Heat shock transcription factor PtHSFA1b plays a critical role in the synthesis of fucoxanthin by modulating the expression of ZEP1 in Phaeodactylum tricornutum

Abstract

Fucoxanthin, a pigment of substantial economic importance, has an understudied transcriptional regulatory mechanism in its biosynthetic pathway. In this study, we identified the heat shock transcription factor PtHSFA1b through a yeast one-hybrid screen as a key regulator that binds to the ZEP1 promoter. Functional analysis revealed that overexpression of PtHSFA1b significantly increased fucoxanthin content, while gene editing of PtHSFA1b led to its reduction. Further investigation demonstrated that PtHSFA1b mediates fucoxanthin biosynthesis by binding to the ZEP1 promoter and directly activating its expression. Genetic studies confirmed that the regulation of fucoxanthin by PtHSFA1b is ZEP1 function-dependent. These findings provide new insights into the transcriptional regulation of fucoxanthin synthesis, offering a foundation for further exploration of its biosynthetic mechanisms.