Vergeer L H T, van der Velde G
Department of Ecology, Laboratory of Aquatic Ecology, University of Nijmegen, Toernooiveld, 6525 ED Nijmegen, The Netherlands fax: ++ 31 24 3652134; e-mail:
Oecologia. 1997 Nov;112(4):481-484. doi: 10.1007/s004420050335.
Under suboptimal growing conditions (e.g. a lack of sunshine), floating leaves of Nymphaea alba and Nuphar lutea can become heavily infected with the fungi Colletotrichum nymphaeae and Pythium F, respectively. These fungi normally act as decomposers of senescent leaves. Mature leaves of Nymphaea alba and Nuphar lutea contain high concentrations of phenolics, secondary substances known for their fungistatic properties. The production of these compounds requires energy and primary metabolites. The hypothesis that suboptimal growing conditions reduce the ability of nymphaeids to maintain a sufficiently high level of phenolics, thereby making them more vulnerable to infection by fungi, was tested. Outdoor mesocosm experiments were used to examine the response of floating leaves of Nymphaea alba and Nuphar lutea to reduced light availability. Shading significantly reduced the phenolic content of the leaves. This was accompanied by higher disease severity. The outcome of this experiment is also discussed in relation to the higher nitrogen content measured in shaded leaves.
在次优生长条件下（例如缺乏阳光），白睡莲和欧洲萍蓬草的浮叶分别会被睡莲炭疽菌和腐霉F严重感染。这些真菌通常作为衰老叶片的分解者。白睡莲和欧洲萍蓬草的成熟叶片含有高浓度的酚类物质，这是一类以其抑菌特性而闻名的次生物质。这些化合物的产生需要能量和初级代谢产物。有一个假说认为，次优生长条件会降低睡莲科植物维持足够高酚类物质水平的能力，从而使它们更容易受到真菌感染，该假说得到了验证。户外中宇宙实验被用于研究白睡莲和欧洲萍蓬草浮叶对光照减少的反应。遮荫显著降低了叶片的酚类物质含量。这伴随着更高的病害严重程度。该实验的结果也结合在遮荫叶片中测得的较高氮含量进行了讨论。
