Identification and functional analysis of growth- regulating factors involved in abiotic stress response in Chrysanthemum L.

A total of 43 GRF genes were identified. Phylogenetic and evolutionary analyses revealed that these genes can be classified into four major clades, with their expansion primarily driven by whole-genome duplication and segmental duplication events. Expression profiling under various abiotic stress conditions - including NaCl, CdCl₂, drought, high temperature, and low temperature - showed that many GRFs were significantly upregulated. Notably, <i>CiGRF7</i> exhibited an expression increase of over 1000-fold under cold and CdCl2 stress, suggesting its key role in abiotic stress responses in <i>Chrysanthemum</i>. Subcellular localization confirmed the nuclear localization of the CiGRF7 protein. Additionally, transcriptional activation assays in yeast demonstrated that CiGRF7 possesses self-activating capabilities. Overall, this study provides a comprehensive overview of the GRF gene family in <i>Chrysanthemum</i>, shedding light on their evolutionary patterns and stress-responsive expression, and offers valuable genetic resources for future research on stress tolerance and growth regulation in this important ornamental and medicinal plant.