Previously, we isolated Chlorella sp. HS2 (referred hereupon as HS2) from a local tidal rock pool and demonstrated its halotolerance and high biomass productivity under different salinity conditions. To further understand acclimation responses of this alga under high salinity stress, we performed transcriptome analysis of triplicated culture samples grown in freshwater and marine conditions at both exponential and stationary growth phases. The results indicated that the transcripts involved in photosynthesis, TCA, and Calvin cycles were downregulated, whereas the upregulation of DNA repair mechanisms and an ABCB subfamily of eukaryotic type ABC transporter was observed at high salinity condition. In addition, while key enzymes associated with glycolysis pathway and triacylglycerol (TAG) synthesis were determined to be upregulated from early growth phase, salinity stress seemed to reduce the carbohydrate content of harvested biomass from 45.6 dw% to 14.7 dw% and nearly triple the total lipid content from 26.0 dw% to 62.0 dw%. These results suggest that the reallocation of storage carbon toward lipids played a significant role in conferring the viability of this alga under high salinity stress by remediating high level of cellular stress partially resulted from ROS generated in oxygen‐evolving thylakoids as observed in a direct measure of photosystem activities.

中文翻译：

---

小球藻的转录组学分析。HS2表明乙酰辅酶A和NADPH辅因子的溢出会引起高脂质积累和耐盐性

以前，我们分离了小球藻sp。HS2（以下称为HS2）来自当地的潮汐岩池，并证明了其在不同盐度条件下的耐盐性和高生物量生产力。为了进一步了解这种藻类在高盐度胁迫下的驯化响应，我们对在指数生长和固定生长阶段在淡水和海洋条件下生长的一式三份培养样品进行了转录组分析。结果表明，在高盐度条件下，参与光合作用，TCA和Calvin循环的转录本被下调，而DNA修复机制和真核型ABC转运蛋白的ABCB亚家族被上调。此外，虽然已确定与糖酵解途径和三酰甘油（TAG）合成相关的关键酶从早期生长阶段就被上调，盐分胁迫似乎使收获的生物质的碳水化合物含量从45.6 dw％降低到14.7 dw％，总脂质含量从26.0 dw％降低到62.0 dw％几乎翻了三倍。这些结果表明，通过在高盐度胁迫下，碳的重新分配在藻类的生存能力中起着重要作用，这可以通过补救由放氧类囊体中产生的ROS所引起的高水平细胞应激来解决，该直接观察到光系统活动。