Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Plant Cell Environ. 2010 Jun;33(6):888-99. doi: 10.1111/j.1365-3040.2010.02114.x. Epub 2010 Jan 15.
Common gardens were established along a approximately 900 km latitudinal transect to examine factors limiting geographical distributions of boreal and temperate tree species in eastern North America. Boreal representatives were trembling aspen (Populus tremuloides Michx.) and paper birch (Betula papyrifera Marsh.), while temperate species were eastern cottonwood (Populus deltoides Bartr ex. Marsh var. deltoides) and sweetgum (Liquidambar styraciflua L.). The species were compared with respect to adjustments of leaf photosynthetic metabolism along the transect, with emphasis on temperature sensitivities of the maximum rate of ribulose bisphosphate (RuBP) carboxylation (E(V)) and regeneration (E(J)). During leaf development, the average air temperature (T(growth)) differed between the coolest and warmest gardens by 12 degrees C. Evidence of photosynthetic thermal acclimation (metabolic shifts compensating for differences in T(growth)) was generally lacking in all species. Namely, neither E(V) nor E(J) was positively related to T(growth). Correspondingly, the optimum temperature (T(opt)) of ambient photosynthesis (A(sat)) did not vary significantly with T(growth). Modest variation in T(opt) was explained by the combination of E(V) plus the slope and curvature of the parabolic temperature response of mesophyll conductance (g(m)). All in all, species differed little in photosynthetic responses to climate. Furthermore, the adaptive importance of photosynthetic thermal acclimation was overshadowed by g(m)'s influence on A(sat)'s temperature response.
建立了一个约 900 公里长的纬度横断面对，以研究限制北美东部北方和温带树种地理分布的因素。北方树种代表是颤杨（Populus tremuloides Michx.）和纸皮桦（Betula papyrifera Marsh.），而温带树种代表是东方棉白杨（Populus deltoides Bartr ex. Marsh var. deltoides）和枫香树（Liquidambar styraciflua L.）。这些物种在横断面上的叶片光合作用代谢方面进行了比较，重点是核酮糖二磷酸（RuBP）羧化（E(V)）和再生（E(J)）的最大速率对温度的敏感性。在叶片发育过程中，最凉爽和最温暖的花园之间的平均空气温度（T(growth)）差异为 12 摄氏度。在所有物种中，都缺乏光合作用热驯化（代谢变化补偿 T(growth)差异）的证据。即，E(V)和 E(J)均与 T(growth)没有正相关关系。相应地，环境光合作用（A(sat)）的最佳温度（T(opt)）与 T(growth)没有显著变化。T(opt)的适度变化可由 E(V)加上质膜导度（g(m)）抛物线温度响应的斜率和曲率的组合来解释。总的来说，物种对气候的光合作用反应差异不大。此外，光合作用热驯化的适应重要性被 g(m)对 A(sat)温度响应的影响所掩盖。
