Photosynthesis and photoinhibition at low temperatures: D1-turnover in Antarctic rhodophytes

在强光低温条件下进行光合作用，会减缓酶反应速度，增加活性氧的生成。然而，这些都是非生物条件，来自南极的大型藻类通常在南极春夏季节暴露在这些条件下。在这个项目中，将在实验室和野外实验中评估高光和低温对南极特有的视紫草类植物的交互作用。在前期考察中发现，低温(0℃)和强光条件对落叶棕榈光合作用有明显的交互作用。最大电子传递速率(ETRmax)在高PAR(400μ摩尔光子m-2s-1)和0°C下下降，而ETRmax在8℃时与初始值相比基本不变。在正在进行的第二年和第三年供资期间，以下调查步骤将侧重于活性氧物种的产生和清除，以及光系统II反应中心蛋白的相关损害和周转(1)。此外，D1丰度的变化将与物种特有的脂组成和编码D1的PSBA基因的表达有关。此外，冰川融化加剧引起的盐度变化的影响将被包括在内，作为调节生理反应的额外因素。这将增加有关藻类生理和极地生态系统功能的新信息。

Performing photosynthesis under high light but low temperature conditions poses the problem of slowed down enzymatic reactions and increased generation of reactive oxygen species. However, these are the abiotic conditions, macroalgae from Antarctica are usually exposed to during the Antarctic spring/summer season. In this project, the interactive effects of high light and low temperature will be evaluated in laboratory and field experiments on endemic Antarctic rhodophytes. During the previous expedition marked interactive effects under low temperature (0 °C) and high light conditions were found on photosynthesis of Palmaria decipiens. The maximum electron transport rate (ETRmax) decreased under high PAR (400μmol photons m-2s-1) and 0°C whereas ETRmax was more or less constant at 8° C compared to initial values. The following steps of investigation during the ongoing second and the applied third year of funding will focus on the generation and scavenging of reactive oxygen species, as well as the related damage and turnover of the reaction centre protein of photosystem II (D1). Moreover, changes in the abundance of D1 will be related to species-specific lipid composition and expression of psbA genes encoding for D1. Furthermore, the effect of salinity changes due to increased glacier melting will be included as an additional factor modulating physiological responses. This will add new information on both algal physiology and polar ecosystem function.