Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
Institut für Botanik, Leopold-Franzens-Universität-Innsbruck, Innsbruck, Austria.
Plant Cell Physiol. 2020 Dec 23;61(11):1986-1994. doi: 10.1093/pcp/pcaa114.
Leaf senescence is an important process for plants to remobilize a variety of metabolites and nutrients to sink tissues, such as developing leaves, fruits and seeds. It has been suggested that reactive oxygen species (ROS) play an important role in the initiation of leaf senescence. Flag leaves of two different barley varieties, cv. Lomerit and cv. Carina, showed differences in the loss of photosystems and in the production of ROS at a late stage of senescence after significant loss of chlorophyll (Krieger-Liszkay et al. 2015). Here, we investigated photosynthetic electron transport and ROS production in primary leaves of these two varieties at earlier stages of senescence. Comparisons were made between plants grown outside in natural light and temperatures and plants grown in temperature-controlled growth chambers under low light intensity. Alterations in the content of photoactive P700, ferredoxin and plastocyanin (PC) photosynthetic electron transport were analyzed using in vivo near-infrared absorbance changes and chlorophyll fluorescence, while ROS were measured with spin-trapping electron paramagnetic resonance spectroscopy. Differences in ROS production between the two varieties were only observed in outdoor plants, whereas a loss of PC was common in both barley varieties regardless of growth conditions. We conclude that the loss of PC is the earliest detectable photosynthetic parameter of leaf senescence while differences in the production of individual ROS species occur later and depend on environmental factors.
叶片衰老对于植物来说是一个非常重要的过程，它可以重新分配各种代谢产物和养分到下沉组织，如发育中的叶片、果实和种子。有研究表明，活性氧（ROS）在叶片衰老的起始过程中发挥着重要作用。在叶绿素大量损失后，两个不同大麦品种（Lomerit 和 Carina）的旗叶在衰老后期的光合系统损失和 ROS 产生方面表现出差异（Krieger-Liszkay 等人，2015 年）。在这里，我们研究了这两个品种的初级叶片在衰老早期的光合作用电子传递和 ROS 产生情况。我们将在自然光和温度下生长的植物与在低温、低光照强度下生长的控温控光生长箱中的植物进行了比较。利用体内近红外吸收变化和叶绿素荧光分析了光活性 P700、铁氧还蛋白和质体蓝素（PC）光合作用电子传递的含量变化，而 ROS 则通过自旋捕获电子顺磁共振波谱进行测量。只有在室外植物中才能观察到两种品种之间 ROS 产生的差异，而无论生长条件如何，PC 的损失在两种大麦品种中都是常见的。我们得出结论，PC 的损失是叶片衰老最早可检测到的光合作用参数，而单个 ROS 物种产生的差异发生较晚，并且取决于环境因素。
