Expression Analysis and Interaction Protein Screening of CoGI, the Key Factor in Photoperiod Regulation of Flowering in Camellia oleifera Abel

Abstract

Photoperiod is a pivotal regulatory factor in the flowering of Camellia oleifera Abel. (C. oleifera). GIGANTEA (GI) serves as a pivotal regulator, not only orchestrating the intricate circadian rhythm but also governing photoperiod-dependent flowering. In order to explore the function of GI in C. oleifera (CoGI), we obtained a CoGI gene-coding sequence and analyzed a CoGI protein sequence using bioinformatics. Furthermore, we conducted a spatiotemporal expression analysis of CoGI. And a yeast two-hybridization assay was used to screen the interacting proteins of CoGI. Evolutionary analysis revealed high conservation of the CoGI protein, which clustered with the GI protein from Camellia sinensis (CsGI) on a common evolutionary branch. The expression of CoGI was different in each part, and a tissue expression analysis revealed that the relative expression level of the CoGI gene is highest in the leaves of C. oleifera, while it is at its lowest in the seed coats. Transgenic Arabidopsis thaliana (Arabidopsis) overexpressing CoGI exhibited early flowering under long-day conditions. In addition, the yeast two-hybrid library screening revealed interactions between seven C. oleifera proteins and CoGI: CoACR9, CoLAO, CoDExH12-like, CoIT1K-like, CoUPF0481, CoIDM3, and CoAt4g27190-like. The findings demonstrated that CoGI is crucial to C. oleifera’s flowering.