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

在强光但低温条件下进行光合作用会造成酶促反应减慢和活性氧产生增加的问题。然而，这些是非生物条件，南极洲的大型藻类通常在南极春/夏季节暴露。在本项目中，将在实验室和野外对南极特有红藻进行实验，以评估强光和低温的交互作用。在之前的考察中，发现低温（0 °C）和强光条件下Palmaria decipiens的光合作用存在显著的交互作用。最大电子传递速率（ETRmax）在高PAR（400μmol photons m-2s-1）和0°C下降低，而ETRmax在8° C下与初始值相比基本不变。在正在进行的第二年和第三年的资助期间，以下调查步骤将侧重于活性氧的产生和清除，以及光系统II（D1）反应中心蛋白的相关损害和周转。此外，D1丰度的变化将与物种特异性脂质组成和编码D1的psbA基因的表达有关。此外，由于冰川融化增加而导致的盐度变化的影响将被列为调节生理反应的额外因素。这将增加关于藻类生理学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.