5月5日，油滴组进行题为“Galactoglycerolipid Lipase PGD1 Is Involved in Thylakoid Membrane Remodeling in Response to Adverse Environmental Conditions in Chlamydomonas”的 journal club。
Photosynthesis occurs in the thylakoid membrane, where the predominant lipid is monogalactosyldiacylglycerol (MGDG).As environmental conditions change, photosynthetic membranes have to adjust. In this study, we used a loss-of-functionChlamydomonas reinhardtii mutant deficient in the MGDG-specific lipase PGD1 (PLASTID GALACTOGLYCEROLIPIDDEGRADATION1) to investigate the link between MGDG turnover, chloroplast ultrastructure, and the production of reactiveoxygen species (ROS) in response to different adverse environmental conditions. The pgd1 mutant showed altered MGDGabundance and acyl composition and altered abundance of photosynthesis complexes, with an increased PSII/PSI ratio.Transmission electron microscopy showed hyperstacking of the thylakoid grana in the pgd1 mutant. The mutant also exhibitedincreased ROS production during N deprivation and high light exposure. Supplementation with bicarbonate or treatment withthe photosynthetic electron transport blocker DCMU protected the cells against oxidative stress in the light and revertedchlorosis of pgd1 cells during N deprivation. Furthermore, exposure to stress conditions such as cold and high osmolarityinduced the expression of PGD1, and loss of PGD1 in the mutant led to increased ROS production and inhibited cell growth.These findings suggest that PGD1 plays essential roles in maintaining appropriate thylakoid membrane composition andstructure, thereby affecting growth and stress tolerance when cells are challenged under adverse conditions.