GhmiR172 regulates petal expansion and anthocyanin biosynthesis by targeting GhARF8 and GhAP2 in Gerbera hybrida

MicroRNA172 (miR172) regulates vegetative phase transition, floral organ formation and many other plant developmental processes. However, its role in regulating petal expansion and anthocyanin biosynthesis in Gerbera hybrida remains unclear. Here, we demonstrated that GhmiR172 promotes petal cell elongation while inhibits anthocyanin accumulation. To identify its potential regulatory targets, we screened the small RNA sequencing and gerbera transcriptome data using psRNATarget, and identified four putative target genes. Among these, GhARF8 and GhAP2 were confirmed as direct targets of GhmiR172 through relative experiments. Further functional verification showed that GhARF8 plays an inhibitory role in regulating petal length, which modulates petal expansion by binding to the GhPRGL promoter. And, GhAP2 promotes anthocyanin accumulation and regulates PAL, F3'H and GT4. Taken together, two regulatory modules led by GhmiR172 were established: the GhmiR172-GhARF8-GhPRGL module and GhmiR172-GhAP2 module, which regulate petal expansion and coloration of ray flower ligule by targeting distinct genes. This study clarifies the molecular mechanism of GhmiR172 targeting GhARF8 and GhAP2 for regulating gerbera petal growth and development.