density and specific growth rate of S. costatum in a dose-dependent manner. S. costatum was more sensitive to the petroleum ether extract than the water extract of S. portulacastrum. GC-MS analysis of the petroleum ether extract revealed 45 lipophilic compounds. Our results suggested that the growth inhibition of S. costatum was due to the allelopathic potential of S. portulacastrum and that certain allelochemicals influenced the algal cell division.
Algal growth, Allelopathy, Cell division, Dose-dependent, Extracts, GC-MS, Sesuvium portulacastrum, Skeletonema costatum
