珊瑚菜和滨旋花离体叶片代谢系统的耐热极限与夏季生长停滞机理的分析

Heat Tolerance Threshold of Leaves in vitro in Glehnia littoralis and Calystegia soldanella Association with the Mechanism of Growth Stagnation in Summer

摘要:

为了解珊瑚菜（Glehnia littoralis）夏季生长停滞的原因，以其伴生种滨旋花（Calystegia soldanella）为参考，对他们的叶片代谢系统的耐热性进行了研究。结果表明，珊瑚菜叶片光合作用的失活温度和膜透性的半致死温度均比滨旋花低大约5℃。珊瑚菜和滨旋花在温度为50℃时仍然保持很高的的呼吸速率（仅分别下降10%和24%），明显高于各自的光合系统和质膜系统的耐热温度。高斯回归分析表明，珊瑚菜的光合速率与呼吸速率比明显低于滨旋花。因此，高温下的光合产物昼夜过度消耗可能是珊瑚菜夏天生长停滞的原因，也可能与其整体较低的耐热性有关。

Abstract:

In order to understand the reason to growth stagnation of Glehnia littoralis in summer, the heat tolerance of leaf metabolic system was studied in comparison with a companion species Calystegia soldanella as reference. The results showed that both of the deactivation temperature of photosynthetic system and the half lethal temperature of cell membrane in G. littoralis were 5℃ lower than those in C. soldanella. In contrast, the activity of the respiration system in both plants were still very high even when the temperatures reached 50℃ with a decline of 10% and 24%, respectively, showing that the respiration system was apparently more heat-resistant than the photosynthetic and membrane systems. The Gaussian regression showed that the ratio of photosynthesis rate to respiration rate was persistently lower in G. littoralis than that in C. soldanella. Therefore, it was suggested that the excessive consumption of the photosynthetic assimilates could be the cause of the summer growth stagnation of G. littoralis. In addition, the overall lower heat-resistance of C. soldanella could also be associated with the summer growth stagnation in G. littoralis, while C. soldanella did not show growth stagnation in summer because of high heat resistance.