Chromochloris zofingiensis, an astaxanthin-producing oleaginous green alga, is emerging as a model for studying carotenogenesis and lipogenesis. While the stimulated biosynthesis of secondary carotenoids and storage lipids by abiotic stresses has long been perceived in C. zofingiensis, the underlying mechanisms particularly under combinatorial stresses remain to be explored. In the present study, the synthesis of carotenoids and lipids was comparatively investigated in C. zofingiensis under high light (HL), salinity stress (SS) and the combinatorial HL and SS (HL + SS) conditions. While HL or SS alone enhanced astaxanthin and lipids moderately, HL + SS had synergistic effect and promoted these compounds considerably. HL + SS also gave rise to the highest productivities. Carotenoid profiling and transcriptional analysis supported the diversion of carotenoid flux from primary carotenoids to secondary carotenoids particularly astaxanthin and violaxanthin cycle that produces zeaxanthin likely contributed to astaxanthin synthesis. Lipid profiling and transcriptional analysis, on the other hand, suggested that both de novo fatty acid synthesis and membrane lipid turnover contributed fatty acyls for supporting triacylglycerol assembly via the acyl CoA-dependent and acyl CoA-independent routes. Astaxanthin and triacylglycerol that share common carbon precursors were induced to synthesize in a coordinated way regulated at the transcriptional level, yet the carbon flux was allocated predominantly to the latter. Taken together, our results demonstrated the beneficial effect of combinatorial stresses on both astaxanthin and triacylglycerol production, identified critical genes involved in carotenogenesis and lipogenesis, and provided new insights into algal astaxanthin biosynthesis.

产虾青素的含油绿藻类Chofmochloris zofingiensis正在作为研究类胡萝卜素生成和脂肪生成的模型而兴起。虽然长期以来人们一直在感知非生物胁迫对次生类胡萝卜素和贮藏脂质的刺激生物合成，但是其潜在的机制，特别是在组合胁迫下，仍有待探索。在本研究中，比较研究了Zofingiensis的类胡萝卜素和脂质的合成。在强光（HL），盐度应力（SS）和组合HL和SS（HL + SS）条件下。单独使用HL或SS可以适度地增强虾青素和脂质，而HL + SS则具有协同作用并显着促进了这些化合物。HL + SS也提高了生产率。类胡萝卜素分析和转录分析支持将类胡萝卜素通量从初级类胡萝卜素转移至次级类胡萝卜素，特别是虾青素和紫黄质循环，产生玉米黄质，可能促进虾青素的合成。另一方面，脂质谱和转录分析表明，从头脂肪酸合成和膜脂质周转均通过酰基辅酶A依赖性和酰基辅酶A依赖性途径贡献了脂肪酰，以支持三酰基甘油组装。共有碳前体的虾青素和三酰基甘油被诱导以协调的方式在转录水平上进行合成，但碳通量主要分配给后者。综上所述，我们的结果证明了组合应激对虾青素和甘油三酯生产的有益影响，确定了与胡萝卜素生成和脂肪生成有关的关键基因，并为藻类虾青素的生物合成提供了新的见识。