Tarayre Michèle, Thompson John D, Escarré José, Linhart Yan B
Centre d'Ecologie Fonctionnelle et Evolutive, C.N.R.S., Route de Mende, BP 5051, F-34033, Montpellier, France.
Environmental, Population and Organismic Biology, University of Colorado at Boulder, 122 Ramaley, Campus Box 334, 80309-0334, Boulder, CO, USA.
Oecologia. 1995 Jan;101(1):110-118. doi: 10.1007/BF00328907.
The ecological role of plant secondary compounds has received a great deal of attention yet little is known regarding variation in the ecological significance of different compounds produced by a single species. This is particularly pertinent to species where variation in compound presence is under genetic control. In this study we have quantified variation in the inhibitory effects of the six dominant monoterpene oils produced by different genotypes (or chemotypes) of Thymus vulgaris on achene germination of an associated species (Brachypodium phoenicoides), and seeds of T. vulgaris itself, in controlled experimental conditions. The experiments involved the germination of seeds of the two species with crushed leaves or pure essences of the six chemotypes, i.e. four experimental trials. A significant inhibitory effect against B. phoenicoides was found for both crushed leaves and the range of concentrations of pure oils used in the trial. The two phenolic compounds had a greater effect than the non-phenolic leaves and pure oils. The significant differences between non-phenols and the controls declined faster over time for crushed leaves and low concentrations of the pure essences than did that between the phenolics and the controls. There was a significant inhibitory effect against the germination of T. vulgaris seeds for the crushed leaves and the pure oils, although the contrast between the non-phenols and the phenols was not significant. The effect of the different oils varied depending on the seed source of the thyme seeds used in the trial. This is suggested to be due to differences in the rates of outcrossing among the sampled populations. The effects of the oils on the associated species, B. phoenicoides, were not found to be greater than their effects on the germination of thyme seeds. The results are discussed in the context of a potential role for such inhibitory effects in relation to the onset of rainfall and suitable germination conditions.
植物次生化合物的生态作用已受到广泛关注，但对于单一物种产生的不同化合物的生态意义的变化却知之甚少。这对于化合物存在差异受遗传控制的物种尤为重要。在本研究中，我们在可控实验条件下，对不同基因型（或化学型）的百里香产生的六种主要单萜油对相关物种（伪苇拂子茅）瘦果萌发以及百里香自身种子萌发的抑制作用的变化进行了量化。实验涉及用六种化学型的碎叶或纯精油处理这两个物种的种子，即四项实验。对于碎叶以及试验中使用的纯油的一系列浓度，均发现对伪苇拂子茅有显著抑制作用。两种酚类化合物的作用比非酚类的叶子和纯油更大。对于碎叶和低浓度纯精油，非酚类与对照之间的显著差异随时间下降的速度比酚类与对照之间的更快。对于碎叶和纯油，对百里香种子萌发有显著抑制作用，尽管非酚类与酚类之间的对比不显著。不同精油的作用因试验中使用的百里香种子的来源而异。这被认为是由于采样种群中外交率的差异所致。未发现精油对相关物种伪苇拂子茅的作用大于其对百里香种子萌发的作用。在降雨开始和适宜萌发条件方面，讨论了这种抑制作用的潜在作用的相关结果。
