Ulva prolifera is a green alga that plays an important role in green tides. Carotenoid biosynthesis is a basic terpenoid metabolism that is very important for maintaining normal life activities in algae. In this study, we first reported the complete sequences of all genes in the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway, which is the only carotenoid synthesis pathway in U. prolifera. Then, we compared these genes with those of other species. Additionally, by detecting the carotenoid contents and expression levels of key genes participating in carotenoid biosynthesis in U. prolifera under three different light (1 000 lx, 5 000 lx and 12 000 lx) and salinity (12, 24 and 40) regimes, we found that carotenoid synthesis could be influenced by light and salinity, such that low light and high salinity could promote the synthesis of carotenoids. The results showed that the expression levels of genes involved in the MEP and the downstream pathway could affect the biosynthesis of carotenoids at the molecular level. This study contributes to a better understanding of the roles of genes participating in carotenoid biosynthesis in U. prolifera and the environmental regulation of these genes.

Ulva prolifera是一种绿藻，在绿潮中起重要作用。类胡萝卜素的生物合成是基本的类萜代谢，对于维持藻类的正常生命活动非常重要。在这项研究中，我们首先报道了2-C-甲基-D-赤藓糖醇4-磷酸（MEP）途径中所有基因的完整序列，这是U. prolifera中唯一的类胡萝卜素合成途径。然后，我们将这些基因与其他物种的基因进行了比较。另外，通过检测参与U. prolifera的类胡萝卜素生物合成的类胡萝卜素含量和关键基因的表达水平在三种不同的光照（1000 lx，5000 lx和12000 lx）和盐度（12、24和40）下，我们发现类胡萝卜素的合成可能受光照和盐度的影响，因此低光照和高盐度可以促进类胡萝卜素的合成。结果表明，参与MEP和下游途径的基因的表达水平可能在分子水平上影响类胡萝卜素的生物合成。这项研究有助于更好地了解参与增生U.prolifera中的类胡萝卜素生物合成的基因的作用以及这些基因的环境调控。