Many abiotic stresses can promote astaxanthin and total fatty acid (TFA) accumulation in microalgae, but their signal molecules remain undetermined. The reactive oxygen species (ROS) derived from NADPH oxidase has been reported to act as signals and regulate many cellular responses in cell responses to biotic and abiotic stresses in higher plants. The present study explored the regulatory effects of NADPH oxidase derived ROS on astaxanthin and TFA accumulation in the green alga Chromochloris zofingiensis under nitrogen starvation. Diphenylene iodonium (DPI) inhibition of NADPH oxidase significantly decreased the cellular ROS level under nitrogen starvation. This was accompanied with the decreasing of astaxanthin and secondary carotenoids content, and the increasing of primary carotenoids content. Molecular studies showed that DPI depressed the expression of PSY, LCYb, and BKT, but elevated that of LCYe, which were coordinated with carotenoids content. Meanwhile, the TFA and neutral lipid contents, and the expression of their key biosynthesis genes, ACCase and PDAT, were also reduced in the DPI-treated cells. Additionally, the addition of ROS scavenger, N-acetylcysteine (NAC), decreased the astaxanthin and TFA contents. Taken together, our results revealed that NADPH oxidase-derived ROS was the key regulator in astaxanthin and fatty acid accumulation under nitrogen starvation.

许多非生物胁迫可以促进虾青素和总脂肪酸（TFA）在微藻中的积累，但它们的信号分子仍未确定。据报道，源自NADPH氧化酶的活性氧（ROS）在高等植物对生物和非生物胁迫的细胞反应中起信号作用并调节许多细胞反应。本研究探讨了NADPH氧化酶衍生的ROS对绿藻Zofingiensis中虾青素和TFA积累的调节作用。在氮饥饿的情况下。联苯碘鎓（DPI）对NADPH氧化酶的抑制作用显着降低了氮饥饿下细胞的ROS水平。这伴随着虾青素和次要类胡萝卜素含量的减少，以及主要类胡萝卜素含量的增加。分子研究表明，DPI抑制了PSY，LCYb和BKT的表达，但提高了LCYe的表达，这与类胡萝卜素的含量有关。同时，在DPI处理的细胞中，TFA和中性脂质含量及其关键生物合成基因ACCase和PDAT的表达也降低了。此外，添加了ROS清除剂N-乙酰半胱氨酸（NAC）可降低虾青素和TFA含量。两者合计，我们的研究结果表明，NADPH氧化酶衍生的ROS是氮饥饿下虾青素和脂肪酸积累的关键调节剂。