Molecular characterization and transcriptional regulation analysis of the Torreya grandis squalene synthase gene involved in sitosterol biosynthesis and drought response

• Published in: Frontiers in plant science 2023-06, Vol.14, p.1136643-1136643
• Main Authors: Zhang, Feicui, Kong, Congcong, Ma, Zhenmin, Chen, Wenchao, Li, Yue, Lou, Heqiang, Wu, Jiasheng
• Format: Article
• Language: English
• Subjects: drought; Plant Science; sitosterol biosynthesis; squalene synthase; Torreya grandis; transcriptional regulation
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2023.1136643

The kernel of cv. 'Merrillii' (Cephalotaxaceae) is a rare nut with a variety of bioactive compounds and a high economic value. β-sitosterol is not only the most abundant plant sterol but also has various biological effects, such as antimicrobial, anticancer, anti-inflammatory, lipid-lowering, antioxidant, and antidiabetic activities. In this study, a squalene synthase gene from , , was identified and functionally characterized. encodes a deduced protein of 410 amino acids. Prokaryotic expression of the TgSQS protein could catalyze farnesyl diphosphate to produce squalene. Transgenic plants overexpressing showed a significant increase in the content of both squalene and β-sitosterol; moreover, their drought tolerance was also stronger than that of the wild type. Transcriptome data from seedlings showed that the expression levels of sterol biosynthesis pathway-related genes, such as , , , , , , , and , increased significantly after drought treatment. We also demonstrated that TgWRKY3 directly bound to the promoter region and regulated its expression through a yeast one-hybrid experiment and a dual luciferase experiment. Together, these findings demonstrate that has a positive role in β-sitosterol biosynthesis and in protecting against drought stress, emphasizing its importance as a metabolic engineering tool for the simultaneous improvement of β-sitosterol biosynthesis and drought tolerance.