褐藻多酚是广泛存在于褐藻中的以间苯三酚为结构单元的多酚类物质，被证实具有抗氧化、抗炎症、抗肿瘤等功能活性，使其在医疗,饮食,化妆品等领域具有广阔的应用价值。同时，褐藻多酚也在褐藻中参与诸如细胞壁形成、紫外线防御以及孢子形成等重要生命过程。III型聚酮合酶在褐藻多酚合成中行使关键作用，为合成途径的关键酶和限速酶。

  近日，海藻种质库团队成员首次在海带目褐藻中，完成了海带III型聚酮合酶基因（sjPKS1）的克隆和序列分析，发现sjPKS1与现有已知的其他3个褐藻物种（水云属及马尾藻属）的III型聚酮合酶基因具有高度的序列相似性，表明了该类基因在褐藻中结构及功能的保守性。研究进一步分析了在不同光强条件下，海带sjPKS1的表达模式及褐藻多酚含量，克隆了sjPKS1的启动子序列，通过酵母单杂交技术完成了sjPKS1启动子区域光调控相关转录因子的筛选，阐明了sjPKS1在不同光照强度下的表达规律。

  该研究得到了国家自然科学基金、中科院战略生物资源能力建设项目等支持。相关结果发表在Journal of applied phycology 杂志上，李静博士为论文第一作者，逄少军研究员为论文通讯作者。

Abstract

Phlorotannins are among the most important defensive molecules in kelp. They have been majorly identified in brown algae so far. Type III polyketide synthase (PKS) is regarded as one of the enzymes catalyzing a major step in the biosynthetic pathway of phlorotannins. In this study, a type III PKS gene (sjPKS1) is characterized from the economic brown alga Saccharina japonica sporophyte. It contains 7 exons and 6 introns. The sjPKS1 open reading frame consists of 1245 nucleotides encoding a protein of 414 amino acids. The sjPKS1 are 87%, 83%, and 82% identical to that of Ectocarpus siliculosus, Sargassum binderi, and Sargassum fusiforme at the nucleotide level, respectively. While the amino acid sequences of sjPKS1 share more than 90% identity to that of the three brown algae species. The sjPKS1 expression at 200 µmol photons m−2 s−1 was significantly higher than at 20 and 50 µmol photons m−2 s−1 in sporophytic seedlings, so did the content of soluble phlorotannins inside the plants. Seven motifs in response to light are identified in the 5′ flanking region of sjPKS1 and two potential transcription factors are predicted by screening yeast one-hybrid library.

Li, J., Pang, S., Su, L. et al. Characterization of a type III polyketide synthase (sjPKS1) gene and its expression in response to light in the economic brown alga Saccharina japonica. J Appl Phycol (2022). https://doi.org/10.1007/s10811-022-02736-9