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首页> 外文期刊>Plant physiology >Increased air temperature during simulated autumn conditions does not increase photosynthetic carbon gain but affects the dissipation of excess energy in seedlings of the evergreen Conifer Jack Pine
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Increased air temperature during simulated autumn conditions does not increase photosynthetic carbon gain but affects the dissipation of excess energy in seedlings of the evergreen Conifer Jack Pine

机译：在模拟的秋季条件下，气温升高不会增加光合碳的吸收，但会影响常绿针叶树杰克松的幼苗中多余能量的耗散

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Temperature and daylength act as environmental signals that determine the length of the growing season in boreal evergreen conifers. Climate change might affect the seasonal development of these trees, as they will experience naturally decreasing daylength during autumn, while at the same time warmer air temperature will maintain photosynthesis and respiration. We characterized the down-regulation of photosynthetic gas exchange and the mechanisms involved in the dissipation of energy in Jack pine (Pinus banksiana) in controlled environments during a simulated summer-autumn transition under natural conditions and conditions with altered air temperature and photoperiod. Using a factorial design, we dissected the effects of daylength and temperature. Control plants were grown at either warm summer conditions with 16-h photoperiod and 22 degrees C or conditions representing a cool autumn with 8 h/7 degrees C. To assess the impact of photoperiod and temperature on photosynthesis and energy dissipation, plants were also grown under either cold summer (16-h photoperiod/7 degrees C) or warm autumn conditions (8-h photoperiod/22 degrees C). Photosynthetic gas exchange was affected by both daylength and temperature. Assimilation and respiration rates under warm autumn conditions were only about one-half of the summer values but were similar to values obtained for cold summer and natural autumn treatments. In contrast, photosynthetic efficiency was largely determined by temperature but not by daylength. Plants of different treatments followed different strategies for dissipating excess energy. Whereas in the warm summer treatment safe dissipation of excess energy was facilitated via zeaxanthin, in all other treatments dissipation of excess energy was facilitated predominantly via increased aggregation of the light-harvesting complex of photosystem II. These differences were accompanied by a lower deepoxidation state and larger amounts of beta-carotene in the warm autumn treatment as well as by changes in the abundance of thylakoid membrane proteins compared to the summer condition. We conclude that photoperiod control of dormancy in Jack pine appears to negate any potential for an increased carbon gain associated with higher temperatures during the autumn season.
机译：温度和昼长是确定北常绿针叶树生长期长度的环境信号。气候变化可能会影响这些树木的季节发展，因为它们在秋季自然会减少日长，与此同时，气温升高将保持光合作用和呼吸作用。在自然条件下以及自然温度和光周期改变的条件下，模拟的夏季-秋季过渡期间，我们表征了受控环境中光合气体交换的下调以及参与松树（Pinus bankiana）能量耗散的机制。使用析因设计，我们剖析了日长和温度的影响。对照植物生长在16 h光照和22摄氏度的温暖夏季条件下或8 h / 7摄氏度代表凉爽的秋天的条件下。为了评估光周期和温度对光合作用和能量耗散的影响，还种植了植物在寒冷的夏天（16小时光照/ 7摄氏度）或温暖的秋天条件下（8小时光照/ 22摄氏度）。光合气体交换受日长和温度的影响。在温暖的秋季条件下，同化和呼吸速率仅为夏季值的一半左右，但与夏季寒冷和秋季自然处理获得的值相似。相反，光合作用效率主要取决于温度，而不取决于日长。不同处理的植物遵循不同的策略来耗散多余的能量。在夏季温暖的处理中，通过玉米黄质促进了多余能量的安全消散，而在所有其他处理中，主要是通过增加了光系统II的光收集复合物的聚集来促进了多余能量的消散。这些差异伴随着温暖的秋季处理中较低的深氧化状态和大量的β-胡萝卜素，以及与夏季相比类囊体膜蛋白丰度的变化。我们得出的结论是，在秋季期间，光周期控制杰克松的休眠似乎消除了与更高温度相关的碳增加的任何潜在可能性。

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