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慢酶促反应和增加活性氧的产生。然而，这些是非生物的条件，来自南极洲的大型藻类通常暴露在南极春夏季节。本项目将通过室内和野外实验，对南极特有红桫椤进行强光和低温的交互作用评价。在之前的考察中，在低温（0°C）和强光条件下，发现了Palmaria decipiens光合作用的显著交互效应。在高PAR （400μmol光子m-2s-1）和0°C下，最大电子传递速率（ETRmax）降低，而在8°C时，ETRmax与初始值相比基本不变。在正在进行的第二年和申请资助的第三年，接下来的研究步骤将集中在活性氧的产生和清除，以及光系统II反应中心蛋白的相关损伤和周转（D1）。此外，D1丰度的变化可能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引起的盐度变化的影响将作为调节生理反应的附加因素包括在内。这将为藻类生理学和极地生态系统功能提供新的信息。

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.