Developmental processes and responses to hormonal stimuli in tea plant (Camellia sinensis) leaves are controlled by GRF and GIF gene families.

Tea plant (Camellia sinensis (L.) O. Kuntze) is an important leaf-type woody crop used for producing of non-alcoholic beverages worldwide. The GROWTH-REGULATING FACTOR (GRF) transcription factors cooperated with GRF-INTERACTING FACTOR (GIF) transcriptional coactivators positively regulate leaf development. In the present study, six GRF and two GIF genes were identified and characterized in the leaf transcriptome of C. sinensis, respectively. The alignment results showed that the feature structures of the predicted homologous GRF and GIF proteins of C. sinensis hold a high identity with Arabidopsis and rice. The presence of C. sinensis miR396 target sites suggested that these miR396 members are the potential post-transcriptional regulators of CsGRF genes. The expression profiles of CsGRF and CsGIF1 genes were higher in tender leaves and consistently downregulated during tea plant leaf development. Those results suggested that these genes may be actively involved in the early stage leaf tissue formation in tea plant. The divergence of CsGRF and CsGIF genes in response to different hormonal stimuli revealed the possible multiple functions of these genes in hormonal regulation. This study provided the potential molecular basis of the CsGRF and CsGIF family genes for future functional research on leaf development and hormonal stimuli in C. sinensis.