Functional Analysis of the CsGPDH Gene in Seed Oil Accumulation of Tea Plant

Oil content is a key indicator determining the quality and economic value of oil crops. Tea plant (Camellia sinensis (L.) O. Kuntze), as an economically significant plant, holds potential application value in oil resource development through its fruit, tea seeds. The glycerol-3-phosphate dehydrogenase gene (GPDH) is a crucial regulatory gene in plant oil biosynthesis. Cloning CsGPDH and conducting an in-depth analysis of its expression characteristics and function aims to provide a theoretical basis for elucidating the molecular mechanism by which CsGPDH regulates oil synthesis in tea plants.

Using ‘Jincha No.18’ as plant material, the full-length sequence of CsGPDH was cloned. Bioinformatics tools were employed to analyze the structural characteristics and evolutionary relationships of its encoded amino acid sequence. Real-time quantitative PCR (qRT-PCR) was used to detect the expression pattern of CsGPDH in different tea plant tissues and during key stages of oil synthesis. Subcellular localization of the encoded protein was observed using laser scanning confocal microscopy. Agrobacterium-mediated genetic transformation was utilized to generate CsGPDH-overexpressing Arabidopsis thaliana plants. Phenotypic analysis was performed on transgenic and wild-type Arabidopsis plants, measuring indicators such as seed oil content and fatty acid composition.

CsGPDH was successfully cloned, with a coding sequence (CDS) length of 1128 bp. The protein encoded by CsGPDH possesses a typical glycerol-3-phosphate dehydrogenase domain and exhibits high sequence similarity with homologous proteins from other species. Subcellular localization revealed that the CsGPDH protein is localized to the plasma membrane and cytoplasm. qRT-PCR analysis showed that CsGPDH expression significantly increased during the middle and late stages of seed development, highly coinciding with the period of rapid oil accumulation. Functional validation in transgenic Arabidopsis demonstrated that overexpression of CsGPDH increased seed oil content by 20.6%-25.2% and significantly elevated the proportion of unsaturated fatty acids (C18:1, C18:2).

CsGPDH expression is regulated by the seed developmental process, showing high expression during the critical phase of oil synthesis. Overexpression of CsGPDH can significantly enhance seed oil content in plants and plays an important positive regulatory role in the plant oil biosynthesis metabolic pathway.