Genome-Wide Characterization of SPL Gene Family in Reveals the Functions of and in Promoting the Accumulation of Secondary Metabolites and Growth of Hairy Root.

SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors play critical roles in regulating diverse aspects of plant growth and development, including vegetative phase change, plant architecture, anthocyanin accumulation, lateral root growth, etc. In the present study, 15 genes were identified based on the genome data of , a well-known medicinal plant. Phylogenetic analysis clustered into eight groups (G1-G8) along with SPLs from , , and . in the same group share similar gene structure and conserved motif composition. -acting elements responding to light, stress and phytohormone widely exist in their promoter regions. Our qRT-PCR results indicated that 15 were differentially expressed in different tissues (root, stem, leaf, flower and calyx), different developmental periods (1, 2 and 3 months after germination) and various conditions (NaCl, MeJA and ABA treatment). Compared with the control, overexpression of or significantly promoted not only the growth of hairy roots, but also the accumulation of total saponins and lobetyolin. Our results established a foundation for further investigation of and provided novel insights into their biological functions. As far as we know, this is the first experimental research on gene function in .