Gurevitch Jessica, Teeri James A, Wood A Michelle
Department of Biology, Barnes Laboratory, The University of Chicago, 5630 S. Ingleside Avenue, 60637, Chicago, IL, USA.
Oecologia. 1986 Sep;70(2):198-204. doi: 10.1007/BF00379240.
Sedum wrightii is one of only a few species in the Crassulaceae for which there is evidence for a high degree of variability in the ratio of daytime to nighttime CO assimilation. There are both environmental and genetic components to this variability. S. wrightii grows over a wide altitudinal gradient. The purpose of this study was to compare low, intermediate, and high altitude populations with respect to the degree of CAM expression and the capability to tolerate limited water availability. We utilized clonallyreplicated genotypes of plants from each population in common environment greenhouse experiments. Genetic differences among the populations were found in long-term water use efficiency, in 24 hour CO exchange patterns, in biomass δC values, in carbon allocation, and in water status and ultimately survival during prolonged drought. The differences among the populations appear to be closely related to differences in the native habitats. The low altitude, desert plants had the greatest ability to grow and survive under conditions of limited water availability and appear to have the greatest shift to nighttime CO uptake during periods without water, while the high altitude plants had the poorest performance under these conditions and appear to shut down net carbon uptake when severely water limited.
厚叶景天是景天科中仅有的少数几个物种之一，有证据表明其白天与夜间CO2同化率存在高度变异性。这种变异性既有环境因素也有遗传因素。厚叶景天生长在广泛的海拔梯度范围内。本研究的目的是比较低海拔、中海拔和高海拔种群在景天酸代谢（CAM）表达程度以及耐受有限水分供应能力方面的差异。我们在共同环境温室实验中使用了来自每个种群的克隆复制植物基因型。在长期水分利用效率、24小时CO2交换模式、生物量δC值、碳分配、水分状况以及最终在长期干旱期间的存活情况等方面，发现了种群间的遗传差异。种群间的差异似乎与原生栖息地的差异密切相关。低海拔的沙漠植物在有限水分供应条件下具有最强的生长和存活能力，并且在缺水期间似乎向夜间CO2吸收的转变最大，而高海拔植物在这些条件下表现最差，并且在严重水分限制时似乎会停止净碳吸收。
