Dionaea UV-A

The objective of this study was to investigate the response of the photosynthetic apparatus of the Venus flytrap (Dionaea muscipula J. Ellis) to UV-A radiation stress as well as the role of selected secondary metabolites in this process. We hypothesized that the short-term application of UV-A radiation would enhance the efficiency of the photosynthesis and synthesis of secondary metabolites, especially naphthoquinones, in Dionaea muscipula plants.
Plants were subjected to 24h UV-A treatment. Subsequently, chl a fluorescence and gas exchange were measured in living plants. On the collected material, analyses of the photosynthetic pigments and photosynthetic apparatus proteins content, as well as the contents and activity of selected antioxidants, were performed. Measurements and analyses were carried out immediately after the stress treatment (UV plants) and another 24h after the termination of UV-A exposure (recovery plants). UV plants showed no changes in the structure and function of their photosynthetic apparatus and increased contents and activities of some an-tioxidants, which led to efficient CO2 carboxylation, while, in recovery plants, a disruption of electron flow was observed, resulting in lower photosynthesis efficiency. Our results revealed that D. muscipula plants underwent two phases of adjustment to UV-A radiation. The first was a reg-ulatory phase related to the exploitation of available mechanisms to prevent the over-reduction of PSII RC. In addition, UV plants increased the accumulation of plumbagin as a potential compo-nent of a protective mechanism against the disruption of redox homeostasis. The second was an acclimatization phase initiated after the running down of the regulatory process and decrease in photosynthesis efficiency.
Keywords: abiotic stress; Dionaea muscipula J. Ellis; photosynthesis; short-wave radiation

本研究旨在探究捕蝇草（Venus flytrap，Dionaea muscipula J. Ellis）的光合装置对紫外A（UV-A）辐射胁迫的响应，以及选定次生代谢产物在该过程中的作用。本研究提出假说：短期施加紫外A辐射可提升捕蝇草植株的光合效率与次生代谢产物（尤其是萘醌类）的合成水平。

实验将植株置于24小时紫外A辐射环境中进行处理。随后，对活体植株测定叶绿素a（chl a）荧光与气体交换参数。对采集的实验材料，我们开展了光合色素与光合装置蛋白含量分析，以及选定抗氧化剂的含量与活性检测。

测定与分析分别在胁迫处理结束后即刻（紫外A处理组植株）、以及紫外A暴露终止后24小时（恢复组植株）两个时间点进行。

紫外A处理组植株的光合装置结构与功能未发生改变，且部分抗氧化剂的含量与活性有所提升，保障了高效的二氧化碳羧化过程；而恢复组植株则出现电子传递流紊乱，导致光合效率降低。

本研究结果表明，捕蝇草植株对紫外A辐射存在两个适应阶段：第一阶段为调控阶段，涉及动用现有机制以防止光系统II反应中心（PSII RC）过度还原；此外，紫外A处理组植株的蓝雪醌（plumbagin）积累量增加，其可作为抵御氧化还原稳态破坏的保护机制的潜在组成部分。第二阶段为驯化阶段，在调控过程消退且光合效率下降后启动。

关键词：非生物胁迫；捕蝇草（Dionaea muscipula J. Ellis）；光合作用；短波辐射