Litvak Marcy E, Constable John V, Monson Russell K
Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder, CO, 80309, USA.
Oecologia. 2002 Aug;132(3):382-391. doi: 10.1007/s00442-002-0964-y. Epub 2002 Aug 1.
We measured the relative control that resource availability (as a supply-side control) and wounding (as a demand-side control) exert on patterns of monoterpene synthesis and concentration in Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] needles. While supply-side controls should alter monoterpene production due to changes in the availability of substrate (carbohydrates), demand-side controls alter the need for a defensive product. We examined these relationships by measuring constitutive (preformed) and wound-induced rates of monoterpene synthesis and pool sizes in trees grown under ambient and elevated (ambient +200 µmol mol) CO, ambient and elevated (ambient +4°C) temperature, and in trees grown under four levels of nitrogen fertilization (0, 50, 100 and 200 µg g N by weight). Monoterpene pool size decreased at elevated CO, increased at elevated temperature and did not change in response to nitrogen fertilization. Overall, we did not find that foliar nitrogen, carbon balance, or rate of monoterpene synthesis alone were consistent predictors of monoterpene concentration in current-year Douglas fir needles. In addition, despite a wound-induced decrease in monoterpene pool size, we found no evidence for induction of monoterpene synthesis in response to wounding. The influence of either resource availability or wounding on rates of monoterpene synthesis or accumulation cannot be explained by traditional supply-side or demand-side controls. We conclude that monoterpene synthesis in first-year Douglas fir needles is controlled by fairly conservative genetic mechanisms and is influenced more by past selection than by current resource state.
我们测定了资源可用性（作为供应端控制因素）和创伤（作为需求端控制因素）对花旗松（[Pseudotsuga menziesii (Mirb.) Franco]）针叶中单萜合成模式和浓度的相对控制作用。供应端控制因素应会因底物（碳水化合物）可用性的变化而改变单萜产量，而需求端控制因素则会改变对防御性产物的需求。我们通过测量在环境CO₂浓度和升高的CO₂浓度（环境浓度 + 200 µmol mol⁻¹）、环境温度和升高的温度（环境温度 + 4°C）下生长的树木，以及在四种氮肥水平（0、50、100和200 µg g⁻¹ N，按重量计）下生长的树木中组成型（预先形成的）和创伤诱导的单萜合成速率及库大小，来研究这些关系。单萜库大小在升高的CO₂浓度下降低，在升高的温度下增加，并且对氮肥添加没有响应。总体而言，我们发现当年花旗松针叶中的单萜浓度，单独的叶氮含量、碳平衡或单萜合成速率都不是一致的预测指标。此外，尽管创伤会导致单萜库大小下降，但我们没有发现创伤诱导单萜合成的证据。资源可用性或创伤对单萜合成或积累速率的影响，无法用传统的供应端或需求端控制来解释。我们得出结论，一年生花旗松针叶中的单萜合成受相当保守的遗传机制控制，更多地受过去的选择影响，而非当前的资源状态影响。
